Sample records for colima volcanic complex

  1. Exceptional recurrence of flank destabilizations in the recent activity of the Colima volcanic complex, Mexico; Recurrence exceptionnelle de destabilisations de flanc dans l`activite recente du complexe volcanique du Colima, Mexique

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    Komorowski, J.C. [IPGP, (Mexico); Siebe, C. [Institut de Geofisica, UNAM (Mexico); Rodriguez, S. [Institut de Geologia, UNAM (Mexico); Cortes, A.; Navarro, C.; Gavilanes, J.C.


    This short paper reports on new {sup 14}C datings of debris flow units from the Nevado de Colima and Fuego de Colima volcanoes in Mexico. These new datings in connection with a detailed stratigraphic study in the deep canyons around the volcanoes has revealed an exceptional recurrence of flank destabilizations of the Fuego de Colima during the last 45000 years. The cumulated volume of debris in the whole Colima massif is estimated to 60-100 km{sup 3}. The correlation between Landsat satellite pictures and the distribution and age of the debris flows shows that both volcanoes are made of several post-destabilization remaining structures, and that both volcanoes were active and simultaneously collapsed 18500 years ago. The numerous fluvial-lacustrine sequences intercalated between the successive flows indicate that the debris flow were partially sedimented under water and could have led to catastrophic tsunamis towards the Pacific coast. Implications of this work are important because a population of more than 200000 inhabitants is living in a zone covered by several debris flows. (J.S.).

  2. Update of the volcanic risk map of Colima volcano, Mexico (United States)

    Suarez-Plascencia, C.; Nuñez Cornu, F. J.; Marquez-Azua, B.


    The Colima volcano, located in western Mexico (19° 30.696 N, 103° 37.026 W) began its current eruptive process in February 10, 1999. This event was the basis for the development of two volcanic hazard maps: one for ballistics (rock fall) lahars, and another one for ash fall. During the period of 2003 to 2008 this volcano has had an intense effusive-explosive activity, similar to the one that took place during the period of 1890 through 1900. Intense pre-Plinian eruption in January 20, 1913, generated little economic losses in the lower parts of the volcano thanks to the low population density and low socio-economic activities at the time The current volcanic activity has triggered ballistic projections, pyroclastic and ash flows, and lahars, all have exceeded the maps limits established in 1999. Vulnerable elements within these areas have gradually changed due to the expansion of the agricultural frontier on the east and southeast sides of the Colima volcano. On the slopes of the northwest side, new blue agave Tequilana weber and avocado orchard crops have emerged along with important production of greenhouse tomato, alfalfa and fruit (citrus) crops that will eventually be processed and dried for exportation to the United States and Europe. Also, in addition to the above, large expanses of corn and sugar cane have been planted on the slopes of the volcano since the nineteenth century. The increased agricultural activity has had a direct impact in the reduction of the available forest land area. Coinciding with this increased activity, the 0.8% growth population during the period of 2000 - 2005, - due to the construction of the Guadalajara-Colima highway-, also increased this impact. The growth in vulnerability changed the level of risk with respect to the one identified in the year 1999 (Suarez, 2000), thus motivating us to perform an update to the risk map at 1:25,000 using vector models of the INEGI, SPOT images of different dates, and fieldwork done in order

  3. Volcanic Ash fall Impact on Vegetation, Colima 2005 (United States)

    Garcia, M. G.; Martin, A.; Fonseca, R.; Nieto, A.; Radillo, R.; Armienta, M.


    An ash sampling network was established arround Colima Volcano in 2005. Ash fall was sampled on the North, Northeast, East, Southeast, South, Southwest and West of the volcano. Samples were analyzed for ash components, geochemistry and leachates. Ash fall ocurred on April (12), May (10, 23), June (2, 6, 9, 10, 12, 14), July (27), September (27), October (23) and November (24). Most of the ash is made of andesitic dome-lithics but shows diferences in crystal, juvenile material and lithic content. In May, some samples contained grey and dark pumice (scoria). Texture varies from phi >4 to phi 0. Leachate concentration were low: SO4 (7.33-54.19) Cl- (2.29-4.97) and F- (0.16-0.37). During 2005, Colima Volcano's ash fall rotted some of the guava and peach fruits and had a drying effect on spearment and epazote plants. Even these small ash amounts could have hindered sugar cane and agave growth.

  4. Land use and Hydrological Characteristics of Volcanic Urban Soils for Flood Susceptibility Modeling, Ciudad de Colima (Mexico) (United States)

    Perez Gonzalez, M. L.; Capra, L.; Borselli, L.; Ortiz, A.


    The fast population rate growth and the unplanned urban development has created an increase of urban floods in the City of Colima. Land use change has transformed the hydrological behavior of the watersheds that participates on the runoff-infiltration processes that governs the pluvial concentrations. After the urban areas enlargement, 13% from 2010 to 2015, rainfall has caused significant damages to the downtown community. Therefore it is important to define the main hydraulic properties of the soils surrounding the city. The soil of the region is derived from the debris avalanche deposits of the Volcano of Colima. The volcanic soil cover is only 10 to 15 cm depth. To test the soils of the region, sampling locations were chosen after making a land use map from a Landsat image. The map was done by selecting and dividing similar surface images patterns into three main classifications: Natural (N1), Agricultural (N5) and Urban (N4) surfaces. Thirty-Three soil samples were collected and grouped in nine out of ten land use subdivisions. The 10thsubdivision, represents the completed urbanized area. The land use model is made using spot 4 1A images from the year 2010 up to year 2015. This land use evolutionary analysis will be a base to evaluate the change of the runoff-infiltration rate, direction, and concentration areas for the future flood susceptibility model. To get the parameters above, several soil analysis were performed. The results were that all the soil samples tested were classified as sandy soils. The water content values were from 7% (N4) to 45% (N1) while bulk density values for the same sample were form 0.65 (N1) to 1.50 (N4) g/cm3. The particle density and the porosity values were from 1.65 g/cm3 /5.5% (N4) - 2.65 g/cm3/ 75.40% (N1). The organic matter content was around 0.1% for urban soils and up to 6% on natural and agricultural soils. Some other test like electric conductivity and pH were performed. The obtained parameters were used to get other

  5. The use of geographical information systems for disaster risk reduction strategies: a case study of Volcan de Colima, Mexico (United States)

    Landeg, O.

    Contemporary disaster risk management requires the analysis of vulnerability and hazard exposure, which is imperative at Volcan de Colima (VdC), Mexico, due to the predicted, large-magnitude eruption forecast to occur before 2025. The methods used to gauge social vulnerability included the development and application of proxies to census records, the undertaking of a building vulnerability survey and the spatial mapping of civil and emergency infrastructure. Hazard exposure was assessed using primary modelling of laharic events and the digitalisation of secondary data sources detailing the modelled extent of pyroclastic flows and tephra deposition associated with a large-magnitude (VEI 5) eruption at VdC. The undertaking and analysis of a risk perception survey of the population enabled an understanding of the cognitive behaviour of residents towards the volcanic risk. In comparison to the published hazard map, the GIS analysis highlighted an underestimation of lahar hazard on the western flank of VdC and the regional tephra hazard. Vulnerability analysis identified three communities where social deprivation is relatively high, and those with significant elderly and transient populations near the volcano. Furthermore, recognition of the possibility of an eruption in the near future was found to be low across the study region. These results also contributed to the analysis of emergency management procedures and the preparedness of the regional authorities. This multidisciplinary research programme demonstrates the success of applying a GIS platform to varied integrative spatial and temporal analysis. Furthermore, ascertaining the impact of future activity at VdC upon its surrounding populations permits the evaluation of emergency preparedness and disaster risk reduction strategies.

  6. Evaluating links between deformation, topography and surface temperature at volcanic domes: Results from a multi-sensor study at Volcán de Colima, Mexico (United States)

    Salzer, Jacqueline T.; Milillo, Pietro; Varley, Nick; Perissin, Daniele; Pantaleo, Michele; Walter, Thomas R.


    Dome building activity is common at many volcanoes and due to the gravitational instability, a dome represents one of the most hazardous volcanic phenomena. Shallow volcanic processes as well as rheological and structural changes of the dome affecting the fluid transport have been linked to transitions in eruptive activity. Also, hydrothermal alteration may affect the structural integrity of the dome, increasing the potential for collapse. However, mapping the deformation and details of fluid escape at the summit of steep sloped volcanoes and integrating these with other types of data is challenging due to difficult access and poor coverage. Here we present for the first time the near-vertical and near-horizontal surface deformation field of a quiescent summit dome and the relationships with degassing and topographic patterns. Our results are derived from high resolution satellite radar interferometry (InSAR) time series based on a year of TerraSAR-X SpotLight acquisitions and Structure from Motion (SfM) processing of overflight infrared data at Volcán de Colima, Mexico. The identified deformation is dominated by localized heterogeneous subsidence of the summit dome exceeding rates of 15 cm/yr, and strongly decreasing over the year 2012, up to the renewal of explosive and extrusive activity in early 2013. We tentatively attribute the deformation to the degassing, cooling and contraction of the dome and shallow conduit material. We also find that the results strongly differ depending on the chosen InSAR time series method, which potentially overprints the true physical complexities of small scale, shallow deformation processes. The combined interpretation of the deformation and infrared data reveals a complex spatial relationship between the degassing pathways and the deformation. While we observe no deformation across the crater rim fumaroles, discontinuities in the deformation field are more commonly observed around the dome rim fumaroles and occasionally on the

  7. Anatomy of the Colima volcano magmatic system, Mexico (United States)

    Spica, Zack; Perton, Mathieu; Legrand, Denis


    Colima volcano is one of the most active volcanoes in continental north America. It is located within the Colima graben on the western part of the Colima rift zone. Although extensively studied, the internal structure and deep magmatic system remains unknown. This research gives new clues to understand how and where magmas are produced and stored at depth. Using ambient seismic noise, we jointly invert for Rayleigh and Love wave dispersion curves for both phase and group velocity, which is applied for the first time in a volcanic environment. We invert for both the shear wave velocity and radial anisotropy. The 3D high resolution shear wave velocity model shows a deep, large and well-delineated elliptic-shape magmatic reservoir below the Colima volcano complex at a depth of about 15 km. On the other hand, the radial anisotropy model shows a significant negative feature (i.e., VSV >VSH) revealed from ≥35 km depth until the top of the magma reservoir at about 12 km depth. The latter suggests the presence of numerous vertical fractures where fluids, rooting from a well-known mantle window, can easily migrate upward and then accumulate in the magma reservoir. Furthermore, the convergence of both a low velocity zone and a negative anisotropy suggests that the magma is mainly stored in conduits or inter-fingered dykes as opposed to horizontally stratified magma reservoir.

  8. Local development and globalization: the case of the formation of the agroindustrial complex of lemon in Colima, México

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    Saúl Martínez González


    Full Text Available The multinational company has been the main vehicle of internationalization of capital and trade integration between countries. The global expansion phase of the transnational corporation is associated with the hegemony of capitalism in the United States, whose influence has been decisive in the territories where it operates. This essay is a case of the influence of transnational company Coca Cola in the formation of the region of Tecoman, Colima, as providing an input to the company during the period dominated by Fordism. This region is formed from exogenous impulses of the needs of lemon essential oil by transnational companies which in turn have determined the stages of growth and expansion in the region that occur in phases of boom and bust. Dependence on oil exports Mexican lime by an American multinational company is determined, in turn, by the behavior of the economic cycle in the United States. This study highlights the stage of formation of the agroindustrial complex and does not attempt to analyze the current situation

  9. The 17 July 1999 block-and-ash flow (BAF) at Colima Volcano: New insights on volcanic granular flows from textural analysis (United States)

    Sarocchi, D.; Sulpizio, R.; Macías, J. L.; Saucedo, R.


    On July 17 1999, a strong explosion occurred at Colima Volcano (Mexico) that produced a 10 km high eruptive column. The partial column collapse originated a block-and-ash flow (BAF) that flowed to the south, along the San Antonio and Montegrande ravines, travelling 3.3 km from the volcano summit. The flow filled the ravines with a volume estimated at 7.9 × 10 5 m 3. The erosion of these deposits occurred between 1999 and 2002 (time of sampling), providing excellent longitudinal outcrops that allowed their detailed textural study. The study was carried out by means of quantitative textural analysis: (1) Rosiwal intersections, for carrying out vertical granulometric profiles; (2) total grain-size analysis, from - 11 to + 9 ϕ; and (3) Fourier and fractal analysis of the particle morphology. Grain size and morphometric parameters obtained with these methods were used to identify vertical and longitudinal variation patterns in the BAF deposit. The grain size variations allowed to infer the main particle segregation mechanisms that acted during transport and deposition of the studied BAFs. The two methods used for studying the particle shape morphologies yielded results with different accuracy and reliability. In particular, fractal analyses have been found to be the most effective in describing the particle support mechanisms that acted during transport and deposition of the studied BAFs. The results highlight the importance of the information obtained by means of these techniques, and provide new insights in transportation and deposition mechanisms of BAFs.

  10. Surface complexation modeling of americium sorption onto volcanic tuff. (United States)

    Ding, M; Kelkar, S; Meijer, A


    Results of a surface complexation model (SCM) for americium sorption on volcanic rocks (devitrified and zeolitic tuff) are presented. The model was developed using PHREEQC and based on laboratory data for americium sorption on quartz. Available data for sorption of americium on quartz as a function of pH in dilute groundwater can be modeled with two surface reactions involving an americium sulfate and an americium carbonate complex. It was assumed in applying the model to volcanic rocks from Yucca Mountain, that the surface properties of volcanic rocks can be represented by a quartz surface. Using groundwaters compositionally representative of Yucca Mountain, americium sorption distribution coefficient (Kd, L/Kg) values were calculated as function of pH. These Kd values are close to the experimentally determined Kd values for americium sorption on volcanic rocks, decreasing with increasing pH in the pH range from 7 to 9. The surface complexation constants, derived in this study, allow prediction of sorption of americium in a natural complex system, taking into account the inherent uncertainty associated with geochemical conditions that occur along transport pathways. Published by Elsevier Ltd.

  11. Fibrous minerals from Somma-Vesuvius volcanic complex (United States)

    Rossi, Manuela; Nestola, Fabrizio; Ghiara, Maria R.; Capitelli, Francesco


    A survey on fibrous minerals coming from the densely populated area of Campania around the Somma-Vesuvius volcanic complex (Italy) was performed by means of a multi-methodological approach, based on morphological analyses, EMPA/WDS and SEM/EDS applications, and unit-cell determination through X-ray diffraction data. Such mineralogical investigation aims to provide suitable tools to the identification of fibrous natural phases, to improve the knowledge of both geochemical, petrogenetic and regional mineralogy of Somma-Vesuvius area, and to emphasize the presence of minerals with fibrous habit in all volcanic environments. The survey also fits well in the calls of health and environment of Horizon 2020 program of the European Commission (Climate Action, Environment, Resource Efficiency and Raw Materials).

  12. Carbonatite ring-complexes explained by caldera-style volcanism. (United States)

    Andersson, Magnus; Malehmir, Alireza; Troll, Valentin R; Dehghannejad, Mahdieh; Juhlin, Christopher; Ask, Maria


    Carbonatites are rare, carbonate-rich magmatic rocks that make up a minute portion of the crust only, yet they are of great relevance for our understanding of crustal and mantle processes. Although they occur in all continents and from Archaean to present, the deeper plumbing system of carbonatite ring-complexes is usually poorly constrained. Here, we show that carbonatite ring-complexes can be explained by caldera-style volcanism. Our geophysical investigation of the Alnö carbonatite ring-complex in central Sweden identifies a solidified saucer-shaped magma chamber at ~3 km depth that links to surface exposures through a ring fault system. Caldera subsidence during final stages of activity caused carbonatite eruptions north of the main complex, providing the crucial element to connect plutonic and eruptive features of carbonatite magmatism. The way carbonatite magmas are stored, transported and erupt at the surface is thus comparable to known emplacement styles from silicic calderas.

  13. Analysis of Vulnerability Around The Colima Volcano, MEXICO (United States)

    Carlos, S. P.


    The Colima volcano located in the western of the Trasmexican Volcanic Belt, in the central portion of the Colima Rift Zone, between the Mexican States of Jalisco and Colima. The volcano since January of 1998 presents a new activity, which has been characterized by two stages: the first one was an effusive phase that begin on 20 November 1998 and finish by the middle of January 1999. On February 10of 1999 a great explosion in the summit marked the beginning of an explosive phase, these facts implies that the eruptive process changes from an effusive model to an explosive one. Suárez-Plascencia et al, 2000, present hazard maps to ballistic projectiles, ashfalls and lahars for this scenario. This work presents the evaluation of the vulnerability in the areas identified as hazardous in the maps for ballistic, ashfalls and lahars, based on the economic elements located in the middle and lower sections of the volcano building, like agriculture, forestry, agroindustries and communication lines (highways, power, telephonic, railroad, etc). The method is based in Geographic Information Systems, using digital cartography scale 1:50,000, digital orthophotos from the Instituto Nacional de Estadística, Geografía e Informática, SPOT and Landsat satellite images from 1997 and 2000 in the bands 1, 2 and 3. The land use maps obtained for 1997 and 2000, were compared with the land use map reported by Suárez in 1992, from these maps an increase of the 5 porcent of the sugar cane area and corn cultivations were observed compared of those of 1990 (1225.7 km2) and a decrease of the forest surface, moving the agricultural limits uphill, and showing also some agave cultivation in the northwest and north hillslopes of the Nevado de Colima. This increment of the agricultural surface results in bigger economic activity in the area, which makes that the vulnerability also be increased to different volcanic products emitted during this phase of activity. The degradation of the soil by the

  14. Morphological Analysis of Apo Volcanic Complex in Southern Mindanao, Philippines: implications on volcano-tectonic evolution of different volcanic units (United States)

    Herrero, T. M. L.; van Wyk de Vries, B.; Lagmay, A. M. A.; Eco, R. C.


    The Apo Volcanic Complex (AVC) is one of the largest volcanic centers in the Philippines, located in the southern island of Mindanao. It is composed of four edifices and several smaller cones. The youngest volcanic unit, the Apo Dome, is the highest elevation in the Philippines. This unit is classified as potentially active, whereas other units, Talomo, Sibulan and Kitubod, are inactive. The study gives insight to the construction and deformation history of the volcanic units and imparts foresight to subsequent events that can affect populated areas. A morphological analysis integrating high-resolution digital terrain models and public domain satellite data and images was done to recognize and discriminate volcanic units and characterize volcano-tectonic features and processes. Morphological domains were defined based on surface textures, slope variation, degrees and controls of erosion, and lineament density and direction. This establishes the relative ages and extent of volcanic units as well as the volcano-tectonic evolution of the complex. Six edifice building events were recognized, two of which form the elevated base of Apo dome. The geodynamic setting of the region is imprinted in the volcanic units as five morphostructural lineaments. They reveal the changes in maximum regional stress through time such as the N-S extension found across the whole volcanic complex displaying the current stress regime. This has implications on the locality and propagation of geothermal activity, magma ascent, and edifice collapses. One main result of the compounded effects of inherited structures and current stress regime is the Sandawa Collapse Zone. This is a large valley formed by several collapses where NE-SW fractures propagate and the increasing lateral spreading by debuttressing continue to eat away the highest peak. The AVC is surrounded by the major metropolitan area of Davao City to the east and the cities of Kidapawan and Digos to the west and south, respectively

  15. Glacial evolution of the Ampato Volcanic Complex (Peru) (United States)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.; Vázquez, L.


    Ice masses on the Western range of the Central Andes are a main source of water resources and act as a geoindicator of variations in the climate of the tropics (Mark, 2008). The study of their evolution is of particular interest since they are situated in the transition zone between the tropical and mid-latitude circulation areas of the atmosphere (Zech et al., 2007). The function of this transition area is currently under debate, and understanding it is essential for the development of global climate models (Kull et al, 2008; Mark, 2008). However our understanding of the evolution of glaciers and their paleoclimatic factors for this sector of the Central Andes is still at a very basic level. This paper presents initial results of a study on the glacial evolution of the Ampato volcanic complex (15°24´- 15° 51´ S, 71° 51´ - 73° W; 6288 m a.s.l.) located in the Western Range of the Central Andes in Southern Peru, 70 km NW of the city of Arequipa. The main objectives are to identify the number of glacial phases the complex has undergone using geomorphological criteria to define a time frame for each phase, based on cosmogenic 36Cl dating of a sequence of moraine deposits; and to estimate the glacier Equilibrium Line Altitude (ELA) of each phase. The Ampato volcanic complex is formed by 3 great andesitic stratovolcanoes, the Nevados HualcaHualca-Sabancaya-Ampato, which started forming between the late Miocene and early Quaternary (Bulmer et al., 1999), aligned N-S and with summits covered with glaciers. The Sabancaya volcano is fully active, with its latest eruption occurring in 2001. Glacial landforms were identified and mapped using photointerpretation of vertical aerial photographs from 1955 (1:35,000 scale, National Geographic Institute of Peru), oblique photographs from 1943 (Aerophotographical Service of Peru), and a geo-referenced high-resolution Mrsid satellite image from 2000 (NASA). This cartography was corrected and improved through fieldwork. It was

  16. Calderas and mineralization: volcanic geology and mineralization in the Chianti caldera complex, Trans-Pecos Texas

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    Duex, T.W.; Henry, C.D.


    This report describes preliminary results of an ongoing study of the volcanic stratigraphy, caldera activity, and known and potential mineralization of the Chinati Mountains area of Trans-Pecos Texas. Many ore deposits are spatially associated with calderas and other volcanic centers. A genetic relationship between calderas and base and precious metal mineralization has been proposed by some and denied by others. Steven and others have demonstrated that calderas provide an important setting for mineralization in the San Juan volcanic field of Colorado. Mineralization is not found in all calderas but is apparently restricted to calderas that had complex, postsubsidence igneous activity. A comparison of volcanic setting, volcanic history, caldera evolution, and evidence of mineralization in Trans-Pecos to those of the San Juan volcanic field, a major mineral producer, indicates that Trans-Pecos Texas also could be an important mineralized region. The Chianti caldera complex in Trans-Pecos Texas contains at least two calderas that have had considerable postsubsidence activity and that display large areas of hydrothermal alteration and mineralization. Abundant prospects in Trans-Pecos and numerous producing mines immediately south of the Trans-Pecos volcanic field in Mexico are additional evidence that ore-grade deposits could occur in Texas.

  17. Unravelling the magmatic system beneath a monogenetic volcanic complex (Jagged Rocks Complex, Hopi Buttes, AZ, USA) (United States)

    Re, G.; Palin, J. M.; White, J. D. L.; Parolari, M.


    The Jagged Rocks complex is the eroded remnant of the plumbing systems of closely spaced monogenetic alkaline volcanic centres in the southern Hopi Buttes Volcanic Field (AZ, USA). It contains different clinopyroxene populations with distinctive textures and geochemical patterns. In the Northwestern part of the complex, which exposes the best developed system of conduits, most of the clinopyroxenes consist of large- to medium-sized resorbed cores overgrown by euhedral rims (type 1), small moderately resorbed greenish cores with the same overgrown rims (type 2), and phlogopite as an accessory phase. By contrast, in the Southern part of the complex the majority of clinopyroxenes are euhedral with oscillatory zonation (type 3) and are accompanied by minor euhedral olivine. The differences between these mineral assemblages indicate a composite history of crystallization and magmatic evolution for the two parts of the complex, governed by different mechanisms and ascent patterns from a single source at 50 km depth (16 kbar). The Northwest system preserves a high-pressure assemblage that cooled rapidly from near-liquidus conditions, suggesting direct ascent from the source to the surface at high-to-moderate transport rates (average 1.25 m/s). By contrast, the Southern system represents magma that advanced upward at much lower overall ascent rates, stalling at times to form small-volume mid-crustal storage zones (e.g., sills or a network of sheeted intrusions); this allowed the re-equilibration of the magma at lower pressure ( 30 km; 8 kbar), and led to nucleation and growth of euhedral clinopyroxene and olivine phenocrysts.

  18. Cryogenic Origin for Mars Analog Carbonates in the Bockfjord Volcanic Complex Svalbard (Norway) (United States)

    Amundsen, H. E. F.; Benning, L.; Blake, D. F.; Fogel, M.; Ming, D.; Skidmore, M.; Steele, A.


    The Sverrefjell and Sigurdfjell eruptive centers in the Bockfjord Volcanic Complex (BVC) on Svalbard (Norway) formed by subglacial eruptions ca. 1 Ma ago. These eruptive centers carry ubiquitous magnesian carbonate deposits including dolomitemagnesite globules similar to those in the Martian meteorite ALH84001. Carbonates in mantle xenoliths are dominated by ALH84001 type carbonate globules that formed during quenching of CO2-rich mantle fluids. Lava hosted carbonates include ALH84001 type carbonate globules occurring throughout lava vesicles and microfractures and massive carbonate deposits associated with vertical volcanic vents. Massive carbonates include < or equal 5 cm thick magnesite deposits protruding downwards into clear blue ice within volcanic vents and carbonate cemented lava breccias associated with volcanic vents. Carbonate cements comprise layered deposits of calcite, dolomite, huntite, magnesite and aragonite associated with ALH84001 type carbonate globules lining lava vesicles. Combined Mossbauer, XRD and VNIR data show that breccia carbonate cements at Sverrefjell are analog to Comanche carbonates at Gusev crater.

  19. Investigation of Along-Arc Geochemical Variations in the Southern Volcanic Zone: Azufre-Planchon-Peteroa Volcanic Complex, Southern Chile (United States)

    Holbik, S. P.; Hickey-Vargas, R.; Tormey, D.


    The Andean Southern Volcanic Zone (SVZ) is a vast and complex continental arc that has been studied extensively to provide an understanding of arc-magma genesis, the origin and chemical evolution of the continental crust, and geochemical compositions of volcanic products. This study focuses on volcanic rocks from the Azufre-Planchon-Peteroa (APP 35°15'S) volcanic complex, within the Transitional SVZ (34.3-37.0 °S), where crustal thickness increases from approximately 30 km in the south (Central SVZ), to 55 km in the north (Northern SVZ). Planchon is the northernmost volcano in the SVZ to erupt basaltic products, while Peteroa is the currently active cone, erupting tephra of andesitic composition, most recently in September of 2011. New data for the APP are consistent with the hypothesis of Tormey et al. (1995) that the APP experienced variable depths of crystal fractionation, and that crustal assimilation at Planchon is restricted to the lower crustal depths, as reflected by limited variability in 87Sr/86Sr isotopes. New δ18O data (26.5‰) from an outcropping dolomitic limestone country rock in the vicinity of the Azufre volcano also confirms the upper crustal source of anomalously high (7.1 and 7.3‰) oxygen isotopic values for Azufre dacites. A trend of high La/Yb (6.5-9.1) and Yb depletion with increasing La/Yb for Planchon basalts is consistent with the role of garnet as a residual or crystallizing phase at lower crustal depths, however, the La/Yb range is small when compared to published data from nearby TSVZ centers such as Nevado de Longavi (La/Yb = 5.5 to 16.7) and San Pedro Pellado (La/Yb =7.2 to 13.6). Geochemical modeling of the Planchon data shows that both hornblende and garnet must be involved in the magmatic evolution, even though erupted basalts are free of major hydrous phases, in order to account for the more limited range of La/Yb. Interestingly, baseline values of La/Yb for basalt and basaltic andesites from throughout the TSVZ, including

  20. Contrasting origin of two clay-rich debris flows at Cayambe Volcanic Complex, Ecuador (United States)

    Detienne, M.; Delmelle, P.; Guevara, A.; Samaniego, P.; Opfergelt, S.; Mothes, P. A.


    We investigate the sedimentological and mineralogical properties of a debris flow deposit west of Cayambe Volcanic Complex, an ice-clad edifice in Ecuador. The deposit exhibits a matrix facies containing up to 16 wt% of clays. However, the stratigraphic relationship of the deposit with respect to the Canguahua Formation, a widespread indurated volcaniclastic material in the Ecuadorian inter-Andean Valley, and the deposit alteration mineralogy differ depending on location. Thus, two different deposits are identified. The Río Granobles debris flow deposit ( 1 km3) is characterised by the alteration mineral assemblage smectite + jarosite, and sulphur isotopic analyses point to a supergene hydrothermal alteration environment. This deposit probably derives from a debris avalanche initiated before 14-21 ka by collapse of a hydrothermally altered rock mass from the volcano summit. In contrast, the alteration mineralogy of the second debris flow deposit, which may itself comprise more than one unit, is dominated by halloysite + smectite and relates to a shallower and more recent (3200 m) volcanic soils. Our study reinforces the significance of hydrothermal alteration in weakening volcano flanks and in favouring rapid transformation of a volcanic debris avalanche into a clay-rich debris flow. It also demonstrates that mineralogical analysis provides crucial information for resolving the origin of a debris flow deposit in volcanic terrains. Finally, we posit that slope instability, promoted by ongoing subglacial hydrothermal alteration, remains a significant hazard at Cayambe Volcanic Complex.

  1. New radiometric and petrological constraints on the evolution of the Pichincha volcanic complex (Ecuador)

    NARCIS (Netherlands)

    Robin, Claude; Samaniego, Pablo; Le Pennec, Jean-Luc; Fornari, Michel; Mothes, Patricia; van der Plicht, Johannes; Stix, J.


    Fieldwork, radiometric ((40)Ar/(39)Ar and (14)C) ages and whole-rock geochemistry allow a reconstruction of eruptive stages at the active, mainly dacitic, Pichincha Volcanic Complex (PVC), whose eruptions have repeatedly threatened Quito, most recently from 1999 to 2001. After the emplacement of

  2. Helminth parasites of the leopard frog Lithobates sp. Colima (Amphibia: Ranidae) from Colima, Mexico. (United States)

    Cabrera-Guzmán, Elisa; Garrido-Olvera, Lorena; León-Règagnon, Virginia


    The helminth fauna inhabiting Lithobates sp. Colima from Ticuizitán, Colima, Mexico, comprises 10 species: 4 digeneans ( Clinostomum sp., Glypthelmins quieta , Haematoloechus sp., and Langeronia macrocirra ), 5 nematodes ( Aplectana itzocanensis , Cosmocerca podicipinus , Foleyellides striatus , Oswaldocruzia subauricularis , and Rhabdias sp.), and 1 cestode (Cyclophyllidea). Glypthelmins quieta , L. macrocirra , and A. itzocanensis represent new host records. These observations, added to previous records from Acapulco, Guerrero, Mexico, indicate that the helminth fauna of Lithobates sp. from Colima comprises 25 taxa. Frogs are being parasitized by 3 infection routes: ingestion of intermediate host, skin penetration by larval forms, and transmission by vectors. Species of Aplectana , Cosmocerca , Foleyellides , and Oswaldocruzia occurred in high prevalence in Colima, similar to a previous study on the same frog species from Guerrero. In Colima, Glypthelmins , Haematoloechus , and Rhabdias also occurred in high prevalence. Haematoloechus species reached the highest mean intensity in both localities. The semiaquatic habits of this species of frog and the availability of particular feeding resources appear to determine the helminth composition and infection levels; however, co-speciation events also play an important role structuring these helminth communities.

  3. Eruptive history, current activity and risk estimation using geospatial information in the Colima volcano, Mexico (United States)

    Suarez-Plascencia, C.; Camarena-Garcia, M.; Nunez-Cornu, F. J.; Flores-Peña, S.


    Colima volcano, also known as Volcan de Fuego (19 30.696 N, 103 37.026 W), is located on the border between the states of Jalisco and Colima, and is the most active volcano in Mexico. In January 20, 1913, Colima had its biggest explosion of the twentieth century, with VEI 4, after the volcano had been dormant for almost 40 years. In 1961, a dome reached the northeastern edge of the crater and started a new lava flow, and from this date maintains constant activity. In February 10, 1999, a new explosion occurred at the summit dome. The activity during the 2001-2005 period was the most intense, but did not exceed VEI 3. The activity resulted in the formation of domes and their destruction after explosive events. The explosions originated eruptive columns, reaching altitudes between 4,500 and 9,000 masl, further pyroclastic flows reaching distances up to 3.5 km from the crater. During the explosive events, ash emissions were generated in all directions reaching distances up to 100 km, slightly affecting the nearby villages: Tuxpan, Tonila, Zapotlan, Cuauhtemoc, Comala, Zapotitlan de Vadillo and Toliman. During 2005 to July 2013, this volcano has had an intense effusive-explosive activity; similar to the one that took place during the period of 1890 through 1905. That was before the Plinian eruption of 1913, where pyroclastic flows reached a distance of 15 km from the crater. In this paper we estimate the risk of Colima volcano through the analysis of the vulnerability variables, hazard and exposure, for which we use: satellite imagery, recurring Fenix helicopter over flights of the state government of Jalisco, the use of the images of Google Earth and the population census 2010 INEGI. With this information and data identified changes in economic activities, development, and use of land. The expansion of the agricultural frontier in the lower sides of the volcano Colima, and with the advancement of traditional crops of sugar cane and corn, increased the growth of

  4. Formation of the Yandangshan volcanic-plutonic complex (SE China) by melt extraction and crystal accumulation (United States)

    Yan, Li-Li; He, Zhen-Yu; Jahn, Bor-ming; Zhao, Zhi-Dan


    The association of volcanic and shallow plutonic rocks in caldera may provide important clues to the geochemical evolution of silicic magma systems. The Yandangshan caldera is a typical example of late Mesozoic volcanic-plutonic complex in SE China. It is composed of a series of rhyolitic extrusives and subvolcanic intrusions of porphyritic quartz syenites. In this work, we conducted petrological and geochemical studies, as well as zircon dating, on the coexisting volcanic and plutonic rocks from the Yandangshan caldera. The results of SHRIMP and LA-ICP-MS zircon U-Pb dating revealed that the crystallization of the rhyolitic extrusives and subvolcanic intrusions was contemporaneous within analytical errors and in a short period (104-98 Ma). Geochemically, the volcanic rocks are characterized by high Rb/Sr and Rb/Ba ratios and depletion in Ba, Sr, P, Eu and Ti, while the shallow plutons show high K, Ba, Al, Fe and low Rb/Sr and Rb/Ba ratios with insignificant negative Eu anomalies. The volcanic and plutonic rocks have a similar range of zircon Hf isotopic compositions (εHf(t) = - 10.0 to + 1.5) and TDM2 model ages of 2.10-1.23 Ga. They also have comparable whole-rock Sr and Nd isotopic compositions ((87Sr/86Sr)i = 0.7084-0.7090; εNd(t) = - 7.8 to - 6.5) and zircon oxygen isotopic compositions (δ18O mainly = 4.5 to 6.0‰). We argue that the volcanic-plutonic complex of the Yandangshan caldera was formed by reworking of Paleoproterozoic lower crusts in the eastern Cathaysia block, and that the complex could be linked by fractional crystallization and crystal accumulation in a shallow magma chamber. The volcanic rocks represent the highly fractionated end-member, whereas the subvolcanic intrusions of porphyritic quartz syenites could be the residual crystal mushes. This case study could have a general implication for the genetic relationship between volcanic and shallow plutonic rocks in calderas.

  5. Geochemical constraints on the link between volcanism and plutonism at the Yunshan caldera complex, SE China (United States)

    Yan, Lili; He, Zhenyu; Beier, Christoph; Klemd, Reiner


    The Yunshan caldera complex is part of a larger scale, ca. 2000-km-long volcanic-plutonic complex belt in the coastal region of SE China. The volcanic rocks in the caldera complex are characterized by high-silica peraluminous and peralkaline rhyolites associated with an intracaldera porphyritic quartz monzonite pluton. In this study, we present zircon U-Pb, Hf and stable O isotopes along with geochemical data of both volcanic and plutonic rocks to evaluate the potential petrogenetic link between volcanism and plutonism in the Yunshan caldera complex. SHRIMP zircon U-Pb geochronology of both volcanic and plutonic rocks yields almost identical ages ranging from 95.6 to 93.1 Ma. The peraluminous and peralkaline rhyolites show negative anomalies of Sr, P, Ti and Ba and to a lesser extent negative Nb and Ta anomalies, along with positive Rb anomalies and `seagull-like' rare earth element (REE) patterns with negative Eu anomalies and low (La/Yb)N ratios. The intracaldera porphyritic quartz monzonite displays minor negative Rb, Nb, Ta, Sr, P and Ti anomalies and a positive Ba anomaly with REE patterns characterized by relatively high (La/Yb)N ratios and lack significant Eu anomalies. The peraluminous and peralkaline rhyolites and the porphyritic quartz monzonite exhibit consistent ɛ Nd( t) of - 3.7 to - 2.2 and display zircon ɛ Hf( t) values of - 2.1 to 3.7. They further have similar, mantle-like, zircon oxygen isotopic compositions (δ18OVSMOW mainly = 4.63 to 5.76‰). We interpret these observations to be in agreement with a crystal mush model in which the parental magma of the volcanic and plutonic rocks of the Yunshan caldera complex was likely produced by interaction of asthenosphere melts with subduction-influenced enriched mantle wedge. The peralkaline rhyolites are interpreted to represent the most differentiated magma that has subsequently experienced significant fluid-melt interactions, whereas the porphyritic quartz monzonite may be representative of the

  6. New insights from high resolution bathymetric surveys in the Panarea volcanic complex (Aeolian Islands, Italy) (United States)

    Anzidei, M.; Esposito, A.


    During November 2002 the portion of the Panarea volcanic complex (Aeolian Islands, Italy), which includes the islets of Dattilo, Panarelli, Lisca Bianca, Bottaro and Lisca Nera, experienced an intense submarine gaseous exhalation that produced a spectacular submarine fumarolic field. The submarine volcanic activity of the Aeolian area was already known during historical times by Tito Livio, Strabone and Plinio (SGA, 1996), that reported exhalation episodes and submarine eruptions. During the last decade geological, structural, geochemical and volcanological studies performed on the Panarea volcanic complex, evidenced a positive gravimetric anomaly, tectonic discontinuities and several centres of geothermal fluid emission (Barberi et al., 1974; Lanzafame and Rossi, 1984; Bellia et al., 1986; Gabianelli et al., 1990; Italiano and Nuccio, 1991; Calanchi et al., 1995,1999). With the aim to estimate the crustal deformation of the submarine area of the archipelago, connected with the exhalation activity, we produced a detailed Marine Digital Terrain Model (MDTM) of the seafloor by means of a high resolution bathymetric survey. We used the multi beam technique coupled with GPS positioning in RTK mode. We obtained a MDTM with an average pixel of 0.5 m. Our MDTM allowed to estimate the location, deep, shape and size of the exhalation centres and seafloor morphological-structural features, opening new questions for the evaluation of the volcanic hazard of Panarea area which date is still debated.

  7. Thermal properties of andesite from Popocatepetl and Volcán de Colima, México. (United States)

    Cardenas-Sanchez, Enrique; De la Cruz-Reina, Servando; Varley, Nick


    The thermal conductivity (K), specific heat (Cp) and the coefficient of heat transfer surface (H) are the basic parameters to describe the process of cooling a volcanic rock fragment released in an explosive event. The analysis of the cooling process by conduction, convection and radiation of heat in volcanic rock fragments, has been limited to basalts, and various minerals such as olivine, pyroxene, quartz, etc. (Miao & Chen, 2014; Branlund & Hofmeister, 2012; Romine et al, 2012;. Schön, 2011; Stroberg et al, 2010;. Schatz & Simmons, 1972). There are no detailed studies on the thermal properties of the andesites, abundant in continental stratovolcanoes, and particularly susceptible from lava domes with frequent destruction processes, such as Popocatepetl and Volcan de Colima. Previously, we developed an algorithm for calculation of the grain-size distribution, degree of fragmentation, the thermal energy released and its possible correlation with Volcanic Explosive Index (VEI) from the cooling curves of fragments from vulcanian and strombolian explosions. These curves were obtained from sequences of time over incandescent deposits recorded at selected pixel thermal images of vulcanian activity in the Popocatepetl and Volcan de Colima, Mexico. However, the model was limited by the lack of thermal parameters of the andesites, forcing a first approximation using basalts data. We present a simple model for the cooling process using andesites samples from Popocatépetl and Volcan de Colima. First, the samples were subjected to a rounding process to minimize surface effects. Then, heated to 800 ° C were extracted from the muffle and cooling rate is measured. The thermal conductivity and coefficient of surface heat are determined using a thermal camera and three thermocouples embedded at various depths within the sample. An inversion method was implemented to determine the thermal properties parameters , by comparing the observed data regarding cooling model for a solid

  8. Evidence for the Jurassic arc volcanism of the Lolotoi complex, Timor: Tectonic implications (United States)

    Park, Seung-Ik; Kwon, Sanghoon; Kim, Sung Won


    We report the first sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages with geochemical data from metavolcanic rocks in the Lolotoi complex, Timor. The zircon U-Pb ages of two andesitic metavolcanic rocks yield a permissible range of the Middle Jurassic extrusion from 177 Ma to 174 Ma. The geochemical data indicate that the origins of the basaltic and andesitic metavolcanic rocks are products of prolonged oceanic crust and arc magmatism, respectively. They are originated from partial melting of lherzolites, providing an insight into the tectonic evolution of the forearc basements of the Banda volcanic arc. Thus, parts of the Banda forearc basement are pieces of allochthonous oceanic basalts and Jurassic arc-related andesites accreted to the Sundaland during the closure of Mesotethys, and are incorporated later into the Great Indonesian Volcanic Arc system along the southeastern margin of the Sundaland.

  9. Colima and Manila: Two cities linked by history


    Paulina Machuca Chávez


    During more than two centuries, Colima and Manila had a close relationship, as a result of the transpacific voyages held by the Manila Galleon. In its voyage towards Acapulco, this ship stopped first in the port of Salagua (Manzanillo, Colima), in order to get food supply and to send the viceroy of the New Spain an official report about the status of the merchandise. In this context, many Asian people (known as "indios chinos" in the New Spain) landed in Colima and established in the h...

  10. Basaltic lava characterization using magnetic susceptibility identification and presence of opaque minerals in Ijen volcanic complex, Banyuwangi, East Java (United States)

    Pratama, Aditya; Hafidz, Abd.; Bijaksana, Satria; Abdurrachman, Mirzam


    Reliable volcanic map and deep understanding of magmatic processes are very important in exploration of natural resources and mitigation of volcanic hazards. The conservative method in volcanic mapping still depends on qualitative approach thus it often failed to characterize volcanic products properly. Rock magnetic methods are quantitative approaches that classify rocks based on their magnetic properties. In this study, magmatic processes in basaltic lavas from Ijen volcanic complex in Banyuwangi, East Java were studied using combined rock magnetic and petrogenesis approaches. Samples of basaltic lavas from 13 localities, taken from three eruption sources were measuredfor their mass-specific magnetic susceptibility. The samples were then also subjected to petrographic and X-ray Fluorescence Spectrometry (XRF) analyses for their minerals composition and petrogenesis. Preliminary results show that the distinction in magnetic characters might be due to the quantity of magnetic minerals contained in rocks.

  11. Morphostructure Control Towards the Development of Mahawu Volcanic Complex, North Sulawesi

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    S. Poedjoprajitno


    Full Text Available DOI: 10.17014/ijog.v7i1.134The studied area, situated in northeastern part of North Sulawesi Arm, is dominantly occupied by the Mahawu, Linau, Tompusu, and Kasurutan volcanic rocks. Using remote sensing data, such as landsat image, black and white panchromatic aerial photograph, and IFSAR image, morphology-origin unit and morphology lineament can be interpreted. Four morphology-origin units, those are Mahawu Volcano Complex, Intra-montane Plain structure, Linau Volcano Complex, and Lacustrine Plain are recognized. Furthermore, morphological lineament pattern was statistically processed to find out the general stress direction in the area to determine the probability of the structural morphology occurrence in the Mahawu Volcano Complex. The result shows that generally the development pattern of volcanic cones are irregular, except the Mahawu Volcano Complex showing a linear pattern. This lineament pattern is interpreted as a NW - SE fault pattern controlling the rise of magma. At least, two tectonic and two eruption periods occurred regularly at different time from the Quaternary age till the present.

  12. Large Early Permian eruptive complexes in northern Saxony, Germany: Volcanic facies analysis and geochemical characterization (United States)

    Hübner, Marcel; Breitkreuz, Christoph; Repstock, Alexander; Heuer, Franziska


    In the course of formation of extensional basins during the Early Permian a widespread volcanic activity led to the deposition of volcanic and volcanosedimentary units in Saxony (Walter 2006, Hoffmann et al. 2013). Situated east of Leipzig, the North Saxonian Volcanic Complex (NSVC) hosts two large caldera complexes, the Rochlitz and Wurzen Volcanic Systems, with diameters of 90 and 52 km, respectively. Volume estimates (> 1000 km3) qualify these as supereruptions according to Mason et al. (2004). In addition to the large caldera systems, the NSVC hosts several small pyroclastic flow deposits ranging from crystal-poor (e.g. Cannewitz and vitrophyric Ebersbach ignimbrites) to crystal-rich units (Wermsdorf and Dornreichenbach ignimbrites). Additionally rhyolitic lava and subvolcanic units are present. The Chemnitz basin (Schneider et al. 2012), located to the south of the NSVC, harbours caldera-outflow facies deposits of the Rochlitz eruption (Fischer 1991), i.e. the partially vitrophyric Planitz ignimbrite. The Rochlitz and Wurzen caldera-fill ignimbrites exhibit relatively high crystal contents with maxima up to 52 and 58 vol.-%, for corresponding 66 and 68 wt.-% SiO2. This is comparable with the 'monotonous intermediates' (Hildreth 1981) in the Cenozoic western USA investigated by Huber et al. (2012). In contrast, the Planitz ignimbrite in the Chemnitz basin reveals predominantly crystal-poor pyroclastics ( 70 analyses), and mineral geochemistry to reconstruct the eruption history and magma genesis of this large Late Paleozoic magmatic complex in Central Europe. Volcanic textures and geochemical trends indicate magma mingling and mixing to have been important during the formation of the Wurzen caldera system. Geothermometric and -barometric calculations based on composition of pyroxene and feldspar suggest deeply seated crustal magma chambers for the NSVC and the Planitz ignimbrite. Fischer, F. (1991): Das Rotliegende des ostthüringisch-westsächsischen Raumes

  13. Identifying Successive Eruption of Guntur Volcanic Complex Using Magnetic Susceptibility and Polarimetric Synthetic Aperture Radar (PolSAR) Data (United States)

    Saepuloh, Asep; Bakker, Erwin


    Identifying distribution and stratigraphic of volcanic products are important not only for mitigating volcanic hazards, but also to know the characteristics of the successive eruptions. Guntur volcanic complex located in Garut, West Java, Indonesia was selected as study area because of the last eruption took place in 1847 and the volcanic activity has been dormant since then, however its seismicity is still active. During the period of July to October 2009, the hypocentre distribution of volcano tectonic earthquakes is mostly located at western flank of the volcano, beneath Guntur - Gandapura craters at the depth of less than 5 km. This study is aimed to identify distribution and succession of volcanic products based on their magnetic properties and backscattering signal of Polarimetric Synthetic Aperture Radar (PolSAR) data. The polarimetric decomposition method was used to identify the distribution of the volcanic products based on their scattering characteristics. Then, the field measurement using SM-30 magnetic susceptibility meter was performed to confirm the units of volcanic products and interpret their successions. According to the polarimetric decomposition method, we could identify fifteen successive eruptions formed Guntur Volcano Complex and termed as Khuluk and Gumuk in Indonesian standard. The successions were produced Gumuk Windu, Gumuk Malang, Gumuk Pulus, Gumuk Putrri, Khuluk Meungpeuk, Gumuk Cakra, Gumuk Gandapura, Gumuk Putri, Gumuk Gajah, Gumuk Batususun, Khuluk Pasirlaku, Gumuk Agung, Gumuk Picung, Gumuk Pasirmalang, Gumuk Masigit, Khuluk Kabuyutan and Khuluk Guntur. The magnetic susceptibility confirmed that the variations of magnetic susceptibility of rocks at each gumuk agreed with their stratigraphy.

  14. Petrologic evolution of divergent peralkaline magmas from the Silent Canyon caldera complex, southwestern Nevada volcanic field (United States)

    Sawyer, D.A.; Sargent, K.A.


    The Silent Canyon volcanic center consists of a buried Miocene peralkaline caldera complex and outlying peralkaline lava domes. Two widespread ash flow sheets, the Tub Spring and overlying Grouse Canyon members of the Miocene Belted Range Tuff, were erupted from the caldera complex and have volumes of 60-100 km3 and 200 km3, respectively. Eruption of the ash flows was preceded by widespread extrusion of precaldera comendite domes and was followed by extrusion of postcollapse peralkaline lavas and tuffs within and outside the caldera complex. Lava flows and tuffs were also deposited between the two major ash flow sheets. Rocks of the Silent Canyon center vary significantly in silica content and peralkalinity. Weakly peralkaline silicic comendites (PI 1.0-1.1) are the most abundant precaldera lavas. Postcollapse lavas range from trachyte to silicic comendite; some have anomalous light rare earth element (LREE) enrichments. Silent Canyon rocks follow a common petrologic evolution from trachyte to low-silica comendite; above 73% SiO2, compositions of the moderately peralkaline comendites diverge from those of the weakly peralkaline silicic comendites. The development of divergent peralkaline magmas, toward both pantelleritic and weakly peralkaline compositions, is unusual in a single volcanic center. -from Authors

  15. Morphometric and magmatic evolution at the Boset-Bericha Volcanic Complex in the Main Ethiopian Rift (United States)

    Siegburg, Melanie; Gernon, Thomas; Bull, Jonathan; Keir, Derek; Taylor, Rex; Nixon, Casey; Abebe, Bekele; Ayele, Atalay


    Tectono-magmatic interactions are an intrinsic feature of continental rifting and break up in the Main Ethiopian Rift (MER). The Boset-Bericha volcanic complex (BBVC) is one of the largest stratovolcanoes in the MER (with a total area of ˜870 km2), with volcanism largely occurring over the last ˜2 Myr. Despite the fact that 4 million people live within 100 km of the volcano, little is known about its eruptive history and how the volcanic system interacts with rift valley tectonics. Here, we present a detailed relative eruption chronology combined with morphometric analyses of different elements of the volcanic complex and petrological analyses to constrain morphometric and magmatic evolution at the BBVC. Additionally, tectonic activity has been characterised around the BBVC, all based on field observations and mapping using high-resolution digital elevation data. The BBVC consists of the Gudda Volcano and the younger Bericha Volcano, two silicic eruption centres located along the NNE-SSW trending rift axis. The fault population predominantly comprises distributed extensional faults parallel to the rift axis, as well as localised discrete faults with displacements of up to 50 m in the rift centre, and up to 200 m in the NE-SW trending border fault system. Multiple cones, craters and fissure systems are also oriented parallel to the rift axis, i.e. perpendicular to the minimum compressive stress. The eruption history of BBVC can be differentiated into 5 main eruption stages, subdivided into at least 12 eruptive phases with a total of 128 mappable lava flows. Crosscutting relationships of lava flows provide a relative chronology of the eruptive history of the BBVC, starting with pre-BBVC rift floor basalts, pre-caldera and caldera activity, three post-caldera phases at the Gudda Volcano and two phases forming the Bericha Volcano. At least four fissure eruption phases occurred along the rift axis temporally in between the main eruptive phases. Morphometric analyses

  16. Petrogenesis and tectonic implications of Early Jurassic volcanic rocks of the Raohe accretionary complex, NE China (United States)

    Wang, Zhi-Hui; Ge, Wen-Chun; Yang, Hao; Bi, Jun-Hui; Ji, Zheng; Dong, Yu; Xu, Wen-Liang


    The Raohe accretionary complex, located at the border between the Russian Far East and Northeastern China, is a significant part of the western Pacific Oceanic tectonic regime. Due to lack of precise age and geochemical constraints, the tectonic setting and petrogenesis of the magmatic rocks in this area remain undefined, resulting in debate about crustal growth mechanisms and subduction-related accretionary processes in Northeastern China. Here, we report whole-rock major and trace element and Sr-Nd isotope data, together with zircon U-Pb ages and in situ zircon Hf isotope data for calc-alkaline andesites, dacites, rhyolites, rhyolitic crystal tuffs, Nb-enriched andesites and basaltic andesites, and high-Mg andesites of the Raohe accretionary complex in NE China. Samples were collected from Late Triassic to Early Jurassic strata. However, geochronological results in this study indicated that the studied magmatism occurred in the Early Jurassic (187-174 Ma). The calc-alkaline volcanic rocks possess geochemical characteristics typical of arc magmas that form at active continental margins, such as moderate enrichments in large ion lithophile elements (LILEs) and light rare earth elements (LREEs), and depletions in high field strength elements (HFSEs). They have positive εHf(t) values of +3.4 to +10.6 and relatively high (87Sr/86Sr)i values of 0.7047-0.7102. While the Nb-enriched andesites and basaltic andesites have higher TiO2, Hf, Nb, and Zr contents and higher Nb/Ta (24.0-87.6), Nb/U (11.9-75.9), (Nb/Th)PM (0.67-2.70), and (Nb/La)PM (1.95-5.00) ratios than typical arc basalts. They have negative εNd(t) values (-5.5 to -6.0) and relatively variable (87Sr/86Sr)i values of 0.7047-0.7114, suggesting an origin via the partial melting of mantle wedge peridotite that had been metasomatized by slab-derived melt. The high-Mg volcanic rocks, characterized by high MgO and Mg#, TiO2, Al2O3, Cr, Ni, (La/Yb)N and (La/Sm)N, but low Ba/Th ratios, are geochemically similar to

  17. Time Series Analysis OF SAR Image Fractal Maps: The Somma-Vesuvio Volcanic Complex Case Study (United States)

    Pepe, Antonio; De Luca, Claudio; Di Martino, Gerardo; Iodice, Antonio; Manzo, Mariarosaria; Pepe, Susi; Riccio, Daniele; Ruello, Giuseppe; Sansosti, Eugenio; Zinno, Ivana


    The fractal dimension is a significant geophysical parameter describing natural surfaces representing the distribution of the roughness over different spatial scale; in case of volcanic structures, it has been related to the specific nature of materials and to the effects of active geodynamic processes. In this work, we present the analysis of the temporal behavior of the fractal dimension estimates generated from multi-pass SAR images relevant to the Somma-Vesuvio volcanic complex (South Italy). To this aim, we consider a Cosmo-SkyMed data-set of 42 stripmap images acquired from ascending orbits between October 2009 and December 2012. Starting from these images, we generate a three-dimensional stack composed by the corresponding fractal maps (ordered according to the acquisition dates), after a proper co-registration. The time-series of the pixel-by-pixel estimated fractal dimension values show that, over invariant natural areas, the fractal dimension values do not reveal significant changes; on the contrary, over urban areas, it correctly assumes values outside the natural surfaces fractality range and show strong fluctuations. As a final result of our analysis, we generate a fractal map that includes only the areas where the fractal dimension is considered reliable and stable (i.e., whose standard deviation computed over the time series is reasonably small). The so-obtained fractal dimension map is then used to identify areas that are homogeneous from a fractal viewpoint. Indeed, the analysis of this map reveals the presence of two distinctive landscape units corresponding to the Mt. Vesuvio and Gran Cono. The comparison with the (simplified) geological map clearly shows the presence in these two areas of volcanic products of different age. The presented fractal dimension map analysis demonstrates the ability to get a figure about the evolution degree of the monitored volcanic edifice and can be profitably extended in the future to other volcanic systems with

  18. Genesis and evolution of the Cerro Prieto Volcanic Complex, Baja California, Mexico (United States)

    García-Sánchez, L.; Macías, J. L.; Sosa-Ceballos, G.; Arce, J. L.; Garduño-Monroy, V. H.; Saucedo, R.; Avellán, D. R.; Rangel, E.; Layer, P. W.; López-Loera, H.; Rocha, V. S.; Cisneros, G.; Reyes-Agustín, G.; Jiménez, A.; Benowitz, J. A.


    The Cerro Prieto Volcanic Complex (CPVC), located in northwestern Mexico, is the only surface manifestation of the Cerro Prieto Geothermal Field, the third largest producer of geothermal energy in the world. This geothermal field and the Salton Sea in the USA sit in a pull-apart basin that belongs to the trans-tensional tectonic zone that includes the San Andreas Fault system and the Salton Trough basin to the NW and the East Pacific Rise to the SE. In spite of its strategic importance in the generation of geothermal energy, the origin of Cerro Prieto and its relationship with the geothermal reservoir were unknown. In this contribution, we discuss the origin, evolution, and mechanisms of formation of this small monogenetic volcano and the magmas that fed the system. The volcanic complex is located on top of the Cerro Prieto left lateral fault to the northwest of the Cerro Prieto Geothermal Field. The complex consists of a lava cone and a series of domes (˜0.15 km3) protruding from Tertiary sandstones and recent unconsolidated sediments of the alluvial plain of the Colorado River. The Cerro Prieto Volcanic Complex consists of seven stratigraphic units emplaced in a brief time span around 78-81 ka. Its activity began with the extrusion of a dacitic lava that came into contact with water-saturated sediments, causing brecciation of the lava. The activity continued with the emplacement of dacitic domes and a dyke that were destroyed by a phreatic explosion emplacing a lithic-rich breccia. This phreatic explosion formed a 300-m-wide and 40-m-deep circular crater. The activity then migrated ˜650 m to the SW where three dacitic lava domes were extruded and ended with the emplacement of a fissure-fed lava flow. Subsequent remobilization of the rocks in the complex has generated debris and hyperconcentrated flow deposits interbedded with fluviatile sediments in the surrounding terrain. All rocks of the CPVC are dacites with phenocrysts of plagioclase, orthopyroxene, and Fe

  19. Aeromagnetic evidence for a volcanic caldera(?) complex beneath the divide of the West Antarctic Ice Sheet (United States)

    Behrendt, John C.; Finn, C.A.; Blankenship, D.; Bell, R.E.


    A 1995-96 aeromagnetic survey over part of the Sinuous Ridge (SR) beneath the West Antarctic Ice Sheet (WAIS) divide shows a 70-km diameter circular pattern of 400-1200-nT anomalies suggesting one of the largest volcanic caldera(?) complexes on earth. Radar-ice-sounding (RIS) shows the northern part of this pattern overlies the SR, and extends south over the Bentley Subglacial Trench (BST). Modeled sources of all but one the caldera(?) anomalies are at the base of <1-2-km thick ice and their volcanic edifices have been glacially removed. The exception is a 700-m high, 15-km wide 'volcano' producing an 800-nT anomaly over the BST. 'Intrusion' of this 'volcano' beneath 3 km of ice probably resulted in pillow basalt rather than easily removed hyaloclastite erupted beneath thinner ice. The background area (-300 to -500-nT) surrounding the caldera(?) is possibly caused by a shallow Curie isotherm. We suggest uplift of the SR forced the advance of the WAIS.A 1995-96 aeromagnetic survey over part of the Sinuous Ridge (SR) beneath the West Antarctic Ice Sheet (WAIS) divide shows a 70-km diameter circular pattern of 400-1200-nT anomalies suggesting one of the largest volcanic caldera(?) complexes on earth. Radar-ice-sounding (RIS) shows the northern part of this pattern overlies the SR, and extends south over the Bentley Subglacial Trench (BST). Modeled sources of all but one the caldera(?) anomalies are at the base of < 1-2-km thick ice and their volcanic edifices have been glacially removed. The exception is a 700-m high, 15-km wide 'volcano' producing an 800-nT anomaly over the BST. 'Intrusion' of this 'volcano' beneath 3 km of ice probably resulted in pillow basalt rather than easily removed hyaloclastite erupted beneath thinner ice. The background area (-300 to -500-nT) surrounding the caldera(?) is possibly caused by a shallow Curie isotherm. We suggest uplift of the SR forced the advance of the WAIS.

  20. Defining Long-Duration Traverses of Lunar Volcanic Complexes with LROC NAC Images (United States)

    Stopar, J. D.; Lawrence, S. J.; Joliff, B. L.; Speyerer, E. J.; Robinson, M. S.


    A long-duration lunar rover [e.g., 1] would be ideal for investigating large volcanic complexes like the Marius Hills (MH) (approximately 300 x 330 km), where widely spaced sampling points are needed to explore the full geologic and compositional variability of the region. Over these distances, a rover would encounter varied surface morphologies (ranging from impact craters to rugged lava shields), each of which need to be considered during the rover design phase. Previous rovers including Apollo, Lunokhod, and most recently Yutu, successfully employed pre-mission orbital data for planning (at scales significantly coarser than that of the surface assets). LROC was specifically designed to provide mission-planning observations at scales useful for accurate rover traverse planning (crewed and robotic) [2]. After-the-fact analyses of the planning data can help improve predictions of future rover performance [e.g., 3-5].

  1. Trace Elements in the Dullstroom Volcanics Provide Insight for the Origin of the Bushveld Igneous Complex (United States)

    Krcmaric, J. A.; Feineman, M. D.; Bybee, G. M.; Ducea, M. N.


    The 2.06 Ga Bushveld Igneous Complex (BIC) in South Africa hosts one of the Earth's oldest and largest mafic layered intrusion. The Critical Zone of the BIC supplies 75% of the world's platinum, as well as significant amounts of palladium, chromium, and vanadium. The economic importance of the BIC has made it a target for numerous studies, but its origin and bulk composition still remain poorly understood today. The Rooiberg Group is a volcanic suite that represents the first pulse of Bushveld magmatism. In this study we present geochemical data from 27 samples of the Dullstroom Formation, which consists of alternating Low-Ti and High-Ti suites of predominantly basaltic andesite, as well as andesite and dacite. These volcanic rocks provide a unique opportunity to assess the bulk composition of mafic magmas associated with the BIC, which is usually obscured by the segregated layering characteristic of the intrusive complex. Whole-rock major element concentrations were determined by ICP-AES analysis and trace element concentrations were determined by Quadrupole ICP-MS analysis. Major element data is consistent with most samples being sub-alkaline tholeiites that range in composition from basalt to dacite. Trace element data reveals the low-Ti and high-Ti series of the Dullstroom are similar in compositions to the low-Ti and high-Ti suites of the Karoo flood basalts, respectively, and both experienced mixing, assimilation and fractional crystallization processes as it resided in an upper crustal magma chamber before being erupted. An enrichment in fluid-compatible elements and a depletion in fluid-incompatible elements suggests a subduction modified sub-continental lithospheric mantle (SCLM) contributed to the genesis of the parental magma.

  2. Jalisco y Colima, México

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    A. Talavera-Villarreal


    Full Text Available Esta investigación se realizó en dos parcelas de limón (Citrus aurantifolia, ubicadas —una de ellas— en el municipio de Autlán de Navarro (AN, Jalisco; y la otra, en Colima, Colima (COL México, durante el periodo de 1998 a 2000. El objetivo fue determinar la dinámica poblacional de la fase larvaria de Phyllocnistis citrella Stainton (minador de la hoja de los cítricos, MHC y la contribución de varios gremios de artrópodos nativos en el control natural del insecto. En AN, las poblaciones de larvas y pupas mostraron dos periodos de abundancia, asociados a los meses de agosto y noviembre, respectivamente; durante los meses de diciembre a mayo de 1999, la incidencia del insecto fue inapreciable. En COL, los periodos de abundancia de la fase larval fueron distintos a los de AN; en primer lugar, de noviembre a junio, las poblaciones se incrementaron paulatinamente; y de julio a septiembre, el MHC fue inapreciable debido a la presencia de un fitopatógeno que eliminó los brotes de los árboles en el sitio experimental. En ambas localidades, los patrones de mortalidad observados muestran que los depredadores tuvieron una incidencia importante en el tercer estadio y la pupa de P. citrella. Por otro lado, en COL fue posible observar que la mortalidad de las larvas del MHC se debió, principalmente, a depredadores que raptan la larva de la mina (82%; otra fracción de la población es depredada por insectos o artrópodos que punzan al insecto y lo consumen en la mina (9.5 % y por ectoparásitos (6.7%; una proporción reducida de la mortalidad (2% no fue posible asignarla a un gremio de depredador. La mortalidad de las pupas se debió, primordialmente, a ectoparásitos (91%, y el resto (9%, no fue posible asignarla a una fuente de mortalidad específica. En adición, se observó que hay una relación denso-dependiente positiva entre la abundancia de P. citrella y la mortalidad causada por los depredadores.

  3. Colima and Manila: Two cities linked by history

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    Paulina Machuca Chávez


    Full Text Available During more than two centuries, Colima and Manila had a close relationship, as a result of the transpacific voyages held by the Manila Galleon. In its voyage towards Acapulco, this ship stopped first in the port of Salagua (Manzanillo, Colima, in order to get food supply and to send the viceroy of the New Spain an official report about the status of the merchandise. In this context, many Asian people (known as "indios chinos" in the New Spain landed in Colima and established in the haciendas de palmas (Machuca, 2009a, very familiar to them because palm trees are native of Asia. Philippine people taught Spaniards and American indians how to use the coconut (Cocos nucifera L. to make beverages, dishes and tools, as well as to build houses known as “palapas”. This heritage survives nowadays, and it takes part in the Colima everyday life. I present ten evidences of the close relationship that existed between these two cities from the second half of the Sixteenth century up to the Independence phase. I consider that this information will be useful to promote a "sister cities"municipal project between Colima and Manila.

  4. Exploring the factors that influence the perception of risk: The case of Volcán de Colima, Mexico (United States)

    Gavilanes-Ruiz, Juan Carlos; Cuevas-Muñiz, Alicia; Varley, Nick; Gwynne, Gemma; Stevenson, John; Saucedo-Girón, Ricardo; Pérez-Pérez, Anaid; Aboukhalil, Mary; Cortés-Cortés, Abel


    Volcán de Colima has increased its activity considerably since 1998 with four periods of effusion and since 2003, daily Vulcanian explosions. During 2005 the magnitude of the explosivity increased, producing many pyroclastic flows, two of which reached over 5 km from the volcano, making them the largest events since the last Plinian eruption in 1913. A significant risk is also presented by the lahar hazard, with various examples of damage to infrastructure during the last few years and 23 people killed in 1955. Nearly 5000 people live in small settlements within 15 km of the volcano. Since 1997 six studies have been carried out in the region in an attempt to define the relationship that exists between the population and its neighbour. Although the methodologies used were different, each study considered the results of the previous and attempted to contribute further data to define geographical variation in the perception of risk. The results of the studies highlight the minor role of increasing activity on risk perception, and distance from the volcano was shown to not directly influence risk perception. In most cases it is the combination of various socio-cultural, historical and political factors that defines the perception of volcanic risk within these villages. By studying the social representation of the risk, such complexity could be better understood. The 1997-2000 information campaign evidently improved risk perception; however, it is clear that this type of program needs to be continued to achieve a long lasting impact. Increased knowledge, however, does not guarantee willing participation in official risk mitigation strategies.

  5. Calc-alkaline lavas from the volcanic complex of Santorini, Aegean Sea, Greece : a petrological, geochemical and stratigraphic study

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    Huijsmans, J.P.P.


    This thesis presents the results of a petrological-geochemical- and stratigraphic study of the calc-alkaline lavas from Santorini, Aegean Sea, Greece. The volcanic complex of Santorini consists of seven eruption centres, of which some have been active contemporaneous. The eruption centres in the

  6. Tree growth response to the 1913 eruption of Volcán de Fuego de Colima, Mexico (United States)

    Biondi, Franco; Estrada, Ignacio Galindo; Gavilanes Ruiz, Juan Carlos; Torres, Alejandro Elizalde


    The impact of volcanic eruptions on forest ecosystems can be investigated using dendrochronological records. While long-range effects are usually mediated by decreased air temperatures, resulting in frost rings or reduced maximum latewood density, local effects include abrupt suppression of radial growth, occasionally followed by greater than normal growth rates. Annual rings in Mexican mountain pine ( Pinus hartwegii Lindl.) on Nevado de Colima, at the western end of the Mexican Neovolcanic Belt, indicate extremely low growth in 1913 and 1914, following the January 1913 Plinian eruption of Volcán de Fuego, 7.7 km to the south. That event, which is listed among the largest explosive eruptions since A.D. 1500, produced ashflow deposits up to 40 m thick and blanketed our study area on Nevado de Colima with a tephra fallout 15-30 cm deep. Radial growth reduction in 1913-14 was ≥30% in 73% of the sampled trees. We geostatistically investigated the ecological impact of the eruption by mapping the decrease in xylem increment and found no evidence of a spatial structure in growth reduction. Little information has been available to date on forest species as biological archives of past environments in the North American tropics, yet this historical case study suggests that treeline tropical sites hold valuable records of prehistoric phenomena, including volcanic eruptions.

  7. The Colima Economy from fifties to the eighties

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    José Luis Villa Aguijosa


    Full Text Available The economic development of Colima, from 50s to 80s decades, was characterized for three stages which are differentiated for some certain features given by the roll that plays the economic sectors from the behaviour of some basic indicators of economic activities like port, agricultural, tourism, mining and industry, an for the economic strategy proposed during these years.In the 50s and 60s years, the economic of Colima took two fundamental characteristics which transcendent to the 70s decade: the supremacy in the participation in the agricultural sector in the gross state product, specialy given with impulse of the industrialization agricultural, and the mining activation, transforming in the base of economic development to Colima. The second stage, is in the 70s decade, and is characterized by the dynamic that industrial stage takes above other sectors with more slowly growing tax, besides it is characterized for one reduction of the growth tax of the gross estate product.The characteristics of economic development of Colima during these years are: standstill of the agricultural activity, trade and services, growth of industry, the urbanization and new economic profile, and makes the bases from the new economic profile of the 80s, in the context of the trade opening. The economy of Colima presented a regional polarization of the activities, a deficient communications and transports, a tourist potential misuse, an important growing of the industrial activities, and the necessity to expand the potential of the Manzanillo port and their big expectatives in the Mexican pacific, and an important growing of an industrial sector highly polarized. This panorama impacted in the profile of the development of Colima in the next decade.The third moment which crosses the economic of Colima, and is presented in the decade of the 80s, is characterized by the beginning of an economic model based in the planning which ;designs; an integrated Colima to the

  8. Space Radar Image of Colima Volcano, Jalisco, Mexico (United States)


    This is an image of the Colima volcano in Jalisco, Mexico, a vigorously active volcano that erupted as recently as July 1994. The eruption partially destroyed a lava dome at the summit and deposited a new layer of ash on the volcano's southern slopes. Surrounding communities face a continuing threat of ash falls and volcanic mudflows from the volcano, which has been designated one of 15 high-risk volcanoes for scientific study during the next decade. This image was acquired by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 24th orbit on October 1, 1994. The image is centered at 19.4 degrees north latitude, 103.7 degrees west longitude. The area shown is approximately 35.7 kilometers by 37.5 kilometers (22 miles by 23 miles). This single-frequency, multi-polarized SIR-C image shows: red as L-band horizontally transmitted and received; green as L-band horizontally transmitted and vertically received; and blue as the ratio of the two channels. The summit area appears orange and the recent deposits fill the valleys along the south and southwest slopes. Observations from space are helping scientists understand the behavior of dangerous volcanoes and will be used to mitigate the effects of future eruptions on surrounding populations. Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves, allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: the L-band (24 cm), the C-band (6 cm) and the X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature

  9. Deformation in the Bataan Volcanic Arc Complex measured with PSInSAR (United States)

    Eco, Rodrigo; Bonus-Ybanez, Audrei; Lagmay, Mahar


    Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) studies on the Bataan Volcanic Arc Complex, Philippines, reveal tectonic deformation of Natib Volcano associated with movement of the Lubao Fault. Differential movement of blocks alongside the north-northeast trending Lubao Fault, measured in terms of line-of-sight (LOS) change in the radar signal, is as much 31.9 mm/year. The Lubao fault, based on PSInSAR time-series analysis of ascending and descending images over a 5-year period, shows oblique-slip right-lateral movement with the eastern block moving downward. Coupled with morphological interpretation of high-resolution digital elevation models, the results of the PSInSAR study highlights earthquake hazards associated with a poorly understood fault that straddles a populated region in Central Luzon. The advancement on the understanding of the kinematics and dynamics of the Lubao Fault is an important step in preparedness efforts against the potential hazard impacts it may create.

  10. Geochemistry of Peralkaline Melts at Kone Volcanic Complex, Main Ethiopian Rift (United States)

    Iddon, F. E.; Edmonds, M.; Jackson, C.; Hutchison, W.; Mather, T. A.; Fontijn, K.; Pyle, D. M.


    The East Africa rift system (EARS) is the archetypal example of continental rifting, with the Main Ethiopian rift (MER) segment offering a unique opportunity to examine the dynamics of peralkaline magmas; the development of central volcanoes; melt distribution and transport in the crust; the volatile budgets of rift magmas and their implications for the formation of ore deposits. The alkali- and halogen-rich magmas of the MER differ from their calc-alkaline counterparts in other settings due to their lower viscosities and higher volatile contents, which have important implications for magma transport, reservoir dynamics and eruptive hazards. The high halogen contents of the magmas give rise to halogen-rich vapor which has the capacity to transport and concentrate metals and REE. The Kone Volcanic complex is one of the lesser studied Quaternary peralkaline centres, located on the axial portion of the MER. It comprises two superimposed calderas, surrounded by ignimbrite deposits and unwelded felsic pyroclastic material, small basaltic vents and rhyolitic domes. Unusually for the central volcanoes of the MER, the caldera has refilled with basaltic lava, not pyroclastic material. We use whole rock and micro-analysis to characterize a range of Kone tephras, glasses, crystal phases and melt inclusions in terms of major, trace and volatile element abundances, alongside detailed textural analysis using QEMSCAN and SEM. The whole rock geochemistry reflects the clear peralkaline nature of the suite, with a distinct compositional gap between 50 wt% and 65 wt% SiO2, controlled largely by fractional crystallization. Trace element systematics illustrate that trachytes entrain alkali feldspars, with the crystal cargo of the entire suite reflecting the structure of the magma reservoir at depth, with liquid-rich lenses and regions of syenitic mush. Melt inclusion geochemistry allows reconstruction of complex, multiphase differentiation processes and the exsolution of both a vapor

  11. Some isotopic and geochemical anomalies observed in Mexico prior to large scale earthquakes and volcanic eruptions

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    Cruz R, S. de la; Armienta, M.A.; Segovia A, N


    A brief account of some experiences obtained in Mexico, related with the identification of geochemical precursors of volcanic eruptions and isotopic precursors of earthquakes and volcanic activity is given. The cases of three recent events of volcanic activity and one large earthquake are discussed in the context of an active geological environment. The positive results in the identification of some geochemical precursors that helped to evaluate the eruptive potential during two volcanic crises (Tacana 1986 and Colima 1991), and the significant radon-in-soil anomalies observed during a volcanic catastrophic eruption (El Chichon, 1982) and prior to a major earthquake (Michoacan, 1985) are critically analysed. (Author)

  12. Volcanological evolution of the Rivi-Capo Volcanic Complex at Salina, Aeolian Islands: magma storage processes and ascent dynamics (United States)

    Nicotra, Eugenio; Viccaro, Marco; De Rosa, Rosanna; Sapienza, Marco


    Lava flows and pyroclastic deposits from strombolian fallout related to the activity of the Rivi and Capo volcanoes, which are representative of early subaerial volcanoes on Salina (Aeolian Islands), have been investigated through a geological-petrological approach. Our geological field survey shows that Rivi and Capo volcanoes are part of a single N50°E aligned volcanic complex, here named Rivi-Capo Volcanic Complex (RCVC). Stratigraphically specific rock sampling has allowed reconstruction of the magma feeding processes through time. Whole rock major element compositions, together with core-to-rim profiles of plagioclase and clinopyroxene crystals, show a general evolution toward more basic compositions through the three formations constituting the Capo volcano and within the Rivi center. MELTS simulations and mass balance modeling suggest that the RCVC rocks are the result of fractional crystallization of plagioclase, clinopyroxene, and olivine (ca. 45 % of solid removed) from a primary magma. In addition to fractional crystallization, continuous recharge and mixing with more basic magma coming from deeper parts of the magmatic plumbing system contributed to the final volcanic rock compositions. Our textural and microanalytical data on plagioclase and clinopyroxene crystals allow the definition of a multilevel magmatic storage system with reservoirs at ~20 and ~3 km below sea level. When processes of magma differentiation, ascent, and storage are considered together with the stratigraphic position of each sample, a history of continuous modification of the RCVC plumbing system can be constructed. Volcanism may have been characterized by fissure-type eruptions during the early stages (Lower Capo, Lower Rivi, and Middle Capo Formations), gradually changing later to central-type volcanism (Upper Capo and Upper Rivi Formations).

  13. The 3-D structure of the Somma-Vesuvius volcanic complex (Italy) inferred from new and historic gravimetric data


    Linde, Niklas; Ricci, Tullio; Baron, Ludovic; Shakas, Alexis; Berrino, Giovanna


    Existing 3-D density models of the Somma-Vesuvius volcanic complex (SVVC), Italy, largely disagree. Despite the scientific and socioeconomic importance of Vesuvius, there is no reliable 3-D density model of the SVVC. A considerable uncertainty prevails concerning the presence (or absence) of a dense body underlying the Vesuvius crater (1944 eruption) that is implied from extensive seismic investigations. We have acquired relative gravity measurements at 297 stations, including measurements in...

  14. The Lepanto Cu–Au deposit, Philippines: A fossil hyperacidic volcanic lake complex (United States)

    Berger, Byron R.; Henley, Richard W.; Lowers, Heather; Pribil, Michael


    Hyperacidic lakes and associated solfatara in active volcanoes are the expression of magmatic gas expansion from source to surface. Here we show for the first time, that the vein system that comprises the ~ 2 Ma high-sulfidation, Lepanto copper–gold deposit in the Mankayan district (Philippines) was associated with a contemporary hyperacidic volcanic lake complex—possibly the first such lake recognized in the geological record. A 15–20‰ difference in sulfur isotopic composition between barite and sulfides and sulfosalts in the vent fumarole encrustations supports the interpretation that SO2-rich volcanic gas vented into the base of the lake and marginal to it and ties the mineralization directly to magmatic gas expansion, fracture propagation, and mineralization that occurred through a series of decompression steps within the feeder fracture network. These data confirm that crater lake environments such as Kawah Ijen (Java, Indonesia) provide modern day analogs of the Lepanto and other high sulfidation Cu–Au depositing environments.We also provide extensive analysis of sulfosalt–sulfide reactions during vein formation within the hyperacidic lake complex. Pyrite ±  silica deposited first at high temperature followed by enargite that preserves the vapor–solid diffusion of, for example, antimony, tin, and tellurium into the vapor from the crystallizing solid. Subsolidus, intra-crystalline diffusion continued as temperature declined. Pyrite and enargite are replaced by Fe-tennantite in the lodes which initially has low Sb/(Sb + As) atomic ratios around 13.5% close to the ideal tennantite formula, but evolves to higher ratios as crystallization proceeds. Fumarole encrustation clasts and sulfosalts in the lake sediment are more highly evolved with a larger range of trace element substitutions, including antimony. Substitution of especially Zn, Te, Ag, and Sn into tennantite records metal and semi-metal fractionation between the expanding magmatic

  15. Neotectonics of Graciosa island (Azores: a contribution to seismic hazard assessment of a volcanic area in a complex geodynamic setting

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    Ana Hipólito


    Full Text Available Graciosa is a mid-Pleistocene to Holocene volcanic island that lies in a complex plate boundary between the North American, Eurasian, and Nubian plates. Large fault scarps displace the oldest (Middle Pleistocene volcanic units, but in the younger areas recent volcanism (Holocene to Upper Pleistocene conceals the surface expression of faulting, limiting neotectonic observations. The large displacement accumulated by the older volcanic units when compared with the younger formations suggests a variability of deformation rates and the possibility of alternating periods of higher and lower tectonic deformation rates; this would increase the recurrence interval of surface rupturing earthquakes. Nevertheless, in historical times a few destructive earthquakes affected the island attesting for its seismic hazard. Regarding the structural data, two main fault systems, incompatible with a single stress field, were identified at Graciosa Island. Thus, it is proposed that the region is affected by two alternating stress fields. The stress field #1 corresponds to the regional stress regime proposed by several authors for the interplate shear zone that constitutes the Azorean segment of the Eurasia-Nubia plate boundary. It is suggested that the stress field #2 will act when the area under the influence of the regional stress field #1 narrows as a result of variations in the differential spreading rates north and south of Azores. The islands closer to the edge of the sheared region will temporarily come under the influence of a different (external stress field (stress field #2. Such data support the concept that, in the Azores, the Eurasia-Nubia boundary corresponds to a complex and wide deformation zone, variable in time.

  16. Stratigraphy, petrology, and geochemistry of the Spurr Volcanic Complex, eastern Aleutian Arc, Alaska. [(Appendix for geothermal fluid chemistry)

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    Nye, C.J.


    The Spurr Volcanic Complex (SVC) is a calcalkaline, medium-K, sequence of andesites erupted over the last quarter of a million years by the easternmost currently active volcanic center in the Aleutian Arc. The ancestral Mt. Spurr was built mostly of andesites of uniform composition (58 to 60% SiO/sub 2/), although andesite production was episodically interrupted by the introduction of new batches of more mafic magma. Near the end of the Pleistocene the ancestral Mt. Spurr underwent Bezyianny-type avalanche caldera formation, resulting in the production of a volcanic debris avalanche with overlying ashflows. Immediately afterward, a large dome (the present Mt. Spurr) was emplaced in the caldera. Both the ashflows and dome are made of acid andesite more silicic than any analyzed lavas from the ancestral Mt. Spurr (60 to 63% SiO/sub 2/), yet contain olivine and amphibole xenocrysts derived from more mafic magma. The mafic magma (53 to 57% SiO/sub 2/) erupted during and after dome emplacement, forming proto-Crater Peak and Crater Peak. Hybrid pyroclastic flows and lavas were also produced. Proto-Crater Peak underwent glacial dissection prior to the formation of Crater Peak in approximately the same location. Appendices II through VIII contain a summary of mineral compositions; Appendix I contains geochemical data. Appendix IX by R.J. Motyka and C.J. Nye describes the chemistry of geothermal fluids. 78 refs., 16 figs., 3 tabs.

  17. New radiometric and petrological constraints on the evolution of the Pichincha volcanic complex (Ecuador) (United States)

    Robin, Claude; Samaniego, Pablo; Le Pennec, Jean-Luc; Fornari, Michel; Mothes, Patricia; van der Plicht, Johannes


    Fieldwork, radiometric (40Ar/39Ar and 14C) ages and whole-rock geochemistry allow a reconstruction of eruptive stages at the active, mainly dacitic, Pichincha Volcanic Complex (PVC), whose eruptions have repeatedly threatened Quito, most recently from 1999 to 2001. After the emplacement of basal lavas dated at ˜1100 to 900 ka, the eruptive activity of the old Rucu Pichincha volcano lasted from ˜850 ka to ˜150 ka before present (BP) and resulted in a 15 × 20 km-wide edifice, which comprises three main building stages: (1) A lower stratocone (Lower Rucu, ˜160 km3 in volume) developed from ˜850 to 600 ka; (2) This edifice was capped by a steeper-sided and less voluminous cone (the Upper Rucu, 40-50 km3), the history of which started 450-430 ka ago and ended around 250 ka with a sector collapse; (3) A smaller (8-10 km3) but more explosive edifice grew in the avalanche amphitheatre and ended Rucu Pichincha's history about 150 ka ago. The Guagua Pichincha volcano (GGP) was developed from 60 ka on the western flank of Rucu with four growth stages separated by major catastrophic events. (1) From ˜60 to 47 ka, a basal effusive stratocone developed, terminating with a large ash-and-pumice flow event. (2) This basal volcano was followed by a long-lasting dome building stage and related explosive episodes, the latter occurring between 28-30 and 22-23 ka. These first two stages formed the main GGP (˜30 km3), a large part of which was removed by a major collapse 11 ka BP. (3) Sustained explosive activity and viscous lava extrusions gave rise to a new edifice, Toaza (4-5 km3 in volume), which in turn collapsed around 4 ka BP. (4) The ensuing amphitheatre was partly filled by the ˜1-km3 Cristal dome, which is the historically active centre of the Pichincha complex. The average output rate for the whole PVC is 0.29 km3/ka. Nevertheless, the chronostratigraphic resolution we obtained for Lower Rucu Pichincha and for the two main edifices of Guagua Pichincha (main GGP and

  18. Mineralogical and geochemical characteristics of BERYL (AQUAMARINE) from the Erongo Volcanic Complex, Namibia (United States)

    Lum, Jullieta Enone; Viljoen, Fanus; Cairncross, Bruce; Frei, Dirk


    The granite hosted pegmatites of the Erongo Volcanic Complex in central Namibia are well known for the wide variety of minerals present, of considerable interest to mineral collectors. These include (amongst others) often spectacular, museum quality examples of beryl, schorl, jeremejevite, fluorite, quartz, goethite and cassiterite. The locality is particularly recognized for hosting a variety of beryl types, including green, yellow (heliodor), colorless (goshenite) and blue/greenish blue (aquamarine) variants. Comprehensive geochemical studies of the Erongo beryls are very limited. The present contribution serves to document the visual characteristics (colour, colour zoning, inclusion content) as well as the major and trace element chemistry of 42 blue, two green and one colorless beryl from Erongo, and to compare these with other localities worldwide. The beryls from Erongo are generally subhedral to euhedral with a well-formed prismatic habit. Idiomorphic crystals, characterised by strong hexagonal prisms, are common. Beryl is commonly associated with schorl, quartz, muscovite, alkali feldspar, plagioclase feldspar, iron oxides, foitite, rossmanite and cassiterite. Aquamarines range from pale blue to deep blue or greenish blue, with marked colour zoning seen in a number of samples. One of the two green beryls examined is of a medium green colour, and is heavily included, while the other specimen has a pale yellowish green colour. The goshenite sample is colourless, clear, and transparent. Numerous cracks are present in the samples examined, and these are usually filled by iron oxides. Inclusions species encountered in the beryl samples are schorl, quartz, muscovite, feldspar, iron oxides and cassiterite, clearly reflective of the host pegmatite mineralogy. Aquamarine and green beryl contain iron as the main chromophore while goshenite is devoid of chromophores. Fe contents in beryl increase with colour intensity, consistent with the known chromatic effects of Fe

  19. Seasonal hydrodynamical features on the continental shelf of Colima (west coast of Mexico

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    José Salas


    Full Text Available Four high-resolution hydrographic surveys were carried out in 2002 on the continental shelf of Colima, Pacific coast of Mexico. The data collected revealed the presence of cyclonic and anticyclonic eddy-like features covering the whole extension of the shelf, which is a rather different pattern from the along-shore general circulation described in previous works. Despite the apparent complexity of the circulation features, the overall shelf-slope exchange pattern is similar in autumn and winter and the opposite in spring. In summer the exchanges also have a similar distribution to autumn and winter, but they are restricted to the upper layers. This suggests that the observed circulation features could result from the interaction between the large-scale seasonal circulation and some kind of local forcing.

  20. Evidence of non-extensivity in the seismicity observed during the 2011–2012 unrest at the Santorini volcanic complex, Greece

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    G. Papadakis


    Full Text Available During the period of October 2011–January 2012, an increase of earthquake activity has been observed in the volcanic complex of Santorini Island, Greece. Herein, the magnitude distribution of earthquakes as well as the temporal distribution of seismicity are studied. The statistics of both parameters exhibit complexity that is evident in the frequency-magnitude distribution and the inter-event time distribution, respectively. Because of this, we have used the analysis framework of non-extensive statistical physics (NESP, which seems suitable for studying complex systems. The observed inter-event time distribution for the swarm-like earthquake events, as well as the energy and the inter-event earthquake energy distributions for the observed seismicity can be successfully described with NESP, indicating the inherent complexity of the Santorini volcanic seismicity along with the applicability of the NESP concept to volcanic earthquake activity, where complex correlations exist.

  1. Aproximación al análisis de la vulnerabilidad del volcán de fuego de Colima (Jalisco, México

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    Luis Hernández Calvento


    Full Text Available Se aborda en este artículo una aproximación al estudio de la vulnerabilidad de la población ante las manifestaciones del Volcán de Fuego de Colima (Estado de Jalisco, México, desde un punto de vista geográfico. Para su desarrollo se plantea el uso de dos escalas: en primer lugar se estudia el entorno del Volcán, haciendo uso de Tecnologías de la Información Geográfica (T.I.G. para el análisis de sus coberturas del suelo; en segundo lugar, se toma como área piloto el núcleo de Juan Barragán, en las inmediaciones del Volcán, y se analizan las motivaciones de la población, sus disponibilidades y medios de evacuación, así como su actitud ante una hipotética manifestación volcánica.An approach to the study of vulnerability in volcanic manifestations of Volcán de Fuego de Colima (State of Jalisco, México, from a geographic point of view, is the aim of this paper. Two scales are used to broach the problem: first and foremost was necessary to analyse the land-cover arround the Volcán de Fuego de Colima, using Geographic Information Technologies (G.I.T.; at the same time, the village of Juan Barragán, neighbouring the volcano, was consider like a pilot area, and so, its population was analized with the purpose of understand their reasons of stay at the area, and their possibilities and chances faced with a hypothetic volcanic manifestation.

  2. Neogene Tiporco Volcanic Complex, San Luis, Argentina: An explosive event in a regional transpressive - local transtensive setting in the pampean flat slab (United States)

    Ibañes, Oscar Damián; Sruoga, Patricia; Japas, María Silvia; Urbina, y. Nilda Esther


    The Neogene Tiporco Volcanic Complex (TVC) is located in the Sierras Pampeanas of San Luis, Argentina, at the southeast of the Pampean flat-slab segment. Based on the comprehensive study of lithofacies and structures, the reconstruction of the volcanic architecture has been carried out. The TVC has been modeled in three subsequent stages: 1) initial updoming, 2) ignimbritic eruptive activity and 3) lava dome emplacement. Interplay of magma injection and transtensional tectonic deformation has been invoked to reproduce TVC evolution.

  3. New magnetotelluric soundings in the Mt. Somma-Vesuvius volcanic complex. Preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Manzella, A.; Volpi, G. [Consiglio Nazionale delle Ricerche, Pisa (Italy). Ist. Internazionale per le Ricerche Geotermiche; Zaja, A. [Padua Univ., Padua (Italy). Dipt. di Geologia, Paleontologia e Geofisica


    The work reports the preliminary results of ten magnetotelluric (MT) soundings recorded in single-site mode above the Mt. Somma-Vesuvius volcanic area in 1997. The quality of data decreases going further from the caldera and approaching the sources of electromagnetic incoherent noise such as villages, antennas and repeaters. After a very accurate data analysis, the apparent resistivity and phase curves were interpreted with a 1D modelling instead a 2D one as it seems a more appropriate interpretative approach looking at the morphology of the curves and taking into account the 3 D geological conditions of the area. The results show an extended conductive structure at a depth of 0.3-1.2 km. It could be connected with a change in the physico-chemical characteristics of the volcano-sedimentary define the response MT curves for sites above this particular volcanic structure. This approach seems to be very interesting in view of specific interpretative targets, such as dimension and position of the magma chamber, when planning future MT surveys.

  4. Colima: The eleventh entity most competitive of the country

    Directory of Open Access Journals (Sweden)

    José Manuel Orozco Plascencia


    Full Text Available According to the I Report of the State Competitiveness 2006, the State of Colima is considered to be the eleventh federal entity more competitive of the country. Number obtained in the favorable results in the national ranking of competitiveness, due to it got a third position to have with a System of Rights Reliable and Objective, besides it got three fifth positions: Sustainable Management of the Environment, Market of Efficient Factors and Precursor Sectors of the World Class, besides of a eighth position to count on a Dynamic Economic and Stables Indicators. Nevertheless, there are some indicators that showed unfavorable results for the entity, for instance, Colima got the 30th place in the factor of Achievement of the International Relations, the 27th position to count on a bad Political and Functional System, and the 24th place to have an Efficient and Effective Government. On average of the sectorial competitiveness, the Pharmaceutical and High-Tech sector holds the fifth position in the national ranking, in order to the priorities for the location of the business investment; the Manufactures are located in the sixth Place; the Textile sector in the eighth, and the more straggler ones like the Agribusiness and Tourism in the ninth position, respectively. Finally, the sensitivity of the investments above an increase of 10% relative to the 120 quantitative variables that revealed that Colima could pass from the eleventh to the third position, this like a result to increase its investment in 3,228 million of pesos for the entity, or increase in 30% the amount per capita for each member of the PEA, equivalent to 12,300 pesos average for employee.

  5. The 3-D structure of the Somma-Vesuvius volcanic complex (Italy) inferred from new and historic gravimetric data. (United States)

    Linde, Niklas; Ricci, Tullio; Baron, Ludovic; Shakas, Alexis; Berrino, Giovanna


    Existing 3-D density models of the Somma-Vesuvius volcanic complex (SVVC), Italy, largely disagree. Despite the scientific and socioeconomic importance of Vesuvius, there is no reliable 3-D density model of the SVVC. A considerable uncertainty prevails concerning the presence (or absence) of a dense body underlying the Vesuvius crater (1944 eruption) that is implied from extensive seismic investigations. We have acquired relative gravity measurements at 297 stations, including measurements in difficult-to-access areas (e.g., the first-ever measurements in the crater). In agreement with seismic investigations, the simultaneous inversion of these and historic data resolves a high-density body that extends from the surface of the Vesuvius crater down to depths that exceed 2 km. A 1.5-km radius horseshoe-shaped dense feature (open in the southwestern sector) enforces the existing model of groundwater circulation within the SVVC. Based on its volcano-tectonic evolution, we interpret volcanic structures that have never been imaged before.

  6. New magnetotelluric soundings in the Mt. Somma-Vesuvius volcanic complex: preliminary results

    Directory of Open Access Journals (Sweden)

    A. Zaja


    Full Text Available During 1997 ten magnetotelluric (MT soundings were recorded in single-site mode above the Mt. Somma-Vesuvius volcanic area. A first campaign of MT measurements was carried out, during spring, by the researchers of the University of Padua with their MSPM acquisition system. During autumn, the researchers of the International Institute of Geothermal Research (CNR Pisa with their Phoenix equipment performed a second campaign. A teach site, the horizontal components of the electrical and magnetic fields were recorded in the frequency band between 300-0.003 Hz. The MSPM system could record signals up to the frequency of 800 Hz. Data were recorded at one common site with both the different equipments to verify the compatibility of the two different acquisition systems. The soundings over the area of the volcano's caldera show a continuous morphology of the apparent resistivity and phase curves with small error bars: it means a good correlation between the orthogonal electrical and magnetic fields. The quality of data decreases going further from the caldera and approaching the sources of electromagnetic incoherent noise such as villages, antennas and repeaters. After a very accurate data analysis, the apparent resistivity and phase curves were interpreted with a 1D modelling instead a 2D one as it seems a more appropriate interpretative approach looking at the morphology of the curves and taking into account the 3D geological conditions of the area. The results show an extended conductive structure at a depth of 0.3-1.2 km. It could be connected with a change in the physico-chemical characteristics of the volcano-sedimentary cover (alteration paragenesis and possible hydrothermalism. A 3D MT forward modelling was then used to define the response MT curves for sites above this particular volcanic structure. This approach seems to be very interesting in view of specific interpretative targets, such as dimension and position of the magma chamber, when

  7. Palaeomagnetic study of the Karacadağ Volcanic Complex, SE Turkey: Monitoring Neogene anticlockwise rotation of the Arabian Plate (United States)

    Koçbulut, Fikret; Akpınar, Zafer; Tatar, Orhan; Piper, John D. A.; Roberts, Andrew. P.


    The Karacadağ Volcanic Centre in south east Turkey is a major basaltic complex sited at the northern margin of the Arabian Plate and emplaced in several pulses between ~ 11 Ma and Late Quaternary times. We have sampled 71 sites in lavas of this complex to constrain the palaeomagnetic record and hence the chronology of magmatic activity and regional rotation. Palaeomagnetic study at sixty two sites yields significant component definition with mixed normal and reversed polarities. From age dating and morphologic criteria we identify three major episodes of lava emplacement and site mean directions of magnetisation for these divisions resolve migration of the palaeofield direction for the northern sector of the Arabian Plate since mid-Miocene times. Successive (reversed polarity) group mean directions are: D/I = 175°/- 50.5° (N = 37, R = 33.13, α95 = 4.1°) for the oldest (Siverek) division (mean age estimate 11.1-6.7 Ma), D/I = 173.4°/- 46.0° (N = 16, R = 15.67, α95 = 5.5°) for the middle (Karacadağ) division (mean age 3.3 Ma) and D/I = 167.7°/- 47.6° (N = 6, R = 5.93, α95 = 7.9°) for the youngest (Ovabağ) division (~ 1.9 Ma - present). The first two results merit a tectonic interpretation and consistent anticlockwise rotation of ~ 9° is recognised in the Karacadağ Volcanic Centre between ~ 11 and 3.3 Ma. The mean directions conform to palaeomagnetic results from other undeformed Neogene igneous complexes of comparable age range further to the west along the northern perimeter of the Arabian Plate. The amount of tectonic rotation observed in Late Pliocene and older volcanic units from this plate is found to be statistically-constant. Tectonism responsible for rotation therefore appears to have been temporally-confined to the last ~ 2 Myr which is long after collision with the Anatolides and closure of the Bitlis suture. This conclusion conforms to the young distributed block rotations recognised in the Anatolides and Aegean and correlates with the

  8. Emplacement and temporal constraints of the Gondwanan intrusive complexes of northern Patagonia: La Esperanza plutono-volcanic case (United States)

    Martínez Dopico, Carmen I.; López de Luchi, Mónica G.; Rapalini, Augusto E.; Wemmer, Klaus; Fanning, C. Mark; Basei, Miguel A. S.


    Two main lines of evidence disagree whether or not the Patagonian blocks collided with Gondwana. All models invoke the voluminous magmatism of the La Esperanza Complex as evidence for active subduction magmatic arc or to a postcollisional setting. The evolution of this bimodal igneous suite is reassessed with field, geochronological (SHRIMP U-Pb zircon and K-Ar mica) and petrophysical data. Emplacement of high-K calk-alkaline granitic magmas occurred at shallow crustal levels (2-8 ± 2 km depth) related to the development and collapse of a caldera associated with a regional NW-SE structural trend. Magmatism involved intermediate hybrid pulses at 273 ± 2 Ma and 255 ± 2 Ma (Prieto Granodiorite) that shifted like a yo-yo to acidic magmas at 260 ± 2 Ma and 250 ± 2 Ma (Donosa and Calvo granites). Absence of solid-state deformation features and the low anisotropy degrees in the granites indicate that its fabric is magmatic in origin. Magnetic fabric in granodiorites displays a concentrical pattern with subhorizontal foliations and lineations. Parallel to the volcanic axis, magnetic foliations and moderately plunging lineations indicate a common feeder system for plutonics and volcanics. Donosa Granite shows a discordant pattern with WNW-ESE ENE-WSW trending low plunging lineations and foliations. The plutono-volcanic system construction (273-255 Ma) followed NW-SE and NE-SW diamond shape faults trends and supracrustal discontinuities. Magmatic Climax is bracketed at 260 Ma. The collapse of the edifice is evidenced by the intrusion of acid magma plugs and dike swarms between 250 and 246 Ma. A similar age range was identified in other areas of Patagonia related to syn and postcollisional tectonic events. No evidence of tectonic activity such as major uplift, metamorphism or thrusting was found excepting regional strike-slip faulting and extension. Therefore, La Esperanza Complex is a high crustal level episode, and as such may not have structurally recorded an active

  9. Relacion entre ganaderia extensiva e incendios en zonas forestales del estado de Colima

    National Research Council Canada - National Science Library

    Galindo, I; Barron, J; Padilla, J.I


    .... En el estado de Colima, en los ultimos anos la practica de la agricultura ha disminuido debido al bajo rendimiento del maiz y, de igual manera, se tiene una disminucion importante del hato ganadero...

  10. El Estribo Volcanic Complex: Evolution from a shield volcano to a cinder cone, Pátzcuaro Lake, Michoacán, México (United States)

    Pola, A.; Macías, J. L.; Osorio-Ocampo, S.; Sosa-Ceballos, G.; Garduño-Monroy, V. H.; Martínez-Martínez, J.


    El Estribo Volcanic Complex (EVC) is located in the northern part of the Michoacán-Guanajuato Volcanic Field within the Trans-Mexican Volcanic Belt (TMVB). El Estribo is located at the southern edge of the E-W Pátzcuaro fault that belongs to the Pátzcuaro-Jarácuaro graben, a western extension of the E-W Morelia-Acambay fault system. Stratigraphy, geochronology, chemistry, and mineral assemblages suggest that the volcanic complex was constructed in two periods separated by a ~ 100 ka volcanic hiatus: a) emission of lava flows that constructed a shield volcano between 126 ka, and b) mixed phreatomagmatic to Strombolian activity that formed a cinder cone ~ 28 ka. The magmas that fed these monogenetic volcanoes were able to use the same feeding system. The cinder cone itself was constructed by Strombolian fallouts and remobilized scoria beds, followed by an erosion period, and by a mixed phreatomagmatic to magmatic phase (Strombolian fallouts ending with lava flows). Soft-sedimentary deformation of beds and impact sags, cross-bedding, as well as pitting and hydrothermal cracks found in particles support the phreatomagmatic phase. The erupted magmas through time ejected basaltic andesitic lava flows (56.21-58.88% SiO2) that built the shield volcano and then basaltic andesitic scoria (57.65-59.05% SiO2) that constructed the cinder cone. Although they used the same feeding system, the geochemical data and the mineral chemistry of the magmas indicate that the shield volcano and the cinder cone were fed by different magma batches erupted thousands of years apart. Therefore, the location of El Estribo Volcanic Complex along an E-W fault that has generated two sector collapses of the shield volcano to the north may be directly linked to this complex redistribution of the magmatic paths to the surface. Our findings show that magmatic feeding systems within monogenetic volcanic fields could be long lived, questioning the classic view of the monogenetic nature of their

  11. Active transmission of human chagas disease in Colima Mexico

    Directory of Open Access Journals (Sweden)

    Rafael Coll-Cárdenas


    Full Text Available Despite efforts to eradicate American trypanosomiasis (AT and Chagas disease from the Americas, there are still areas of active transmission that can eventually become a source of reinfection in previously controlled regions. Mexico could be one of those areas, where there are no formal preventive control programs despite the presence of communities infested by Triatominae bugs infected with Trypanosoma cruzi. This study explored the prevalence of T. cruzi infection in 405 habitants of 17 communities in the state of Colima, on the Pacific Mexican coast, through a seroepidemiological probabilistic survey. The results revealed a point seroprevalence of 2.4% positive for anti-T. cruzi. In addition, 2 clinical cases of chronic and 2 of acute Chagas disease were detected in the explored communities. These findings confirm the risk of active transmission of AT in Western Mexico, especially in rural and suburban communities infested with intra-domestic triatominae, where control programs should be implemented.

  12. Seismic damage in the electrical substations of the Colima state; Dano sismico en las subestaciones electricas del estado de Colima

    Energy Technology Data Exchange (ETDEWEB)

    Mena H, Ulises; Lopez L, Alberto; Guerrero F, Vicente A. [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)


    On the 21 of January of 2003, at 20:06:36 hrs (Mexico center time) an earthquake occurred at the Pacific coast with a magnitude of 7.6 degrees in the Richter scale, whose epicenter was located near the state of Colima and it was felt in a large extent of the Mexican Republic. The earthquake caused numerous material damages in the structures (houses, churches, offices, etc) and vital lines, mainly in the infrastructure of the electrical sector of the region, leaving without electrical energy a large part of the nearby populations and some colonies of distant zones such as in Mexico City. The cause of the interruption of the electrical energy was due to the collapse of some of the equipment of 400 and 230 KV of the electrical transmission substations, among which are Manzanillo II and Colima II. With the experience acquired in the earthquake of October 9, 1995 in Manzanillo, in which also the facilities and equipment of the electrical substations were affected considerably, and as a part of the infrastructure project on the analysis of seismic risk of vital lines that is being developed at this moment at the Instituto de Investigaciones Electricas (IIE), it was decided to inspect the electrical substations of the zone, where the greater damages in the facilities and equipment were reported, to analyze and to determine the main causes of their failure. [Spanish] El 21 de enero de 2003, a las 20:06:36 hrs (hora del centro de Mexico) ocurrio un sismo en la costa del Pacifico con una magnitud de 7.6 grados en escala Richter, cuyo epicentro se localizo cerca del estado de Colima y se percibio en gran parte de la republica mexicana. El sismo causo cuantiosos danos materiales en las estructuras (viviendas, iglesias, oficinas, etc) y lineas vitales, principalmente en la infraestructura del sector electrico de la region, dejando sin energia electrica a gran parte de las poblaciones cercanas y algunas colonias de zonas lejanas como es la ciudad de Mexico. La causa del corte de

  13. Evolution of Icelandic Central Volcanoes: Evidence from the Austurhorn Plutonic and Vestmannaeyjar Volcanic Complexes (United States)


    which host the Austurhorn intrusive complex. Clast lithologies do not include pyroclastic breccias, zeolitized basalts or silicic compositions, all of...tb-I b-38 db- 13X d--2 + + b 3 9 -2 0 -3 1 g b -3 PHV A6 N E S OFS Figure 4.2 Sample locality map for rocks referred to in this text. Heavy lines denote...clinopyroxene accumulation results in a concave-down pattern. 230 n gb-8 mm3m lm mlllm IIIIII~lN phases (e.g., epidote, hornblende, zeolites , clays). There are

  14. The Plinius/Colima CA-U3 test on fission-product aerosol release over a VVER-type corium pool; L'essai Plinius/Colima CA-U3 sur le relachement des aerosols de produits de fission au-dessus d'un bain de corium de type VVER

    Energy Technology Data Exchange (ETDEWEB)

    Journeau, Ch.; Piluso, P.; Correggio, P.; Godin-Jacqmin, L


    In a hypothetical case of severe accident in a PWR type VVER-440, a complex corium pool could be formed and fission products could be released. In order to study aerosols release in terms of mechanisms, kinetics, nature or quantity, and to better precise the source term of VVER-440, a series of experiments have been performed in the Colima facility and the test Colima CA-U3 has been successfully performed thanks to technological modifications to melt a prototypical corium at 2760 C degrees. Specific instrumentation has allowed us to follow the evolution of the corium melt and the release, transport and deposition of the fission products. The main conclusions are: -) there is a large release of Cr, Te, Sr, Pr and Rh (>95%w), -) there is a significant release of Fe (50%w), -) there is a small release of Ba, Ce, La, Nb, Nd and Y (<90%w), -) there is a very small release of U in proportion (<5%w) but it is one of the major released species in mass, and -) there is no release of Zr. The Colima experimental results are consistent with previous experiments on irradiated fuels except for Ba, Fe and U releases. (A.C.)

  15. Magma ascent and lava dome evolution at Volcán de Colima, Mexico (United States)

    Varley, N. R.; Arámbula, R.; Lavallée, Y.; Bernstein, M.; Ryan, A. G.; Maskell, A.


    The transition between explosive and effusive activity can be triggered by subtle variations in parameters which dictate the efficiency and speed of degassing from an ascending magma body. Indirect methods have to be utilized to constrain these parameters, to test and refine numerical models, which ultimately permit a more powerful interpretation of monitoring data. Recent activity at Volcán de Colima has included many transitions between different regimes, offering a great opportunity to examine conduit processes. Explosive activity peaked in 2005 with 30 Vulcanian eruptions producing pyroclastic flows, some reaching >5km from the volcano. Each event was associated with a swarm of long-period (LP) seismic events. A poor correlation between swarm characteristics and the size of the explosion suggests independence between the source mechanisms of each phenomenon. The LP events were divided into 10 families, all of which reappeared in different swarms and the majority continued to occur after the Vulcanian explosion. This is evidence of the complexity of the upper edifice, with the source regions for the LP events remaining unaffected by the explosions. We believe they are produced by brittle deformation once a certain strain-rate threshold has been surpassed. The explosions were associated with rapidly ascending magma bodies that were degassing and crystallizing near the surface, each one being destroyed in the subsequent explosion. Magma sometimes reached the crater, with small short-lived domes being observed. In some cases a post-explosion increase in amplitude of the LP events might have reflected an increase in effusion rate after an unloading of material higher in the vent. Volcán de Colima has produced 5 episodes of effusive activity in the last 11 years. These have been of variable duration and intensity, with over 2 orders of magnitude variation in the effusion rate. The current phase has been characterised by a remarkably sustained (from Jan. 07 to at

  16. Explosive and Phreatomagmatic Activity from San Salvador Volcanic Complex (El Salvador) and Their Effects on El Cambio Archaeological Site: a Review of the Last 3000 yrs. Based on Volcanic Stratigraphy Data (United States)

    Ferrés, D.; Delgado, H.; Pullinger, C.; Castillo, R.; Chávez, H. I.


    El Cambio archeological site (ECAS; Zapotitán Valley), 4 km NW from the San Salvador Volcanic Complex comprises 3000 yrs. of pyroclastic record. Sheets (1983) identified different levels rich in cultural remains intercalated within the volcanic deposits, indicating that different prehistoric settings were affected by San Salvador volcano eruptions, and giving information on the reoccupation frequency in the area. Accordingly, ECAS was occupied since the Late Pre-Classic period until before the last plinian eruption of Ilopango Caldera (425AD) reference, that originated the Tierra Blanca Joven (TBJ), pyroclastic deposits generally used as key-layer in stratigraphic reconstructions. Within the next two centuries, there is no evidence of human occupation at ECAS until the end of Late Classic which was a period of maximum splendor in the valley. During this time the area was affected by at least 3 eruptions from the San Salvador volcanic complex that produced the: Laguna Caldera volcanic fall deposits (which affected Joya de Cerén archeological site in 625AD), "Talpetate" surge deposits or Toba de San Andrés (600-900AD), and fall deposits of El Playón volcano (1658). We report new data on volcanic stratigraphy and archeological history including the following: a) the phreatomagmatic nature of eruptions that affected the area, the new excavations allowed the detailed study of surge deposits indicating magma-water interaction at Laguna Caldera and El Playón, previously considered strombolian eruptions; b)document the occupation of ECAS during Middle Pre-Classic period, new surge deposits below TBJ have been identified (with Middle Pre-Classic artifacts and pottery), that had not been documented before, extending the historic record up to 3000 yrs. BP. and c) detailed study of the "Talpetate" deposits, this sequence consists of fall, pyroclastic flow and surge deposits, present in the rim and slopes of San Salvador Volcano, which can be correlated with surge deposits

  17. Glacial recession in the Tropical Andes from the Little Ice Age: the case of Ampato Volcanic Complex (Southern Peru (United States)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.


    the Ampato volcanic complex (15º24´- 15º 51´ S, 71º 51´ - 73º W; 6.288 masl), one of the most important complexes of the northern sector of the CVZ. Photointerpretation of aerial photographs and teledetection through satellite images of Huayuray Valley (15º 41´ 14´´ S - 71º 51´ 53´´ W), located to the north of the complex, aided in accurately reconstructing the area occupied by the ice mass at different times (LIA, 1955, 2000 and 2008). Also the paleo-ELA (Equilibrium Line Altitude) and the ELA were calculated using the Accumulation Area (AA) method (Kaser and Osmaston, 2002; Osmaston, 2005) in a GIS. The ELA shows the relationship between climate and glacier mass balance (González Trueba, 2005). The data from Huayuray Valley show that the glaciers reached a minimum altitude of 5400 masl and covered an area of ~2.81 Km2 during the LIA. The paleo-ELA was located at ~5780 masl, ~120 m below the current ELA (~5900 m). Based on a vertical thermal gradient of 0.65ºC/100 m, the temperature during this event would have been about 0.7º C colder than present temperature in the Ampato volcanic complex. In 1955, Huayuray glacier covered ~2.45 km2, 12.8% less than in the LIA. In the same year, the glaciers in the Huayuray valley reached a minimum elevation of ~5660 masl and the ELA rose ~20 m, to 5800 masl. In only 45 years (1955 - 2000) the surface area of the ice was significantly reduced (~1 km2), i.e. 40.8%. The ELA continued to rise, until it reached 5890 masl in 2000. From 2000 - 2008, the Huayuray glacier was reduced to ~0.78 km2 and the ELA rised ~10 m to reach the 5900 masl These results from the CVZ confirm the dramatic recession of the glaciers in the tropical Andes during recent decades. They also suggest that if the rate of recession associated with the period 2000-2008 continues, glaciers in the Ampato volcanic complex will disappear in 10 years approximately. References González Trueba, J.J. (2005): La Pequeña Edad del Hielo en los Picos de

  18. Shallow sub-surface structure of the central volcanic complex of Tenerife, Canary Islands: implications for the evolution and the recent reactivation of the Las Canadas caldera

    Energy Technology Data Exchange (ETDEWEB)

    Gottsmann, J [Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ (United Kingdom); Camacho, A G; Fernandez, J [Instituto de Astronomia y Geodesia (CSIC-UCM), Ciudad Universitaria, Pza. de Ciencias, 3, 28040 Madrid (Spain); MartI, J [Institute of Earth Sciences ' Jaume Almera' , CSIC, Lluis Sole SabarIs s/n, Barcelona 08028 (Spain); Wooller, L; Rymer, H [Department of Earth and Environmental Sciences, Open University, Walton Hall, Milton Keynes, MK7 6AA (United Kingdom); GarcIa, A [Department of Volcanology, Museo Nacional de Ciencias Naturales, CSIC, C/ Jose Gutierrez Abascal, 2, 28006 Madrid (Spain)], E-mail:


    We present a new local Bouguer anomaly map of the Central Volcanic Complex (CVC) of Tenerife, Spain. The high-density core of the CVC and the pronounced gravity low centred in the Las Canadas caldera (LCC) in greater detail than previously available. Mathematical construction of a subsurface model from the local anomaly data, employing a 3-D inversion enables mapping of the shallow structure beneath the complex, giving unprecedented insights into the sub-surface architecture of the complex, and shedding light on its evolution.

  19. Micro-earthquake signal analysis and hypocenter determination around Lokon volcano complex

    Energy Technology Data Exchange (ETDEWEB)

    Firmansyah, Rizky, E-mail: [Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Nugraha, Andri Dian, E-mail: [Global Geophysical Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Bandung, 40132 (Indonesia); Kristianto, E-mail: [Center for Volcanology and Geological Hazard Mitigation (CVGHM), Geological Agency, Bandung, 40122 (Indonesia)


    Mount Lokon is one of five active volcanoes which is located in the North Sulawesi region. Since June 26{sup th}, 2011, standby alert set by the Center for Volcanology and Geological Hazard Mitigation (CVGHM) for this mountain. The Mount Lokon volcano erupted on July 4{sup th}, 2011 and still continuously erupted until August 28{sup th}, 2011. Due to its high seismic activity, this study is focused to analysis of micro-earthquake signal and determine the micro-earthquake hypocenter location around the complex area of Lokon-Empung Volcano before eruption phase in 2011 (time periods of January, 2009 up to March, 2010). Determination of the hypocenter location was conducted with Geiger Adaptive Damping (GAD) method. We used initial model from previous study in Volcan de Colima, Mexico. The reason behind the model selection was based on the same characteristics that shared between Mount Lokon and Colima including andesitic stratovolcano and small-plinian explosions volcanian types. In this study, a picking events was limited to the volcano-tectonics of A and B types, hybrid, long-period that has a clear signal onset, and local tectonic with different maximum S – P time are not more than three seconds. As a result, we observed the micro-earthquakes occurred in the area north-west of Mount Lokon region.

  20. Nephelines from the Somma-Vesuvius volcanic complex (Southern Italy): crystal-chemical, structural and genetic investigations (United States)

    Balassone, Giuseppina; Kahlenberg, Volker; Altomare, Angela; Mormone, Angela; Rizzi, Rosanna; Saviano, Michele; Mondillo, Nicola


    Sixteen nephelines from different geological occurrences were sampled at the type-locality, the Somma-Vesuvius volcanic complex (southern Italy), and investigated for their chemistry and crystal structure obtained by both single-crystal and powder X-ray diffraction. Nepheline-bearing samples are metamorphic or from magmatic ejecta and pumice deposits. The lower K contents characterize the pumice- and some metamorphic-derived nephelines, whereas the higher ones are found in some samples from magmatic nodules. The amount of the anorthite molecule, quite low on average, can be more variable in the metamorphic nephelines. The crystal-structure investigations on Somma-Vesuvius samples compare well with previous studies of natural nephelines. All 16 nepheline samples adopt space group P63. The observed lattice parameters vary between 9.9768-9.9946 Å (for a) and 8.3614-8.3777 Å (for c), respectively. Furthermore, chemical analysis revealed that all specimens exhibit an excess of Si relative the ideal Si:Al ratio of 1:1. The analysis of the T-O distances in our samples clearly indicates a distinct ordering process of aluminium and silicon on the tetrahedral sites which is an agreement with Loewenstein's rule. A linear correlation between the distance of symmetry equivalent split atoms O(1)-O(1)' and the T(1)-O(1)- T(2) tilt angle was observed. The average ( B = Na) distances of all crystals are very similar which is consistent with the outcome of the site population refinement indicating full occupancy with sodium. Oriented precession-type sections of reciprocal space indicated the presence of at least the most intense family of satellite peaks, demonstrating that this group of satellite reflections can occur not only in nephelines from pegmatites and ijolites but also in rocks from completely different petrological settings.

  1. Geometry of laccolith margins: 2D and 3D models of the Late Paleozoic Halle Volcanic Complex (Germany) (United States)

    Schmiedel, T.; Breitkreuz, C.; Görz, I.; Ehling, B.-C.


    Well data and core samples from the Late Paleozoic Halle Volcanic Complex (HVC) have been used to describe the geometry of the rhyolitic porphyritic laccoliths and their margins. The HVC formed between 301 and 292 Ma in the intramontane Saale basin, and it comprises mainly rhyolitic subvolcanic bodies (~300 km3) as well as minor lava flows and volcaniclastic deposits. The major HVC laccolith units display aspect ratios ranging between 0.04 and 0.07, and they are separated by tilted and deformed Carboniferous-Permian host sediments. For the margin of the Landsberg laccolith, a major coarsely porphyritic unit of the HVC, an exceptional data set of 63 wells concentrated in an area of 10 km2 reaching to depth of 710 m exists. It was used to explore the 3D geometry and textures, and to deduce an intrusion model. For a 3D visualization of the Landsberg laccolith margin, Geological Object Computer Aided Design; Paradigm® software (GOCAD) was used. Curve objects have been derived from the intrusion-host contacts. Automated GOCAD® methods for 3D modelling failed. As a result, manual refinement was essential. A major finding of the 3D modelling is the presence of prolate sediment rafts, up to 1,400 m in length and up to 500 m in thickness, surrounded by Landsberg rhyolite. The sedimentary rafts dip away from the laccolith centre. The engulfing laccolith sheets reach thickness of 100-300 m. For other HVC laccolith units (Löbejün, Petersberg, Brachstedt), well data reveal vertical rhyolite/sediment contacts or magma lobes fingering into the host sediments. HVC laccolith contact textures include small-scale shearing of the intruding magma and of the host sediment. In addition, internal shear zones have been detected inside the rhyolite bodies. The present study suggests that the emplacement of successive magma sheets was an important process during laccolith growth in the HVC.

  2. Spatio-temporal reconstruction of lahars on the southern slopes of Colima volcano, Mexico - A dendrogeomorphic approach (United States)

    Franco-Ramos, Osvaldo; Stoffel, Markus; Vázquez-Selem, Lorenzo; Capra, Lucia


    Historical records of lahar occurrence and distribution are typically scarce in volcanic environments, even more so if they occur outside of human settlements. In the context of hazard assessment and process understanding, documenting their temporal frequency and drivers of activity might be crucial. On forested volcanoes, lahars may significantly damage trees along their flow paths, and sometimes even eliminate entire forest stands. This study is based on growth disturbances in trees affected by lahars (i) to assess the potential of dendrogeomorphic techniques in lahar research and (ii) to analyze the temporal frequency and spatial patterns of lahars at Montegrande and Arena, two of the most active of the ephemeral streams on the southern sector of Colima volcano. A total of 78 Pinus leiophylla live trees were sampled along the ravines, yielding evidence for 20 lahar events after the AD 1913 eruption, adding seven events to the historic records. Although the number of lahars reconstructed with tree-ring records can only be considered as a minimum frequency, the method clearly improves the local lahar chronology. Despite the scarcity of meteorological records at the study sites, the timing of reconstructed lahars points to heavy rainfalls after explosive activity as the main driver of events.

  3. Evolving metasomatic agent in the North Andean subduction, deduced from magma composition of the long-lived Pichincha volcanic complex (Ecuador) (United States)

    Samaniego, P.; Robin, C.; Chazot, G.; Bourdon, E. P.; Jo, C.


    Geochemical studies of long-lived volcanic complexes are crucial for the understanding of the nature and composition of the subduction component of arc magmatism. The Pichincha Volcanic Complex (Northern Andean Volcanic Zone) consists of: (1) an older, highly eroded edifice, the Rucu Pichincha, whose lavas are mostly andesites, erupted from 1100 to 150 ka; and (2) a younger, essentially dacitic, Guagua Pichincha composite edifice, with three main construction phases (Basal Guagua Pichincha, Toaza and Cristal) which formed over the last 60 ka. This structural evolution was accompanied by a progressive increase of most incompatible trace element abundances and ratios, as well as by a sharp decrease of fluid-mobile to fluid-immobile element ratios. Geochemical data indicate that fractional crystallization of an amphibole-rich cumulate could account for the evolution from the Guagua Pichincha andesites to dacites. However, in order to explain the passage from the Rucu Pichincha andesites to Guagua Pichincha dacites, the mineralogical and geochemical data indicate the predominance of magma mixing processes between a mafic, trace-element depleted, mantle-derived end-member, and a siliceous, trace-element enriched, adakitic end-member. The systematic variation of trace element abundances and ratios in primitive samples of this volcanic complex leads us to propose that the Rucu Pichincha magmas came from a hydrous-fluid metasomatized mantle wedge, whereas Guagua Pichincha magmas are related to partial melting of a siliceous-melt metasomatized mantle. This temporal evolution implies a change from dehydration to partial melting of the slab, which may be associated with an increase in the geothermal gradient along the slab due to the presence of the subducted Carnegie Ridge at the subduction system. This work emphasizes the importance of studying arc-magma systems over long periods of time (of at least 1 million of years), in order to evaluate the potential variations of the

  4. Holocene tephra succession of Puyehue-Cordón Caulle and Antillanca/Casablanca volcanic complexes, southern Andes (40-41°S) (United States)

    Naranjo, J. A.; Singer, B. S.; Jicha, B. R.; Moreno, H.; Lara, L. E.


    Puyehue-Cordón Caulle and Antillanca volcanic complexes are two of at least 50 active frontal arc volcanoes that define the 1400 km-long Southern Volcanic Zone of Chile. Holocene tephra deposits in Chile and Argentina (40-41°S) up to 100 km east of these volcanoes comprise at least five voluminous ( 1 to 8 km3) pyroclastic-fall layers that preceded several recently deposited Cordón Caulle pumice fallouts. Field observations of proximal, medium, and distal facies of the deposits, in conjunction with geochronology and geochemistry of the volcanic complexes, indicate that three fall layers are derived from Puyehue volcano (Puyehue 1 and 2, and Mil Hojas), whereas two are sourced from the Antillanca complex (Playas Blanca-Negra, and Nahuel Huapi Tephra), 20 km to the south. The oldest tephra (calibrated 14C age 10.49 ± 0.12 ka, 2σ), found only at medium-distal facies, is deposited directly on granitic moraine boulders and consists of deeply weathered, orange dacitic pumice lapilli. The next prominent tephra at 7 ka comprises dacitic pumice and its age is equivalent to a rhyodacitic dome exposed in the Puyehue summit crater. Above these deposits there are phases of a complex eruption consisting of a conspicuous compositionally-zoned tephra. It also comprises a pyroclastic density current, together with lithic rich and scoriaceous fallout deposits. Mineralogical, geochemical, and Sr isotope evidence, plus the isopach maps, confirm that this sequence of eruptive events is sourced from Antillanca at 1932 ± 68 yrBP. The total volume of this eruptive sequence exceeds 8 km3, making it the largest Holocene eruption from either volcanic complex. This eruption was likely responsible for the destruction of an ancestral Antillanca volcano and the formation of a 4.5 km diameter caldera. A distinctive younger unit in the region is a voluminous rhyodacitic pumice fall (calibrated 14C age 1.11 ± 0.07 ka), above which a series of several alternating dark lithic and pumice

  5. Geochronology and magmatic evolution of the Dieng Volcanic Complex, Central Java, Indonesia and their relationships to geothermal resources (United States)

    Harijoko, Agung; Uruma, Ryusuke; Wibowo, Haryo Edi; Setijadji, Lucas Doni; Imai, Akira; Yonezu, Kotaro; Watanabe, Koichiro


    We analyzed new radiometric dating and petrological data of DVC in an attempt to reconstruct volcanic history as groundwork to understand magmatic temporal and spatial evolution. The magma of DVC can be divided on the basis of mineral composition into three types: olivine bearing basalt-basaltic andesite, pyroxene basaltic andesite-andesite, and biotite andesite-dacite, which coincide with three volcanic episodes of DVC: pre-caldera, second, and youngest episode, respectively. The pre-caldera episode was active no later than 1 Ma, the second episode occurred between 0.3 and 0.4 Ma, and the youngest occurred after 0.27 Ma. Plots of CaO, K2O, Al2O3, and Rb/Sr against FeO*/MgO and/or MgO suggest that each volcanic episode has distinct differentiation trends, indicating the presence of multiple shallow magma chambers. The close spatial relationship between the geothermal manifestation, geophysical anomalies, geothermal production zones and volcanic edifices supports the presence of multiple shallow magma chambers beneath DVC, which act as a heat source for the existing geothermal system.

  6. Discovery of a Plains Caldera Complex and Extinct Lava Lake in Arabia Terra, Mars: Implications for the Discovery of Additional Highland Volcanic Source Regions (United States)

    Bleacher, Jacob; Michalski, Joseph


    Several irregularly shaped topographic depressions occur near the dichotomy boundary in northern Arabia Terra, Mars. The geomorphology of these features suggests that they formed by collapse, opposed to meteor impact. At least one depression (approx.55 by 85 km) displays geologic features indicating a complex, multi-stage collapse history. Features within and around the collapse structure indicate volcanic processes. The complex occurs within Hesperian ridged plains of likely volcanic origin and displays no crater rim or evidence for ejecta. Instead the depression consists of a series of circumferential graben and down-dropped blocks which also display upper surfaces similar to ridged plain lavas. Large blocks within the depression are tilted towards the crater center, and display graben that appear to have originally been linked with circumferential graben outside of the complex related to earlier collapse events. A nearly 700 m high mound exists along a graben within the complex that might be a vent. The deepest depression displays two sets of nearly continuous terraces, which we interpret as high-stands of a drained lava lake. These features appear similar to the black ledge described during the Kilauea Iki eruption in 1959. A lacustrine origin for the terraces seems unlikely because of the paucity of channels found in or around the depression that could be linked to aqueous surface processes. In addition, there is no obvious evidence for lacustrine sediments within the basin. Together with the presence of significant faulting that is indicative of collapse we conclude that this crater complex represents a large caldera formed in the Late Noachian to Early Hesperian. Other linear and irregular depressions in the region also might be linked to ancient volcanism. If that hypothesis is correct, it suggests that northern Arabia Terra could contain a large, previously unrecognized highland igneous province. Evacuation of magma via explosive and effusive activity

  7. Volcanic Gas (United States)

    ... often escape continuously into the atmosphere from the soil, volcanic vents , fumaroles , and hydrothermal systems. By far the ... after falling into a snow depression surrounding a volcanic fumarole and filled ... of CO 2 gas in soils can also damage or destroy vegetation, as is ...

  8. On the predictability of volcano-tectonic events by low frequency seismic noise analysis at Teide-Pico Viejo volcanic complex, Canary Islands

    Directory of Open Access Journals (Sweden)

    M. Tárraga


    Full Text Available The island of Tenerife (Canary Islands, Spain, is showing possible signs of reawakening after its last basaltic strombolian eruption, dated 1909 at Chinyero. The main concern relates to the central active volcanic complex Teide - Pico Viejo, which poses serious hazards to the properties and population of the island of Tenerife (Canary Islands, Spain, and which has erupted several times during the last 5000 years, including a subplinian phonolitic eruption (Montaña Blanca about 2000 years ago. In this paper we show the presence of low frequency seismic noise which possibly includes tremor of volcanic origin and we investigate the feasibility of using it to forecast, via the material failure forecast method, the time of occurrence of discrete events that could be called Volcano-Tectonic or simply Tectonic (i.e. non volcanic on the basis of their relationship to volcanic activity. In order to avoid subjectivity in the forecast procedure, an automatic program has been developed to generate forecasts, validated by Bayes theorem. A parameter called 'forecast gain' measures (and for the first time quantitatively what is gained in probabilistic terms by applying the (automatic failure forecast method. The clear correlation between the obtained forecasts and the occurrence of (Volcano-Tectonic seismic events - a clear indication of a relationship between the continuous seismic noise and the discrete seismic events - is the explanation for the high value of this 'forecast gain' in both 2004 and 2005 and an indication that the events are Volcano-Tectonic rather than purely Tectonic.

  9. The Mons Rümker volcanic complex of the Moon: A candidate landing site for the Chang'E-5 mission (United States)

    Zhao, Jiannan; Xiao, Long; Qiao, Le; Glotch, Timothy D.; Huang, Qian


    Mons Rümker is a large volcanic complex in Oceanus Procellarum on the Moon and is a candidate landing site for China's Chang'E-5 sample return mission. We conducted a comprehensive study of the topography, geomorphology, composition, and stratigraphy of the Mons Rümker region with multisource remote sensing data in order to better understand the geology of the region and provide further support for the Chang'E-5 mission. The results show that the Rümker plateau stands 200-1300 m above the surrounding mare surface and 75% of the plateau has a slope of less than 3° at a baseline length of 30 m. Domes are the most prominent volcanic landforms in Mons Rümker and a total of 22 domes were identified and divided into two types that may represent different stages of volcanic activity. Spectral analyses indicated that Mons Rümker is covered by low-Ti basalt and the dominant mafic mineral is high-calcium pyroxene, though signs of mixing of highland materials and basalt have been found. Mons Rümker has three main basalt units, and their absolute model ages are 3.71 Ga, 3.58 Ga, and 3.51 Ga, respectively. Steep-sided domes could be the youngest volcanic features on the plateau with indications that they were active until the Eratosthenian. A new geologic map of the study region was produced and used to interpret and discuss the geologic evolution of the region. Finally, we propose two candidate landing sites for the Chang'E-5 mission.

  10. Quaternary volcanism in the Acambay graben, Mexican Volcanic Belt: Re-evaluation for potential volcanic danger in central Mexico (United States)

    Aguirre-Diaz, G. J.; Pedrazzi, D.; Lacan, P.; Roldan-Quintana, J.; Ortuňo, M.; Zuniga, R. R.; Laurence, A.


    The Mexican Volcanic Belt (MVB) is best known for the major active stratovolcanoes, such as Popocatépetl, Citlaltépetl and Colima. The most common stratovolcanoes in this province are modest-size cones with heights of 800 to 1000 m. Examples are Tequila, Sangangüey, Las Navajas, Culiacán, La Joya, El Zamorano, Temascalcingo and Altamirano; these last two were formed within the Acambay Graben in central MVB. The Acambay graben (20 x 70 km) is 100 km to the NW of Mexico City, with E-W trending seismically active normal faults; in particular the Acambay-Tixmadejé fault related to a mB =7 earthquake in 1912. Within the graben there are many volcanic structures, including calderas, domes, cinder cones and stratovolcanoes; Temascalcingo and Altamirano are the largest, with about 800 and 900 m heights, respectively. Temascalcingo is mostly composed of dacitic lavas and block and ash flow deposits. Includes a 3 x 2.5 km summit caldera and a magmatic sector collapse event with the associated debris avalanche deposit. 14C ages of 37-12 ka correspond to the volcano's latest phases that produced pyroclastic deposits. A major plinian eruption formed the San Mateo Pumice with an age of deposits, and pumice fallouts. Morphologically is better preserved than Temascalcingo, and it should be younger. 14C ages of 4.0-2.5 ka were performed in charcoal within pyroclastic flow deposits that apparently were erupted from Altamirano. An undated 3 m thick pumice fallout on the flanks of Altamirano volcano could be also Holocene. It represents a major explosive event. The relatively young ages found in volcanic deposits within the Acambay graben raise the volcanic danger level in this area, originally thought as an inactive volcanic zone. The two major volcanoes, Temascalcingo and Altamirano, should be considered as dormant volcanoes that could restart activity at any time. We thanks grant DGAPA-UNAM-PAPIIT IN-104615.

  11. Evolving metasomatic agent in the Northern Andean subduction zone, deduced from magma composition of the long-lived Pichincha volcanic complex (Ecuador) (United States)

    Samaniego, Pablo; Robin, Claude; Chazot, Gilles; Bourdon, Erwan; Cotten, Joseph


    Geochemical studies of long-lived volcanic complexes are crucial for the understanding of the nature and composition of the subduction component of arc magmatism. The Pichincha Volcanic Complex (Northern Andean Volcanic Zone) consists of: (1) an old, highly eroded edifice, the Rucu Pichincha, whose lavas are mostly andesites, erupted from 1,100 to 150 ka; and (2) a younger, essentially dacitic, Guagua Pichincha composite edifice, with three main construction phases (Basal Guagua Pichincha, Toaza, and Cristal) which developed over the last 60 ka. This structural evolution was accompanied by a progressive increase of most incompatible trace element abundances and ratios, as well as by a sharp decrease of fluid-mobile to fluid-immobile element ratios. Geochemical data indicate that fractional crystallization of an amphibole-rich cumulate may account for the evolution from the Guagua Pichincha andesites to dacites. However, in order to explain the transition between the Rucu Pichincha andesites and Guagua Pichincha dacites, the mineralogical and geochemical data indicate the predominance of magma mixing processes between a mafic, trace-element depleted, mantle-derived end-member, and a siliceous, trace-element enriched, adakitic end-member. The systematic variation of trace element abundances and ratios in primitive samples leads us to propose that the Rucu Pichincha magmas came from a hydrous-fluid metasomatized mantle wedge, whereas Guagua Pichincha magmas are related to partial melting of a siliceous-melt metasomatized mantle. This temporal evolution implies a change from dehydration to partial melting of the slab, which may be associated with an increase in the geothermal gradient along the slab due to the presence of the subducted Carnegie Ridge at the subduction system. This work emphasizes the importance of studying arc-magma systems over long periods of time (of at least 1 million of years), in order to evaluate the potential variations of the slab contribution

  12. Analysis of James Ross Island volcanic complex and sedimentary basin based on high-resolution aeromagnetic data (United States)

    Ghidella, M. E.; Zambrano, O. M.; Ferraccioli, F.; Lirio, J. M.; Zakrajsek, A. F.; Ferris, J.; Jordan, T. A.


    High-resolution aeromagnetic surveys provide a geophysical tool to help image the subsurface structure of volcanoes and their tectonic framework. Here we interpret high-resolution aeromagnetic data and models for James Ross archipelago and surrounding regions to provide a new perspective on Neogene magmatism emplaced along the eastern margin of the Antarctic Peninsula. Based on the analysis and modelling of magnetic anomalies we were able to image the subglacial extent of Miocene to Recent alkaline rocks of the James Ross Island Volcanic Group and map tectonic structures that appear to have exerted important controls on Neogene magmatism. High-amplitude linear anomalies detected over Mount Haddington stratovolcano were modelled as caused by subvertical feeder bodies extending to a depth of at least 3 km. These feeder bodies may have been emplaced along a N-S oriented volcano-tectonic rift zone. We also identified several effusive subglacial centres and imaged two concentric magnetic arcs, which we related to Neogene volcanic and subvolcanic lineaments, likely controlled by Mid-Cretaceous strike-slip fault belts and associated deformation zones. The regional magnetic quiet zone that encompasses James Ross Island is caused by the thick sedimentary infill of the Larsen Basin, and a low-amplitude magnetic high within the basin is inferred to reflect a basement push-up structure associated with strike-slip faulting along the eastern edge of the Antarctic Peninsula. In the offshore regions magnetic anomalies southwest of Tabarin Peninsula and west of Vega Island may reflect recent volcanic structures that have yet to emerge from the sea-floor.

  13. Characterising Complex Ice-Tephra Spatial Feedbacks of Post-Volcanic Eruption Glacial Ablation Using Terrestrial Laser Scanning (United States)

    Vircavs, L.; Nield, J. M.; Chiverrell, R. C.; Darby, S. E.; Leyland, J.; Jacobs, B.


    Volcanic eruptions in glacio-volcanic regions regularly deposit significant quantities of volcanic ash (tephra) over nearby glaciers. This ash debris can remain for decades as it is transported through the system and has the ability to alter surface albedo, thermal insulation and ultimately surface roughness which can significantly modify the glacial response to climate perturbations. We used terrestrial laser scanning (TLS) to measure daily ice-ash surface interactions for a week in July 2011 following tephra fallout from the May 2011 Grímsvötn eruption onto Svínafellsjökull, Iceland. TLS is well suited to process studies and enabled repeat measurements to be collected of ice surface topography and signal absorption at high spatial resolution in three dimensions rather than traditional transect type studies. Our data confirm ablation rates either reduce or increase under thick (insulating) and thin (reduced albedo) ash deposits, respectively. Fourier transform analysis of the TLS data identified that a three-fold increase in aerodynamic roughness was attributable to an increase in larger (>0.2m) surface features. These surface features include micro cryoconite holes, debris cones and meltwater channels. Moreover, the temporal sequence of TLS measurements revealed the importance of ash redistribution by meltwater in generating differential melting which then modifies roughness and ash patchiness, such that the net effect of these spatial ash-ice feedbacks was to reduce ablation rates by up to 59%. This reduction in ablation rates despite increases in temperature and solar radiation was confirmed by manual stake measurements and is the reverse of modelled ablation trends without surficial ash. The modulating effects of these previously undocumented ash-ice feedbacks on ablation rates are, therefore, significant and must be correctly parameterized if ash-covered glacier mass balances are to be predicted correctly.

  14. Seismic characterization of low-magnitude floods and lahars at La Lumbre ravine, Volcán de Colima (Mexico) (United States)

    Coviello, Velio; Capra, Lucia; Márquez, Víctor H.; Procter, Jonathan; Walsh, Braden


    Volcán de Colima currently is the most active volcano in Mexico where a number of rain-induced lahars occur each year. After an explosive phase, lahar frequency increases due to the immediate reworking of pyroclastic material and it progressively decreases in the following years. This behavior was distinctly observed during the two last rainy seasons that followed the intense volcanic activity of July 2015. La Lumbre ravine drains the West-Southwestern slopes of Volcán de Colima and is one of the most active channels of the volcano. Since 2014, monitoring is performed in a heavily instrumented cross-section located at 1580 m a.s.l. on the left bank of the channel. At the present day, the monitoring station is equipped with a raingauge, two stage sensors, a videocamera, and different seismic devices. At La Lumbre, lahars initiate as dilute, sediment-laden stream flows and with the entrainment of additional sediment they evolve into hyper-concentrations and debris flows. The hydro-repellency mechanism of the highly vegetated volcanic soils can explain the high frequency of lahars triggered by low-intensity rainfall events: under these hydrophobic conditions, infiltration is inhibited and runoff is facilitated at less highly peaked discharges that are more likely to initiate lahars that can have an impact on the inhabited areas located downstream. This is the reason why the possibility to detect not only large lahars but also low-magnitude flows is particularly important at La Lumbre. Here we present monitoring data of processes ranging from stream flows to large lahars that occurred during the last rainy seasons along La Lumbre ravine. In particular, we investigate the possibility to estimate the sediment concentration of debris flood and small lahars using a very easy-to-install and low-cost seismic sensor, i.e. a geophone, installed outside the flow path. For instance, we show how a hyper-concentrated flow characterized by a mean velocity of less than 1 meter per

  15. A 2006 earthquakes series at the Colima rift and its relationship to the Rivera-Cocos plate boundary (United States)

    Yamamoto, J.; Jimenez, Z.


    From July 31 through 13 August 2006 a series of fourteen earthquakes (M 3.9 to 6.1) occurred in the western end of the Central Mexican Volcanic Belt (CMVB) in twenty five days period. The most prominent earthquake (Mw 6.1) occurred on 11 August 2006 at 14:30 UTC (9:30 local time) approximately at 18.37° N, 101.25° W and 81 km depth. The epicenter was less than 40 km from Huetamo, Michoacan a 41,250-inhabitant city and 60 km from the El Infiernillo dam embayment the third largest hydroelectric plant in Mexico. This earthquake was widely felt through out the region with minor to moderate reported damage. In Mexico City 250 km away from the epicenter the earthquake, produced alarm among the population and several buildings evacuated. The earthquake series developed into two activity clusters one centered in the coast and separated about 300 km from a second inland cluster. The initial coastal cluster consisted of a nearly linear activity distribution which includes two shallow-depth earthquakes and reverse faulting mechanism with a slight left lateral strike-slip component and a possible fault planes trending roughly east-west. Two normal faulting earthquakes located at the extremes of the graben system, and fault planes oriented in a nearly north-south direction followed. The earthquakes are located approximately between the trench and the coast along the El Gordo-Colima graben system, which has been proposed as the continuation of the diffuse boundary between the Rivera and Cocos plates. The reverse faulting earthquakes are congruent either, with the expected subduction of the Rivera or Cocos plate under the North America plate and the normal faulting earthquake that can be associated to motions in the graben.

  16. New approach on volatile contents determination in silicate melt inclusions: A coupling X-ray microtomography and geochemical approach in Los Humeros caldera complex (Eastern Mexican Volcanic Belt) (United States)

    Creon, L.; Levresse, G.; Carrasco Nuñez, G.


    Volatile contents and magma degassing behavior are known to affect the style, frequency, and intensity of near-surface magmatic processes. For this reason, much effort have been devoted to characterize the volatile evolution of shallow magmatic systems to better constrain volcanic history. Silicate melt inclusions (SMI) represent samples of melt that were isolated from the bulk magma at depth, thus preserving the PTX conditions of the pre-eruptive material. SMI are often affected by the formation of a bubble after trapping; this is a natural consequence of the PVTX properties of crystal-melt-volatile systems. Previous workers have recognized that bubble formation is an obstacle, which affects the interpretation of SMI trapping conditions based only on analysis of the glass phase. Indeed, they explained that bubbles can contain a significant percentage of the volatiles, particularly for those with low solubility in the melt (e.g. CO2). In this study, we propose to define the pre-eruptive PTX conditions of Los Humeros magma chamber using SMI from the various eruption events within 460 and 30 Ka. An innovative analytical coupling has been used in order to determine: (1) the volume of the SMI glass and bubble, using high resolution 3D X-ray microtomography; (2) the density and composition of the bubbles, using Raman spectroscopy; (3) the volatile element contents in glass, using NanoSIMS; and, (4) the major elements composition of the glass, using EPMA. The recalculated volatile concentrations of the total SMI (glass + bubble), illustrate clearly that the volatile content determinations using only the glass phase, underestimate drastically the total volatile content and therefore induce significant error on the determination of the pre-eruptive volcanic budget and on the constrain on the volcanic and thermal history. This study had moreover highlighted the complex evolution of Los Humeros composite magma chamber and, gave constrains for geothermal exploration purpose.

  17. Isotopic cycling in a tropical treeline environment: North American monsoon dynamics at Nevado de Colima, Mexico (United States)

    Hartsough, Peter Christopher

    High elevation sites are especially sensitive to environmental change. One way to get a longer perspective on global change in mountain regions is paleoenvironmental records from tree rings. Data on the response of high elevation species to climatic events is sparse and records used for reconstruction often necessarily come from lower elevation, higher latitude stations. We have set up a unique field site where we are co-monitoring tree growth and weather in real time. In May 2001 we established a monitoring site at 3770m (12,370ft) on Nevado de Colima (19° 34.8'N, 103° 37.3'W) at the western end of the trans-volcanic belt in Southwestern Mexico. The monitoring site consists of an automated weather station and two dendrometer networks for the simultaneous measurement of climate and tree growth parameters. Although we have experienced several equipment setbacks due to the challenging environment, important results relating to growth dynamics and response to climate have surfaced. This field site, near the edge of the tropics, is an important monitoring location for both intra and extra tropical circulation systems. Historical records in the area are of short duration (less than 60 years) so determining the nature of decadal or longer scale fluctuations requires the use of proxy records. Mexican Mountain Pines (Pinus hartwegii Lindl.) growing on Nevado de Colima are under the influence of several large-scale climate features---most notably the North American Monsoon and ENSO. Dendrochronology studies in the region have shown a sensitivity of tree growth to warm season precipitation. The North American Monsoon is still a poorly understood system and an historical perspective is needed for increased confidence in predictive models and forecasting. Careful measurement of tree growth over the five years of the project has led to a clearly defined dormant period over the relatively arid winter. Dendrometer data have shown onset of growth to be closely tied to soil

  18. The Transition From Effusive to Explosive Volcanism, Crustal Recycling and Granitic Plutonism in the Paleocene Sifton Range Complex, Yukon Territory, Canada (United States)

    Miskovic, A.; Francis, D.


    The uplifted plutons of the eastern Coast Plutonic Complex (CPC) of the northern Canadian Cordillera are in contact with coeval volcanic suites of the early Tertiary Sloko-Skukum Group, and offer a unique opportunity for addressing the relationship between continental calc-alkaline volcanic sequences and subduction-related granitoid suites. The Sifton Range complex (SRC) is the Yukon's largest Paleogene erosional remnant (240 km2), comprising 900 m of volcanic stratigraphy, and is intruded by the CPC granites dated at 57.2 Ma. It displays a classic subduction-related geochemical signature with depletions in HFSE relative to LILE. The volcanic rocks range between medium and high-K orogenic suites, and display a transitional calc-alkaline to tholeiitic fractionation trend. The epizonal two-feldspar granites are chemically indistinguishable from the evolved SRC lavas and are characterized by highly elevated LREE (La/Sm N ch = 5-11), and Th (12-18 ppm) concentrations. Furthermore, the complex exhibits a striking relationship between rock compositions and styles of eruption, such that a reduction in abundance of lavas with increasing SiO2 is correlated with the appearance of evolved pyroclastic rocks and granitic plutonism. Crystal fractionation models of the compositional interval between basaltic andesite and andesite (52-62 wt.% SiO2) using the thermodynamic algorithms Melts of Ghiorso and Sack (1995), and Xstaln (Francis) are consistent with evolution at moderately wet (1.5 wt.% H2O), upper crustal (1.5 kb) conditions with fO2 close to the QFM buffer. Two-step, assimilation-fractional crystallization (AFC) models are required to explain the anomalous Th concentrations of the evolved rocks, and involve contamination by the enriched SRC rhyolite of up to 33 % by mass over the dacite range, followed by assimilation of over 150 % by mass beyond rhyodacite compositions (> 67 wt.% SiO2). The unrealistically high contamination parameter (r > 2.5, De Paolo, 1981) of the

  19. 2D resistivity survey in complex geological structure area. Application to the volcanic area; Fukuzatsuna chishitsu kozo chiiki ni okeru hiteiko nijigen tansa. Kazangan chiiki deno tekiorei

    Energy Technology Data Exchange (ETDEWEB)

    Asakawa, S.; Ikuma, T.; Tanifuji, R. [DIA Consultants Co. Ltd., Tokyo (Japan)


    Introduced herein is an application of 2D resistivity survey to a volcanic rock area where the survey result is difficult to interpret because of its complex geological structure. In a dam site survey, main problems involve the permeability of water through faults and weathered, altered zones. At this site, a 2D resistivity survey was conducted, a 2D geological structure was deduced from the resistivity section, and the result was examined. It was found that resistivity distribution was closely related to hydrographic factors, but no obvious correlation was detected between rock classes and R, Q, and D. In conducting investigations into a section planned for a highway tunnel, it was learned that the problem was a volcanic ash layer to collapse instantly upon absorbing water, and the distribution of the ash layer, not to be disclosed by boring, was subjected to a 2D resistivity survey. The survey was conducted into the structure above where the tunnel would run, and further into the face, and studies were made about what layer was reflected by the resistivity distribution obtained by analysis. The result of the analysis agreed with the details of the layer that was disclosed afterward. 4 figs., 1 tab.

  20. Source of the great A.D. 1257 mystery eruption unveiled, Samalas volcano, Rinjani Volcanic Complex, Indonesia. (United States)

    Lavigne, Franck; Degeai, Jean-Philippe; Komorowski, Jean-Christophe; Guillet, Sébastien; Robert, Vincent; Lahitte, Pierre; Oppenheimer, Clive; Stoffel, Markus; Vidal, Céline M; Surono; Pratomo, Indyo; Wassmer, Patrick; Hajdas, Irka; Hadmoko, Danang Sri; de Belizal, Edouard


    Polar ice core records attest to a colossal volcanic eruption that took place ca. A.D. 1257 or 1258, most probably in the tropics. Estimates based on sulfate deposition in these records suggest that it yielded the largest volcanic sulfur release to the stratosphere of the past 7,000 y. Tree rings, medieval chronicles, and computational models corroborate the expected worldwide atmospheric and climatic effects of this eruption. However, until now there has been no convincing candidate for the mid-13th century "mystery eruption." Drawing upon compelling evidence from stratigraphic and geomorphic data, physical volcanology, radiocarbon dating, tephra geochemistry, and chronicles, we argue the source of this long-sought eruption is the Samalas volcano, adjacent to Mount Rinjani on Lombok Island, Indonesia. At least 40 km(3) (dense-rock equivalent) of tephra were deposited and the eruption column reached an altitude of up to 43 km. Three principal pumice fallout deposits mantle the region and thick pyroclastic flow deposits are found at the coast, 25 km from source. With an estimated magnitude of 7, this event ranks among the largest Holocene explosive eruptions. Radiocarbon dates on charcoal are consistent with a mid-13th century eruption. In addition, glass geochemistry of the associated pumice deposits matches that of shards found in both Arctic and Antarctic ice cores, providing compelling evidence to link the prominent A.D. 1258/1259 ice core sulfate spike to Samalas. We further constrain the timing of the mystery eruption based on tephra dispersal and historical records, suggesting it occurred between May and October A.D. 1257.

  1. Enterprises and entrepreneurs in Colima and Villa de Alvarez: A paradox or Schumpeter anti law

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    Juan González García


    Full Text Available On the basis of the Schumpeterian conception about the characteristics of the innovating entrepreneur, this article offers a general explanation for the weak economic performance followed by the small firm sector within the municipalities of Colima and Villa de Alvarez. The analysis, which considers entrepreneurship as the main variable of explanation, suggests that the small firms have few Schumpeterian characteristics, while prevails a low propensity to innovate and compete, and a high risk aversion.

  2. The ash-fall hazard from a Plinian eruption at Colima Volcano, Mexico

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    Rita Fonseca


    Full Text Available The historical eruptive activity at Colima Volcano has been characterized by Strombolian and Merapi type eruptions and Vulcanian explosions associated with dome growth, which have ended in a Plinian eruption about every 100 years. The situation now prevailing at Colima Volcano is similar to that which preceded these explosive eruptions, when a dome fills the crater. This study proposes seven scenarios for the ash-fall from a Plinian eruption, based on historical eruptive activity, isopach thickness from the 1913 Plinian eruption, land use, socioeconomic data, and a 15-year statistical wind study realized with daily radiosonde data grouped according to four altitudinal levels: 4,000-9,000 (I; 9,000-14,000 (II; 14,000-17,000 (III and 17,000-28,000 (IV m a.s.l., based on common wind speeds and directions. We have integrated the wind distribution at level IV and estimated the ash dispersion for a Plinian eruption. From January to March, the main impact would be towards the northeast, in April and in October, towards the east, in May, towards the north-northeast or north-northwest, from June to August, towards the northwest, in September, towards the west, and in November and December, towards the west-southwest. The fallout would damage the coniferous forests of the Colima National Park, two lagoons and three lakes. More than 30 million people living in Guadalajara, Mexico City, Leon and Colima would suffer eye, respiratory and skin problems. The proximal areas, such as Ciudad Guzman, would be subject to roof collapsing and communication problems. The agricultural and livestock sectors would suffer severe financial losses. The Queseria sugar mill, the Atenquique paper mill, and the cement plants in Zapotiltic would halt work due to chimney obstruction and machinery abrasion. Four thermoelectric plants, twenty airports and four commercial ports would be affected if the eruption occurs in summer.

  3. Strong interseismic coupling, fault afterslip, and viscoelastic flow before and after the Oct. 9, 1995 Colima-Jalisco earthquake: continuous GPS measurements from Colima, Mexico (United States)

    Azua, B.M.; DeMets, C.; Masterlark, Timothy


    Continuous GPS measurements from Colima, Mexico during 4/93-6/01, bracketing the Oct. 9, 1995 M = 8.0 Colima-Jalisco earthquake, provide new constraints on Rivera plate subduction mechanics. Modeling of margin-normal strain accumulation before the earthquake suggests the Rivera-North America subduction interface was fully locked. Transient postseismic motion from 10/ 95-6/97 is well fit by a model that includes logarithmically-decaying fault afterslip, elastic strain from shallow fault relocking, and possibly a minor viscoelastic response, but is fit poorly by models that assume a dominant Maxwell viscoelastic response of the lower crust and upper mantle, independent of the assumed viscosities. Landward, margin-normal motion since mid-1997 is parallel to but ??? 75% slower than the pre-seismic velocity. Afterslip alone fails to account for this slowdown. The viscoelastic response predicted by a FEM correctly resolves the remaining velocity difference within the uncertainties. Both processes thus offset elastic strain accumulating from the relocked subduction interface.

  4. Three thousand years of flank and central vent eruptions of the San Salvador volcanic complex (El Salvador) and their effects on El Cambio archeological site: a review based on tephrostratigraphy (United States)

    Ferrés, D.; Delgado Granados, H.; Hernández, W.; Pullinger, C.; Chávez, H.; Castillo Taracena, C. R.; Cañas-Dinarte, C.


    The volcanic events of the last 3,000 years at San Salvador volcanic complex are reviewed using detailed stratigraphic records exposed in new excavations between 2005 and 2007, at El Cambio archeological site (Zapotitán Valley, El Salvador), and in other outcrops on the northern and northwestern sectors of the complex. The sequences that overlie Tierra Blanca Joven (cal. 429 ± 107 ad), from the Ilopango caldera, comprise the Loma Caldera (cal. 590 ± 90 ad) and El Playón (1658-1671) deposits and the San Andrés Tuff (cal. 1031 ± 29 ad), related to El Boquerón Volcano. The surge deposits within the El Playón, San Andrés Tuff and overlying Talpetate II sequences indicate the significance of phreatomagmatic phases in both central vent and flank eruptions during the last 1,600 years. Newly identified volcanic deposits underlying Tierra Blanca Joven at El Cambio extend the stratigraphic record of the area to 3,000 years bp. Paleosols interstratified with those deposits contain cultural artifacts which could be associated with the Middle Preclassic period (900-400 bc). If correct, human occupation of the site during the Preclassic period was more intense than previously known and volcanic eruptions must have affected prehistoric settlements. The archeological findings provide information on how prehistoric populations dealt with volcanic hazards, thousands of years ago in the eastern Zapotitán Valley, where several housing projects are currently being developed. The new stratigraphic and volcanological data can be used as a basis for local and regional hazard assessment related to future secondary vent activity in the San Salvador Volcanic Complex.

  5. Subvolcanic contact metasomatism at El Laco Volcanic Complex, Central Andes Metasomatismo de contacto subvolcánico en el Complejo Volcánico El Laco, Andes centrales

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    José A Naranjo


    Full Text Available Studies of drill cores from the Pasos Blancos area at El Laco in the central Andes, northern Chile, give evidence of an intense and extensive subvolcanic contact-metasomatic process. This process resulted from shallow-level emplacement of very volatile-rich iron-oxide magma, with discharge of volatiles that resulted in extensive fracturing of overlying volcanic rocks. The brecciated rocks were altered (mainly extensive scapolitization and formation of pyroxene by hot magmatic fluids emitted from the cooling intrusion , and accompanied by magnetite deposition. With time and decreasing temperature, the metasomatic fluids evolved to fluids of hydrothermal character, and a final recent geothermal event took place that deposited superficial gypsum over a large part of the El Laco Volcanic Complex.Estudios realizados en testigos de sondajes en el area de Pasos Blancos en El Laco, en los Andes Centrales del norte de Chile, dan evidencias de un intenso y extenso proceso subvolcánico de metasomatismo de contacto. Este proceso es el resultado de un emplazamiento a poca profundidad de un magma de óxido de fierro muy rico en volátiles y cuya descarga de gases produjo un intenso fracturamiento de las rocas sobrepuestas. Las rocas brechizadas fueron alteradas (principalmente una extensa escapolitización y formación de piroxeno, junto con la depositación de magnetita, por los fluidos magmáticos calientes emitidos por la intrusión durante su enfriamiento. Los fluidos metasomáticos evolucionaron en el tiempo y con la disminución de temperatura, a fluidos de carácter hidrotermal y finalmente tuvo lugar un evento geotérmico reciente, el cual depositó yeso superficial en gran parte del Complejo Volcánico El Laco.

  6. Volcanic gas (United States)

    McGee, Kenneth A.; Gerlach, Terrance M.


    In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

  7. Microeconomic analysis of the demand of tortilla in the towns of Colima and Villa de Alvarez in the State of Colima

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    Juan Manuel Sánchez Vázquez


    Full Text Available After the increase in the demand for corn to produce ethanol last year, the international price of corn went up by 65%, which in turn made the tortilla price to go up between 40% and 100%. In response, both the federal and local governments triggered urgent actions to keep prices from increasing and affecting poor people. The purpose of this paper is to determine the factors that compose the demand function of tortilla. In addition, we want to specify the effect of a change in each of those factors. In particular, we wish to find out the effect of a price change in the consumption of tortilla. We conclude that in Colima- Villa de Álvarez the demand for tortilla has almost null price-demand elasticity. The main reason is that the tortilla is an inferior good in the sense that a price increase affects more to poor families than to rich ones.

  8. Transmisión interepidémica del dengue en la ciudad de Colima, México Interepidemic transmission of dengue in Colima City, Mexico

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    Francisco Espinoza-Gómez


    Full Text Available OBJETIVO: Determinar la presencia de dengue interepidémico en una comunidad infestada por Aedes aegypti, y analizar sus características epidemiológicas. MATERIAL Y MÉTODOS: Entre 2001 y 2002 se realizó un estudio probabilístico longitudinal en 245 habitantes de la ciudad de Colima, México. En cada caso se registraron: edad, sexo, nivel socioeconómico, cuadro clínico sugestivo de dengue, y se buscó la presencia de IgG e IgM antidengue por inmunocromatografía rápida y por ELISA, en un seguimiento de siete meses. Los datos se analizaron mediante tablas de contingencia y regresión de Poisson univariada. RESULTADOS: Doce individuos resultaron con infección reciente (incidencia de 1.77%; IC 95%: 0.9-3.1%, ocho de ellos refirieron cuadro clínico reciente (ji2=19.6; p=0.0001, RM: 19.6. La regresión de Poisson no reveló correlación de la infección reciente con edad, sexo, ni con nivel socioeconómico. CONCLUSIONES: En comunidades infestadas por A aegypti, como Colima, pueden ocurrir infecciones continuas por dengue sin epidemia aparente. Dichas infecciones no parecen asociarse con la edad, el sexo, ni con el nivel socioeconómico, pero sí con el cuadro clínico, el cual podría considerarse como indicador precoz de posible transmisión interepidémica.OBJECTIVE: To determine the occurrence of interepidemic dengue in a community infested with Aedes aegypti and to analyze its epidemiologic characteristics. MATERIAL AND METHODS: A longitudinal probabilistic study was carried out in Colima City between 2001 and 2002. The sample population consisted of 245 subjects. The following were recorded for each subject: sex, age, socio-economic level and dengue fever symptoms, testing for serum IgG and IgM antidengue, using quick immunochromatography as well as ELISA tests, in a seven-month follow-up period. RESULTS: Twelve individuals showed recent dengue infection (incidence: 1.77%; 95%: confidence interval 0.9-3.1%. Of these, eight had recent

  9. The Colima Volcano Database: an online tool for a global data access (United States)

    Capra, L.; Manea, M.; Manea, V.; Norini, G.


    The Colima Volcano is currently the most active Mexican volcano. After the 1913 plinian activity, the volcano presented scattered eruptive phases that lasted few years each, but since 1991 its activity became more persistent, with vulcanian eruptions, and extrusion of lava flows and domes. During the last 15 years the volcano suffered several eruptive episodes, as in 1991, 1994, 1998-1999, 2001-2003, 2004 and 2005, with the emplacement of pyroclastic flows. During rain seasons lahars are frequently affecting several infrastructures such as bridges and electric towers. Researchers from different institutions are currently working on several key aspects of the volcano, as remote sensing, field data of old and recent volcaniclastic deposits, structural framework, monitoring (rainfall data and visual observation of lahars), and laboratory experiment (analogue models and numerical simulations). Each investigation is focused on specific processes, but it is fundamental to visualize the global status of the volcano in order to understand its behavior and to mitigate future hazards. The Colima Volcano Database represents an initiative aimed to collect, on a systematic basis, the complete set of data obtained so far on the volcano, and to continuously update the database with new data. All the information is compiled from published works and updated frequently. All maps (such as the geological map of the volcano and the hazard zonations compiled from previous works) and point data (such as stratigraphic sections, sedimentology and diagrams of rainfall intensities) can be viewed with Google Earth and is really straightforward to be access by the scientific community and the general public. In this format everyone with Internet access can view the information and zoom to the scale they wish. The WebGIS is hosted on the Computational Geodynamics Laboratory web server and it is based entirely on Open Source software. The website can be visited at:

  10. Concesiones, explotación minera y conflicto en la frontera Jalisco-Colima


    Hirineo Martínez Barragán


    El presente trabajo constituye un avance del estado de la cuestión de la minería: la legislación, la producción, los beneficios y las afectaciones, en particular dentro de la frontera entre Cuautitlán de García Barragán, Jalisco, y Minatitlán, Colima. El trabajo resulta relevante porque la explotación minera en México ha crecido de manera exponencial en los últimos años, y tras ello ha dejado poblados enteros afectados en sus propiedades agrarias, e...

  11. Volcanic Catastrophes (United States)

    Eichelberger, J. C.


    The big news from 20th century geophysics may not be plate tectonics but rather the surprise return of catastrophism, following its apparent 19th century defeat to uniformitarianism. Divine miracles and plagues had yielded to the logic of integrating observations of everyday change over time. Yet the brilliant interpretation of the Cretaceous-Tertiary Boundary iridium anomaly introduced an empirically based catastrophism. Undoubtedly, decades of contemplating our own nuclear self-destruction played a role in this. Concepts of nuclear winter, volcanic winter, and meteor impact winter are closely allied. And once the veil of threat of all-out nuclear exchange began to lift, we could begin to imagine slower routes to destruction as "global change". As a way to end our world, fire is a good one. Three-dimensional magma chambers do not have as severe a magnitude limitation as essentially two-dimensional faults. Thus, while we have experienced earthquakes that are as big as they get, we have not experienced volcanic eruptions nearly as great as those preserved in the geologic record. The range extends to events almost three orders of magnitude greater than any eruptions of the 20th century. Such a calamity now would at the very least bring society to a temporary halt globally, and cause death and destruction on a continental scale. At maximum, there is the possibility of hindering photosynthesis and threatening life more generally. It has even been speculated that the relative genetic homogeneity of humankind derives from an evolutionary "bottleneck" from near-extinction in a volcanic cataclysm. This is somewhat more palatable to contemplate than a return to a form of Original Sin, in which we arrived at homogeneity by a sort of "ethnic cleansing". Lacking a written record of truly great eruptions, our sense of human impact must necessarily be aided by archeological and anthropological investigations. For example, there is much to be learned about the influence of

  12. Reconstructing the paleo-topography and paleo-environmental features of the Sarno River plain (Italy) before the AD 79 eruption of Somma-Vesuvius volcanic complex (United States)

    Vogel, Sebastian; Märker, Michael


    SSP1.4 Understanding mixed siliciclastic-volcaniclastic depositional systems and their relationships with geodynamics or GD2.3/CL4.14/GM5.8/MPRG22/SSP3.5 Reconstruction of ancient continents: Dating and characterization of paleosurfaces Reconstructing the paleo-topography and paleo-environmental features of the Sarno River plain (Italy) before the AD 79 eruption of Somma-Vesuvius volcanic complex Sebastian Vogel[1] & Michael Märker[1] [1] Heidelberg Academy of Sciences and Humanities c/o University of Tübingen, Rümelinstraße 19-23, D-72070 Tübingen, Germany. Within the geoarchaeological research project "Reconstruction of the Ancient Cultural Landscape of the Sarno River Plain" undertaken by the German Archaeological Institute in cooperation with the Heidelberg Academy of Sciences and Humanities/University of Tübingen a methodology was developed to model the spatial dispersion of volcanic deposits of Somma-Vesuvius volcanic complex since its Plinian eruption AD 79. Eventually, this was done to reconstruct the paleo-topography and paleo-environment of the Sarno River plain before the eruption AD 79. We collected, localized and digitized more than 1,800 core drillings to gain a representative network of stratigraphical information covering the entire plain. Besides other stratigraphical data including the characteristics of the pre-AD 79 stratum, the depth to the pre-AD 79 paleo-surface was identified from the available drilling documentation. Instead of applying a simple interpolation of the drilling data, we reconstructed the pre-AD 79 paleo-surface with a sophisticated geostatistical methodology using a machine based learning approach based on classification and regression trees. We hypothesize that the present-day topography reflects the ancient topography, because the eruption of AD 79 coated the ancient topography, leaving ancient physiographic elements of the Sarno River plain still recognizable in the present-day topography. Therefore, a high resolution

  13. Anatomy of a deep crustal volcanic conduit system; The Reinfjord Ultramafic Complex, Seiland Igneous Province, Northern Norway (United States)

    Grant, Thomas B.; Larsen, Rune B.; Anker-Rasch, Lars; Grannes, Kim Rune; Iljina, Markku; McEnroe, Suzanne; Nikolaisen, Even; Schanche, Mona; Øen, Endre


    The Reinfjord Ultramafic Complex, Seiland Igneous Province represents a lower crustal magma chamber (25-30 km depth) that likely records a deep conduit system for mantle derived melts ascending through the continental crust. It consists of cumulates of dunite, wehrlite, olivine clinopyroxene as well as subordinate lherzolite and websterites, intruded into gabbro-norite and metasediment gneisses. Field, petrographic and geochemical data show that the intrusion developed through fractional crystallization and interactions between new batches of magma and partially solidified cumulates. This resulted in a 'reverse fractionation sequence' whereby cumulates became progressively more MgO and olivine rich with time. Contamination by partial melting of the gabbro-norite is evident in the marginal zones, but is limited in the central parts of the intrusion. Interrupted crystallization sequences of olivine → olivine + clinopyroxene and the absence of significant amounts of more evolved melts, suggests that large volumes of melt passed through the system to shallower levels in the crust leaving behind the cumulate sequences observed at Reinfjord. Therefore, the Reinfjord Ultramafic Complex represents a deep crustal conduit system, through which mantle derived melts passed. The parent melts are likely to have formed from partial melting of mantle with residual garnet and clinopyroxene.

  14. Polybaric melting of a single mantle source during the Neogene Siverek phase of the Karacadaǧ Volcanic Complex, SE Turkey (United States)

    Ekici, Taner; Macpherson, Colin G.; Otlu, Nazmi


    Siverek plateau basalts represent the Neogene activity of the Karacadağ Volcanic Complex in southeast Turkey and can be divided into two groups based on incompatible element concentrations. Group 1 is largely basaltic, containing some alkali basalts, while Group 2 consists of alkali basalts, trachybasalts and tephrites. The lavas display a range in major element concentrations that are consistent with restricted amounts of differentiation in the crust. Melts from both groups have experienced variable, small amounts of interaction with crustal rocks, which is responsible for most of the isotopic heterogeneity and caused significant Ba-enrichment. Neither fractional crystallisation nor crustal contamination can account for the differences in trace element enrichment observed between the two groups. Group 1 is derived mainly from the spinel lherzolite field by > 1% partial melting. Group 2 lavas were derived from very similar mantle but by smaller degrees of melting and contain a larger relative contribution from garnet-lherzolite. The Siverek plateau lavas are indistinguishable from contemporaneous magmatism in the Karasu Valley of southern Turkey and in northernmost Syria. Together, these plateau basalt fields represent mantle upwelling and melting beneath the thinned and/or weakened Arabian Plate as it migrated northwards during the Neogene.

  15. Multiple rhyolite magmas and basalt injection in the 17.7 ka Rerewhakaaitu eruption episode from Tarawera volcanic complex, New Zealand (United States)

    Shane, Phil; Martin, S. B.; Smith, V. C.; Beggs, K. F.; Darragh, M. B.; Cole, J. W.; Nairn, I. A.


    The 17.7 ka Rerewhakaaitu eruption episode (volume ˜ 5 km 3 DRE rhyolite magma) was the second of five major episodes that have built the Tarawera volcanic complex in the Okataina Volcanic Centre over the past 22 kyr. The Rerewhakaaitu episode produced a widespread tephra fall deposit, associated proximal pyroclastic flow deposits, and voluminous rhyolite lava extrusions. Two different rhyolite magmas (T1 and T2) were simultaneously erupted from the main vent area throughout much of the eruption episode. T1 magma was a crystal-poor orthopyroxene-hornblende rhyolite that is highly evolved (whole rock SiO 2 = 77 wt.%), with a moderate temperature (˜ 760 °C, based on Fe-Ti oxides). T2 is a crystal-rich biotite-hornblende rhyolite that is less evolved (SiO 2 = 75 wt.%), with a Fe-Ti oxide temperature of ˜ 700 °C. Ejecta from the simultaneous and sequential eruption of these two magmas include some pumice clasts with mixed (hybrid) and mingled glass compositions and crystal populations. A third rhyolite magma (T3) was extruded from another vent 3 km distant to form an apparently contemporaneous lava dome. T3 was the least evolved (SiO 2 = 74 wt.%) and hottest (˜ 820 °C) of the three magmas. Saturation pressures calculated using dissolved H 2O and CO 2 contents of melt inclusions in quartz crystals indicate that T2 magma stagnated and crystallised at about 12 km depth, while small quartz crystals in T1 magma grew during ascent through ˜ 8 km depths. Some T1 and T2 rhyolite clasts contain vesicular brown blebs with widely variable (andesite to rhyolite) glass compositions, accompanied by olivine, clinopyroxene and calcic plagioclase crystals that are interpreted as xenocrysts derived from injected basalt. Temperatures over 1000 °C estimated from pyroxene phase equilibria in these clasts reflect intrusion of the more mafic magma, which is now identified as the priming and triggering mechanism for three of the four post-22 ka Tarawera rhyolite eruption episodes

  16. Phenocryst complexity in andesites and dacites from the Tequila volcanic field, Mexico: resolving the effects of degassing vs. magma mixing (United States)

    Frey, Holli M.; Lange, Rebecca A.


    The petrology of five phenocryst-poor (2-5%) andesites and dacites, all of which were erupted from different short-lived, monogenetic vents, is compared to that of phenocryst-rich (10-25%) andesites erupted from the adjacent stratovolcano, Volcán Tequila, in the Mexican arc. Despite differences in phenocryst abundances, these magmas have comparable phase assemblages (plagioclase + orthopyroxene + titanomagnetite + ilmenite + apatite ± augite ± hornblende), and similarly wide variations in phenocryst compositions, coupled to complex zoning patterns. For the phenocryst-poor lavas, equilibrium pairs of two Fe-Ti oxides lead to a narrow range of calculated temperatures for each sample that range from 934 (±24) to 1,073 (±6)°C and oxygen fugacities that range from +0.1 to +0.7 log units relative to the Ni-NiO buffer. Application of the plagioclase-liquid hygrometer to each sample at these calculated temperatures leads to maximum melt water concentrations of 4.6-3.1 wt% during plagioclase crystallization, indicating that the magmas were fluid saturated at depths ≥6.4-4.5 km. There is a wide, continuous range in the composition of plagioclase (≤44 mol% An) and orthopyroxene (≤16% Mg#) phenocrysts in each sample, which is consistent with a loss of dissolved water (≤2.8 wt%) from the melt phase during degassing as the magmas ascended rapidly to the surface. Evidence is presented that shows the effect of dissolved water is to reduce the activity of MgO relative to FeO in the melt phase, which indicates that degassing will also affect the Mg# of pyroxene phenocrysts, with higher melt water concentrations favoring Fe-rich pyroxene. Both plagioclase and orthopyroxene commonly display diffusion-limited growth textures (e.g., skeletal and hopper crystals, large interior melt hollows, and swallow tails), which are consistent with large undercoolings produced by degassing-induced crystallization. Therefore, degassing is proposed as a possible cause for the phenocryst

  17. Decoding magma plumbing and geochemical evolution beneath the Lastarria volcanic complex (Northern Chile)-Evidence for multiple magma storage regions (United States)

    Stechern, André; Just, Tobias; Holtz, François; Blume-Oeste, Magdalena; Namur, Olivier


    The petrology of quaternary andesites and dacites from Lastarria volcano was investigated to reconstruct the magma plumbing and storage conditions beneath the volcano. The mineral phase compositions and whole-rock major and trace element compositions were used to constrain temperature, pressure and possible mechanisms for magma differentiation. The applied thermobarometric models include two-pyroxene thermobarometry, plagioclase-melt thermometry, amphibole composition thermobarometry, and Fe-Ti oxide thermo-oxybarometry. The overall temperature estimation is in the range 840 °C to 1060 °C. Calculated oxygen fugacity ranges between NNO to NNO + 1. Results of the geo-barometric calculations reveal multiple magma storage regions, with a distinct storage level in the uppermost crust ( 6.5-8 km depth), a broad zone at mid-crustal levels ( 10-18 km depth), and a likely deeper zone at intermediate to lower crustal levels (> 20 km depth). The highest temperatures in the range 940-1040 °C are recorded in minerals stored in the mid-crustal levels ( 10-18 km depth). The whole-rock compositions clearly indicate that magma mixing is the main parameter controlling the general differentiation trends. Complex zoning patterns and textures in the plagioclase phenocrysts confirm reheating and remobilization processes due to magma replenishment.

  18. Recording the transition from flare-up to steady-state arc magmatism at the Purico-Chascon volcanic complex, northern Chile (United States)

    Burns, Dale H.; de Silva, Shanaka L.; Tepley, Frank; Schmitt, Axel K.; Loewen, Matthew W.


    The long-term evolution of continental magmatic arcs is episodic, where a few transient events of high magmatic flux or flare-ups punctuate the low-flux magmatism or "steady state" that makes up most of the arc history. How this duality manifests in terms of differences in crustal architecture, magma dynamics and chemistry, and the time scale over which transitions occur is poorly known. Herein we use multiscale geochemical and isotopic characteristics coupled with geothermobarometry at the Purico-Chascon Volcanic Complex (PCVC) in the Central Andes to identify a transition from flare-up to steady state arc magmatism over ∼800 kyr during which significant changes in upper crustal magmatic dynamics are recorded. The PCVC is one of the youngest volcanic centers related to a 10-1 Ma ignimbrite flare-up in the Altiplano-Puna Volcanic Complex of the Central Andes. Activity at the PCVC initiated 0.98 ± 0.03 Ma with the eruption of a large 80-100 km3 crystal-rich dacite ignimbrite. High, restricted 87Sr/86Sr isotope ratios between 0.7085 and 0.7090 in the bulk rock and plagioclase crystals from the Purico ignimbrite, combined with mineral chemistry and phase relationships indicate the dacite magma accumulated and evolved at relatively low temperatures around 800-850 °C in the upper crust at 4-8 km depth. Minor andesite pumice erupted late in the ignimbrite sequence records a second higher temperature (965 °C), higher pressure environment (17-20 km), but with similar restricted radiogenic bulk rock 87Sr/86Sr = 0.7089-0.7091 to the dacites. The compositional and isotopic characteristics of the Purico ignimbrite implicate an extensive zone of upper crustal mixing, assimilation, storage and homogenization (MASH) between ∼30 and 4 km beneath the PCVC ∼1 Ma. The final eruptions at the PCVC host lava of Cerro Chascon, the largest of the domes, record two distinct magmatic environments; an upper crustal environment identical to that recorded in the Purico ignimbrite, and

  19. Monogenetic volcanic hazards and assessment (United States)

    Connor, C.; Connor, L. J.; Richardson, J. A.


    Many of the Earth's major cities are build on the products of monogenetic volcanic eruptions and within geologically active basaltic volcanic fields. These cities include Mexico City (Mexico), Auckland (New Zealand), Melbourne (Australia), and Portland (USA) to name a few. Volcanic hazards in these areas are complex, and involve the potential formation of new volcanic vents and associated hazards, such as lava flows, tephra fallout, and ballistic hazards. Hazard assessment is complicated by the low recurrence rate of volcanism in most volcanic fields. We have developed a two-stage process for probabilistic modeling monogenetic volcanic hazards. The first step is an estimation of the possible locations of future eruptive vents based on kernel density estimation and recurrence rate of volcanism using Monte Carlo simulation and accounting for uncertainties in age determinations. The second step is convolution of this spatial density / recurrence rate model with hazard codes for modeling lava inundation, tephra fallout, and ballistic impacts. A methodology is presented using this two-stage approach to estimate lava flow hazard in several monogenetic volcanic fields, including at a nuclear power plant site near the Shamiram Plateau, a Quaternary volcanic field in Armenia. The location of possible future vents is determined by estimating spatial density from a distribution of 18 mapped vents using a 2-D elliptical Gaussian kernel function. The SAMSE method, a modified asymptotic mean squared error approach, uses the distribution of known eruptive vents to optimally determine a smoothing bandwidth for the Gaussian kernel function. The result is a probability map of vent density. A large random sample (N=10000) of vent locations is drawn from this probability map. For each randomly sampled vent location, a lava flow inundation model is executed. Lava flow input parameters (volume and average thickness) are determined from distributions fit to field observations of the low

  20. The Colima Volcano WebGIS: system acquisition, application and database development in an open-source environment (United States)

    Manea, M.; Norini, G.; Capra, L.; Manea, V. C.


    The Colima Volcano is currently the most active Mexican volcano. After the 1913 plinian activity the volcano presented several eruptive phases that lasted few years, but since 1991 its activity became more persistent with vulcanian eruptions, lava and dome extrusions. During the last 15 years the volcano suffered several eruptive episodes as in 1991, 1994, 1998-1999, 2001-2003, 2004 and 2005 with the emplacement of pyroclastic flows. During rain seasons lahars are frequent affecting several infrastructures such as bridges and electric towers. Researchers from different institutions (Mexico, USA, Germany, Italy, and Spain) are currently working on several aspects of the volcano, from remote sensing, field data of old and recent deposits, structural framework, monitoring (rain, seismicity, deformation and visual observations) and laboratory experiments (analogue models and numerical simulations). Each investigation is focused to explain a single process, but it is fundamental to visualize the global status of the volcano in order to understand its behavior and to mitigate future hazards. The Colima Volcano WebGIS represents an initiative aimed to collect and store on a systematic basis all the data obtained so far for the volcano and to continuously update the database with new information. The Colima Volcano WebGIS is hosted on the Computational Geodynamics Laboratory web server and it is based entirely on Open Source software. The web pages, written in php/html will extract information from a mysql relational database, which will host the information needed for the MapBender application. There will be two types of intended users: 1) researchers working on the Colima Volcano, interested in this project and collaborating in common projects will be provided with open access to the database and will be able to introduce their own data, results, interpretation or recommendations; 2) general users, interested in accessing information on Colima Volcano will be provided

  1. Study Programme On Contemporary Cultures In Colima, Mexico. Shortcuts And Long Ways Round To Plenitude

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    Jesús Galindo Cáceres


    Full Text Available El texto presenta la historia aparentemente irrepetible del Programa de Estudios sobre las Culturas Contemporáneas de Colima, México. El autor presenta a lo largo de seis distintos apartados un relato que relaciona elementos de trayectorias individuales, grupales y colectivas, con una historia de la ciencia social en México a lo largo de más de tres décadas. El Programa Cultura fue posible por una combinación de accidentes y visiones luminosas. Emergió en el medio con menos condiciones posibles para un proyecto de altos estudios, desde ahí creció, se desarrolló, llegó a su plenitud, y después decayó y se fue retrayendo a la inercia de la vida institucional universitaria común. Esta es la historia de un programa de investigación ejemplar, una historia para ser conocida, disfrutada, y divulgada. This work describes the seemingly unrepeatable story of the Study Programme on Contemporary Cultures in Colima, Mexico. In six sections, the author describes the relation between individual, group and collective paths in a Mexican social science narrative spanning more than three decades. The Programa Cultura [Culture Programme] was made possible thanks to a combination of coincidences and brilliant visions. Despite the precarious conditions for conducting a top research project, It came into being, developed, and reached its plenitude, before flagging and falling victim of the inertia of everyday institutional life at university. This is the story of an exemplary research programme, a story that should be known, enjoyed and disseminated.

  2. Riqueza y biogeografía de la flora arbórea del estado de Colima, México Tree flora richness and biogeography of the State of Colima, Mexico

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    Eloy Padilla-Velarde


    Full Text Available Con base en la revisión de obras taxonómico-florísticas, ejemplares de los herbarios IBUG, IEB, MEXU y ZEA y la colecta de 800 ejemplares botánicos, se registran 92 familias, 285 géneros y 550 especies de plantas arbóreas para el estado de Colima. Las familias mejor representadas a nivel de género y especie son Fabaceae (42 y 115, respectivamente, Euphorbiaceae (19 y 36 y Rubiaceae (13 y 23. Los géneros con mayor número de especies son Quercus (22, Bursera (19, Ficus (12, Lonchocarpus (11 y Senna (11. Únicamente 3 especies son endémicas de Colima, mientras que 22 se comparten sólo con otro estado (21 especies con Jalisco y otra con Michoacán. Un 43.4% están restringidas al territorio mexicano y 40.2% son de amplia distribución. El 56.6% de las especies se encuentran en un solo tipo de vegetación, destacando por su grado de restricción (37.7% y número de especies (66.8%, el bosque tropical caducifolio. Un total de 33 especies se encuentra bajo alguna categoría de riesgo; el 64% han sido localizadas dentro de la Reserva de la Biosfera Sierra de Manantlán, cuyo territorio se comparte entre Colima y Jalisco. Se aportan recomendaciones específicas para realizar exploraciones florísticas y acciones de conservación para la flora arbórea de Colima.As a result of the revision of taxonomic publications, herbaria specimens (IBUG, IEB, MEXU y ZEA, and field work (800 specimens collected, we register 92 families, 285 genera, and 550 tree species in the State of Colima. The families with more genera and species are Fabaceae (42 and 115, respectively, Euphorbiaceae (19 and 36, and Rubiaceae (13 and 23. The richest genera are Quercus (22, Bursera (19, Ficus (12, Lonchocarpus (11, and Senna (11. We found that only 3 species are endemic of Colima and 22 species are shared only with another state (21 with Jalisco and one with Michoacan. A total of 43.4% species are endemic to Mexico and 40.2% are widely distributed. 56.6% of the species are

  3. The Eruptive History of the Talpa-Mascota-San Sebastian Volcanic Field in Western Mexico. (United States)

    Ownby, S.; Lange, R.; Carmichael, I. S.; Hall, C.


    The eruptive history of the Talpa-Mascota-San Sebastian (TMSS) volcanic field in the Jalisco Block (JB) of western Mexico is presented. The JB is bounded by the Tepic-Zacoalco and Colima grabens, as well as the Middle America Trench where the Rivera plate subducts beneath North America. The TMSS volcanic field spans ˜2030 km2 and contains ˜123 small cones and flows of minette, absarokite, basic hornblende lamprophyre, basaltic andesite, and andesite. The petrology of these lavas is described in Lange and Carmichael (1990, 1991) and Carmichael et al. (1996). Of the ˜123 distinguishable eruptive units within this volcanic field, 26 samples have been dated by the 40Ar/39Ar method, and are combined with 10 dates from a previous abstract and nine dates from the literature (for a total of 45). The oldest lavas (2.35 to 0.5 Ma) are found in the Talpa region, whereas the youngest lavas (predominantly Mexico. These age results confirm that the potassic lavas of Mascota (not unlike those erupted 3-4 Myr ago in the Sierra Nevada batholith; Farmer et al., 2002) are part of line of similar volcanism that youngs to the N-NW. The Los Volcanes field was active from 3.4-1.5 Myr ago (Wallace and Carmichael, 1992), whereas two dates from the Ayutla volcanic field give ages of 4.4 and 4.5 Ma (Righter and Rosas-Elguera, 2001). It thus appears that this line of potassic volcanism within the interior of the Jalisco block is not a coeval "volcanic front", which raises the possibility that it may not be directly related to active subduction of the Rivera plate.

  4. Evidence for different processes of magma evolution in El Tatio volcanic region (22°16' to 22°30' S, Central Volcanic Zones, Andes)


    De Astis, G.; Lucchi, F.; Tranne, C. A.; Rossi, P. L.


    We report new petrographic and geochemical data on volcanic rocks erupted over the last 9 Ma ca. within El Tatio volcanic region (Western Cordillera – CVZ). They originated from compound volcanism alternating composite volcano activities, lava domes formation and minor low-mild explosive eruptions, whereas ignimbrite-like deposits outcropping in the region originated from external caldera system (Altiplano Puna Volcanic Complex). The volcanics – mostly erupted in the last 1 Ma - have composit...

  5. Crustal-scale recycling in caldera complexes and rift zones along the Yellowstone hotspot track: O and Hf isotopic evidence in diverse zircons from voluminous rhyolites of the Picabo volcanic field, Idaho (United States)

    Drew, Dana L.; Bindeman, Ilya N.; Watts, Kathryn E.; Schmitt, Axel K.; Fu, Bin; McCurry, Michael


    Rhyolites of the Picabo volcanic field (10.4-6.6 Ma) in eastern Idaho are preserved as thick ignimbrites and lavas along the margins of the Snake River Plain (SRP), and within a deep (>3 km) borehole near the central axis of the Yellowstone hotspot track. In this study we present new O and Hf isotope data and U-Pb geochronology for individual zircons, O isotope data for major phenocrysts (quartz, plagioclase, and pyroxene), whole rock Sr and Nd isotope ratios, and whole rock geochemistry for a suite of Picabo rhyolites. We synthesize our new datasets with published Ar-Ar geochronology to establish the eruptive framework of the Picabo volcanic field, and interpret its petrogenetic history in the context of other well-studied caldera complexes in the SRP. Caldera complex evolution at Picabo began with eruption of the 10.44±0.27 Ma (U-Pb) Tuff of Arbon Valley (TAV), a chemically zoned and normal-δ18O (δ18O magma=7.9‰) unit with high, zoned 87Sr/86Sri (0.71488-0.72520), and low-ɛNd(0) (-18) and ɛHf(0) (-28). The TAV and an associated post caldera lava flow possess the lowest ɛNd(0) (-23), indicating ˜40-60% derivation from the Archean upper crust. Normal-δ18O rhyolites were followed by a series of lower-δ18O eruptions with more typical (lower crustal) Sr-Nd-Hf isotope ratios and whole rock chemistry. The voluminous 8.25±0.26 Ma West Pocatello rhyolite has the lowest δ18O value (δ18Omelt=3.3‰), and we correlate it to a 1,000 m thick intracaldera tuff present in the INEL-1 borehole (with published zircon ages 8.04-8.35 Ma, and similarly low-δ18O zircon values). The significant (4-5‰) decrease in magmatic-δ18O values in Picabo rhyolites is accompanied by an increase in zircon δ18O heterogeneity from ˜1‰ variation in the TAV to >5‰ variation in the late-stage low-δ18O rhyolites, a trend similar to what is characteristic of Heise and Yellowstone, and which indicates remelting of variably hydrothermally altered tuffs followed by rapid batch

  6. Crustal-scale recycling in caldera complexes and rift zones along the Yellowstone hotspot track: O and Hf isotopic evidence in diverse zircons from voluminous rhyolites of the Picabo volcanic field, Idaho (United States)

    Drew, Dana L.; Bindeman, Ilya N.; Watts, Kathryn E.; Schmitt, Axel K.; Fu, Bin; McCurry, Michael


    Rhyolites of the Picabo volcanic field (10.4–6.6 Ma) in eastern Idaho are preserved as thick ignimbrites and lavas along the margins of the Snake River Plain (SRP), and within a deep (>3 km) borehole near the central axis of the Yellowstone hotspot track. In this study we present new O and Hf isotope data and U–Pb geochronology for individual zircons, O isotope data for major phenocrysts (quartz, plagioclase, and pyroxene), whole rock Sr and Nd isotope ratios, and whole rock geochemistry for a suite of Picabo rhyolites. We synthesize our new datasets with published Ar–Ar geochronology to establish the eruptive framework of the Picabo volcanic field, and interpret its petrogenetic history in the context of other well-studied caldera complexes in the SRP. Caldera complex evolution at Picabo began with eruption of the 10.44±0.27 Ma (U–Pb) Tuff of Arbon Valley (TAV), a chemically zoned and normal-δ18O (δ18O magma=7.9‰) unit with high, zoned 87Sr/86Sri (0.71488–0.72520), and low-εNd(0) (−18) and εHf(0) (−28). The TAV and an associated post caldera lava flow possess the lowest εNd(0) (−23), indicating ∼40–60% derivation from the Archean upper crust. Normal-δ18O rhyolites were followed by a series of lower-δ18O eruptions with more typical (lower crustal) Sr–Nd–Hf isotope ratios and whole rock chemistry. The voluminous 8.25±0.26 Ma West Pocatello rhyolite has the lowest δ18O value (δ18Omelt=3.3‰), and we correlate it to a 1,000 m thick intracaldera tuff present in the INEL-1 borehole (with published zircon ages 8.04–8.35 Ma, and similarly low-δ18O zircon values). The significant (4–5‰) decrease in magmatic-δ18O values in Picabo rhyolites is accompanied by an increase in zircon δ18O heterogeneity from ∼1‰ variation in the TAV to >5‰ variation in the late-stage low-δ18O rhyolites, a trend similar to what is characteristic of Heise and Yellowstone, and which indicates remelting of variably hydrothermally altered tuffs

  7. Cabildo, negociación y vino de cocos: el caso de la villa de Colima en el siglo XVII

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    Machuca Chávez, Claudia Paulina


    Full Text Available After a huge production of cocoa plantings during the Sixteenth century, the town of Colima in the New Spain lost this culturing because of climate difficulties and because of the preference that the Crown made on cocoa plantings in South America. For the benefit of its settlers, the arrival of “indios chinos”, an Asian community at the town of Colima permitted the development of a small industry based on a coconut drink —“vino de cocos”—, which became the most important economic activity during the Seventeenth century. Even when it was considered a “native drink” at first —and therefore forbidden— the town council of Colima was a fundamental institution in the negotiation with viceroys and the Real Audiencia of Mexico in order to get licenses that permitted not only its elaboration but also its distribution alongside a regional market.

    Después de una intensa producción de cacao durante el siglo XVI, la villa de Colima de la Nueva España sufrió la pérdida de este cultivo por causas climáticas y por el apoyo preferente de la Corona a los sembradíos de cacao en Sudamérica. Para el beneficio de sus habitantes, la llegada de “indios chinos” o asiáticos a la villa de Colima propició el desarrollo de una pequeña industria, la del vino de cocos, que a la postre se convertiría en la principal actividad económica de la villa durante todo el siglo XVII. Aunque en un principio se consideró como una “bebida de la tierra” —y por consiguiente, prohibida—, el Cabildo colimense fue una institución clave en la negociación con los virreyes y la Real Audiencia de México para conseguir licencias que permitieran no sólo su fabricación, sino su eventual distribución en el mercado regional novohispano.

  8. Faults and volcanoes: Main volcanic structures in the Acambay Graben, Mexico (United States)

    Aguirre-Diaz, G. J.; Pedrazzi, D.; Suñe-Puchol, I.; Lacan, P.


    The Mexican Volcanic Belt (MVB) province is best known by the major stratovolcanoes, such as Popocatepetl and Colima, but most of the province is formed by modest size stratovolcanoes and monogenetic cones. Regional fault systems were developed together with the building of the volcanic province; the most notorious one is Chapala-Tula Fault System (CTFS), which runs parallel to the central sector of the MVB, and thus it is also referred to as the Intra-Arc fault system. Acambay graben (AG) is part of this central system. It is a 20 x 70 km depression located 100 km to the NW of Mexico City, at the easternmost end of the E-W trending CTFS, and was formed as the result of NS to NE oriented extension. Seismically active normal faults, such as the Acambay-Tixmadejé fault, with a mB =7 earthquake in 1912, delimit the AG. The graben includes several volcanic structures and associated deposits ranging in age from Miocene to 3 ka. The main structures are two stratovolcanoes, Altamirano (900 m high) and Temascalcingo (800 m high). There are also several Miocene-Pliocene lava domes, and Quaternary small cinder cones and shield volcanoes. Faulting of the Acambay graben affects all these volcanic forms, but depending on their ages, the volcanoes are cut by several faults or by a few. That is the case of Altamirano and Temascalcingo volcanoes, where the former is almost unaffected whereas the latter is highly dissected by faults. Altamirano is younger than Temascalcingo; youngest pyroclastic deposits from Altamirano are dated at 12-3 ka, and those from Temascalcingo at 40-25 ka (radiocarbon ages). The relatively young ages found in volcanic deposits within the Acambay graben raise the volcanic danger level in this area, originally marked as an inactive volcanic zone, but activity could restart at any time. Supported by DGAPA-PAPIIT-UNAM grant IN-104615.


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    Nuchnudee Chaisatit


    Full Text Available Resumen: Abillal es una comunidad rural, ubicada en el municipio de Manzanillo, Estado de Colima. Cuenta con riquezas tanto naturales como culturales donde los pobladores están realizando la actividad turística rural pero no está dando buen resultado por la falta de conocimiento y asesoría del plan estratégica para un óptimo manejo integral del turismo. Objetivo: Mejorar el plan estratégico comercial para impulsar el turismo rural en la comunidad del Abillal. La investigación se desarrolló con la metodología deductiva a través del trabajo de campo y análisis de  los indicadores para conocer los factores de la demanda turística. Resultado Mediante un análisis para identificar las fortalezas, oportunidades, debilidades y amenazas (FODA le logro realizar un plan de acción con estrategias que permitieran el impulso turístico de la comunidad de Abillal entre las acciones implementadas se realizó el levantamiento del inventario turístico rural en la comunidad del Abillal, se incluyó e involucro a los ejidatarios en las actividades turísticas y se realizaron los primeros recorridos a la comunidad rural obteniendo muy buenos resultados y propiciando de esta manera la derrama económica  en la comunidad. Palabras Clave: Turismo Rural. Estrategia. Abillal. Mexico

  10. Concesiones, explotación minera y conflicto en la frontera Jalisco-Colima

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    Hirineo Martínez Barragán


    Full Text Available El presente trabajo constituye un avance del estado de la cuestión de la minería: la legislación, la producción, los beneficios y las afectaciones, en particular dentro de la frontera entre Cuautitlán de García Barragán, Jalisco, y Minatitlán, Colima. El trabajo resulta relevante porque la explotación minera en México ha crecido de manera exponencial en los últimos años, y tras ello ha dejado poblados enteros afectados en sus propiedades agrarias, en sus recursos naturales y en sus organizaciones socioterritoriales; la incursión de estas empresas transnacionales ha dejado a su paso deforestación, tierras estériles, contaminación de agua, aire y viento. El objetivo es documentar este hecho con relación a otros, vinculado a procesos globales, lo que se ha hecho mediante la investigación de archivo, hemerográfica, cartográfica y de campo. Como resultado a este trabajo documental, se explica la situación de esta región, que abona a la situación global de México y Latinoamérica.

  11. Using Automated Point Dendrometers to Analyze Tropical Treeline Stem Growth at Nevado de Colima, Mexico

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    Franco Biondi


    Full Text Available The relationship between wood growth and environmental variability at the tropical treeline of North America was investigated using automated, solar-powered sensors (a meteorological station and two dendrometer clusters installed on Nevado de Colima, Mexico (19° 35’ N, 103° 37’ W, 3,760 m a.s.l.. Pure stands of Pinus hartwegii Lindl. (Mexican mountain pine were targeted because of their suitability for tree-ring analysis in low-latitude, high-elevation, North American Monsoon environments. Stem size and hydroclimatic variables recorded at half-hour intervals were summarized on a daily timescale. Power outages, insect outbreaks, and sensor failures limited the analysis to non-consecutive months during 2001–2003 at one dendrometer site, and during 2002–2005 at the other. Combined data from the two sites showed that maximum radial growth rates occur in late spring (May, as soil temperature increases, and incoming short-wave radiation reaches its highest values. Early season (April–May radial increment correlated directly with temperature, especially of the soil, and with solar radiation. Stem expansion at the start of the summer monsoon (June–July was mostly influenced by moisture, and revealed a drought signal, while late season relationships were more varied.

  12. Using automated point dendrometers to analyze tropical treeline stem growth at Nevado de Colima, Mexico. (United States)

    Biondi, Franco; Hartsough, Peter


    The relationship between wood growth and environmental variability at the tropical treeline of North America was investigated using automated, solar-powered sensors (a meteorological station and two dendrometer clusters) installed on Nevado de Colima, Mexico (19° 35' N, 103° 37' W, 3,760 m a.s.l.). Pure stands of Pinus hartwegii Lindl. (Mexican mountain pine) were targeted because of their suitability for tree-ring analysis in low-latitude, high-elevation, North American Monsoon environments. Stem size and hydroclimatic variables recorded at half-hour intervals were summarized on a daily timescale. Power outages, insect outbreaks, and sensor failures limited the analysis to non-consecutive months during 2001-2003 at one dendrometer site, and during 2002-2005 at the other. Combined data from the two sites showed that maximum radial growth rates occur in late spring (May), as soil temperature increases, and incoming short-wave radiation reaches its highest values. Early season (April-May) radial increment correlated directly with temperature, especially of the soil, and with solar radiation. Stem expansion at the start of the summer monsoon (June-July) was mostly influenced by moisture, and revealed a drought signal, while late season relationships were more varied.

  13. Controls on volcanism at intraplate basaltic volcanic fields (United States)

    van den Hove, Jackson C.; Van Otterloo, Jozua; Betts, Peter G.; Ailleres, Laurent; Cas, Ray A. F.


    A broad range of controlling mechanisms is described for intraplate basaltic volcanic fields (IBVFs) in the literature. These correspond with those relating to shallow tectonic processes and to deep mantle plumes. Accurate measurement of the physical parameters of intraplate volcanism is fundamental to gain an understanding of the controlling factors that influence the scale and location of a specific IBVF. Detailed volume and geochronology data are required for this; however, these are not available for many IBVFs. In this study the primary controls on magma genesis and transportation are established for the Pliocene-Recent Newer Volcanics Province (NVP) of south-eastern Australia as a case-study for one of such IBVF. The NVP is a large and spatio-temporally complex IBVF that has been described as either being related to a deep mantle plume, or upper mantle and crustal processes. We use innovative high resolution aeromagnetic and 3D modelling analysis, constrained by well-log data, to calculate its dimensions, volume and long-term eruptive flux. Our estimates suggest volcanic deposits cover an area of 23,100 ± 530 km2 and have a preserved dense rock equivalent of erupted volcanics of least 680 km3, and may have been as large as 900 km3. The long-term mean eruptive flux of the NVP is estimated between 0.15 and 0.20 km3/ka, which is relatively high compared with other IBVFs. Our comparison with other IBVFs shows eruptive fluxes vary up to two orders of magnitude within individual fields. Most examples where a range of eruptive flux is available for an IBVF show a correlation between eruptive flux and the rate of local tectonic processes, suggesting tectonic control. Limited age dating of the NVP has been used to suggest there were pulses in its eruptive flux, which are not resolvable using current data. These changes in eruptive flux are not directly relatable to the rate of any interpreted tectonic driver such as edge-driven convection. However, the NVP and other

  14. Assessing hydraulic connections across a complex sequence of volcanic rocks - Analysis of U-20 WW multiple-well aquifer test, Pahute Mesa, Nevada National Security Site, Nevada (United States)

    Garcia, C. Amanda; Fenelon, Joseph M.; Halford, Keith J.; Reiner, Steven R.; Laczniak, Randell J.


    Groundwater beneath Pahute Mesa flows through a complexly layered sequence of volcanic rock aquifers and confining units that have been faulted into distinct structural blocks. Hydraulic property estimates of rocks and structures in this flow system are necessary to assess radionuclide migration near underground nuclear testing areas. The U.S. Geological Survey (USGS) used a 12 month (October 1, 2008— October 1, 2009) intermittent pumping schedule of well U-20 WW and continuously monitored water levels in observation wells ER-20-6 #3, UE-20bh 1, and U-20bg as a multi-well aquifer test to evaluate hydraulic connections across structural blocks, bulk hydraulic properties of volcanic rocks, and the hydraulic significance of a major fault. Measured water levels were approximated using synthetic water levels generated from an analytical model. Synthetic water levels are a summation of environmental water-level fluctuations and a Theis (1935) transform of the pumping signal from flow rate to water-level change. Drawdown was estimated by summing residual differences between measured and synthetic water levels and the Theis-transformed pumping signal from April to September 2009. Drawdown estimates were used in a three‑dimensional numerical model to estimate hydraulic properties of distinct aquifers, confining units, and a major fault.

  15. Riqueza y biogeografía de la flora arbórea del estado de Colima, México Tree flora richness and biogeography of the State of Colima, Mexico


    Eloy Padilla-Velarde; Ramón Cuevas-Guzmán; Guillermo Ibarra-Manríquez; Saúl Moreno-Gómez


    Con base en la revisión de obras taxonómico-florísticas, ejemplares de los herbarios IBUG, IEB, MEXU y ZEA y la colecta de 800 ejemplares botánicos, se registran 92 familias, 285 géneros y 550 especies de plantas arbóreas para el estado de Colima. Las familias mejor representadas a nivel de género y especie son Fabaceae (42 y 115, respectivamente), Euphorbiaceae (19 y 36) y Rubiaceae (13 y 23). Los géneros con mayor número de especies son Quercus (22), Bursera (19), Ficus (12), Lonchocarpus (...

  16. Silicate volcanism on Io (United States)

    Carr, M. H.


    This paper is mainly concerned with the nature of volcanic eruptions on Io, taking into account questions regarding the presence of silicates or sulfur as principal component. Attention is given to the generation of silicate magma, the viscous dissipation in the melt zone, thermal anomalies at eruption sites, and Ionian volcanism. According to the information available about Io, it appears that its volcanism and hence its surface materials are dominantly silicic. Several percent of volatile materials such as sulfur, but also including sodium- and potassium-rich materials, may also be present. The volatile materials at the surface are continually vaporized and melted as a result of the high rates of silicate volcanism.

  17. Volcanic facies analysis of a subaqueous basalt lava-flow complex at Hruškovec, NW Croatia — Evidence of advanced rifting in the Tethyan domain (United States)

    Palinkaš, Ladislav A.; Bermanec, Vladimir; Borojević Šoštarić, Sibila; Kolar-Jurkovšek, Tea; Palinkaš, Sabina Strmić; Molnar, Ferenc; Kniewald, Goran


    The Hru\\vskovec quarry of basaltoid rocks is situated on the northwestern slopes of Mt. Kalnik, within the Zagorje-Mid-Transdanubian zone, a part of the North-western Dinarides. The basaltoids are inter-bedded with radiolarites of the Middle and Upper Triassic age (Langobardian, Carnian-Norian). Spilites, altered diabases and meta-basalts form part of Triassic volcanic-sedimentary sequence, made of sandstones, shales, micritic limestone, altered vitric tuffs and radiolarian cherts, incorporated tectonically into the Jurassic-Cretaceous mélange. The architecture of the 2 km long and 100 m high pile of the extrusive basaltoid rocks is interpreted as a subaqueous basaltic lava flow. The presented research deals with a variety of volcanic facies of the subaqueous basaltic lava flow, which consists of several facial units: 1. Coherent pillow lavas, with massive core; the bending rims around the massive core, 30-50 cm thick, are dissected by polygonal columnar joints radiating from the pillow centres; 2. Closely packed pillows; densely packed and contorted pillows due to emplacement accommodation, clearly younging upward; 3. Pillow fragment breccia; clast supported, matrix poor, monomict breccia, formed proximal to the axis of the extrusion; 4. Isolated pillow breccia; matrix supported, clast poor breccia, made of lava pipes and tubes, within a matrix of fine-grained sideromelan granules and shards; 5. Pyjama-style pillows; spherical, decimetre to meter size pillow lava balls, grown and chilled in isostatic state (i.e. in a state of diminished density contrast) within water-soaked sediments, named after peculiar alternating basaltic shelves inside the sphere, which are encrusted with white secondary minerals; 6. Peperite and peperitic hyaloclastites; blocky and globular peperites developed at the contact of soft, wet sediment and hot intruding magma. Discovery of peperite and peperitic hyaloclastites within the Triassic radiolarian cherts, shales, and micritic

  18. Seismic and experimental insights into relative velocity changes at Volcán de Colima in 1998 (United States)

    Lamb, O. D.; De Angelis, S.; Wall, R.; Varley, N. R.; Reyes Dávila, G. A.; Arámbula-Mendoza, R.; Hornby, A. J.; Kendrick, J. E.; Lavallée, Y.


    Temporal changes in seismic velocity before eruptions have been measured in a few volcanoes around the world, raising its potential as a forecasting tool. Here we use seismic data from Volcán de Colima, Mexico, to investigate the effect of ascending magma on seismic wave propagation in the edifice. In addition, we use acoustic emissions from laboratory experiments to test the mechanism inferred from the seismic data. Volcán de Colima entered a new phase of eruptive activity in late 1998 with the extrusion of a new lava dome and flow. A multi-station detection algorithm was used to build a catalogue of 17,893 earthquakes from continuous data recorded by the local seismic network between 1 October 1998 and 1 January 1999. Coda wave interferometry was employed to assess relative seismic velocity change between pairs of repeating earthquakes at each station in the seismic network. First, 1,313 repeating events were identified using waveform correlation, before a stretching technique calculated the relative velocity change of each pair. Linear inversion of these measurements allowed us to retrieve the time history of seismic velocity change within the observation period. We infer that the variation in seismic velocity resulted from changes in the local stress regime caused by dyke formation during magma ascent. Using acoustic emissions recorded during Brazilian tensile tests on andesite from Volcán de Colima, we demonstrate that a decrease in seismic velocity can be attributed to crack dilation due to tensile stress. This study highlights how a multi-disciplinary approach to understanding geophysical signals can help future interpretations of pre-eruptive activity at volcanoes.

  19. Riesgos potenciales de salud por consumo de agua con arsénico en Colima, México

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    Oliver Mendoza-Cano


    Full Text Available Objetivo. Estimar los riesgos potenciales de salud debidos a la ingestión crónica de arsénico (As en agua en Colima, México. Material y métodos. Se muestrearon aleatoriamente 36 pozos en 10 acuíferos locales. El análisis se hizo mediante ICP-OES siguiendo estándares internacionales. Se realizó una interpolación geoestadística con ArcGIS, implementando un modelo de ponderación del inverso de la distancia, para estimar la ruta de exposición de consumo en cada localidad. Se calcularon los coeficientes de peligro (HQy riesgo carcinogénico (R. Resultados. El HQ promedio ponderado de As para Colima es 2.41. Existen valores de HQ>1 para As que indican efectos adversos no carcinogénicos para la salud por ingestión continua y prolongada de agua; esto podría afectar a 183 832 individuos en el estado. El riesgo calculado de desarrollar cáncer debido a las concentraciones de arsénico en aguas subterráneas (R es de 1.089E-3; estadísticamente esto podría ocasionar 446 casos de cáncer. Conclusiones. Los niveles actuales de arsénico en el agua de pozo incrementan los riesgos carcinogénicos y no carcinogénicos de salud humana en Colima.

  20. Cymothoa exigua (Isopoda: Cymothoidae) parasitando al pargo Lurjanus peru (Pisces: Lutjanidae) en Manzanillo, Colima, México


    Alvarez, Fernando; Flores, Mario


    El isópodo ectoparásito Cymotho(l uiRua (Isopoda: Cymolhoidac) se encontró parasitando al pargo Lurjanus I'UU en la." coslas de Manzanillo. Colima. En una muestra de 64 individuos parasitados y de 167 no parasilados: la 10ngilUd total de individuos parasitado fue de 143 - 475 mm. Los m:lchos de C. aiRu(j midieron de 8 - 19 mm (hembras de 18 - 39 mm). Los isópodos macho se clasificaron como "solitarios" y "encontrados con hembras" para identificar las tallas a las que ocurre el cambio de sexo ...

  1. Gastropods and bivalves of commercial interest from the continental shelf of Jalisco and Colima, México

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    E. Ríos-Jara


    Full Text Available The distribution and abundance with respect to depth and type of substratum of 20 species of gastropods and 4 species of bivalves of economic importance were examined in the continental shelf of Jalisco and Colima, México. These species were taken with net trawls at depths from 24 to 83 m in August, 1988. Most individuals and species of gastropods were collected in stations with sandy silt substratum. Bivalves were collected in sandy silt and medium sand substrata. The six most abundant species represented 81.2% of all gastropods and bivalves collected. These species are: Cantharus pallidus, Fusinus dupetittouarsi, Ficus ventricosa, Hexaplex brassica, Harpa conoidalis and Arca pacifica

  2. Diagnostic and strategic planning for the agricultural chain of coconut and mango in the State of Colima

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    Renato Francisco González Sánchez


    Full Text Available This paper presents a synthesis of the studies related to the agricultural chains of mango and coconut industries, as well as the strategic programs of economic agents linked to those industries in Colima, Mexico. This work is based upon an empirical approach, in which interviews, polling and group discussions with economic agents of each industry were the basis for information collection. This work attempts to establish the effects of the new market oriented economy model on the mentioned agricultural chains and its economic agents, and proposes that there exists alternatives to the Mexican agricultural crisis, which are linked to agents association and entrepreneurial skills of its organizations.

  3. Frecuencia y factores de riesgo asociados a sobrepeso y obesidad en universitarios de colima, méxico


    Trujillo-Hernández, Benjamín; Vásquez, Clemente; Almanza-Silva, José R.; Jaramillo-Virgen, María E.; Mellin-Landa, Tadeana E.; Valle-Figueroa, Ofelia B.; Pérez-Ayala, Roberto; Millán-Guerrero, Rebeca O.; Prieto-Díaz-Chávez, Emilio; Newton-Sánchez, Oscar


    Objetivo Determinar la frecuencia y factores de riesgo para sobrepeso y obesidad en jóvenes universitarios. Métodos Se realizó un estudio transversal analítico en 821 alumnos inscritos de la Universidad de Colima. Entre las variables analizadas se encuentran: edad, género, alcoholismo, tabaquismo y utilización de medicamentos o sustancias para control de peso. Resultados Se estudiaron 821 alumnos (380 hombres y 441 mujeres) con una edad promedio de 20,9±2,5 años. Las frecuencias de sobrepes...

  4. Relación entre ganadería extensiva e incendios en zonas forestales del estado de Colima


    I. Galindo; J. Barrón; J. I. Padilla


    Las estadísticas oficiales de México indican que, en su mayoría, los incendios forestales son causados por la práctica de actividades agropecuarias en terrenos forestales; tal es el caso de la agricultura migratoria (roza, tumba y quema), así como la quema de pastos para el brote del renuevo en época de sequía. Con base en esta afirmación, es de esperarse que una disminución de estas actividades causales, reduzca la presencia de incendios forestales. En el estado de Colima, en los últimos año...

  5. Fault-slip distribution of the 1995 Colima-Jalisco, Mexico, earthquake (United States)

    Mendoza, C.; Hartzell, S.


    Broadband teleseismic P waves have been analyzed to recover the rupture history of the large (M(s) 7.4) Colima-Jalisco, Mexico, shallow interplate thrust earthquake of 9 October 1995. Ground-displacement records in the period range of 1-60 sec are inverted using a linear, finite-fault waveform inversion procedure that allows a variable dislocation duration on a prescribed fault. The method is applied using both a narrow fault that simulates a line source with a dislocation window of 50 sec and a wide fault with a possible rise time of up to 20 sec that additionally allows slip updip and downdip from the hypocenter. The line-source analysis provides a spatio-temporal image of the slip distribution consisting of several large sources located northwest of the hypocenter and spanning a range of rupture velocities. The two-dimensional finite-fault inversion allows slip over this rupture-velocity range and indicates that the greatest coseismic displacement (3-4 m) is located between 70 and 130 km from the hypocenter at depths shallower than about 15 km. Slip in this shallow region consists of two major sources, one of which is delayed by about 10 sec relative to a coherent propagation of rupture along the plate interface. These two slip sources account for about one-third of the total P-wave seismic moment of 8.3 X 1027 dyne-cm (M(w) 7.9) and may have been responsible for the local tsunami observed along the coast following the earthquake.

  6. Fracture and compaction of andesite in a volcanic edifice. (United States)

    Heap, M J; Farquharson, J I; Baud, P; Lavallée, Y; Reuschlé, T

    The failure mode of lava-dilatant or compactant-depends on the physical attributes of the lava, primarily the porosity and pore size, and the conditions under which it deforms. The failure mode for edifice host rock has attendant implications for the structural stability of the edifice and the efficiency of the sidewall outgassing of the volcanic conduit. In this contribution, we present a systematic experimental study on the failure mode of edifice-forming andesitic rocks (porosity from 7 to 25 %) from Volcán de Colima, Mexico. The experiments show that, at shallow depths (1 km), while low-porosity (explosive potential of a volcano may therefore be subject to increase over time if the progressive compaction and permeability reduction in the lower edifice cannot be offset by the formation of permeable fracture pathways in the upper edifice. The mode of failure of the edifice host rock is therefore likely to be an important factor controlling lateral outgassing and thus eruption style (effusive versus explosive) at stratovolcanoes.

  7. Pre-eruptive rejuvenations of crystalline mush by reservoir heating: the case of trachy-dacitic lavas of Quetrupillán Volcanic Complex, Chile (39º30' lat. S) (United States)

    Brahm, R.; Parada, M. Á.; Morgado, E. E.; Contreras, C.


    The Southern Volcanic Zone of the Andes is dominated by mainly basaltic to andesitic products, as is the case of the Villarrica 2015 eruption. An exception is the case of the nearby Quetrupillán Volcanic Complex (QVC). The QVC forms part of the NW-SE Villarrica-Quetrupillán-Lanín active volcanic chain and contains products of mainly trachy-dacitic composition that differs from the basaltic and basaltic-andesite composition of the neighboring stratovolcanoes. The studied Holocene QVC trachy-dacites exhibit similar geochemical, mineralogical features. They are crystal-poor (glass-rich groundmass. Two groups of plagioclase phenocrysts were found: Group 1 plagioclases are commonly associated with pyroxene in crystal clots and with oscillatory zoning of An40-50, and Group 2 plagioclases occur as isolated crystals of variable composition (An70-85), with rims of similar composition to Group 1. Some Group 2 crystals have cores with compositions similar to the rims with resorption features. Clinopyroxenes within clots have compositions of En40-46Fs11-21Wo39-43 similar to the isolated clinopyroxenes. Orthopyroxene phenocrysts have composition of En36-68Fs15-34Wo03-04. Microphenocrysts of magnetite-ilmenite pairs (Mt14-36-Il90-94) were identified. Pyroxene phenocrysts are in disequilibrium with the whole-rock composition, suggesting that they are antecrysts. Two-pyroxene thermometry gives temperatures of 911-980ºC, while the Mt-Il equilibrium gives higher temperatures of 963-1114ºC, for the later stages of lava crystallization. The presence of a crystalline mush is suggested by the abundance of crystal clots in disequilibrium with the host rock composition whose calculated formation conditions of 0.5-1.5 kbar, 950-990ºC and 2.1-3.1 wt% of H2O, were obtained from a Rhyolite-MELTS simulation. Rejuvenation of a crystal mush by reservoir heating events is suggested due to resorption, regrowth and complex zonation of plagioclases and the higher temperatures obtained from the

  8. Microzonation of seismic risk in a low-rise Latin American city based on the macroseismic evaluation of the vulnerability of residential buildings: Colima city, México

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    V. M. Zobin


    Full Text Available A macroseismic methodology of seismic risk microzonation in a low-rise city based on the vulnerability of residential buildings is proposed and applied to Colima city, Mexico. The seismic risk microzonation for Colima consists of two elements: the mapping of residential blocks according to their vulnerability level and the calculation of an expert-opinion based damage probability matrix (DPM for a given level of earthquake intensity and a given type of residential block. A specified exposure time to the seismic risk for this zonation is equal to the interval between two destructive earthquakes. The damage probability matrices were calculated for three types of urban buildings and five types of residential blocks in Colima. It was shown that only 9% of 1409 residential blocks are able to resist to the Modify Mercalli (MM intensity VII and VIII earthquakes without significant damage. The proposed DPM-2007 is in good accordance with the experimental damage curves based on the macroseismic evaluation of 3332 residential buildings in Colima that was carried out after the 21 January 2003 intensity MM VII earthquake. This methodology and the calculated PDM-2007 curves may be applied also to seismic risk microzonation for many low-rise cities in Latin America, Asia, and Africa.

  9. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.


    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean integrates volcanic radiative cooling and responds over a wide range of time scales. The associated processes, especially ocean heat uptake, play a key role in ongoing climate change. However, they are not well constrained by observations, and attempts to simulate them in current climate models used for climate predictions yield a range of uncertainty. Volcanic impacts on the ocean provide an independent means of assessing these processes. This study focuses on quantification of the seasonal to multidecadal time scale response of the ocean to explosive volcanism. It employs the coupled climate model CM2.1, developed recently at the National Oceanic and Atmospheric Administration\\'s Geophysical Fluid Dynamics Laboratory, to simulate the response to the 1991 Pinatubo and the 1815 Tambora eruptions, which were the largest in the 20th and 19th centuries, respectively. The simulated climate perturbations compare well with available observations for the Pinatubo period. The stronger Tambora forcing produces responses with higher signal-to-noise ratio. Volcanic cooling tends to strengthen the Atlantic meridional overturning circulation. Sea ice extent appears to be sensitive to volcanic forcing, especially during the warm season. Because of the extremely long relaxation time of ocean subsurface temperature and sea level, the perturbations caused by the Tambora eruption could have lasted well into the 20th century.

  10. The 40Ar/39Ar age record and geodynamic significance of Indo-Madagascar and Deccan flood basalt volcanism in the Sarnu-Dandali alkaline complex, Rajasthan, northwestern India (United States)

    Vijayan, Anjali; Pande, Kanchan; Sheth, Hetu; Kant Sharma, Kamal


    The Sarnu-Dandali alkaline complex in Rajasthan, northwestern India, is considered to represent early, pre-tholeiite magmatism in the Deccan Traps continental flood basalt (CFB) province, based on a single 40Ar/39Ar age of 68.57 Ma. Rhyolites found in the complex are considered to be 750 Ma Malani basement. Our new 40Ar/39Ar ages of 88.9-86.8 Ma (for syenites, nephelinite, phonolite and rhyolite) and 66.3 ± 0.4 Ma (2σ, melanephelinite) provide clear evidence that whereas the Sarnu-Dandali complex has Deccan-age components, it is dominantly an older (by ˜20 million years) alkaline complex, with rhyolites included. Sarnu-Dandali is thus an alkaline igneous center active at least twice in the Late Cretaceous, and also much before as suggested by a basalt flow underlying the Early Cretaceous Sarnu Sandstone. The 89-86 Ma 40Ar/39Ar ages fully overlap with those for the Indo-Madagascar CFB province formed during continental break-up between India (plus Seychelles) and Madagascar. Recent 40Ar/39Ar work has shown polychronous emplacement (over ≥ 45 million years) of the Mundwara alkaline complex in Rajasthan, 100 km from Sarnu-Dandali, and 84-80 Ma ages obtained from Mundwara also arguably represent late stages of the Indo-Madagascar CFB volcanism. Remnants of the Indo-Madagascar CFB province are known from several localities in southern India but hitherto unknown from northwestern India 2000 km away. Additional equivalents buried under the vast Deccan Traps are highly likely. We relate the Sarnu-Dandali and Mundwara complexes to decompression melting of ancient, subduction-fluxed, enriched mantle lithosphere due to periodic lithospheric extension during much of the Cretaceous, and hundreds of kilometers inland from the India-Madagascar and India-Seychelles rifted margins.

  11. Geology and petrology of the Vulsinian volcanic area (Latium, Italy)

    NARCIS (Netherlands)

    Varekamp, J.C.


    The Vulsinian volcanic area is situated in Latium, west central Italy. This quarternary volcanic complex consists of a series of layered tuffs, lava flows, ignimbrites, and many small cinder and ash cones. A steep central edifice is lacking due to the relatively large amount of pyroclastic deposits.

  12. Geology and petrology of the Vulsinian volcanic area (Latium, Italy)

    NARCIS (Netherlands)

    Varekamp, J.C.


    The Vulsinian volcanic area is situated in Latium, west central Italy. This quarternary volcanic complex consists of a series of layered tuffs, lava flows, ignimbrites, and many small cinder and ash cones. A steep central edifice is lacking due to the relatively large amount of pyroclastic

  13. Characterization of a high elevation tropical pine forest for isotopic analysis of the North American Monsoon System: Nevado de Colima, Mexico (United States)

    Hartsough, P.; Biondi, F.


    The area watered by the North American Monsoon encompasses a vast geographic region, from tropical Mexico to the deserts of the Great Basin. The system is ultimately driven by tropical ocean-atmosphere interactions, which in turn orchestrate global climate variability over a range of timescales. Instrumental observations at the end points of the system span only the past few decades in the tropical south and are limited to only a few decades more in the desert north. At both locations, high-resolution proxy records of climate can supplement existing data. The Mexican mountain pine (Pinus hartwegii) has been shown to hold a paleoclimate record at a high elevation site in tropical Mexico. Warm-season precipitation regime is the dominant year-to-year signal in a 400-year tree-ring chronology from Nevado de Colima, Mexico, where an automated weather station and a range of automatic tree growth sensors (phytograms, point and band dendrometers) have been installed at 3770 m (12,370 ft) elevation. Co-measuring tree growth and climate over a three-year period, has contributed to a better understanding of the complex response of low latitude, high elevation trees to changing environmental conditions. This characterization is necessary for interpretation of the stable isotopic record of Monsoon fluctuation as recorded by the trees. Stable isotopic characterization of the source waters before and after the Monsoon has been completed and analysis of tree ring cellulose is underway. Preliminary results show a strong seasonal isotopic signal and highlight the importance of context dependent analysis.

  14. Volcanic rock properties control sector collapse events (United States)

    Hughes, Amy; Kendrick, Jackie; Lavallée, Yan; Hornby, Adrian; Di Toro, Giulio


    Volcanoes constructed by superimposed layers of varying volcanic materials are inherently unstable structures. The heterogeneity of weak and strong layers consisting of ash, tephra and lavas, each with varying coherencies, porosities, crystallinities, glass content and ultimately, strength, can promote volcanic flank and sector collapses. These volcanoes often exist in areas with complex regional tectonics adding to instability caused by heterogeneity, flank overburden, magma movement and emplacement in addition to hydrothermal alteration and anomalous geothermal gradients. Recent studies conducted on the faulting properties of volcanic rocks at variable slip rates show the rate-weakening dependence of the friction coefficients (up to 90% reduction)[1], caused by a wide range of factors such as the generation of gouge and frictional melt lubrication [2]. Experimental data from experiments conducted on volcanic products suggests that frictional melt occurs at slip rates similar to those of plug flow in volcanic conduits [1] and the bases of mass material movements such as debris avalanches from volcanic flanks [3]. In volcanic rock, the generation of frictional heat may prompt the remobilisation of interstitial glass below melting temperatures due to passing of the glass transition temperature at ˜650-750 ˚C [4]. In addition, the crushing of pores in high porosity samples can lead to increased comminution and strain localisation along slip surfaces. Here we present the results of friction tests on both high density, glass rich samples from Santaguito (Guatemala) and synthetic glass samples with varying porosities (0-25%) to better understand frictional properties underlying volcanic collapse events. 1. Kendrick, J.E., et al., Extreme frictional processes in the volcanic conduit of Mount St. Helens (USA) during the 2004-2008 eruption. J. Structural Geology, 2012. 2. Di Toro, G., et al., Fault lubrication during earthquakes. Nature, 2011. 471(7339): p. 494-498. 3

  15. Structural controls on fluid circulation at the Caviahue-Copahue Volcanic Complex (CCVC) geothermal area (Chile-Argentina), revealed by soil CO2 and temperature, self-potential, and helium isotopes (United States)

    Roulleau, Emilie; Bravo, Francisco; Pinti, Daniele L.; Barde-Cabusson, Stéphanie; Pizarro, Marcela; Tardani, Daniele; Muñoz, Carlos; Sanchez, Juan; Sano, Yuji; Takahata, Naoto; de la Cal, Federico; Esteban, Carlos; Morata, Diego


    Natural geothermal systems are limited areas characterized by anomalously high heat flow caused by recent tectonic or magmatic activity. The heat source at depth is the result of the emplacement of magma bodies, controlled by the regional volcano-tectonic setting. In contrast, at a local scale a well-developed fault-fracture network favors the development of hydrothermal cells, and promotes the vertical advection of fluids and heat. The Southern Volcanic Zone (SVZ), straddling Chile and Argentina, has an important, yet unexplored and undeveloped geothermal potential. Studies on the lithological and tectonic controls of the hydrothermal circulation are therefore important for a correct assessment of the geothermal potential of the region. Here, new and dense self-potential (SP), soil CO2 and temperature (T) measurements, and helium isotope data measured in fumaroles and thermal springs from the geothermal area located in the north-eastern flank of the Copahue volcanic edifice, within the Caviahue Caldera (the Caviahue-Copahue Volcanic Complex - CCVC) are presented. Our results allowed to the constraint of the structural origin of the active thermal areas and the understanding of the evolution of the geothermal system. NE-striking faults in the area, characterized by a combination of SP, CO2, and T maxima and high 3He/4He ratios (up to 8.16 ± 0.21Ra, whereas atmospheric Ra is 1.382 × 10- 6), promote the formation of vertical permeability preferential pathways for fluid circulation. WNW-striking faults represent low-permeability pathways for hydrothermal fluid ascent, but promote infiltration of meteoric water at shallow depths, which dilute the hydrothermal input. The region is scattered with SP, CO2, and T minima, representing self-sealed zones characterized by impermeable altered rocks at depth, which create local barriers for fluid ascent. The NE-striking faults seem to be associated with the upflowing zones of the geothermal system, where the boiling process

  16. Volcanic Rocks and Features (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanoes have contributed significantly to the formation of the surface of our planet. Volcanism produced the crust we live on and most of the air we breathe. The...

  17. Diagnóstico y prevalencia de hipertensión arterial en menores de 19 años en la ciudad de Colima Diagnosis and prevalence of high blood pressure in children aged under 19 in Colima City

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    Javier Cervantes


    Full Text Available OBJETIVO: Estimar la prevalencia de hipertensión arterial en menores de 19 años de Colima, Colima, México. MATERIAL Y MÉTODOS: Estudio transversal realizado en 1992 a partir de las mediciones de la tensión arterial (TA de 400 menores, distribuidos por sexo y edad. Se calcularon: promedio, varianza y Anova por edad; coeficientes de correlación y determinación entre edad y TA; se compararon los grupos con pruebas t de Student, F y U de Mann-Whitney con Z para sexos seleccionados según la curva de distribución; asimismo, se calculó percentil 95 para definir cifras anormales. RESULTADOS: El coeficiente de correlación es lineal, el de determinación lo confirma, se distinguen con pOBJECTIVE: To assess the prevalence of high blood pressure among young children. MATERIAL AND METHODS: This is a cross-sectional study, conducted in 1992 in Colima City, Mexico. Blood pressure readings were obtained from 400 children aged under 19. Statistical analysis consisted of calculation of means, variance, and Anova by group age. Association between age and blood pressure was assessed with correlation and determination coefficients. Comparisons by sex were made using Student's t, F, Mann-Whitney's U, and Z tests. Percentile 95th was used to define normal figures. RESULTS: A lineal correlation coefficient was found and confirmed by the determination coefficient. Groups where this association was statistically significant at p<0.01 were: a children aged under 2; b children from 2 to 13 years of age; and c those over 13 years of age. High blood pressure figures for each group were: a 92/50 mm/Hg; 110/70 mm/Hg; and 133/84 mm/Hg, respectively. CONCLUSIONS: The prevalence of high blood pressure in younger children may be 8% for systolic pressure and 9% for diastolic pressure.

  18. Subsistence fisheries in the Sierra Manantlán Biosphere Reserve (Jalisco/Colima, Mexico

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    Norman Mercado-Silva


    Full Text Available Las reservas de la biósfera enfrentan el doble objetivo de proteger ecosistemas ejemplares y proveer a las comunidades locales con oportunidades de desarrollo. Las pesquerías de subsistencia están presentes en muchas áreas protegidas en México, pero son poco conocidas. Los pescadores de subsistencia tienen pocas oportunidades para expresar sus opiniones acerca de la calidad de los ecosistemas de los cuales dependen para sobrevivir. Utilizamos encuestas para describir las pesquerías de subsistencia del Río Ayuquila, (Jalisco, Colima, México y documentar las perspectivas que los pescadores tienen de la calidad ambiental del río y el manejo que se le da al mismo. La pesquería de subsistencia en el Ayuquila tiene gran importancia para las comunidades rurales de la Reserva de la Biósfera Sierra de Manantlán, pero está poco organizada, y es secundaria en importancia a actividades agropecuarias en la región. La pesquería ha sido afectada por la contaminación y la sobreexplotación, pero esfuerzos realizados por la dirección de la reserva y los gobiernos locales han resultado en mejoras a lo largo del tiempo. Estas mejoras se ven reflejadas en las opiniones que los pescadores tienen acerca de la situación ambiental actual del río, y de las instituciones que se encargan de darle manejo. Describimos cómo procesos regionales han afectado al manejo que se da al río e identificamos áreas donde es posible mejorar su situación. El empoderamiento de los pescadores de subsistencia es posible a través de su participación en encuestas como las que aquí presentamos y que pueden ser utilizadas por instituciones regionales para mejorar las condiciones de vida de los pobladores y las estrategias de conservación de recursos naturales.

  19. Languages of volcanic landscapes (United States)

    Frederick J. Swanson


    As a young geologist in 1980, I felt a powerful attraction to volcanoes, and I thought I knew volcanoes rather well. I had studied volcanology. I had climbed volcanic peaks in the Cascades. And I had tried to be an attentive citizen of my volcanic region, the Pacific Northwest. But when I had a chance to go with other scientists to Mount St. Helens within days of its...

  20. Descripción de una especie nueva de alacrán con importancia médica del género Centruroides (Scorpiones: Buthidae) del estado de Colima, México Description of a new species of scorpion of medical importance of the genus Centruroides (Scorpiones: Buthidae) from the state of Colima, Mexico


    Javier Ponce-Saavedra; Oscar F. Francke


    Se describe Centruroides hirsutipalpus sp. nov. de la región de Minatitlán, Colima. Se compara con las especies morfológica y geográficamente más cercanas, C. elegans Thorell y C. tecomanus Hoffmann y con otras especies "rayadas" de Centruroides del centro-occidente de México. Es ésta una especie con importancia médica que no se había recolectado previamente.Centruroides hirsutipalpus sp. nov. from the region of Minatitlán, Colima, Mexico is described. The new species is compared with C. eleg...

  1. Volcanic activity in the Acambay Graben: a < 25 Ka subplinian eruption from the Temascalcingo volcano and implications for volcanic hazard. (United States)

    Pedrazzi, Dario; Aguirre Díaz, Gerardo; Sunyé Puchol, Ivan; Bartolini, Stefania; Geyer, Adelina


    The Trans-Mexican Volcanic Belt (TMVB) contains a large number of stratovolcanoes, some well-known, as Popocatepetl, Iztaccihuatl, Nevado de Toluca, or Colima and many others of more modest dimensions that are not well known but constitute the majority in the TMVB. Such volcanoes are, for example, Tequila, San Juan, Sangangüey, Cerro Culiacán, Cerro Grande, El Zamorano, La Joya, Palo Huerfano, Jocotitlán, Altamirano and Temascalcingo, among many others. The Temascalcingo volcano (TV) is an andesitic-dacitic stratovolcano located in the Trans-Mexican Volcanic Belt (TMVB) at the eastern part of the Acambay Graben (northwest portion of Estado de México). The TV is composed mainly by dacitic, porphyritic lavas, block and ash deposits and subordinate pumice fall deposits and ignimbrites (Roldán-Quintana et al., 2011). The volcanic structure includes a summit caldera that has a rectangular shape, 2.5×3.5 km, with the largest side oriented E-W, parallel to major normal faults affecting the edifice. The San Mateo Pumice eruption is one of the greatest paroxysmal episodes of this volcano with pumice deposits mainly exposed at the scarp of the Acambay-Tixmadeje fault and at the northern and northeastern flanks of TV. It overlies a paleosol dated at 25 Ka. A NE-trending dispersion was obtained from field data covering an area of at least 80 km2. These deposits overlie older lava flows and mud flows and are discontinuously covered and eroded by younger reworked deposits of Temascalcingo volcano. This event represents a highly explosive phase that generated a relatively thick and widespread pumice fallout deposit that may occur again in future eruptions. A similar eruption today would have a significantly impact in the region, overall due to the fact that there has been no systematic assessment of the volcanic hazard in any of the studies that have been conducted so far in the area. So, this is a pending and urgent subject that must be tackled without delay. Financed by

  2. Felsic Volcanics on the Moon (United States)

    Jolliff, B. L.; Lawrence, S. J.; Stopar, J.; Braden, S.; Hawke, B. R.; Robinson, M. S.; Glotch, T. D.; Greenhagen, B. T.; Seddio, S. M.


    Lunar Reconnaissance Orbiter (LRO) imaging and thermal data provide new morphologic and compositional evidence for features that appear to be expressions of nonmare silicic volcanism. Examples reflecting a range of sizes and volcanic styles include the Gruithuisen and Mairan Domes, and the Hansteen Alpha (H-A) and Compton-Belkovich (C-B) volcanic complexes. In this work we combine new observations with existing compositional remote sensing and Apollo sample data to assess possible origins. Images and digital topographic data at 100 m scale (Wide Angle Camera) and ~0.5 to 2 m (Narrow Angle Camera) reveal (1) slopes on volcanic constructs of ~12° to 27°, (2) potential endogenic summit depressions, (3) small domical features with dense boulder populations, and (4) irregular collapse features. Morphologies in plan view range from the circular to elliptical Gruithuisen γ and δ domes (~340 km2 each), to smaller cumulodomes such as Mairan T and C-B α (~30 km2, each), to the H-A (~375 km2) and C-B (~680 km2) volcanic complexes. Heights range from ~800-1800 m, and most domes are relatively flat-topped or have a central depression. Positions of the Christiansen Feature in LRO Diviner data reflect silicic compositions [1]. Clementine UVVIS-derived FeO varies from ~5 to 10 wt%. Lunar Prospector Th data indicate model values of 20-55 ppm [2,3], which are consistent with compositions ranging from KREEP basalt to lunar granite. The Apollo collection contains small rocks and breccia clasts of felsic/granitic lithologies. Apollo 12 samples include small, pristine and brecciated granitic rock fragments and a large, polymict breccia (12013) consisting of felsic material (quartz & K-feldspar-rich) and mafic phases (similar to KREEP basalt). Many of the evolved lunar rocks have geochemically complementary compositions. The lithologic associations and the lack of samples with intermediate composition suggest a form of magmatic differentiation that produced mafic and felsic

  3. Análisis de los factores de riesgo de la hipertensión arterial en Colima, México Analysis of risk factors for hypertension in Colima, Mexico

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    Francisco Espinoza-Gómez


    Full Text Available OBJETIVO: Evaluar la posible asociación de la edad, el sexo, el sobrepeso, los antecedentes familiares de hipertensión arterial (HTA, el alcoholismo y el sedentarismo con la HTA en la población adulta de la ciudad de Colima, México. MÉTODOS: Estudio transversal analítico de base poblacional. Se aplicó una encuesta estructurada a 280 adultos mayores de 30 años que residían en la ciudad mexicana de Colima en 2001 y 2002. Las variables estudiadas fueron el sexo, la edad, el peso, la talla, los antecedentes familiares de HTA, la práctica de ejercicio físico, el tabaquismo y el consumo de alcohol. La presión arterial (PA se midió por el método auscultatorio. Las mediciones limítrofes o dudosas se repitieron cuatro o cinco días después. Se consideró que había HTA cuando la PA sistólica era >140 mm Hg y la presión arterial diastólica era > 90 mm Hg, o la persona estaba bajo tratamiento antihipertensivo. Se calcularon las razones de posibilidades (odds ratios, RP de las variables estudiadas y sus intervalos de confianza de 95% (IC95%. La asociación entre las variables y la HTA se estimó mediante regresión logística y la interacción mediante el coeficiente de productos de interacción. RESULTADOS: La prevalencia bruta de HTA fue de 28,6%. La prevalencia fue mayor en hombres que en mujeres (42,1% frente a 19,2%, respectivamente; RP = 3,04; IC95%: 1,8 a 5,2 y en personas mayores de 49 años que en personas de 30 a 49 años (36,8% frente a 21,9%, respectivamente; RP = 2,07; IC95%: 1,22 a 3,50. Los antecedentes familiares de HTA y el sobrepeso mostraron asociación con la HTA, mientras que la práctica de ejercicio físico tuvo un efecto protector (RP = 0,45; 0,23 a 0,86. Se encontró interacción entre la HTA y la edad (> 50 años, los antecedentes familiares de HTA, el sobrepeso y la práctica de ejercicio físico, particularmente en mujeres. CONCLUSIONES: La prevalencia de HTA en Colima es muy semejante a la encontrada a nivel

  4. Volcano crisis response at Yellowstone volcanic complex - after-action report for exercise held at Salt Lake City, Utah, November 15, 2011 (United States)

    Pierson, Thomas C.; Driedger, Carolyn L.; Tilling, Robert I.


    A functional tabletop exercise was run on November 14-15, 2011 in Salt Lake City, Utah, to test crisis response capabilities, communication protocols, and decision-making by the staff of the multi-agency Yellowstone Volcano Observatory (YVO) as they reacted to a hypothetical exercise scenario of accelerating volcanic unrest at the Yellowstone caldera. The exercise simulated a rapid build-up of seismic activity, ground deformation, and hot-spring water-chemistry and temperature anomalies that culminated in a small- to moderate-size phreatomagmatic eruption within Yellowstone National Park. The YVO scientific team's responses to the unfolding events in the scenario and to simulated requests for information by stakeholders and the media were assessed by (a) the exercise organizers; (b) several non-YVO scientists, who observed and queried participants, and took notes throughout the exercise; and (c) the participants themselves, who kept logs of their actions during the exercise and later participated in a group debriefing session and filled out detailed questionnaires. These evaluations were tabulated, interpreted, and summarized for this report, and on the basis of this information, recommendations have been made. Overall, the YVO teams performed their jobs very well. The exercise revealed that YVO scientists were able to successfully provide critical hazards information, issue information statements, and appropriately raise alert levels during a fast-moving crisis. Based on the exercise, it is recommended that several measures be taken to increase YVO effectiveness during a crisis: 1. Improve role clarification within and between YVO science teams. 2. Improve communications tools and protocols for data-sharing and consensus-building among YVO scientists, who are geographically and administratively dispersed among various institutions across the United States. 3. Familiarize YVO staff with Incident Command System (ICS) procedures and protocols, and provide more in

  5. Volcanic hazards to airports (United States)

    Guffanti, M.; Mayberry, G.C.; Casadevall, T.J.; Wunderman, R.


    Volcanic activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. Analysis of a new compilation of incidents of airports impacted by volcanic activity from 1944 through 2006 reveals that, at a minimum, 101 airports in 28 countries were affected on 171 occasions by eruptions at 46 volcanoes. Since 1980, five airports per year on average have been affected by volcanic activity, which indicates that volcanic hazards to airports are not rare on a worldwide basis. The main hazard to airports is ashfall, with accumulations of only a few millimeters sufficient to force temporary closures of some airports. A substantial portion of incidents has been caused by ash in airspace in the vicinity of airports, without accumulation of ash on the ground. On a few occasions, airports have been impacted by hazards other than ash (pyroclastic flow, lava flow, gas emission, and phreatic explosion). Several airports have been affected repeatedly by volcanic hazards. Four airports have been affected the most often and likely will continue to be among the most vulnerable owing to continued nearby volcanic activity: Fontanarossa International Airport in Catania, Italy; Ted Stevens Anchorage International Airport in Alaska, USA; Mariscal Sucre International Airport in Quito, Ecuador; and Tokua Airport in Kokopo, Papua New Guinea. The USA has the most airports affected by volcanic activity (17) on the most occasions (33) and hosts the second highest number of volcanoes that have caused the disruptions (5, after Indonesia with 7). One-fifth of the affected airports are within 30 km of the source volcanoes, approximately half are located within 150 km of the source volcanoes, and about three-quarters are within 300 km; nearly one-fifth are located more than 500 km away from the source volcanoes. The volcanoes that have caused the most impacts are Soufriere Hills on the island of Montserrat in the British West Indies

  6. Volcanism in Eastern Africa (United States)

    Cauthen, Clay; Coombs, Cassandra R.


    In 1891, the Virunga Mountains of Eastern Zaire were first acknowledged as volcanoes, and since then, the Virunga Mountain chain has demonstrated its potentially violent volcanic nature. The Virunga Mountains lie across the Eastern African Rift in an E-W direction located north of Lake Kivu. Mt. Nyamuragira and Mt. Nyiragongo present the most hazard of the eight mountains making up Virunga volcanic field, with the most recent activity during the 1970-90's. In 1977, after almost eighty years of moderate activity and periods of quiescence, Mt. Nyamuragira became highly active with lava flows that extruded from fissures on flanks circumscribing the volcano. The flows destroyed vast areas of vegetation and Zairian National Park areas, but no casualties were reported. Mt. Nyiragongo exhibited the same type volcanic activity, in association with regional tectonics that effected Mt. Nyamuragira, with variations of lava lake levels, lava fountains, and lava flows that resided in Lake Kivu. Mt. Nyiragongo, recently named a Decade volcano, presents both a direct and an indirect hazard to the inhabitants and properties located near the volcano. The Virunga volcanoes pose four major threats: volcanic eruptions, lava flows, toxic gas emission (CH4 and CO2), and earthquakes. Thus, the volcanoes of the Eastern African volcanic field emanate harm to the surrounding area by the forecast of volcanic eruptions. During the JSC Summer Fellowship program, we will acquire and collate remote sensing, photographic (Space Shuttle images), topographic and field data. In addition, maps of the extent and morphology(ies) of the features will be constructed using digital image information. The database generated will serve to create a Geographic Information System for easy access of information of the Eastem African volcanic field. The analysis of volcanism in Eastern Africa will permit a comparison for those areas from which we have field data. Results from this summer's work will permit

  7. Transmisión interepidémica del dengue en la ciudad de Colima, México

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    Espinoza-Gómez Francisco


    Full Text Available OBJETIVO: Determinar la presencia de dengue interepidémico en una comunidad infestada por Aedes aegypti, y analizar sus características epidemiológicas. MATERIAL Y MÉTODOS: Entre 2001 y 2002 se realizó un estudio probabilístico longitudinal en 245 habitantes de la ciudad de Colima, México. En cada caso se registraron: edad, sexo, nivel socioeconómico, cuadro clínico sugestivo de dengue, y se buscó la presencia de IgG e IgM antidengue por inmunocromatografía rápida y por ELISA, en un seguimiento de siete meses. Los datos se analizaron mediante tablas de contingencia y regresión de Poisson univariada. RESULTADOS: Doce individuos resultaron con infección reciente (incidencia de 1.77%; IC 95%: 0.9-3.1%, ocho de ellos refirieron cuadro clínico reciente (ji2=19.6; p=0.0001, RM: 19.6. La regresión de Poisson no reveló correlación de la infección reciente con edad, sexo, ni con nivel socioeconómico. CONCLUSIONES: En comunidades infestadas por A aegypti, como Colima, pueden ocurrir infecciones continuas por dengue sin epidemia aparente. Dichas infecciones no parecen asociarse con la edad, el sexo, ni con el nivel socioeconómico, pero sí con el cuadro clínico, el cual podría considerarse como indicador precoz de posible transmisión interepidémica.

  8. Relación entre ganadería extensiva e incendios en zonas forestales del estado de Colima

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    I. Galindo


    Full Text Available Las estadísticas oficiales de México indican que, en su mayoría, los incendios forestales son causados por la práctica de actividades agropecuarias en terrenos forestales; tal es el caso de la agricultura migratoria (roza, tumba y quema, así como la quema de pastos para el brote del renuevo en época de sequía. Con base en esta afirmación, es de esperarse que una disminución de estas actividades causales, reduzca la presencia de incendios forestales. En el estado de Colima, en los últimos años la práctica de la agricultura ha disminuido debido al bajo rendimiento del maíz y, de igual manera, se tiene una disminución importante del hato ganadero estatal, que en su mayoría se desarrolla en áreas forestales, por lo que habría que esperar una disminución en el número de incendios forestales en la entidad. En este trabajo se plantea la hipótesis de que debe existir una correlación entre las actividades de pastoreo extensivo medida en cabezas de ganado bovino y la incidencia de incendios forestales, por municipio. Para tal efecto, se utilizó la serie de tiempo de 1996 a 2006 de los incendios forestales detectados vía satélite, y datos oficiales sobre la actividad ganadera de 2000 a 2007 por municipio. Los resultados confirman la hipótesis de trabajo mediante una correlación no-lineal de 0.86. Se sugiere instrumentar prácticas silvopastoriles sustentables en los municipios afectados para detener el deterioro de los recursos naturales del estado de Colima.

  9. The roles of fractional crystallization, magma mixing, crystal mush remobilization and volatile-melt interactions in the genesis of a young basalt-peralkaline rhyolite suite, the greater Olkaria volcanic complex, Kenya Rift valley (United States)

    Macdonald, R.; Belkin, H.E.; Fitton, J.G.; Rogers, N.W.; Nejbert, K.; Tindle, A.G.; Marshall, A.S.


    The Greater Olkaria Volcanic Complex is a young (???20 ka) multi-centred lava and dome field dominated by the eruption of peralkaline rhyolites. Basaltic and trachytic magmas have been erupted peripherally to the complex and also form, with mugearites and benmoreites, an extensive suite of magmatic inclusions in the rhyolites. The eruptive rocks commonly represent mixed magmas and the magmatic inclusions are themselves two-, three- or four-component mixes. All rock types may carry xenocrysts of alkali feldspar, and less commonly plagioclase, derived from magma mixing and by remobilization of crystal mushes and/or plutonic rocks. Xenoliths in the range gabbro-syenite are common in the lavas and magmatic inclusions, the more salic varieties sometimes containing silicic glass representing partial melts and ranging in composition from anorthite ?? corundum- to acmite-normative. The peralkaline varieties are broadly similar, in major element terms, to the eruptive peralkaline rhyolites. The basalt-trachyte suite formed by a combination of fractional crystallization, magma mixing and resorption of earlier-formed crystals. Matrix glass in metaluminous trachytes has a peralkaline rhyolitic composition, indicating that the eruptive rhyolites may have formed by fractional crystallization of trachyte. Anomalous trace element enrichments (e.g. ??? 2000 ppm Y in a benmoreite) and negative Ce anomalies may have resulted from various Na- and K-enriched fluids evolving from melts of intermediate composition and either being lost from the system or enriched in other parts of the reservoirs. A small group of nepheline-normative, usually peralkaline, magmatic inclusions was formed by fluid transfer between peralkaline rhyolitic and benmoreitic magmas. The plumbing system of the complex consists of several independent reservoirs and conduits, repeatedly recharged by batches of mafic magma, with ubiquitous magma mixing. ?? The Author 2008. Published by Oxford University Press. All

  10. A mixture of exponentials distribution for a simple and precise assessment of the volcanic hazard

    Directory of Open Access Journals (Sweden)

    A. T. Mendoza-Rosas


    Full Text Available The assessment of volcanic hazard is the first step for disaster mitigation. The distribution of repose periods between eruptions provides important information about the probability of new eruptions occurring within given time intervals. The quality of the probability estimate, i.e., of the hazard assessment, depends on the capacity of the chosen statistical model to describe the actual distribution of the repose times. In this work, we use a mixture of exponentials distribution, namely the sum of exponential distributions characterized by the different eruption occurrence rates that may be recognized inspecting the cumulative number of eruptions with time in specific VEI (Volcanic Explosivity Index categories. The most striking property of an exponential mixture density is that the shape of the density function is flexible in a way similar to the frequently used Weibull distribution, matching long-tailed distributions and allowing clustering and time dependence of the eruption sequence, with distribution parameters that can be readily obtained from the observed occurrence rates. Thus, the mixture of exponentials turns out to be more precise and much easier to apply than the Weibull distribution. We recommended the use of a mixture of exponentials distribution when regimes with well-defined eruption rates can be identified in the cumulative series of events. As an example, we apply the mixture of exponential distributions to the repose-time sequences between explosive eruptions of the Colima and Popocatépetl volcanoes, México, and compare the results obtained with the Weibull and other distributions.

  11. Instrumental monitoring of lahars for warning purposes: new developments along the Colima Volcano, Mexico (United States)

    Coviello, Velio; Capra, Lucia; Vázquez, Rosario; Márquez, Víctor H.; Cruz, Sergio


    , upstream to downstream. Here we propose a new application and development of this method to early detect and characterize rain-triggered lahars occurring along the Colima Volcano, one of the most active volcanoes in Mexico. Two monitoring stations are installed along the Southwestern flank of the volcano, in the Montegrande and the Lumbre basins. Both sites are equipped with a GVD array and a videocamera. Along the Montegrande ravine is also installed an infrasound sensor while the Lumbre monitoring station integrates a flow stage sensor. The new detection algorithm, currently under testing, is still based on the SNR but detected by two different sensors installed at the same cross-section: a geophone paired with a stage sensor or an infrasound device. Preliminary results show how this can be an effective solution to adopt along channels where is possible to monitor only one cross-section with a heavily instrumented station.

  12. Volcanic hazards and public response (United States)

    Peterson, Donald W.


    Although scientific understanding of volcanoes is advancing, eruptions continue to take a substantial toll of life and property. Some of these losses could be reduced by better advance preparation, more effective flow of information between scientists and public officials, and better understanding of volcanic behavior by all segments of the public. The greatest losses generally occur at volcanoes that erupt infrequently where people are not accustomed to dealing with them. Scientists sometimes tend to feel that the blame for poor decisions in emergency management lies chiefly with officials or journalists because of their failure to understand the threat. However, the underlying problem embraces a set of more complex issues comprising three pervasive factors. The first factor is the volcano: signals given by restless volcanoes are often ambiguous and difficult to interpret, especially at long-quiescent volcanoes. The second factor is people: people confront hazardous volcanoes in widely divergent ways, and many have difficulty in dealing with the uncertainties inherent in volcanic unrest. The third factor is the scientists: volcanologists correctly place their highest priority on monitoring and hazard assessment, but they sometimes fail to explain clearly their conclusions to responsible officials and the public, which may lead to inadequate public response. Of all groups in society, volcanologists have the clearest understanding of the hazards and vagaries of volcanic activity; they thereby assume an ethical obligation to convey effectively their knowledge to benefit all of society. If society resists, their obligation nevertheless remains. They must use the same ingenuity and creativity in dealing with information for the public that they use in solving scientific problems. When this falls short, even excellent scientific results may be nullified.

  13. Precambrian Lunar Volcanic Protolife

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    Jack Green


    Full Text Available Five representative terrestrial analogs of lunar craters are detailed relevant to Precambrian fumarolic activity. Fumarolic fluids contain the ingredients for protolife. Energy sources to derive formaldehyde, amino acids and related compounds could be by flow charging, charge separation and volcanic shock. With no photodecomposition in shadow, most fumarolic fluids at 40 K would persist over geologically long time periods. Relatively abundant tungsten would permit creation of critical enzymes, Fischer-Tropsch reactions could form polycyclic aromatic hydrocarbons and soluble volcanic polyphosphates would enable assembly of nucleic acids. Fumarolic stimuli factors are described. Orbital and lander sensors specific to protolife exploration including combined Raman/laser-induced breakdown spectrocsopy are evaluated.

  14. Volcanic activity and climatic changes. (United States)

    Bryson, R A; Goodman, B M


    Radiocarbon dates of volcanic activity suggest variations that appear to be related to climatic changes. Historical eruption records also show variations on the scale of years to centuries. These records can be combined with simple climatic models to estimate the impact of various volcanic activity levels. From this analysis it appears that climatic prediction in the range of 2 years to many decades requires broad-scale volcanic activity prediction. Statistical analysis of the volcanic record suggests that some predictability is possible.

  15. Volcanic eruptions; energy and size (United States)

    de la Cruz-Reyna, S.


    The Earth is a dynamic planet. Many different processes are continuously developing, creating a delicate balance between the energy stored and generated in its interior and the heat lost into space. The heat in continuously transferred through complex self-regulating convection mechanisms on a planetary scale. The distribution of terrestrial heat flow reveals some of the fine structure of the energy transport mechanisms in the outer layers of the Earth. Of these mechanisms in the outer layers of the Earth. Of these mechanisms, volcanism is indeed the most remarkable, for it allows energy to be transported in rapid bursts to the surface. In order to maintain the subtle balance of the terrestrial heat machine, one may expect that some law or principle restricts the ways in which these volcanic bursts affect the overall energy transfer of the Earth. For instance, we know that the geothermal flux of the planet amounts to 1028 erg/year. On the other hand, a single large event like the Lava Creek Tuff eruption that formed Yellowstone caldera over half a million years ago may release the same amount of energy in a very small area, over a short period of time. 


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    George Pararas-Carayannis


    Full Text Available Earthquakes, volcanic eruptions, volcanic island flank failures and underwater slides have generated numerous destructive tsunamis in the Caribbean region. Convergent, compressional and collisional tectonic activity caused primarily from the eastward movement of the Caribbean Plate in relation to the North American, Atlantic and South American Plates, is responsible for zones of subduction in the region, the formation of island arcs and the evolution of particular volcanic centers on the overlying plate. The inter-plate tectonic interaction and deformation along these marginal boundaries result in moderate seismic and volcanic events that can generate tsunamis by a number of different mechanisms. The active geo-dynamic processes have created the Lesser Antilles, an arc of small islands with volcanoes characterized by both effusive and explosive activity. Eruption mechanisms of these Caribbean volcanoes are complex and often anomalous. Collapses of lava domes often precede major eruptions, which may vary in intensity from Strombolian to Plinian. Locally catastrophic, short-period tsunami-like waves can be generated directly by lateral, direct or channelized volcanic blast episodes, or in combination with collateral air pressure perturbations, nuéss ardentes, pyroclastic flows, lahars, or cascading debris avalanches. Submarine volcanic caldera collapses can also generate locally destructive tsunami waves. Volcanoes in the Eastern Caribbean Region have unstable flanks. Destructive local tsunamis may be generated from aerial and submarine volcanic edifice mass edifice flank failures, which may be triggered by volcanic episodes, lava dome collapses, or simply by gravitational instabilities. The present report evaluates volcanic mechanisms, resulting flank failure processes and their potential for tsunami generation. More specifically, the report evaluates recent volcanic eruption mechanisms of the Soufriere Hills volcano on Montserrat, of Mt. Pel

  17. Modeling volcanic ash dispersal

    CERN Multimedia

    CERN. Geneva


    The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard...

  18. Origins of cryptic variation in the Ediacaran-Fortunian rhyolitic ignimbrites of the Saldanha Bay Volcanic Complex, Western Cape, South Africa (United States)

    Clemens, J. D.; Stevens, G.; Frei, D.; Joseph, C. S. A.


    The Saldanha eruption centre, on the West Coast of South Africa, consists of 542 Ma, intracaldera, S-type, rhyolite ignimbrites divided into the basal Saldanha Ignimbrite and the partly overlying Jacob's Bay Ignimbrite. Depleted-mantle Nd model ages suggest magma sources younger than the Early Mesoproterozoic, and located within the Neoproterozoic Malmesbury Group and Swartland complex metasedimentary and metavolcanic rocks that form the regional basement. The Sr isotope systematics suggest that the dominant source rocks were metavolcaniclastic rocks and metagreywackes, and that the magmas formed from separate batches extracted from the same heterogeneous source. No apparent magma mixing trends relate the Saldanha to the Jacob's Bay Ignimbrites, or either of these to the magmas that formed the Plankiesbaai or Tsaarsbank Ignimbrites in the neighbouring Postberg eruption centre. The magmas were extracted from their source rocks carrying small but significant proportions of peritectic and restitic accessory minerals. Variations in the content of this entrained crystal cargo were responsible for most of the chemical variations in the magmas. Although we cannot construct a cogent crystal fractionation model to relate these groups of magmas, at least some crystal fractionation occurred, as an overlay on the primary signal due to peritectic assemblage entrainment (PAE). Thus, the causes of the cryptic chemical variation among the ignimbrite magmas of the Saldanha centre are variable, but dominated by the compositions of the parent melts and PAE. The preservation of clear, source-inherited chemical signatures, in individual samples, calls into question the common interpretation of silicic calderas as having been formed in large magma reservoirs, with magma compositions shaped by magma mingling, mixing, and fractional crystallization. The Saldanha rocks suggest a more intimate connection between source and erupted magma, and perhaps indicate that silicic magmas are too

  19. Propiedades insecticidas de la ceniza del complejo volcánico Puyehue-Cordón Caulle y su posible impacto ambiental: Insecticidal properties of ashes from the volcanic complex Puyehue-Caulle Range and their possible environmental impact

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    Micaela Buteler


    insecticidal effect of volcanic ash and its environmental impact, focusing on the ash accumulated as a result of the eruption of the volcanic complex Puyehue- Caulle Range currently affecting an area of over 7.5 million hectares in the Argentine Patagonia. The chemical composition of ashes from the Puyehue-Caulle Range was analyzed by EDS showing that its major components are O, Si, Al, Fe, Na and K. Laboratory bioassays using two species of insects as a biological model, found that the ashes thoroughly adhere to the insect body surface and are toxic to both species tested, when mixed into the substrate at low concentrations. Susceptibility to ashes differs between the two species when tested in a seven day continuous exposure bioassay [CL99(Oryzaephilus surinamensis L. = 10.25 mg.g-1; CL99((Tribolium castaneum (Herbst = 4.96 mg.g-1]. These results agree with those reported in the literature on effects of volcanic eruptions and suggest that the impact of the ashes from the Puyehue-Caulle Range volcanic complex on the insect community may be radical in the acute deposition phase, with substantial qualitative effects in the chronic phase of exposure. Also, the recovery of populations affected by ash in desert areas where dry ash persists will be slower, and this will have tangible and long-term consequences for insect host plants, pollination and on the development of populations of vertebrate insectivores. By contrast, the presence of ash in humid regions will impact the ecosystem by the addition of nutrients, which in combination with water retention by the ash will lead to a qualitative and quantitative recovery of the populations under favorable conditions.

  20. The Online GVP/USGS Weekly Volcanic Activity Report: Providing Timely Information About Worldwide Volcanism (United States)

    Mayberry, G. C.; Guffanti, M. C.; Luhr, J. F.; Venzke, E. A.; Wunderman, R. L.


    over 60 volcanoes, with an average of 10 volcanoes discussed each week. Notable volcanic activity during November 2000-November 2001 included an eruption beginning on 6 February at Nyamuragira in the Democratic Republic of the Congo; it issued low-viscosity lava flows that traveled towards inhabited towns, and also produced ash clouds that adversely effected the health of residents and livestock near the volcano. Eruptions at Mayon in the Philippines on 24 June and 25 July caused local authorities to raise the alert to the highest level, close area airports, and evacuate thousands of residents near the volcano. Most recently a large flank eruption at Etna in Italy began on 17 July and gained worldwide attention as extensive lava flows threatened a small town and a tourist complex. While the information found in the Weekly Volcanic Activity Report, ranging from large eruptions to small precursory events, is of interest to the general public, it has also proven to be a valuable resource to volcano observatory staff, universities, researchers, secondary schools, and the aviation community.

  1. Reproducción de la morena, Gymnothorax equatorialis (Pisces: Muraenidae en Jalisco y Colima, México

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    G Lucano-Ramírez


    Full Text Available Con el fin de analizar los aspectos reproductivos de Gymnothorax equatorialis se recolectaron mensualmente 707 organismos en las costas de Jalisco y Colima, México, de diciembre de 1995 a diciembre de 1998 y de agosto a diciembre de 1999. Las hembras fueron más numerosas y presentaron una longitud (54.7 cm mayor a la de los machos (52.1 cm. La fecundidad total mínima fue de 9 660 huevos, la máxima de 99 992 y la media fue 32 029 huevos. La talla en la que el 50 % de los individuos presentan gónadas maduras (L50 fue de 43.7 cm de longitud total en hembras y de 42.7 cm en machos. Los ovarios presentaron dos tipos de ovocitos, los pequeños inmaduros en fase cromatina nucleolo (85.1 µm y los grandes maduros en fase de vitelogénesis secundaria (701.6 µm. En el testículo maduro se observó una gran cantidad de espermatozoides en el tubo seminal y el desarrollo del testículo es de tipo lobular. Con base en las características de las gónadas y la evolución temporal del índice gonadosomático, se concluye que G. equatorialis se reproduce dos veces al año (a mediados y finales del año.Reproduction of the fish Gymnothorax equatorialis (Pisces: Muraenidae in Jalisco and Colima, Mexico. A total of 707 Gymnothorax equatorialis were collected monthly in the Jalisco and Colima coast, Mexico, from December 1995 to December 1998 and from August to November 1999, in order to determine their reproduction patterns. Females outnumbered and had longer bodies (mean length 54.7 cm than males (52.1 cm. The minimum, maximum and mean values of total fecundity were respectively 9 660, 99 992 and 32 029 eggs. The total body length at which 50 percent of individuals have ripe gonads (L50 was 43.7 cm for females and 42.7 cm TL for males. Ovaries had two main types of oocytes: small inmature in cromatin nucleolus phase (85.1 µm and large mature in secundary vitellogenesis phase (701.6 µm. High numbers of spermatozoa were observed in the seminal tubes of ripe

  2. Backprojection of volcanic tremor (United States)

    Haney, Matthew M.


    Backprojection has become a powerful tool for imaging the rupture process of global earthquakes. We demonstrate the ability of backprojection to illuminate and track volcanic sources as well. We apply the method to the seismic network from Okmok Volcano, Alaska, at the time of an escalation in tremor during the 2008 eruption. Although we are able to focus the wavefield close to the location of the active cone, the network array response lacks sufficient resolution to reveal kilometer-scale changes in tremor location. By deconvolving the response in successive backprojection images, we enhance resolution and find that the tremor source moved toward an intracaldera lake prior to its escalation. The increased tremor therefore resulted from magma-water interaction, in agreement with the overall phreatomagmatic character of the eruption. Imaging of eruption tremor shows that time reversal methods, such as backprojection, can provide new insights into the temporal evolution of volcanic sources.

  3. Growth of the Pacific jack Caranx caninus (Pisces: Carangidae from the coast of Colima, México

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    Elaine Espino Barr


    Full Text Available The Pacific jack Caranx caninus is a common species fished by artisanal fishermen off the coast of Colima, México. During 2002, monthly samples of morphometric data and otoliths were taken to determine age and growth. Seven age groups were identified. The highest growth, 14.4 cm, takes place during the first year of life. During the second year, C. caninus grows 11.76 cm; the third year 9.61 cm; the fourth 7.85 cm; the fifth 6.41 cm and sixth year 5.24 cm. The constants of von Bertalanffy´s growth equation were: L∞ = 83.26 cm, W∞ = 18.138 g, K = 0.202, t o = -0.283 and A0.95 = 15 years. Growth curves of other species of the same genus were calculated in order to compare them with the one obtained in the present work. The gonadosomatic index presented higher values during November and May. The periods of more intensive feeding are from August to February. Rev. Biol. Trop. 56 (1: 171-179. Epub 2008 March 31.El jurel Caranx caninus es una especie común que se captura en la pesca artesanal frente a las costas de Colima, México. Mensualmente, durante 2002, se tomaron datos morfométricos y muestras de otolitos para determinar la edad y el crecimiento. Se encontraron siete grupos de edad; durante el primer año de vida se da el mayor crecimiento, hasta 14.4 cm. Durante el segundo año, C. caninus crece 11.76 cm; el tercero 9.61 cm; el cuarto 7.85 cm; el quinto 6.41 cm y el último año crece 5.24 cm. Las constantes de la ecuación de crecimiento de von Bertalanffy fueron: L∞ = 83.26 cm, W∞ = 18.138 g, K = 0.202, to = -0.283 y la longevidad A0.95 = 15 años. Las curvas de crecimiento de otras especies del mismo género se compararon con las obtenidas en el presente trabajo. El índice gonadosomático presentó valores más altos durante noviembre y mayo. Los periodos de tiempo de alimentación más intensa son de agosto a febrero.

  4. Waterbirds (other than Laridae nesting in the middle section of Laguna Cuyutlán, Colima, México

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    Eric Mellink


    Full Text Available Laguna de Cuyutlán, in the state of Colima, Mexico, is the only large coastal wetland in a span of roughly 1150 km. Despite this, the study of its birds has been largely neglected. Between 2003 and 2006 we assessed the waterbirds nesting in the middle portion of Laguna Cuyutlán, a large tropical coastal lagoon, through field visits. We documented the nesting of 15 species of non-Laridae waterbirds: Neotropic Cormorant (Phalacrocorax brasilianus, Tricolored Egret (Egretta tricolor, Snowy Egret (Egretta thula, Little Blue Heron (Egretta caerulea, Great Egret (Ardea alba, Cattle Egret (Bubulcus ibis, Black-crowned Nightheron (Nycticorax nycticorax, Yellow-crowned Night-heron (Nyctanassa violacea, Green Heron (Butorides virescens, Roseate Spoonbill (Platalea ajaja, White Ibis (Eudocimus albus, Black-bellied Whistling-duck (Dendrocygna autumnalis, Clapper Rail (Rallus longirostris, Snowy Plover (Charadrius alexandrinus, and Black-necked Stilt (Himantopus mexicanus. These add to six species of Laridae known to nest in that area: Laughing Gulls (Larus atricilla, Royal Terns (Thalasseus maximus, Gull-billed Terns (Gelochelidon nilotica, Forster’s Terns (S. forsteri, Least Terns (Sternula antillarum, and Black Skimmer (Rynchops niger, and to at least 57 species using it during the non-breeding season. With such bird assemblages, Laguna Cuyutlán is an important site for waterbirds, which should be given conservation status. Rev. Biol. Trop. 56 (1: 391-397. Epub 2008 March 31.Durante la prospección de la parte media de la Laguna Cuyutlán, una gran laguna costera en Colima, México, entre 2003 y 2006, documentamos la anidación de 15 especies de aves acuáticas que no pertenecer a la familia Laridae: Phalacrocorax brasilianus, Egretta tricolor, Egretta thula, Egretta caerulea, Ardea alba, Bubulcus ibis, Nycticorax nycticorax, Nyctanassa violacea, Butorides virescens, Platalea ajaja, Eudocimus albus, Dendrocygna autumnalis, Rallus longirostris

  5. Volcanic eruptions on Io (United States)

    Strom, R. G.; Schneider, N. M.; Terrile, R. J.; Cook, A. F.; Hansen, C.


    Nine eruption plumes which were observed during the Voyager 1 encounter with Io are discussed. During the Voyager 2 encounter, four months later, eight of the eruptions were still active although the largest became inactive sometime between the two encounters. Plumes range in height from 60 to over 300 km with corresponding ejection velocities of 0.5 to 1.0 km/s and plume sources are located on several plains and consist of fissures or calderas. The shape and brightness distribution together with the pattern of the surface deposition on a plume 3 is simulated by a ballistic model with a constant ejection velocity of 0.5 km/s and ejection angles which vary from 0-55 deg. The distribution of active and recent eruptions is concentrated in the equatorial regions and indicates that volcanic activity is more frequent and intense in the equatorial regions than in the polar regions. Due to the geologic setting of certain plume sources and large reservoirs of volatiles required for the active eruptions, it is concluded that sulfur volcanism rather than silicate volcanism is the most likely driving mechanism for the eruption plumes.

  6. Combining High Resolution InSAR and infrared photogrammetry for studying dome degassing and densification mechanisms at Volcán de Colima, Mexico (United States)

    Salzer, Jacqueline T.; Milillo, Pietro; Varley, Nick; Perissin, Daniele; Pantaleo, Michele; Walter, Thomas R.


    Active volcanoes often display cyclic behaviour with alternating quiescent and eruptive periods. Continuously monitoring volcanic processes such as deformation, seismicity and degassing, irrespective of their current status, is crucial for understanding the parameters governing the fluid transport within the edifice and the transitions between different regimes. However, mapping the deformation and details of fluid escape at the summit of steep sloped volcanoes and integrating these with other types of data is challenging. Here we present for the first time the near-3D surface deformation field derived from high resolution radar interferometry (InSAR) acquired by the satellite TerraSAR-X at a degassing volcano dome and interpret the results in combination with overflight infrared and topographic data. We find that the results strongly differ depending on the chosen InSAR time series method, which potentially overprints the true physical complexities of small scale, shallow deformation processes. We present a new method for accurate mapping of heterogeneities in the dome deformation, and comparison to the topography and precisely located surface temperature anomalies. The identified deformation is dominated by strong but highly localized subsidence of the summit dome. Our results highlight the competing effects of the topography, permeability and shallow volcanic structures controlling the degassing pathways. On small spatial scales compaction sufficiently reduced the dome permeability to redirect the fluid flow. High resolution InSAR monitoring of volcanic domes thus provides valuable data for constraining models of their internal structure, degassing pathways and densification processes.

  7. Bloom of Gymnodinium catenatum in Bahía Santiago and Bahía Manzanillo, Colima, Mexico. (United States)

    Quijano-Scheggia, Sonia; Olivos-Ortiz, Aramis; Bustillos-Guzmán, José J; Garcés, Esther; Gaviño-Rodríguez, Juan H; Galicia-Pérez, Marco A; Patiño-Barragan, Manuel; Band-Schmidt, Christine J; Hernández-Sandoval, Francisco J; López-Cortés, David J


    Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88 microM DIN, 0.78 microM PO4 and 24.34 microM SiO2) were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x 10(7) cells/L). Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC) in local oysters (1525.8 microg STXeq/100g), and in phytoplankton (10.9 pg STXeq/cells) samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells), most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico.

  8. Bloom of Gymnodinium catenatum in Bahía Santiago and Bahía Manzanillo, Colima, Mexico

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    Sonia Quijano-Scheggia


    Full Text Available Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88μM DIN, 0.78μM PO4 and 24.34μM SiO2 were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x10(7cells/L. Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC in local oysters (1525.8μg STXeq/100g, and in phytoplankton (10.9pg STXeq/cells samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells, most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico.

  9. Thermal, atmospheric and ionospheric anomalies around the time of the Colima M7.8 earthquake of 21 January 2003

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    S. A. Pulinets


    Full Text Available The paper examines the possible relationship of anomalous variations of different atmospheric and ionospheric parameters observed around the time of a strong earthquake (Mw 7.8 which occurred in Mexico (state of Colima on 21 January 2003. These variations are interpreted within the framework of the developed model of the Lithosphere-Atmosphere-Ionosphere coupling. The main attention is focused on the processes in the near ground layer of the atmosphere involving the ionization of air by radon, the water molecules' attachment to the formed ions, and the corresponding changes in the latent heat. Model considerations are supported by experimental measurements showing the local diminution of air humidity one week prior to the earthquake, accompanied by the anomalous thermal infrared (TIR signals and surface latent heat flux (SLHF and anomalous variations of the total electron content (TEC registered over the epicenter of the impending earthquake three days prior to the main earthquake event. Statistical processing of the data of the GPS receivers network, together with various other atmospheric parameters demonstrate the possibility of an early warning of an impending strong earthquake.

  10. Cost-Effectiveness of the Strategies to Reduce the Incidence of Dengue in Colima, México. (United States)

    Mendoza-Cano, Oliver; Hernandez-Suarez, Carlos Moisés; Trujillo, Xochitl; Ochoa Diaz-Lopez, Héctor; Lugo-Radillo, Agustin; Espinoza-Gomez, Francisco; de la Cruz-Ruiz, Miriam; Sánchez-Piña, Ramón Alberto; Murillo-Zamora, Efrén


    Dengue fever is considered to be one of the most important arboviral diseases globally. Unsuccessful vector-control strategies might be due to the lack of sustainable community participation. The state of Colima, located in the Western region of Mexico, is a dengue-endemic area despite vector-control activities implemented, which may be due to an insufficient health economic analysis of these interventions. A randomized controlled community trial took place in five urban municipalities where 24 clusters were included. The study groups ( n = 4) included an intervention to improve the community participation in vector control (A), ultra-low volume (ULV) spraying (B), both interventions (AB), and a control group. The main outcomes investigated were dengue cumulative incidence, disability-adjusted life years (DALYs), and the direct costs per intervention. The cumulative incidence of dengue was 17.4%, A; 14.3%, B; 14.4%, AB; and 30.2% in the control group. The highest efficiency and effectiveness were observed in group B (0.526 and 6.97, respectively) and intervention A was more likely to be cost-effective ($3952.84 per DALY avoided) followed by intervention B ($4472.09 per DALY avoided). Our findings suggest that efforts to improve community participation in vector control and ULV-spraying alone are cost-effective and may be useful to reduce the vector density and dengue incidence.

  11. Probabilistic Tsunami Hazard Analysis of the Pacific Coast of Mexico: Case Study Based on the 1995 Colima Earthquake Tsunami

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    Nobuhito Mori


    Full Text Available This study develops a novel computational framework to carry out probabilistic tsunami hazard assessment for the Pacific coast of Mexico. The new approach enables the consideration of stochastic tsunami source scenarios having variable fault geometry and heterogeneous slip that are constrained by an extensive database of rupture models for historical earthquakes around the world. The assessment focuses upon the 1995 Jalisco–Colima Earthquake Tsunami from a retrospective viewpoint. Numerous source scenarios of large subduction earthquakes are generated to assess the sensitivity and variability of tsunami inundation characteristics of the target region. Analyses of nine slip models along the Mexican Pacific coast are performed, and statistical characteristics of slips (e.g., coherent structures of slip spectra are estimated. The source variability allows exploring a wide range of tsunami scenarios for a moment magnitude (Mw 8 subduction earthquake in the Mexican Pacific region to conduct thorough sensitivity analyses and to quantify the tsunami height variability. The numerical results indicate a strong sensitivity of maximum tsunami height to major slip locations in the source and indicate major uncertainty at the first peak of tsunami waves.

  12. [The frequency of risk factors associated with obesity and being overweight in university students from Colima, Mexico]. (United States)

    Trujillo-Hernández, Benjamín; Vásquez, Clemente; Almanza-Silva, José R; Jaramillo-Virgen, María E; Mellin-Landa, Tadeana E; Valle-Figueroa, Ofelia B; Pérez-Ayala, Roberto; Millán-Guerrero, Rebeca O; Prieto-Díaz-Chávez, Emilio; Newton-Sánchez, Oscar


    Determining risk factor frequency regarding obesity and being overweight in university students. A cross-sectional analytic study was carried out on 821 students from the University of Colima. Some variables analysed were age, gender, alcoholism, smoking and weight-control drug use. 821 students were included (380 male, 441 female), 20.9±2.5 average age. 27.8 % of males were overweight and 14.7 % suffered from obesity; this was 17 % and 5.2 % in females, respectively. Smoking (2.1 OR; 1.4-3.8 95 % CI; p=0.01) and alcoholism (2.1 OR; 1.2-3.6 95 % CI; p=0.003) were associated with being overweight and being obese. Weight-control drug use was a protective factor in both genders (0.4 OR; 0.2-0.8 95 % CI; p=0.01); diet control was only a protective factor in women (2.2. OR; 1.1-3.4 95 % CI; p=0.01). 31.6 % of university students were overweight and suffered from obesity. Smoking and alcoholism in males were associated with being overweight and suffering from obesity. Weight-control and diet-control drug use were protective factors.

  13. Thermal, atmospheric and ionospheric anomalies around the time of the Colima M7.8 earthquake of 21 January 2003

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    S. A. Pulinets


    Full Text Available The paper examines the possible relationship of anomalous variations of different atmospheric and ionospheric parameters observed around the time of a strong earthquake (Mw 7.8 which occurred in Mexico (state of Colima on 21 January 2003. These variations are interpreted within the framework of the developed model of the Lithosphere-Atmosphere-Ionosphere coupling. The main attention is focused on the processes in the near ground layer of the atmosphere involving the ionization of air by radon, the water molecules' attachment to the formed ions, and the corresponding changes in the latent heat. Model considerations are supported by experimental measurements showing the local diminution of air humidity one week prior to the earthquake, accompanied by the anomalous thermal infrared (TIR signals and surface latent heat flux (SLHF and anomalous variations of the total electron content (TEC registered over the epicenter of the impending earthquake three days prior to the main earthquake event. Statistical processing of the data of the GPS receivers network, together with various other atmospheric parameters demonstrate the possibility of an early warning of an impending strong earthquake.

  14. The Zuni-Bandera Volcanic Field, NM: An Analog for Exploring Planetary Volcanic Terrains (United States)

    Bleacher, J. E.; Garry, W. B.; Zimbelman, J. R.; Crumpler, L. S.; Aubele, J. C.


    of several overlapping flows in a limited area and also shows the challenge of exploring expansive (100-1000’s square kilometers) volcanic terrains on other planets. The Zuni-Bandera field represents one style of geologic processes (volcanic field development) and in essence is an “end-member” of volcanic field analogs. Results from these studies must be considered with comparable results from other geologic terrains to better represent the complexities of exploring other planetary surfaces.

  15. The Role of Volcanic Activity in Climate and Global Change

    KAUST Repository

    Stenchikov, Georgiy L.


    Explosive volcanic eruptions are magnificent events that in many ways affect the Earth\\'s natural processes and climate. They cause sporadic perturbations of the planet\\'s energy balance, activating complex climate feedbacks and providing unique opportunities to better quantify those processes. We know that explosive eruptions cause cooling in the atmosphere for a few years, but we have just recently realized that volcanic signals can be seen in the subsurface ocean for decades. The volcanic forcing of the previous two centuries offsets the ocean heat uptake and diminishes global warming by about 30%. The explosive volcanism of the twenty-first century is unlikely to either cause any significant climate signal or to delay the pace of global warming. The recent interest in dynamic, microphysical, chemical, and climate impacts of volcanic eruptions is also excited by the fact that these impacts provide a natural analogue for climate geoengineering schemes involving deliberate development of an artificial aerosol layer in the lower stratosphere to counteract global warming. In this chapter we aim to discuss these recently discovered volcanic effects and specifically pay attention to how we can learn about the hidden Earth-system mechanisms activated by explosive volcanic eruptions. To demonstrate these effects we use our own model results when possible along with available observations, as well as review closely related recent publications.

  16. Prevention of Catastrophic Volcanic Eruptions


    Fujii, Yoshiaki; Kodama, Jun-ichi; Fukuda, Daisuke; Dassanayake, Abn


    Giant volcanic eruptions emit sulphate aerosols as well as volcanic ash. Needless to say that volcanic ash causes significant damage to the environment and human at large. However, the aerosols are even worse. They reach the Stratosphere and stay there for months to years reflecting insolation. As a result, air temperature at the Earth's surfaces drops. Even a slight temperature drop may cause severe food shortage. Yellowstone supervolcano, for example, can even make human in the Northern Hem...

  17. Stability of volcanic conduits during explosive eruptions (United States)

    Aravena, Álvaro; de'Michieli Vitturi, Mattia; Cioni, Raffaello; Neri, Augusto


    consider volcanic conduits with depth-dependent radius, two plausible and previously untested geometries have been studied, evidencing major and complex modifications in some eruptive parameters (particularly, exit pressure and mass discharge rate), and suggesting that the geometry acquired by the conduit as it is widened influences the eruptive dynamics.

  18. Volcanic Ash Nephelometer Probe Project (United States)

    National Aeronautics and Space Administration — Advanced dropsondes that could effectively be guided through atmospheric regions of interest such as volcanic plumes may enable unprecedented observations of...

  19. Climatic fluctuations as a significant contributing factor for volcanic collapses. Evidence from Mexico during the Late Pleistocene (United States)

    Capra, L.; Bernal-Uruchurtu, J. P.; Carrasco, G.


    Climate oscillations have significantly contributed to the planet's evolution, including volcanic activity. Major glaciations have been considered not only as a triggering mechanism for large magmatic eruptions but also inducing volcano instability. Generally, volcano instability can be inferred from detailed volcanological and structural studies of a volcano and its associated depositional sequence, but the triggering mechanism has been always difficult to infer. In this paper, we present evidence of how climatic variations during the Late Pleistocene could have forced sector collapses of the main Mexican stratovolcanoes and enhanced the mobility of associated massive flows inducing the transformation of debris avalanche into debris flows. In particular, the climatic record based on atmospheric moisture content from robustly dated lake record from Guatemala and a U/Th dated speleothem from New Mexico are used here as indicators of summer and winter precipitation. Depositional sequences associated with Late Pleistocene sector collapses of Volcan de Colima, Nevado de Toluca, Citlaltepetl (Pico de Orizaba) and Cofre de Perote volcanoes are here analyzed. Comparing the timing of the event with the climatic record, a combination of summer and/or winter pluvial conditions could have forced and triggered the failure of already unstable volcanoes, even during glacier advances (as for the Citlaltepetl event). Independently of the main cause of the volcano instability (magmatic or tectonic) it is important to highlight that the climatic factor played an important role in enhancing the volcano instability and promoted the lateral transformation of debris avalanches, which under dry conditions would have affected more limited areas.

  20. New insight from noble gas and stable isotopes of geothermal/hydrothermal fluids at Caviahue-Copahue Volcanic Complex: Boiling steam separation and water-rock interaction at shallow depth (United States)

    Roulleau, Emilie; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; Vinet, Nicolas; Bravo, Francisco; Muñoz, Carlos; Sanchez, Juan


    We measured noble gas and stable isotopes of the geothermal and hydrothermal fluids of the Caviahue-Copahue Volcanic Complex (CCVC), one of the most important geothermal systems in Argentina/Chile, in order to provide new insights into fluid circulation and origin. With the exception of Anfiteatro and Chancho-co geothermal systems, mantle-derived helium dominates in the CCVC fluids, with measured 3He/4He ratios up to 7.86Ra in 2015. Their positive δ15N is an evidence for subducted sediment-derived nitrogen, which is commonly observed in subduction settings. Both He-N2-Ar composition and positive correlation between δD-H2O and δ18O-H2O suggest that the fluids from Anfiteatro and Chancho-co (and partly from Pucon-Mahuida as well, on the southern flank of Copahue volcano) represent a meteoric water composition with a minor magmatic contribution. The Ne, Kr and Xe isotopic compositions are entirely of atmospheric origin, but processes of boiling and steam separation have led to fractionation of their elemental abundances. We modeled the CCVC fluid evolution using Rayleigh distillation curves, considering an initial air saturated geothermal water (ASGW) end-member at 250 and 300 °C, followed by boiling and steam separation at lower temperatures (from 200 °C to 150 °C). Between 2014 and 2015, the CCVC hydrogen and oxygen isotopes shifted from local meteoric water-dominated to andesitic water-dominated signature. This shift is associated with an increase of δ13C values and Stotal, HCl and He contents. These characteristics are consistent with a change in the gas ascent pathway between 2014 and 2015, which in turn induced higher magmatic-hydrothermal contribution in the fluid signature. The composition of the magmatic source of the CCVC fluids is: 3He/4He = 7.7Ra, δ15N = + 6‰, and δ13C = - 6.5‰. Mixing models between air-corrected He and N suggest the involvement of 0.5% to 5% of subducted sediments in the magmatic source. The magmatic sulfur isotopic

  1. Volcanic Soils as Sources of Novel CO-OxidizingParaburkholderiaandBurkholderia:Paraburkholderia hiiakaesp. nov.,Paraburkholderia metrosiderisp. nov.,Paraburkholderia paradisisp. nov.,Paraburkholderia peleaesp. nov., andBurkholderia alpinasp. nov. a Member of theBurkholderia cepaciaComplex. (United States)

    Weber, Carolyn F; King, Gary M


    Previous studies showed that members of the Burkholderiales were important in the succession of aerobic, molybdenum-dependent CO oxidizing-bacteria on volcanic soils. During these studies, four isolates were obtained from Kilauea Volcano (Hawai'i, USA); one strain was isolated from Pico de Orizaba (Mexico) during a separate study. Based on 16S rRNA gene sequence similarities, the Pico de Orizaba isolate and the isolates from Kilauea Volcano were provisionally assigned to the genera Burkholderia and Paraburkholderia , respectively. Each of the isolates possessed a form I coxL gene that encoded the catalytic subunit of carbon monoxide dehydrogenase (CODH); none of the most closely related type strains possessed coxL or oxidized CO. Genome sequences for Paraburkholderia type strains facilitated an analysis of 16S rRNA gene sequence similarities and average nucleotide identities (ANI). ANI did not exceed 95% (the recommended cutoff for species differentiation) for any of the pairwise comparisons among 27 reference strains related to the new isolates. However, since the highest 16S rRNA gene sequence similarity among this set of reference strains was 98.93%, DNA-DNA hybridizations (DDH) were performed for two isolates whose 16S rRNA gene sequence similarities with their nearest phylogenetic neighbors were 98.96 and 99.11%. In both cases DDH values were <16%. Based on multiple variables, four of the isolates represent novel species within the Paraburkholderia : Paraburkholderia hiiakae sp. nov. (type strain I2 T = DSM 28029 T = LMG 27952 T ); Paraburkholderia paradisi sp. nov. (type strain WA T = DSM 28027 T = LMG 27949 T ); Paraburkholderia peleae sp. nov. (type strain PP52-1 T = DSM 28028 T = LMG 27950 T ); and Paraburkholderia metrosideri sp. nov. (type strain DNBP6-1 T = DSM 28030 T = LMG 28140 T ). The remaining isolate represents the first CO-oxidizing member of the Burkholderia cepacia complex: Burkholderia alpina sp. nov. (type strain PO-04-17-38 T = DSM 28031 T

  2. Volcan Reventador's Unusual Umbrella (United States)

    Chakraborty, P.; Gioia, G.; Kieffer, S. W.


    In the past two decades, field observations of the deposits of volcanoes have been supplemented by systemmatic, and sometimes, opportunistic photographic documentation. Two photographs of the umbrella of the December 3, 2002 eruption of Volcan Reventador, Ecuador, reveal a prominently scalloped umbrella that is unlike any umbrella previously documented on a volcanic column. The material in the umbrella was being swept off a descending pyroclastic flow, and was, therefore, a co-ignimbrite cloud. We propose that the scallops are the result of a turbulent Rayleigh-Taylor (RT) instability with no precedents in volcanology. We ascribe the rare loss of buoyancy that drives this instability to the fact that the Reventador column fed on a cool co-ignimbrite cloud. On the basis of the observed wavelength of the scallops, we estimate a value for the eddy viscosity of the umbrella of 4000 ~m2/s. This value is consistent with a previously obtained lower bound (200 ~m2/s, K. Wohletz, priv. comm., 2005). We do not know the fate of the material in the umbrella subsequent to the photos. The analysis suggests that the umbrella was negatively buoyant. Field work on the co-ignimbrite deposits might reveal whether or not the material reimpacted, and if so, where and whether or not this material was involved in the hazardous flows that affected the main oil pipeline across Ecuador.

  3. Competitividad de las agroindustrias del limón pertenecientes al clúster del limón mexicano en Colima, México


    Magaña Sánchez, Pablo Adrián; Padilla Bernal, Luz Evelia; Vargas Hernández, José G.


    El presente trabajo se refiere al estudio del nivel de competitividad de las Agroindustrias del Limón pertenecientes al clúster del limón mexicano en Colima, México en base al modelo del IMD (International Institute for Management Development) como teoría de soporte. En este estudio se diseño y utilizó un instrumento de medición de acuerdo al modelo anteriormente mencionado adaptando las variables para el contexto de nuestro estudio. Es necesario mencionar que el modelo del IMD se utilizó par...

  4. Complexity

    Indian Academy of Sciences (India)

    Rahul Pandit


    Oct 31, 2008 ... ”The more complex a thing is, the more you can talk about it.” - attributed to Giorgio Parisi. ▻ ”C'est magnifique, mais ce n'est pas de la science.” (It is magnificent, but not all of it is science.) - attributed ... Earliest examples: theoretical computer science, algorithmic complexity, etc. ▻ Rapid progress after the ...

  5. Short-lived and discontinuous intraplate volcanism in the South Pacific: Hot spots or extensional volcanism? (United States)

    Koppers, Anthony A. P.; Staudigel, Hubert; Pringle, Malcolm S.; Wijbrans, Jan R.


    South Pacific intraplate volcanoes have been active since the Early Cretaceous. Their HIMU-EMI-EMII mantle sources can be traced back into the West Pacific Seamount Province (WPSP) using plate tectonic reconstructions, implying that these distinctive components are enduring features within the Earth's mantle for, at least, the last 120 Myr. These correlations are eminent on the scale of the WPSP and the South Pacific Thermal and Isotopic Anomaly (SOPITA), but the evolution of single hot spots emerges notably more complicated. Hot spots in the WPSP and SOPITA mantle regions typically display intermittent volcanic activity, longevities shorter than 40 Myr, superposition of hot spot volcanism, and motion relative to other hot spots. In this review, we use 40Ar/39Ar seamount ages and Sr-Nd-Pb isotopic signatures to map out Cretaceous volcanism in the WPSP and to characterize its evolution with respect to the currently active hot spots in the SOPITA region. Our plate tectonic reconstructions indicate cessation of volcanism during the Cretaceous for the Typhoon and Japanese hot spots; whereas the currently active Samoan, Society, Pitcairn and Marquesas hot spots lack long-lived counterparts in the WPSP. These hot spots may have become active during the last 20 Myr only. The other WPSP seamount trails can be only "indirectly" reconciled with hot spots in the SOPITA region. Complex age distributions in the Magellan, Anewetak, Ralik and Ratak seamount trails would necessitate the superposition of multiple volcanic trails generated by the Macdonald, Rurutu and Rarotonga hot spots during the Cretaceous; whereas HIMU-type seamounts in the Southern Wake seamount trail would require 350-500 km of hot spot motion over the last 100 Myr following its origination along the Mangaia-Rurutu "hotline" in the Cook-Austral Islands. These observations, however, violate all assumptions of the classical Wilson-Morgan hot spot hypothesis, indicating that long-lived, deep and fixed mantle

  6. Bloom of Gymnodinium catenatum in Bahía Santiago and Bahía Manzanillo, Colima, Mexico

    Directory of Open Access Journals (Sweden)

    Sonia Quijano-Scheggia


    Full Text Available Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88μM DIN, 0.78μM PO4 and 24.34μM SiO2 were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x10(7cells/L. Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC in local oysters (1525.8μg STXeq/100g, and in phytoplankton (10.9pg STXeq/cells samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells, most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico.La proliferación de Gymnodinium son motivo de preocupación, debido a que en algunas circunstancias producen toxinas, que tienen consecuencias desfavorables para los ecosistemas marinos, la salud humana y la economía. Este trabajo describe las condiciones fisicoquímicas presentes durante una proliferación algal detectado en mayo de 2010 en la Bahía de Santiago y Bahía Manzanillo (Colima, México. La proliferación algal inició poco tiempo después de registrarse las temperaturas oceánicas superficiales más bajas del año, las cuales permitieron un aumento de las

  7. On a Possible Unified Scaling Law for Volcanic Eruption Durations. (United States)

    Cannavò, Flavio; Nunnari, Giuseppe


    Volcanoes constitute dissipative systems with many degrees of freedom. Their eruptions are the result of complex processes that involve interacting chemical-physical systems. At present, due to the complexity of involved phenomena and to the lack of precise measurements, both analytical and numerical models are unable to simultaneously include the main processes involved in eruptions thus making forecasts of volcanic dynamics rather unreliable. On the other hand, accurate forecasts of some eruption parameters, such as the duration, could be a key factor in natural hazard estimation and mitigation. Analyzing a large database with most of all the known volcanic eruptions, we have determined that the duration of eruptions seems to be described by a universal distribution which characterizes eruption duration dynamics. In particular, this paper presents a plausible global power-law distribution of durations of volcanic eruptions that holds worldwide for different volcanic environments. We also introduce a new, simple and realistic pipe model that can follow the same found empirical distribution. Since the proposed model belongs to the family of the self-organized systems it may support the hypothesis that simple mechanisms can lead naturally to the emergent complexity in volcanic behaviour.

  8. From olivine nephelinite, basanite and basalt to peralkaline trachyphonolite and comendite in the Ankaratra volcanic complex, Madagascar: 40Ar/39Ar ages, phase compositions and bulk-rock geochemical and isotopic evolution (United States)

    Cucciniello, Ciro; Melluso, Leone; le Roex, Anton P.; Jourdan, Fred; Morra, Vincenzo; de'Gennaro, Roberto; Grifa, Celestino


    The Ankaratra volcanic field covers an area of 3800 km2 in central Madagascar and comprises of lava flows, lava domes, scoria cones, tuff rings and maars emplaced at different ages (Miocene to Recent). The volcanic products include ultramafic-mafic (olivine-leucite nephelinite, basanite, alkali basalt, hawaiite and tholeiitic basalt), intermediate (mugearite and benmoreite) and felsic rocks (trachyphonolite, quartz trachyte and rhyolite), the latter often peralkaline. The 40Ar/39Ar determinations for mafic lavas yield ages of 17.45 ± 0.12 Ma, 16.63 ± 0.08 Ma and 8.62 ± 0.09 Ma, indicating a prolonged magmatic activity. The mineralogical and geochemical variations suggest that the magmatic evolution of the alkali basalt-hawaiite-mugearite-benmoreite-trachyte series can be accounted for by removal of olivine, feldspars, clinopyroxene, Fe-Ti oxides and accessory phases, producing residual trachytic and trachyphonolitic compositions mineralogically very similar to those of other volcanic areas and tectonic settings. The Ankaratra olivine leucite nephelinites, basanites and tholeiitic basalts do not seem to be associated with significant amounts of evolved comagmatic rocks. The 87Sr/86Sr (0.70504-0.71012), 143Nd/144Nd (0.51259-0.51244) and 206Pb/204Pb (17.705-18.563) isotopic ratios of trachytes and comendite are consistent with open-system processes. However, other trachyphonolites have 143Nd/144Nd (0.51280), 206Pb/204Pb (18.648), 207Pb/204Pb (15.582) and 208Pb/204Pb (38.795) similar to those of mafic rocks, suggesting differentiation processes without appreciable interaction with crustal materials. The Ankaratra volcanism is to be directly linked to a broadly E-W-trending intracontinental extension. A large-scale thermal anomaly, associated with an anomalously hot source region, is not required to explain the Cenozoic magmatism of Madagascar.

  9. Self-potential anomalies in some Italian volcanic areas

    Directory of Open Access Journals (Sweden)

    C. Silenziario


    Full Text Available The study of Self-Potential (SP space and time variations in volcanic areas may provide useful information on both the geometrical structure of the volcanic apparatuses and the dynamical behaviour of the feeding and uprising systems. In this paper, the results obtained on the islands of Vulcano (Eolian arc and Ponza (Pontine archipelago and on the Mt. Somma-Vesuvius complex are shown. On the island of Vulcano and on the Mt. Somma-Vesuvius apparatus areal SP surveys were performed with the aim of evidencing anomalies closely associated to the zones of major volcanic activity. On the island of Vulcano a profile across the fumaroles along the crater rim of the Fossa Cone was also carried out in order to have a direct relationship between fumarolic fracture migration and flow rate and SP anomaly space and time variations. The areal survey on the island of Ponza, which is considered an inactive area, is assumed as a reference test with which to compare the amplitude and pattern of the anomalies in the active areas. A tentative interpretation of the SP anomalies in volcanic areas is suggested in terms of electrokinetic phenomena, related to the movement of fluids of both volcanic and non-volcanic origin.

  10. Detection of antibodies and risk factors for infection with bovine respiratory syncytial virus and parainfluenza virus 3 in dual-purpose farms in Colima, Mexico. (United States)

    Figueroa-Chávez, Daniel; Segura-Correa, José C; García-Márquez, Luís Jorge; Pescador-Rubio, Alfonso; Valdivia-Flores, Arturo Gerardo


    A cross-sectional study was carried out, from November 2007 to March 2008, to estimate the prevalence of and to determine risk factors associated with bovine syncytial respiratory virus (BRSV) and parainfluenza 3 virus (PIV3) in dual-purpose herds in Colima, México. One hundred and seventy-six sera from 33 herds for PIV3 and 232 sera from 44 herds for BRSV were used. Sera were analyzed by indirect ELISA for the detection of antibodies against BRSV and PIV3 in cattle herds to determine the seroprevalence of respiratory diseases. The apparent and true prevalences for PIV3 were 60.8% and 54.4% and for BRSV 52.2% and 50.8%, respectively. The percentage of herds showing at least one positive animal was 78.7% for PIV3, and 93.2% for BRSV. Age (≤ 12, 13-48, and >48 months old) and respiratory signs (no, yes) showed significant association (P < 0.05) with PIV3 and age with BRSV. This study showed that animals were exposed to both viruses and that age was the main risk factor. The need to establish new vaccination plans to effectively protect cattle against those infections in the state of Colima, Mexico is suggested.

  11. [Psychomotor skills assessment in basic procedures of laparoscopic surgery in undergraduate medical students at the School of Medicine of the University of Colima]. (United States)

    Prieto-Díaz-Chávez, Emilio; Medina-Chávez, José Luís; Martínez-Lira, Rafael; Millán-Guerrero, Rebeca; Vázquez-Jiménez, Clemente; Trujillo-Hernández, Benjamín


    The changes in recent decades in the training of medical student seem to agree that the educational model for professional skills is most appropriate. The virtual simulator translates skills acquired the operating room, in the Faculty of Medicine of the University of Colima noticed the need to prepare the students of pregrade transferring surgical trainees' skills in basic laparoscopic activities that require a simple cognitive effort. The hypothesis in this study was to evaluate the acquisition of skills in laparoscopic simulator in students of pregrade. Educational research, analytical comparison, which was conducted within the activities of the program of Problem Based Learning in the program of Education and Surgical Technique, Faculty of Medicine of the University of Colima. All participants in the simulator achieved a significantly better during the task one after three repetitions (p= 0.001). The evaluation of final students calcification, we observed significant differences in means being lower during the initial assessment (8.60 ± 0.76) compared to the end (8.96 ± 0.58) p= 0.001. The acquisition of skills in the simulator is longer but at the end is better than the acquisition of skills from the traditional method, showing that leads to the acquisition of skills that promote the transfer of skills to the surgical environment.


    Asian citrus psyllids (Diaphorina citri) were individually analyzed by qPCR to detect Candidatus Liberibacter asiaticus (CLas). The psyllids were collected in Mexican lime (Citrus aurantifolia) trees in five commercial orchards in Tecomán and Manzanillo, Colima with severe symptoms of classical mott...

  13. Aspects of mineral transformation during weathering of volcanic materials : the microscopic and submicroscopic level

    NARCIS (Netherlands)

    Jongmans, A.G.


    Mineral transformation at the earth surface is a complex process. In volcanic ejecta, such transformations tend to be fairly rapid. Many weathering studies on volcanic materials have been carried out at different scales of observations, mostly using bulk samples. However, to get a proper

  14. Major-element geochemistry of the Silent Canyon-Black Mountain peralkaline volcanic centers, northwestern Nevada Test Site: applications to an assessment of renewed volcanism (United States)

    Crowe, Bruce M.; Sargent, Kenneth A.


    The Silent Canyon and Black Mountain volcanic centers are located in the northern part of the Nevada Test Site. The Silent Canyon volcanic center is a buried cauldron complex of Miocene age (13-15 m.y.). Black Mountain volcanic center is an elliptical-shaped cauldron complex of late Miocene age. The lavas and tuffs of the two centers comprise a subalkaline-peralkaline association. Rock types range from quartz normative subalkaline trachyte and rhyolite to peralkaline comendite. The Gold Flat Member of the Thirsty Canyon Tuff (Black Mountain) is a pantellerite. The major-element geochemistry of the Black Mountain-Silent Canyon volcanic centers differs in the total range and distribution of Si02, contents, the degree of peralkalinity (molecular Na2O+K2O>Al2O3) and in the values of total iron and alumina through the range of rock types. These differences indicate that the suites were unrelated and evolved from differing magma bodies. The Black Mountain volcanic cycle represents a renewed phase of volcanism following cessation of the Timber Mountain-Silent Canyon volcanic cycles. Consequently, there is a small but numerically incalculable probability of recurrence of Black Mountain-type volcanism within the Nevada Test Site region. This represents a potential risk with respect to deep geologic storage of high-level radioactive waste at the Nevada Test Site.

  15. Volcanology: Volcanic bipolar disorder explained (United States)

    Jellinek, Mark


    Eruptions come in a range of magnitudes. Numerical simulations and laboratory experiments show that rare, giant super-eruptions and smaller, more frequent events reflect a transition in the essential driving forces for volcanism.

  16. Hygroscopic properties of volcanic ash

    National Research Council Canada - National Science Library

    T. L. Lathem; P. Kumar; A. Nenes; J. Dufek; I. N. Sokolik; M. Trail; A. Russell


      Volcanic ash is hygroscopic Water vapor adsorption is the main proceess controlling ash hygroscopicity The results can be parameterized in a simple correlation for use in models Limited observational...

  17. Volcanic ash impacts on critical infrastructure (United States)

    Wilson, Thomas M.; Stewart, Carol; Sword-Daniels, Victoria; Leonard, Graham S.; Johnston, David M.; Cole, Jim W.; Wardman, Johnny; Wilson, Grant; Barnard, Scott T.


    Volcanic eruptions can produce a wide range of hazards. Although phenomena such as pyroclastic flows and surges, sector collapses, lahars and ballistic blocks are the most destructive and dangerous, volcanic ash is by far the most widely distributed eruption product. Although ash falls rarely endanger human life directly, threats to public health and disruption to critical infrastructure services, aviation and primary production can lead to significant societal impacts. Even relatively small eruptions can cause widespread disruption, damage and economic loss. Volcanic eruptions are, in general, infrequent and somewhat exotic occurrences, and consequently in many parts of the world, the management of critical infrastructure during volcanic crises can be improved with greater knowledge of the likely impacts. This article presents an overview of volcanic ash impacts on critical infrastructure, other than aviation and fuel supply, illustrated by findings from impact assessment reconnaissance trips carried out to a wide range of locations worldwide by our international research group and local collaborators. ‘Critical infrastructure’ includes those assets, frequently taken for granted, which are essential for the functioning of a society and economy. Electricity networks are very vulnerable to disruption from volcanic ash falls. This is particularly the case when fine ash is erupted because it has a greater tendency to adhere to line and substation insulators, where it can cause flashover (unintended electrical discharge) which can in turn cause widespread and disruptive outages. Weather conditions are a major determinant of flashover risk. Dry ash is not conductive, and heavy rain will wash ash from insulators, but light rain/mist will mobilise readily-soluble salts on the surface of the ash grains and lower the ash layer’s resistivity. Wet ash is also heavier than dry ash, increasing the risk of line breakage or tower/pole collapse. Particular issues for water

  18. Volcanic hazards and aviation safety (United States)

    Casadevall, Thomas J.; Thompson, Theodore B.; Ewert, John W.; ,


    An aeronautical chart was developed to determine the relative proximity of volcanoes or ash clouds to the airports and flight corridors that may be affected by volcanic debris. The map aims to inform and increase awareness about the close spatial relationship between volcanoes and aviation operations. It shows the locations of the active volcanoes together with selected aeronautical navigation aids and great-circle routes. The map mitigates the threat that volcanic hazards pose to aircraft and improves aviation safety.

  19. Los volcanes y los hombres


    García, Carmen


    Desde las entrañas de la tierra, los volcanes han creado la atmósfera, el agua de los océanos, y esculpido los relieves del planeta: son, pues, los zahoríes de la vida. Existen volcanes que los hombres explotan o cultivan, y otros sobre los cuales se han construido observatorios en los que se llevan a cabo avanzadas investigaciones científicas.


    Directory of Open Access Journals (Sweden)

    Citlalli P. Téllez-García


    Full Text Available En el Estero Palo Verde, ubicado en el vaso IV de la Laguna de Cuyutlán, estado de Colima, se establecieron 48 unidades de muestreo (UM en tres rodales de mangle: 10 UM en rodal monoespecífico de Laguncularia racemosa, 25 UM en rodal monoespecífico de Rhizophora mangle y 13 UM en rodal mixto de L. racemosa-R. mangle. Se registró altura del dosel, diámetro del tronco, densidad de adultos y de repoblación, también se calculó área basal y volumen de madera. Los resultados indicaron que la densidad, área basal y volumen, para la categoría diamétrica (CD de 5 cm fueron significativamente diferentes (P < 0.05 entre los rodales monoespecíficos de R. mangle (2,500 árboles•ha-1, 4.2 m2•ha-1 y 22 m3•ha-1, respectivamente y L. racemosa (700 árboles•ha-1, 1.9 m2•ha-1 y 10 m3•ha-1, respectivamente. En las CD de 20 a 30 cm, el área basal fue significativamente mayor (P < 0.05 en el rodal monoespecífico de L. racemosa (1.6 - 3.8 m2•ha-1 que en el mixto de L. racemosa-R. mangle (0.5 - 2.5 m2•ha-1. La repoblación natural fue más abundante en el rodal de R. mangle (138 a 270 individuos•ha-1 que en el de L. racemosa (70 a 80 individuos•ha-1. Los valores estructurales mayores se alcanzaron para altura del dosel (10 m en el rodal de L. racemosa; para diámetro (40 cm y área basal (14.1 m2•ha-1 en el rodal de L. racemosa-R. mangle; y para repoblación natural (624 individuos•ha-1 en el rodal de R. mangle.

  1. Statistical Analysis of the Recent Unrest at Volcán de Colima, Mexico, Monitored With a Doppler Radar (United States)

    Scharff, L.; Hort, M. K.; Varley, N. R.; Röh, F.; Schultz, A.


    Volcán de Colima was equipped with a Doppler radar monitoring station in 2007 (March to July) and from March 2014 to 11 July 2015, when a pyroclastic flow partly destroyed the instrument. The Doppler radar measures the velocity of ejecta (>0.5 mm) and the reflected energy (a proxy for their cumulative size) within the eruption cloud. These data constrain the dynamics of the eruption cloud between 100-200m above the vent, where the field of view is located. We measure the precise timing of surface activity when tephra is included, while pure gas emissions (white steam clouds and fumaroles) are transparent to the radar. In 2007 a new dome grew slowly within the crater, accompanied by almost daily tephra emissions. This continued until 2011, when a larger explosion signalled the end of the effusion. After 18 months of quiescence, a new eruptive episode commenced in January 2013 and continues to date (Aug. 2015). Analysis of the temporal trends of ejecta velocities reveals that tephra emissions are pulsed. This matches observations, where the ash concentration commonly varies between discrete pulses. The statistical analysis of times between pulses best fits a log-logistic distribution. A log-logistic distribution indicates the interplay of two competing processes: for example short duration pressure release within a few seconds through a shallow fracture network vs. long term (tens of seconds) gas supply from deeper regions. Or it could be the competition of processes affecting the magma viscosity: rapid degassing acting to increase it, whilst a temperature increase from latent heat or shear heat generation acts to decrease the viscosity. The repose-times (in 2007) also follow a log-logistic distribution with different parameters. A single set of parameters fitting both the repose- and inter-pulse-times has not been found. In the recent data set (2014-2015) the number of events remarkably increased from 29 per month (June 2014) up to 23 per day in February 2015. The

  2. Building Better Volcanic Hazard Maps Through Scientific and Stakeholder Collaboration (United States)

    Thompson, M. A.; Lindsay, J. M.; Calder, E.


    All across the world information about natural hazards such as volcanic eruptions, earthquakes and tsunami is shared and communicated using maps that show which locations are potentially exposed to hazards of varying intensities. Unlike earthquakes and tsunami, which typically produce one dominant hazardous phenomenon (ground shaking and inundation, respectively) volcanic eruptions can produce a wide variety of phenomena that range from near-vent (e.g. pyroclastic flows, ground shaking) to distal (e.g. volcanic ash, inundation via tsunami), and that vary in intensity depending on the type and location of the volcano. This complexity poses challenges in depicting volcanic hazard on a map, and to date there has been no consistent approach, with a wide range of hazard maps produced and little evaluation of their relative efficacy. Moreover, in traditional hazard mapping practice, scientists analyse data about a hazard, and then display the results on a map that is then presented to stakeholders. This one-way, top-down approach to hazard communication does not necessarily translate into effective hazard education, or, as tragically demonstrated by Nevado del Ruiz, Columbia in 1985, its use in risk mitigation by civil authorities. Furthermore, messages taken away from a hazard map can be strongly influenced by its visual design. Thus, hazard maps are more likely to be useful, usable and used if relevant stakeholders are engaged during the hazard map process to ensure a) the map is designed in a relevant way and b) the map takes into account how users interpret and read different map features and designs. The IAVCEI Commission on Volcanic Hazards and Risk has recently launched a Hazard Mapping Working Group to collate some of these experiences in graphically depicting volcanic hazard from around the world, including Latin America and the Caribbean, with the aim of preparing some Considerations for Producing Volcanic Hazard Maps that may help map makers in the future.

  3. Synthesis of morphotectonics and volcanics of the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Mukherjee, A.D.; Iyer, S.D.

    The Central Indian Ocean Basin (CIOB) is an enigmatic ocean basin in the young and tectonically complex Indian Ocean. Major tectonic and volcanic forms identified are fracture zones, abyssal hills, seamounts and ridges and a unique zone...

  4. The Satah Mountain and Baldface Mountain volcanic fields: Pleistocene hot spot volcanism in the Anahim Volcanic Belt, west-central British Columbia, Canada (United States)

    Kuehn, Christian; Guest, Bernard; Russell, James K.; Benowitz, Jeff A.


    The Satah Mountain and Baldface Mountain volcanic fields (SMVF, BMVF) comprise more than three dozen small volcanic centers and erosional remnants thereof. These fields are located in the Chilcotin Highland of west-central British Columbia, Canada, and are spatially associated with the Anahim Volcanic Belt (AVB), a linear feature of alkaline to peralkaline plutonic and volcanic centers of Miocene to Holocene ages. The AVB has been postulated to be the track of a hot spot passing beneath the westward moving Cordilleran lithosphere. We test the AVB hot spot model by applying whole-rock 40Ar/39Ar geochronology ( n = 24) and geochemistry. Whole-rock chemical compositions of volcanic rock samples ( n = 59) from these two fields suggest a strong geochemical affinity with the nearby Itcha Range shield volcano; however, SMVF and BMVF centers are mostly small in volume (<1 km3) and differ in composition from one another, even where they are in close spatial proximity. Trace element and REE patterns of mafic AVB lavas are similar to ocean island basalts (OIB), suggesting a mantle source for these lavas. The age ranges for the SMVF ( n = 11; ~2.21 to ~1.43 Ma) and BMVF ( n = 7; ~3.91 to ~0.91 Ma) are largely coeval with the Itcha Range. The distribution of volcanoes in these two volcanic fields is potentially consistent with the postulated AVB hot spot track. Eruption rates in the SMVF were high enough to build an elongated ridge that deviates from the E-W trend of the AVB by almost 90°. This deviation might reflect the mechanisms and processes facilitating magma generation and ascent through the lithosphere in this tectonically complex region and may also indicate interaction of the potential hot spot with (pre)existing fracture systems in vicinity of the Itcha Range.

  5. Undrained behaviour of volcanic soils under monotonic and cyclic loading (United States)

    de Cristofaro, Martina; Brunzo, Antonia; Mottola, Luciano; Netti, Nadia; Olivares, Lucio; Orense, Rolando; Asadi, Sadeq


    Undrained behaviour of volcanic soils under monotonic and cyclic loading. In this study, we focus on the undrained behaviour of volcanic deposits under monotonic and cyclic loading in order to define the susceptibility to liquefaction of granular volcanic deposits. We assume that, in the case of saturated granular volcanic deposits susceptible to liquefaction, an undrained unstable behaviour can be responsible for both, the evolution of flowslide due to rainfall and liquefaction under seismic loading. Starting from these considerations we define a complex experimental program to analyze their undrained behaviour through laboratory testing on reconstituted specimens of cohesionless volcanic soils. The first part of the experimental program is devoted to the use of the steady state concept to evaluate the influence of void ratio and effective confining pressure on the undrained behaviour of Cervinara pyroclastic soils (Italy) under monotonic and cyclic loading. The second part of the experimental program is devoted to the analysis of the influence of particles crushing of pumice soils from Rangiriri (New Zeland) in both monotonic and cyclic undrained triaxial tests.

  6. Assessing the process of designing and implementing electronic health records in a statewide public health system: the case of Colima, Mexico. (United States)

    Hernández-Ávila, Juan Eugenio; Palacio-Mejía, Lina Sofia; Lara-Esqueda, Agustín; Silvestre, Eva; Agudelo-Botero, Marcela; Diana, Mark L; Hotchkiss, David R; Plaza, Beatriz; Sanchez Parbul, Alicia


    The findings of a case study assessing the design and implementation of an electronic health record (EHR) in the public health system of Colima, Mexico, its perceived benefits and limitations, and recommendations for improving the implementation process are presented. In-depth interviews and focus group discussions were used to examine the experience of the actors and stakeholders participating in the design and implementation of EHRs. Results indicate that the main driving force behind the use of EHRs was to improve reporting to the two of the main government health and social development programs. Significant challenges to the success of the EHR include resistance by physicians to use the ICD-10 to code diagnoses, insufficient attention to recurrent resources needed to maintain the system, and pressure from federal programs to establish parallel information systems. Operating funds and more importantly political commitment are required to ensure sustainability of the EHRs in Colimaima.

  7. Elementos para una propuesta educativa de un museo interactivo de ciencia, tecnología y cultura en el estado de Colima


    Maciel-Morán, Minerva


    En este trabajo de investigación se discuten y diseñan elementos para una propuesta educativa de un museo interactivo de ciencia, tecnología y cultura en el estado de Colima. Para ello, se analizan otras propuestas de museos o centros de ciencia con el fin de saber cuáles son las bases pedagógicas de las que se parte para la planeación y diseño de exhibiciones. El trabajo, plantea una discusión sobre la divulgación de la ciencia dentro de la cultura científica y humanista, su evolución en la ...

  8. About the use of radon in the surveillance of volcanoes from Central America; De l`utilisation du radon dans la surveillance des volcans d`amerique centrale

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, E. [Obviscori, Heridia (Costa Rica); Garcia Vindas, R.; Monnin, M.; Seidel, J.L. [Centre National de la Recherche Scientifique (CNRS), 34 -Montpellier (France). Centre d`Etudes Phytosociologiques et Ecologiques Louis-Emberger; Segovia, N. [ININ, Mexico (Mexico)


    Anomalous fluctuations of radon content in soil gases, fumaroles or thermal sources associated with volcanic systems are considered as precursors of deep degassing phenomena. Radon measurements in soil gases were performed for several years on three active volcanoes of Costa-Rica (Arenal, Irazu, Poas), also on El Chichon and Colima volcanoes in Mexico and more recently on the Popocatepetl since its reactivation in December 1994. Data acquisition was initially performed using plastic detectors with a 15 days integration. Since 1993, autonomous automatic probes are used and give hourly measurements. A nine stations network for ground measurements is installed on the Poas since 1982. Radon and Cl{sup -}, F{sup -} and SO{sub 4}{sup 2-} variations of the main crater lake are examined and correlated with the volcanic activity which led to the decay and disappearing of the lake in April 1989. On the Irazu, five stations were installed in 1982 and 3 automatic ones were added in November 1993. Results obtained so far are discussed according to the phreatic eruption of December 1994. The Popocatepetl measurements obtained since December 1994 are presented too. Abstract only. (J.S.).

  9. Sismos y volcanes en Colombia


    Duque Escobar, Gonzalo


    Notas sobre las zonas de amenaza sísmica y principales fuentes sísmicas de Colombia, y los segmentos volcánicos de los Andes colombianos con los principales volcanes activos, de conformidad con los estudios del Ingeominas. Anexos a títulos con sus correspondientes enlaces, para ofrecer artículos relacionados con sismos y volcanes, en los que se consideran aspectos de interés para la gestión del riesgo sísmico y volcánico en Colombia

  10. Venus - False Color of Volcanic Plains (United States)


    of a single volcanic complex, where a large body of molten rock formed beneath the surface feeding each of the volcanoes above. The presence of fractures in the west, partially surrounding the volcanoes supports this theory.

  11. Reduced cooling following future volcanic eruptions (United States)

    Hopcroft, Peter O.; Kandlbauer, Jessy; Valdes, Paul J.; Sparks, R. Stephen J.


    Volcanic eruptions are an important influence on decadal to centennial climate variability. Large eruptions lead to the formation of a stratospheric sulphate aerosol layer which can cause short-term global cooling. This response is modulated by feedback processes in the earth system, but the influence from future warming has not been assessed before. Using earth system model simulations we find that the eruption-induced cooling is significantly weaker in the future state. This is predominantly due to an increase in planetary albedo caused by increased tropospheric aerosol loading with a contribution from associated changes in cloud properties. The increased albedo of the troposphere reduces the effective volcanic aerosol radiative forcing. Reduced sea-ice coverage and hence feedbacks also contribute over high-latitudes, and an enhanced winter warming signal emerges in the future eruption ensemble. These findings show that the eruption response is a complex function of the environmental conditions, which has implications for the role of eruptions in climate variability in the future and potentially in the past.

  12. Understanding thermal energy and mass transport in major volcanic centers (United States)

    Hermance, John F.


    An understanding of the thermal regions of the earth's interior and their associated dynamic processes is of central importance, not only to basic science but to a number of national priorities including resource and the mitigation of volcanic and earthquake hazards. Major thermal anomalies over large regions of the continent are associated with intraplate rifts and transform faults (e.g., the Salton Trough and the Rio Grande Rift), distributed extensional tectonics (e.g., the Basin and Range Province), and plate margins (e.g., the Cascade Range). However, it is clear that of all classes of volcanic phenomena within the conterminous United States, the major intraplate silicic caldera complexes (e.g., Yellowstone, the Valles Caldera, the Long Valley/Mono Craters volcanic complex) appear to have, according to present estimates, the highest accessible geothermal resource base and the greatest destructive power during major eruptive phases. In addition, the exhumed fossil analogs of these systems are associated with extensive mineralization and economic ore deposits. What is lacking, however, is a predictive scientific theory describing the fundamental physio-chemical processes responsible for the development and longterm sustenance of these major volcanic centers in space and time.

  13. The volcanic and tectonic history of Enceladus (United States)

    Kargel, J.S.; Pozio, S.


    Enceladus has a protracted history of impact cratering, cryo-volcanism, and extensional, compressional, and probable strike-slip faulting. It is unique in having some of the outer Solar System's least and most heavily cratered surfaces. Enceladus' cratering record, tectonic features, and relief elements have been analyzed more comprehensively than done previously. Like few other icy satellites, Enceladus seems to have experienced major lateral lithospheric motions; it may be the only icy satellite with global features indicating probable lithospheric convergence and folding. Ridged plains, 500 km across, consist of a central labyrinthine ridge complex atop a broad dome surrounded by smooth plains and peripheral sinuous ridge belts. The ridged plains have few if any signs of extension, almost no craters, and an average age of just 107 to 108 years. Ridge belts have local relief ranging from 500 to 2000 m and tend to occur near the bottoms of broad regional troughs between swells. Our reanalysis of Peter Thomas' (Dermott, S. F., and P. C. Thomas, 1994, The determination of the mass and mean density of Enceladus from its observed shape, Icarus, 109, 241-257) limb profiles indicates that high peaks, probably ridge belts, also occur in unmapped areas. Sinuous ridges appear foldlike and are similar to terrestrial fold belts such as the Appalachians. If they are indeed folds, it may require that the ridged plains are mechanically (perhaps volcanically) layered. Regional topography suggests that folding may have occurred along zones of convective downwelling. The cratered plains, in contrast to the ridged plains, are heavily cratered and exhibit extensional structures but no obvious signs of compression. Cratered plains contain a possible strike-slip fault (Isbanir Fossa), along which two pairs of fractures seem to have 15 km of right-lateral offset. The oldest cratered plains might date from shortly after the formation of the saturnian system or the impact disruption and

  14. he Importance of the use of the Information and Communication Technologies(ICT in the Small and Medium-size Enterprises(SMEs of trade, industry and services in Colima and Villa de Alvarez

    Directory of Open Access Journals (Sweden)

    Mayrén Polanco Gaytán


    Full Text Available The ICT revolution has increased the use of technology because of knowledge intensive economy that aims to improve efficiency and productivity levels in the enterprises due to ICT. This is the reason to quantify the adoption degree of ICT used by the small and medium enterprises (SME in Colima and Villa de Alvarez. The aggregation level hides the diversity in the behavior patterns of the SME, as a result the SME in commerce and services have similar patterns in the adoption of ICT, while the manufacturing follows a different one. Finally, it has been quantify the ICT diffusion index at the messo level of aggregation for the first time. The ICT diffusion index shows the heterogeneity in the adoption of ICT by the states in México and in the municipalities in Colima.

  15. Quantitative physical models of volcanic phenomena for hazards assessment of critical infrastructures (United States)

    Costa, Antonio


    Volcanic hazards may have destructive effects on economy, transport, and natural environments at both local and regional scale. Hazardous phenomena include pyroclastic density currents, tephra fall, gas emissions, lava flows, debris flows and avalanches, and lahars. Volcanic hazards assessment is based on available information to characterize potential volcanic sources in the region of interest and to determine whether specific volcanic phenomena might reach a given site. Volcanic hazards assessment is focussed on estimating the distances that volcanic phenomena could travel from potential sources and their intensity at the considered site. Epistemic and aleatory uncertainties strongly affect the resulting hazards assessment. Within the context of critical infrastructures, volcanic eruptions are rare natural events that can create severe hazards. In addition to being rare events, evidence of many past volcanic eruptions is poorly preserved in the geologic record. The models used for describing the impact of volcanic phenomena generally represent a range of model complexities, from simplified physics based conceptual models to highly coupled thermo fluid dynamical approaches. Modelling approaches represent a hierarchy of complexity, which reflects increasing requirements for well characterized data in order to produce a broader range of output information. In selecting models for the hazard analysis related to a specific phenomenon, questions that need to be answered by the models must be carefully considered. Independently of the model, the final hazards assessment strongly depends on input derived from detailed volcanological investigations, such as mapping and stratigraphic correlations. For each phenomenon, an overview of currently available approaches for the evaluation of future hazards will be presented with the aim to provide a foundation for future work in developing an international consensus on volcanic hazards assessment methods.

  16. Spatial variation of volcanic rock geochemistry in the Virunga Volcanic Province: Statistical analysis of an integrated database (United States)

    Barette, Florian; Poppe, Sam; Smets, Benoît; Benbakkar, Mhammed; Kervyn, Matthieu


    We present an integrated, spatially-explicit database of existing geochemical major-element analyses available from (post-) colonial scientific reports, PhD Theses and international publications for the Virunga Volcanic Province, located in the western branch of the East African Rift System. This volcanic province is characterised by alkaline volcanism, including silica-undersaturated, alkaline and potassic lavas. The database contains a total of 908 geochemical analyses of eruptive rocks for the entire volcanic province with a localisation for most samples. A preliminary analysis of the overall consistency of the database, using statistical techniques on sets of geochemical analyses with contrasted analytical methods or dates, demonstrates that the database is consistent. We applied a principal component analysis and cluster analysis on whole-rock major element compositions included in the database to study the spatial variation of the chemical composition of eruptive products in the Virunga Volcanic Province. These statistical analyses identify spatially distributed clusters of eruptive products. The known geochemical contrasts are highlighted by the spatial analysis, such as the unique geochemical signature of Nyiragongo lavas compared to other Virunga lavas, the geochemical heterogeneity of the Bulengo area, and the trachyte flows of Karisimbi volcano. Most importantly, we identified separate clusters of eruptive products which originate from primitive magmatic sources. These lavas of primitive composition are preferentially located along NE-SW inherited rift structures, often at distance from the central Virunga volcanoes. Our results illustrate the relevance of a spatial analysis on integrated geochemical data for a volcanic province, as a complement to classical petrological investigations. This approach indeed helps to characterise geochemical variations within a complex of magmatic systems and to identify specific petrologic and geochemical investigations

  17. Paleoarchean trace fossils in altered volcanic glass. (United States)

    Staudigel, Hubert; Furnes, Harald; DeWit, Maarten


    Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement textures based on textural and geochronological data from pillow lavas in the Hooggenoeg Complex of the Barberton Greenstone Belt in South Africa. We use this controversy to explore the strengths and weaknesses of arguments made in support or rejection of the biogenicity interpretation of bioalteration trace fossils in Cenozoic basalt glasses and their putative equivalents in Paleoarchean greenstones. Our analysis suggests that biogenicity cannot be taken for granted for all titanite-based textures in metamorphosed basalt glass, but a cautious and critical evaluation of evidence suggests that biogenicity remains the most likely interpretation for previously described titanite microtextures in Paleoarchean pillow lavas.

  18. Paleoarchean trace fossils in altered volcanic glass (United States)

    Staudigel, Hubert; Furnes, Harald; DeWit, Maarten


    Microbial corrosion textures in volcanic glass from Cenozoic seafloor basalts and the corresponding titanite replacement microtextures in metamorphosed Paleoarchean pillow lavas have been interpreted as evidence for a deep biosphere dating back in time through the earliest periods of preserved life on earth. This interpretation has been recently challenged for Paleoarchean titanite replacement textures based on textural and geochronological data from pillow lavas in the Hooggenoeg Complex of the Barberton Greenstone Belt in South Africa. We use this controversy to explore the strengths and weaknesses of arguments made in support or rejection of the biogenicity interpretation of bioalteration trace fossils in Cenozoic basalt glasses and their putative equivalents in Paleoarchean greenstones. Our analysis suggests that biogenicity cannot be taken for granted for all titanite-based textures in metamorphosed basalt glass, but a cautious and critical evaluation of evidence suggests that biogenicity remains the most likely interpretation for previously described titanite microtextures in Paleoarchean pillow lavas. PMID:26038543

  19. Potential volcanic impacts on future climate variability (United States)

    Bethke, Ingo; Outten, Stephen; Otterå, Odd Helge; Hawkins, Ed; Wagner, Sebastian; Sigl, Michael; Thorne, Peter


    Volcanic activity plays a strong role in modulating climate variability. Most model projections of the twenty-first century, however, under-sample future volcanic effects by not representing the range of plausible eruption scenarios. Here, we explore how sixty possible volcanic futures, consistent with ice-core records, impact climate variability projections of the Norwegian Earth System Model (NorESM) under RCP4.5 (ref. ). The inclusion of volcanic forcing enhances climate variability on annual-to-decadal timescales. Although decades with negative global temperature trends become ~50% more commonplace with volcanic activity, these are unlikely to be able to mitigate long-term anthropogenic warming. Volcanic activity also impacts probabilistic projections of global radiation, sea level, ocean circulation, and sea-ice variability, the local-scale effects of which are detectable when quantifying the time of emergence. These results highlight the importance and feasibility of representing volcanic uncertainty in future climate assessments.

  20. Local to global: a collaborative approach to volcanic risk assessment (United States)

    Calder, Eliza; Loughlin, Sue; Barsotti, Sara; Bonadonna, Costanza; Jenkins, Susanna


    -economic conditions tending to influence longer term well-being and recovery. The volcanological community includes almost 100 Volcano Observatories worldwide, the official institutions responsible for monitoring volcanoes. They may be dedicated institutions, or operate from national institutions (geological surveys, universities, met agencies). They have a key role in early warning, forecasting and long term hazard assessment (often in the form of volcanic hazards maps). The complexity of volcanic systems means that once unrest begins there are multiple potential eruptive outcomes and short term forecasts can change rapidly. This local knowledge of individual volcanoes underpins hazard and risk assessments developed at national, regional and global scales. Combining this local expertise with the knowledge of the international research community (including interdisciplinary perspectives) creates a powerful partnership. A collaborative approach is therefore needed to develop effective volcanic risk assessments at regional to global scale. The World Organisation of Volcano Observatories is a Commission of IAVCEI, alongside other Commissions such as 'Hazard and Risk' (with an active working group on volcanic hazards maps) and the 'Cities and Volcanoes' Commission. The Global Volcano Model network is a collaborative initiative developing hazards and risk information at national to global scales, underpinned by local expertise. Partners include IAVCEI, Smithsonian Institution, International Volcanic Health Hazard Network, VHub and other initiatives and institutions.

  1. Reference data set of volcanic ash physicochemical and optical properties (United States)

    Vogel, A.; Diplas, S.; Durant, A. J.; Azar, A. S.; Sunding, M. F.; Rose, W. I.; Sytchkova, A.; Bonadonna, C.; Krüger, K.; Stohl, A.


    Uncertainty in the physicochemical and optical properties of volcanic ash particles creates errors in the detection and modeling of volcanic ash clouds and in quantification of their potential impacts. In this study, we provide a data set that describes the physicochemical and optical properties of a representative selection of volcanic ash samples from nine different volcanic eruptions covering a wide range of silica contents (50-80 wt % SiO2). We measured and calculated parameters describing the physical (size distribution, complex shape, and dense-rock equivalent mass density), chemical (bulk and surface composition), and optical (complex refractive index from ultraviolet to near-infrared wavelengths) properties of the volcanic ash and classified the samples according to their SiO2 and total alkali contents into the common igneous rock types basalt to rhyolite. We found that the mass density ranges between ρ = 2.49 and 2.98 g/cm3 for rhyolitic to basaltic ash types and that the particle shape varies with changing particle size (d λ = 300 nm and 1500 nm depend systematically on the composition of the samples. The real part values vary from n = 1.38 to 1.66 depending on ash type and wavelength and the imaginary part values from k = 0.00027 to 0.00268. We place our results into the context of existing data and thus provide a comprehensive data set that can be used for future and historic eruptions, when only basic information about the magma type producing the ash is known.

  2. The Volcanic Hazards Assessment Support System for the Online Hazard Assessment and Risk Mitigation of Quaternary Volcanoes in the World

    Directory of Open Access Journals (Sweden)

    Shinji Takarada


    Full Text Available Volcanic hazards assessment tools are essential for risk mitigation of volcanic activities. A number of offline volcanic hazard assessment tools have been provided, but in most cases, they require relatively complex installation procedure and usage. This situation causes limited usage of volcanic hazard assessment tools among volcanologists and volcanic hazards communities. In addition, volcanic eruption chronology and detailed database of each volcano in the world are essential key information for volcanic hazard assessment, but most of them are isolated and not connected to and with each other. The Volcanic Hazard Assessment Support System aims to implement a user-friendly, WebGIS-based, open-access online system for potential hazards assessment and risk-mitigation of Quaternary volcanoes in the world. The users can get up-to-date information such as eruption chronology and geophysical monitoring data of a specific volcano using the direct link system to major volcano databases on the system. Currently, the system provides 3 simple, powerful and notable deterministic modeling simulation codes of volcanic processes, such as Energy Cone, Titan2D and Tephra2. The system provides deterministic tools because probabilistic assessment tools are normally much more computationally demanding. By using the volcano hazard assessment system, the area that would be affected by volcanic eruptions in any location near the volcano can be estimated using numerical simulations. The system is being implemented using the ASTER Global DEM covering 2790 Quaternary volcanoes in the world. The system can be used to evaluate volcanic hazards and move this toward risk-potential by overlaying the estimated distribution of volcanic gravity flows or tephra falls on major roads, houses and evacuation areas using the GIS-enabled systems. The system is developed for all users in the world who need volcanic hazards assessment tools.

  3. Source mechanisms of volcanic tsunamis. (United States)

    Paris, Raphaël


    Volcanic tsunamis are generated by a variety of mechanisms, including volcano-tectonic earthquakes, slope instabilities, pyroclastic flows, underwater explosions, shock waves and caldera collapse. In this review, we focus on the lessons that can be learnt from past events and address the influence of parameters such as volume flux of mass flows, explosion energy or duration of caldera collapse on tsunami generation. The diversity of waves in terms of amplitude, period, form, dispersion, etc. poses difficulties for integration and harmonization of sources to be used for numerical models and probabilistic tsunami hazard maps. In many cases, monitoring and warning of volcanic tsunamis remain challenging (further technical and scientific developments being necessary) and must be coupled with policies of population preparedness. © 2015 The Author(s).

  4. A submarine volcanic eruption leads to a novel microbial habitat. (United States)

    Danovaro, Roberto; Canals, Miquel; Tangherlini, Michael; Dell'Anno, Antonio; Gambi, Cristina; Lastras, Galderic; Amblas, David; Sanchez-Vidal, Anna; Frigola, Jaime; Calafat, Antoni M; Pedrosa-Pàmies, Rut; Rivera, Jesus; Rayo, Xavier; Corinaldesi, Cinzia


    Submarine volcanic eruptions are major catastrophic events that allow investigation of the colonization mechanisms of newly formed seabed. We explored the seafloor after the eruption of the Tagoro submarine volcano off El Hierro Island, Canary Archipelago. Near the summit of the volcanic cone, at about 130 m depth, we found massive mats of long, white filaments that we named Venus's hair. Microscopic and molecular analyses revealed that these filaments are made of bacterial trichomes enveloped within a sheath and colonized by epibiotic bacteria. Metagenomic analyses of the filaments identified a new genus and species of the order Thiotrichales, Thiolava veneris. Venus's hair shows an unprecedented array of metabolic pathways, spanning from the exploitation of organic and inorganic carbon released by volcanic degassing to the uptake of sulfur and nitrogen compounds. This unique metabolic plasticity provides key competitive advantages for the colonization of the new habitat created by the submarine eruption. A specialized and highly diverse food web thrives on the complex three-dimensional habitat formed by these microorganisms, providing evidence that Venus's hair can drive the restart of biological systems after submarine volcanic eruptions.

  5. Felsic volcanism in a basic shield (El Hierro, Canary Islands). Implications in terms of volcanic hazards. (United States)

    Pedrazzi, Dario; Becerril Carretero, Laura; Martí Molist, Joan; Meletlidis, Stavros; Galindo Jiménez, Inés


    El Hierro, the southwesternmost and smallest island of the Canary Archipelago, is a complex basaltic shield volcano characterized by mainly effusive volcanism with both Strombolian and Hawaiian activity. Explosive felsic volcanism is not a common feature of the archipelago and, so far, it has only been reported on the central islands of Tenerife and Gran Canaria, where it has been responsible for the formation of large central volcanic complexes. The presence of felsic rocks on the other islands of the archipelago and specifically on El Hierro is mostly restricted to subvolcanic intrusions and a few lava flows, generally associated with the oldest parts of the islands. We hereby report the presence of a trachytic pumice deposit on the island of El Hierro, referred to here as the Malpaso Member. A detailed stratigraphic, lithological, and sedimentological study was carried out on the deposits of this explosive episode of felsic composition, which is the only one found on the Canary Islands apart from those of Gran Canaria and Tenerife. Four different subunits were identified on the basis of their lithological and granulometrical characteristics. The products of the eruption correspond to a single eruptive event and cover an area of about 13 km2. This deposit originated from a base-surge-type explosive eruption with a subsequent radial emplacement of dilute PDC currents, was emplaced from the vent that would have been located in a similar position to the volcano of Tanganasoga. The low vesicularity of juvenile fragments and the morphological characteristics of the fine particles, as well as the high proportion of lithic fragments and the ash-rich nature of the deposit, suggest that magma/water interaction controlled the dynamics of the eruption. This study demonstrates that magmas from El Hierro could have the potential for producing an explosive eruption, in an environment in which the majority of the eruptions are basaltic and effusive in nature. Bearing in mind

  6. Spreading dynamic of viscous volcanic ash in stimulated jet engine conditions (United States)

    song, wenjia; Lavallée, Yan; Hess, Kai-Uwe; Kueppers, Ulrich; Cimarelli, Corrado


    The ingestion of volcanic ash is widely recognised as a potentially fatal hazard for aircraft operation. The volcanic ash deposition process in a jet turbine is potentially complex. Volcanic ash in the air stream enters the inner liners of the combustors and partially or completely melts under the flames up to 2000 °C, at which point part of the ash deposits in the combustor fuel nozzle. Molten volcanic particles within high energy airflow escape the combustor to enter the turbine and impact the stationary (e.g., inlet nozzle guide vanes) and rotating airfoils (e.g., first stage high-pressure turbine blades) at high speed (up to Mach 1.25) in different directions, with the result that ash may stick, flow and remain liquid or solidify. Thus, the wetting behaviour of molten volcanic ash particle is fundamental to investigate impingement phenomena of ash droplet on the surface of real jet engine operation. The topic of wetting has received tremendous interest from both fundamental and applied points of view. However, due to the interdisciplinary gap between jet engine engineering and geology science, explicit investigation of wetting behaviour of volcanic ash at high temperature is in its infancy. We have taken a big step towards meeting this challenge. Here, we experimentally and theoretically investigate the wetting behaviour of viscous volcanic ash over a wide temperature range from 1100 to 1550 °C using an improved sessile-drop method. The results of our experiment demonstrate that temperature and viscosity play a critical role in determining the wetting possibility and governing the spreading kinetics of volcanic ash at high temperatures. Our systemic analysis of spreading of molten volcanic ash systems allows us to report on the fundamental differences between the mechanisms controlling spreading of organic liquids at room temperature and molten volcanic ash droplets.

  7. Volcanism and associated hazards: The Andean perspective (United States)

    Tilling, R.I.


    Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (volcano risk in the Andean region. But much remains to be done.

  8. Disruptive event analysis: volcanism and igneous intrusion

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.M.


    An evaluation is made of the disruptive effects of volcanic activity with respect to long term isolation of radioactive waste through deep geologic storage. Three major questions are considered. First, what is the range of disruption effects of a radioactive waste repository by volcanic activity. Second, is it possible, by selective siting of a repository, to reduce the risk of disruption by future volcanic activity. And third, can the probability of repository disruption by volcanic activity be quantified. The main variables involved in the evaluation of the consequences of repository disruption by volcanic activity are the geometry of the magma-repository intersection (partly controlled by depth of burial) and the nature of volcanism. Potential radionuclide dispersal by volcanic transport within the biosphere ranges in distance from several kilometers to global. Risk from the most catastrophic types of eruptions can be reduced by careful site selection to maximize lag time prior to the onset of activity. Certain areas or volcanic provinces within the western United States have been sites of significant volcanism and should be avoided as potential sites for a radioactive waste repository. Examples of projection of future sites of active volcanism are discussed for three areas of the western United States. Probability calculations require two types of data: a numerical rate or frequency of volcanic activity and a numerical evaluation of the areal extent of volcanic disruption for a designated region. The former is clearly beyond the current state of art in volcanology. The latter can be approximated with a reasonable degree of satisfaction. In this report, simplified probability calculations are attempted for areas of past volcanic activity.

  9. Mechanical interaction between volcanic systems in Libya (United States)

    Elshaafi, Abdelsalam; Gudmundsson, Agust


    The spatial distributions of monogenetic volcanoes, primarily volcanic craters, within the four principal volcanic provinces of Libya are examined and presented on a volcano-density map. Six main volcanic clusters have been identified, referred to as volcanic systems. Remarkably, the Al Haruj (AHVP) and Nuqay (NVP) volcanic provinces have double-peak volcano-density distributions, while the Gharyan (GVP) and As Sawda (SVP) volcanic provinces have single-peak volcano-density distributions. We interpret each volcano-density peak as corresponding to a separate volcanic system, so that there is a total of six systems in these four provinces. There was an overlap in volcanic activity in these provinces with at least three simultaneously active. We propose that each of the 6 volcanic systems was/is supplied with magma from a large sill-like reservoir - similar in lateral dimensions to the systems/clusters themselves. Numerical results show zones of high tensile and shear stresses between the reservoirs that coincide roughly with the main swarms of extension (dykes and volcanic fissures) and shear (faults) fractures in the areas. The most recent volcanic eruptions in Libya fall within the modelled high-stress concentration zones, primarily eruptions in the volcano Waw an Namus and the Holocene Al Mashaqaq lava flow. There are no known eruptions in Libya in historical time, but some or all the volcanic systems may have had one or more arrested historical dyke injections. In particular, part of the recurrent seismic events in the Hun Graben in the northwest Libya may be related to dyke propagation and arrest. If some of the inferred magma reservoirs are still fluid, as is likely, they pose earthquake and volcanic hazards to parts of Libya, particularly to the city of Gharyan and Zallah town, as well as to many oil-field operations.

  10. The pace of arc volcanism (United States)

    Palmer, M. R.; Fraass, A. J.; Hatfield, R. G.; McCanta, M. C.


    Being able to reconstruct the long-term history of activity at an island arc volcanic centre has important implications for a wide variety of geologic processes. On-land records are frequently incomplete and radiometric dating is complicated in many systems. Here, we describe the application of rapid and non-destructive measurements of sediment physical properties (colour reflectance, gamma ray attenuation and magnetic susceptibility) from marine sediments recovered from IODP site U1396 to produce a tephra index (TI). This approach is combined with palaeomagnetic and foram isotope stratigraphy to yield a 4.5 Myr record of volcanic activity in the northern Lesser Antilles. Pb isotope data on visible tephra layers and volcanological models suggest the tephra is predominantly derived from the nearby island of Montserrat. When examined over a range of time-averaged intervals, the TI record shows long term (order 106 year) cycles of relative quiescence and heightened activity. In accordance with the model of Hall & Kincaid (2001, Science, 292, 2472), this record suggests that the long-term pace of volcanic activity in the northern Lesser Antilles is established by diapirs rising from deep within the mantle wedge. The diapirs do not themselves act as the major source of melt, but rather they create a conduit network that facilitates the rapid rise of melt to the surface. Within the order 106 year cycles, there are shorter-term fluctuations (order 104 years) that may reflect cycles of edifice growth and destruction, and/or pulses of melt rising through conduit networks established by the rising diapirs. The U1396 TI record provides the most complete and non-aliased long-term record of activity at an island arc volcanic center yet determined. It thus provides the first field evidence that can be used to test models of the deep mantle processes that control the pace of arc volcanism. Importantly, the approach presented here is readily applicable to other arc and island

  11. Noachian Martian Volcanics a Water Source (United States)

    Zent, A. P.; Glaze, L. S.; Baloga, S. M.; Fonda, Mark (Technical Monitor)


    H2O was supplied to the Noachian atmosphere by eruptions, or in association with large impacts. Most water outgassed into an extremely cold atmosphere, and condensate deposits were inevitable. High heat flow could lead to subglacial melting only if ice thicknesses were greater than 500-1000m, which is extremely unlikely. Subareal melting and flow is contingent upon temperatures periodically exceeding 273 K, and retarding evaporative loss of the flow. In still air, evaporation into a dry atmosphere is in the free convection regime, and a stream with 2 cu m/s discharge, flowing 1 m/s could persist for hundreds of days and cover distances greater than any valley reach. The zero-wind-shear condition is considered implausible however. We investigate the possibility that evaporation rates were suppressed because the atmosphere was regionally charged with H2O as it moved over snow/ice fields. Our initial concern is precipitation from volcanic plumes. A Kilauea-style eruption on the martian surface would cover a 10km circular deposit with 10cm of H2O, if all H2O could be precipitated near the vent. The characteristics of the eruption at the vent, (vent size, temperature, H2O content, etc.) are independent of the environmental conditions. The subsequent behavior of the plume, including precipitation of ash and H2O condensate depends strongly on the environment. Hence, the proximal fate of volcanic H2O is amenable to treatment in a model. A simple bulk thermodynamic model of the rise of an H2O plume through a stably stratified CO2 atmosphere, with only adiabatic cooling, produces runaway plume rise. A more complex treatment includes the effects of latent heat release, wind shear along the plume, divergence of ash and H2O, and will yield more realistic estimates of H2O transport in eruptive plumes. Results of these simulations will be presented.

  12. Probabilistic estimation of long-term volcanic hazard with assimilation of geophysics and tectonic data (United States)

    Jaquet, O.; Lantuéjoul, C.; Goto, J.


    Risk assessments in relation to the siting of potential geological repositories require the estimation of long-term volcanic hazard. Owing to their tectonic situation, many industrial regions around the world are concerned by such evaluation. For sites near volcanically active regions, the prevailing source of uncertainty is long-term volcanic hazard. The complexity and non-linearity of volcanic processes, the space-time variability in terms of distribution and intensity for volcanic events and the limited amount of information make probabilistic estimation of volcanic hazard ineluctable. The needs for reliable methodologies for volcanic and tectonic hazard assessments in Japan have stimulated the development of specific stochastic models for improving uncertainty characterization. A conditional Cox process with a multivariate potential was developed for the assimilation of geophysics and tectonic data (gravity data, GPS strain rate data and active faults). The theoretical basis and concepts of the proposed model are given and a methodological illustration is provided using data from the island of Kyushu.

  13. An accelerated data assimilation approach for volcanic ash forecast (United States)

    Fu, Guangliang; Lin, Haixiang; Heemink, Arnold; Segers, Arjo; Lu, Sha


    The 2010 Eyjafjallajökull volcano eruption had serious consequences to civil aviation. This has initiated a lot of research on volcanic ash forecast in recent years. Ensemble-based data assimilation uses the observation data to improve the parameter and state estimation and subsequently the volcanic ash forecast accuracy. Due to the computational complexity of ensemble-based algorithms and the large scale of real-life applications, application of these methods usually introduces a large computational cost, particularly in the analysis step of assimilation processes. Because the other time-consuming part in the single CPU case, the forecast step, can be efficiently and easily parallelized. In this study, we focus on speeding up of the analysis step. For volcanic ash assimilation of aircraft-based measurements, the most time-consuming part in the analysis step has been shown to be the computation of the Kalman gain matrix. After a careful study on the characteristics of ensemble ash states, we propose a model-reduced Kalman gain (MR-Gain) approach which transforms the ensemble state matrix into a low-rank matrix by a multiplication with an index matrix which recorded the sparsity information of the ensemble state matrix, and thus the computational cost of all the ensemble-related matrix multiplications are reduced. After the computation of Kalman gain, using the previously recorded state index, the full analyzed ensemble states are reconstructed. The result shows the MR-Gain approach is exact, which can be used to replace the original full matrix with a much low computation cost. Computer experiments show that the computing time for the analysis step with the new approach is a factor of ten times faster than the conventional analysis step. The result also shows that with the accelerated analysis step in volcanic ash assimilation system, the total amount of computing time for volcanic ash forecast can be significantly reduced by up to a factor of 5.

  14. Volcanic caves of East Africa - an overview


    Jim W. Simons


    Numerous Tertiary to recent volcanoes are located in East Africa. Thus, much of the region is made up volcanic rock, which hosts the largest and greatest variety of East Africas caves. Exploration of volcanic caves has preoccupied members of Cave Exploration Group of East Africa (CEGEA) for the past 30 years. The various publications edited by CEGEA are in this respect a treasure troves of speleological information. In the present paper an overview on the most important volcanic caves and are...

  15. HASSET: a probability event tree tool to evaluate future volcanic scenarios using Bayesian inference. Presented as a plugin for QGIS. (United States)

    Sobradelo, Rosa; Bartolini, Stefania; Martí, Joan


    Event tree structures constitute one of the most useful and necessary tools of modern volcanology to assess the volcanic hazard of future volcanic scenarios. They are particularly relevant to evaluate long- and short-term probabilities of occurrence of possible volcanic scenarios and their potential impacts on urbanized areas. Here we introduce HASSET, a Hazard Assessment Event Tree probability tool, built on an event tree structure that uses Bayesian inference to estimate the probability of occurrence of a future volcanic scenario, and to evaluate the most relevant sources of uncertainty from the corresponding volcanic system. HASSET includes hazard assessment of non-eruptive and non-magmatic volcanic scenarios, that is, episodes of unrest that do not evolve into volcanic eruption but have an associated volcanic hazard (eg. sector collapse and phreatic explosion), as well as those with external triggers as primary sources of unrest (as opposed to magmatic unrest alone). Additionally, HASSET introduces the Delta method to assess how precise the probability estimates are, by reporting a one standard deviation variability interval around the expected value for each scenario. HASSET is presented as a free software package in the form of a plugin for the open source geographic information system Quantum Gis (QGIS), providing a graphically supported computation of the event tree structure in an interactive and user-friendly way. We also include an example of HASSET applied to Teide-Pico Viejo volcanic complex (Spain).

  16. Paleomagnetism of the Late Triassic Hound Island Volcanics: Revisited (United States)

    Haeussler, Peter J.; Coe, Robert S.; Onstott, T.C.


    The collision and accretion of the Alexander terrane profoundly influenced the geologic history of Alaska and western Canada; however, the terrane's displacement history is only poorly constrained by sparse paleomagnetic studies. We studied the paleomagnetism of the Hound Island Volcanics in order to evaluate the location of the Alexander terrane in Late Triassic time. We collected 618 samples at 102 sites in and near the Keku Strait, Alaska, from the Late Triassic Hound Island Volcanics, the Permian Pybus Formation, and 23-Ma gabbroic intrusions. We found three components of magnetization in the Hound Island Volcanics. The high-temperature component (component A) resides in hematite and magnetite and was found only in highly oxidized lava flows in a geographically restricted area. We think it is primary, or acquired soon after eruption of the lavas, principally because the directions pass a fold test. The paleolatitude indicated by this component (19.2° ± 10.3°) is similar to those determined for various portions of Wrangellia, consistent with the geologic interpretation that the Alexander terrane was with the Wrangellia terrane in Late Triassic time. We found two overprint directions in the Hound Island Volcanics. Component B was acquired 23 m.y. ago due to intrusion of gabbroic dikes and sills. This interpretation is indicated by the similarity of upper-hemisphere directions in the Hound Island Volcanics to those in the gabbro. Component C, found in both the Hound Island Volcanics and the Permian Pybus Formation, is oriented northeast and down, fails a regional fold test, and was acquired after regional deformation around 90 to 100 Ma. This overprint direction yields a paleolatitude similar to, but slightly higher than, slightly older rocks from the Coast Plutonic Complex, suggesting that the Alexander terrane was displaced 17° in early Late Cretaceous time. The occurrence of these two separate overprinting events provides a satisfying explanation of the

  17. Nephelometric Dropsonde for Volcanic Ash Project (United States)

    National Aeronautics and Space Administration — Advanced dropsondes that could effectively be guided through atmospheric regions of interest such as volcanic plumes could enable unprecedented observations of...


    Directory of Open Access Journals (Sweden)

    Alejandra Almaraz-Sánchez


    Full Text Available El objetivo del presente estudio fue identificar morfológica y molecularmente la micoflora que posee propiedades antagonistas sobre Phytophthora cinnamomi, asociada al suelo del bosque de encino (Quercus spp. de El Arrayanal, Colima, y de Tecoanapa, Guerrero. En estas localidades se realizaron dos muestreos de suelo colectándose muestras compuestas de suelo-raíz alrededor de los árboles con diferentes edades y condiciones sanitarias en rodales afectados por P. cinnamomi. Los hongos se identificaron morfológicamente mediante la técnica de dilución de suelo PDA-TS (papa-dextrosaagar-tergitol-estreztomicina. Con los aislamientos obtenidos se realizaron pruebas de antagonismo in vitro. Los aislamientos de Trichoderma, Cordyceps bassiana y Paecilomyces son los que ejercieron mejor biocontrol al reducir el desarrollo de P. cinnamomi mostrando mecanismos sobresalientes de competencia por espacio y micoparasitismo. Los hongos se caracterizaron molecularmente amplificando la región intergénica (ITS de los genes ribosomales mediante la técnica de amplificación por reacción en cadena de la polimerasa (PCR. Se reportan por vez primera a C. bassiana, Cladosporium tenuissimun y seis especies de Trichoderma asociadas al bosque de encino en México.


    Directory of Open Access Journals (Sweden)



    Full Text Available La presente investigación expone las prácticas de liderazgo en 301 Pequeñas y Medianas Empresas (PyMEs. 121 del estado de Hidalgo, 87 de Colima y 93 de Tamaulipas, del país, México. Este estudio se basa en el Inventario de las Prácticas de Liderazgo (IPL de Kouzes y Posner en sus cinco dimensiones, desafiar los procesos, inspirar una visión compartida, habilitar a los demás para que actúen, modelar el camino y dar aliento al corazón, demuestra concluyentemente, una igualdad de comportamiento gerencial entre las PyMEs de tres estados, objetivo de la presente investigación. Esto es, una independencia en el comportamiento gerencial con relación al contexto empresarial y económico regional. Se siguió el marco teórico de liderazgo, fundamentalmente el de Kouzes y Posner, el Contexto de las PyMEs de los tres estados, se estableció tres muestras regionales, validando el test del IPL en español. Finalmente, se realizó la prueba sobre la bondad de ajuste de muestras y comprobando la hipótesis a través de la prueba de igualdad de promedio entre muestras.

  20. Mezcales y diversidad biocultural en los alrededores del Volcán de Colima. El caso de los productores tradicionales de Zapotitlán de Vadillo

    Directory of Open Access Journals (Sweden)

    Carlos Lucio


    Full Text Available El mezcal de los alrededores del Volcán de Colima pertenece a una gran tradición productora que se sostiene en un amplio conocimiento ecológico tradicional, y en prácticas de manejo de los recursos naturales que demuestran la existencia de un vínculo inextricable entre diversidad biológica y cultural, lo cual constituye un caso ejemplar de diversidad biocultural. Los productores de mezcal en el sur de Jalisco han implementado modalidades de aprovechamiento sustentable en las más de veinte variedades locales de agave, que hacen del occidente de México una de las áreas más importantes para la conservación “in situ” de especies y variedades locales de agave mezcalero. Además el tipo de prácticas agroecológicas de estos productores reflejan claramente la importancia de la cultura indígena- campesina en la conservación de la biodiversidad.

  1. Monogenetic volcanism in the Cordillera Central of Colombia: unknown volcanic fields associated with the northernmost Andes' volcanic chain related subduction (United States)

    Murcia, Hugo; Borrero, Carlos; Németh, Károly


    Monogenetic volcanic fields are commonly related to rifts and/or intraplate tectonic settings. However, although less common, they appear also associated with subduction zones, including both front and back-arc volcanoes. To nourish this uncommon tectonic location, it is shown here that monogenetic volcanic fields, in addition to polygenetic volcanoes, also appear at the northernmost part of the Andes Northern Volcanic Zone (NVZ) (2° S to 4°30´N). These fields are associated with the main axe of the Quaternary active volcanic structures; they are linked to the polygenetic Cerro Bravo - Cerro Machín Volcanic Chain ( 80 km long; CBCMVC) in Colombia, the chain that hosts the iconic Nevado del Ruiz volcano. To the present, three monogenetic volcanic fields, with a typical calc-alkaline signature, have been identified in both sides of this chain: 1) Villamaría - Termales Monogenetic Volcanic Field (VTMVF) located to the northwestern part (>5 km) of the CBCMVC. This field is made up of at least 14 volcanoes aligned with the Villamaría - Termales fault zone. The volcanism has been mainly effusive, represented by lava domes and some lava flows. The volcanoes are andesitic to dacitic in composition. It is inferred that the magmatic source is a magma chamber close to Nevado del Ruiz volcano. Based on stratigraphic relationships, it is assumed that the last eruption occurred 10 wt.%) in the whole CBCMVC. Its source is related to the same magmas that feed the volcanoes in the CBCMVC. Stratigraphic relationships show that the volcanoes are younger than the underlying alluvial and volcaniclastic Ibagué fan (<1 Ma). Overall, it is clear that monogenetic volcanic fields are not atypical in the area, although their relationship with the magmatism feeding the polygenetic arc of the Andes' volcanic chain related subduction, is still unknown.

  2. Soils of volcanic regions in Europe

    NARCIS (Netherlands)

    Arnalds, O.; Bartoli, F.; Buurman, P.; Oskarsson, H.; Stoops, G.; García-Rodeja, E.


    Soils of volcanic areas often exhibit unique properties differentiating them from other soils on Earth. This book gives comprehensive coverage of soils in volcanic regions within Europe, dealing with most aspects of modern day soil science. It covers a range of issues such as mineralogy, chemistry,

  3. The Western Arabian intracontinental volcanic fields as a potential UNESCO World Heritage site (United States)

    Németh, Károly; Moufti, Mohammed R.


    considerred to be associated with dispersed intracontinental volcanic fields. In addition the nominated volcanic region also hosts the largest and youngest historic eruption (Al Madinah Eruption) in Western Saudi Arabia took place at 1256-AD, lasted 52 days and produced at least 0.29-km3 of pahoehoe-to-aa transitional lava fields that were emitted through a 2.3 km-long fissure and associated spatter-to-scoria cone complexes. The Western Arabian intracontinental volcanic fields provide the best exposed and most diverse type of intracontinental volcanic fields on Earth that also occupies the largest surface area. In addition, this chain of volcanic fields are also host significant archaeological and human occupation sites help to understand early human evolution as well as hosting several historic locations with high cultural heritage values. These generally intact and well-exposed volcanic zones hosting globally unique geoheritage sites can form the basis of complex geoeducational programs through the establishment of various volcanic geoparks in the region that can link together a UNESCO World Heritage Site on the basis of their global universal volcanic geoheritage values.

  4. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    primitive basalts and trachybasalts but also more evolved samples from the retroarc region and the larger volcanoes Payún Matrú and Payún Liso are presented. The samples cover a broad range of compositions from intraplate lavas similar to ocean island basalts to arc andesites. A common feature found...... are isotopically similar to the Andean Southern Volcanic Zone arc rocks and their mantle source possibly resembled the source of South Atlantic N-MORB prior to addition of fluids and melts from the subduction channel. However, it must have been more enriched than the estimates of depleted upper mantle from...... the lithosphere is thinnest and possibly in areas of elevated mantle temperatures. The pyroxenite melts formed at deeper levels react with the surrounding peridotite and thereby changes composition leading to eruption of melts which experienced variable degrees of melt-peridotite interaction. This can presumably...

  5. Timing and development of the Heise volcanic field, Snake River Plain, Idaho, western USA (United States)

    Morgan, L.A.; McIntosh, W.C.


    The Snake River Plain (SRP) developed over the last 16 Ma as a bimodal volcanic province in response to the southwest movement of the North American plate over a fixed melting anomaly. Volcanism along the SRP is dominated by eruptions of explosive high-silica rhyolites and represents some of the largest eruptions known. Basaltic eruptions represent the final stages of volcanism, forming a thin cap above voluminous rhyolitic deposits. Volcanism progressed, generally from west to east, along the plain episodically in successive volcanic fields comprised of nested caldera complexes with major caldera-forming eruptions within a particular field separated by ca. 0.5-1 Ma, similar to, and in continuation with, the present-day Yellowstone Plateau volcanic field. Passage of the North American plate over the melting anomaly at a particular point in time and space was accompanied by uplift, regional tectonism, massive explosive eruptions, and caldera subsidence, and followed by basaltic volcanism and general subsidence. The Heise volcan ic field in the eastern SRP, Idaho, represents an adjacent and slightly older field immediately to the southwest of the Yellowstone Plateau volcanic field. Five large-volume (>0.5 km3) rhyolitic ignimbrites constitute a time-stratigraphic framework of late Miocene to early Pliocene volcanism for the study region. Field relations and high-precision 40Ar/39Ar age determinations establish that four of these regional ignimbrites were erupted from the Heise volcanic field and form the framework of the Heise Group. These are the Blacktail Creek Tuff (6.62 ?? 0.03 Ma), Walcott Tuff (6.27 ?? 0.04 Ma), Conant Creek Tuff (5.51 ?? 0.13 Ma), and Kilgore Tuff (4.45 ?? 0.05 Ma; all errors reported at ?? 2??). The fifth widespread ignimbrite in the regions is the Arbon Valley Tuff Member of the Starlight Formation (10.21 ?? 0.03 Ma), which erupted from a caldera source outside of the Heise volcanic field. These results establish the Conant Creek Tuff as a

  6. Geomorphological Approach for Regional Zoning In The Merapi Volcanic Area

    Directory of Open Access Journals (Sweden)

    Langgeng Wahyu Santosa


    Full Text Available Geomorphologial approach can be used as the basic for identifying and analyzing the natural resources potentials, especially in volcanic landscape. Based on its geomorphology, Merapi volcanic landscape can be divided into 5 morphological units, i.e.: volcanic cone, volcanic slope, volcanic foot, volcanic foot plain, and fluvio-volcanic plain. Each of these morphological units has specific characteristic and natural resources potential. Based on the condition of geomorphology, the regional zoning can be compiled to support the land use planning and to maintain the conservation of environmental function in the Merapi Volcanic area.

  7. Volcanism and associated hazards: the Andean perspective (United States)

    Tilling, R. I.


    Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years) than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions") recognized worldwide that have occurred from the Ordovician to the Pleistocene. The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru). The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars) were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent hazardous eruptions in Chile, Colombia, Ecuador, and Peru has spurred significant improvements in reducing volcano risk in the Andean region. But much remains to be done.

  8. Io Eclipse/Volcanic Eruption (United States)


    This image was acquired while Io was in eclipse (in Jupiter's shadow) during Galileo's eighth orbit, and reveals several dynamic processes. The most intense features are red, while glows of lesser intensity are yellow or green, and very faint glows appear blue in this color-coded image. The small red or yellow spots mark the sites of high-temperature magma erupting onto the surface in lava flows or lava lakes.This image reveals a field of bright spots near Io's sub-Jupiter point (right-hand side of image). The sub-Jupiter hemisphere always faces Jupiter just as the Moon's nearside always faces Earth. There are extended diffuse glows on the equatorial limbs or edges of the planet (right and left sides). The glow on the left is over the active volcanic plume Prometheus, but whereas Prometheus appears to be 75 kilometers (46.6 miles) high in reflected light, here the diffuse glow extends about 800 kilometers (497 miles) from Io's limb. This extended glow indicates that gas or small particles reach much greater heights than the dense inner plume. The diffuse glow on the right side reaches a height of 400 kilometers (249 miles), and includes a prominence with a plume-like shape. However, no volcanic plume has been seen at this location in reflected light. This type of observation is revealing the relationships between Io's volcanism, atmosphere and exosphere.Taken on May 6, 1997, north is toward the top. The image was taken with the clear filter of the solid state imaging (CCD) system on NASA's Galileo spacecraft at a range of 1.8 million kilometers (1.1 million miles).The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL Background information and educational

  9. Characterization of submicrometer exsolution lamellae in volcanic pyroxenes (Invited) (United States)

    Herrin, J. S.; Costa Rodriguez, F.; Tay, Y.; Liu, H.; Phua, E. J.


    . Since lamellae might be highly localized, extraction of oriented TEM foils requires the use of FIB. We present a study of the Puyehue-Cordón Caulle Volcanic Complex (PCCVC) of the Chilean Andes, which has experienced three plinian or subplinian rhyodacite eruptions within the past century (1922, 1960, and 2011). We characterized lamellae in augite from these eruptions, all showing remarkable similarity. Then, using theoretical kinetic models for lamellae formation, calculated pre-eruptive temperatures determined from pyroxene thermodynamic models, measured lamellae spacing, and 3D reservoir cooling models, we infer that these three eruptions, spaced decades and kilometers apart, originated from a common long-lived (several thousands of years) and relatively large (tens of km3) magma reservoir. The results of this study highlight both the large eruption potential of the PCCVC and the potential utility of exsolution lamellae in volcanic pyroxenes to constrain the sizes of magma bodies below active volcanoes.

  10. PTML Model for Proteome Mining of B-Cell Epitopes and Theoretical-Experimental Study of Bm86 Protein Sequences from Colima, Mexico. (United States)

    Martínez-Arzate, Saúl G; Tenorio-Borroto, Esvieta; Barbabosa Pliego, Alberto; Díaz-Albiter, Héctor M; Vázquez-Chagoyán, Juan C; González-Díaz, Humbert


    In this work, we developed a general perturbation theory and machine learning method for data mining of proteomes to discover new B-cell epitopes useful for vaccine design. The method predicts the epitope activity εq(cqj) of one query peptide (q-peptide) under a set of experimental query conditions (cqj). The method uses as input the sequence of the q-peptide. The method also uses as input information about the sequence and epitope activity εr(crj) of a peptide of reference (r-peptide) assayed under similar experimental conditions (crj). The model proposed here is able to classify 1 048 190 pairs of query and reference peptide sequences from the proteome of many organisms reported on IEDB database. These pairs have variations (perturbations) under sequence or assay conditions. The model has accuracy, sensitivity, and specificity between 71 and 80% for training and external validation series. The retrieved information contains structural changes in 83 683 peptides sequences (Seq) determined in experimental assays with boundary conditions involving 1448 epitope organisms (Org), 323 host organisms (Host), 15 types of in vivo process (Proc), 28 experimental techniques (Tech), and 505 adjuvant additives (Adj). Afterward, we reported the experimental sampling, isolation, and sequencing of 15 complete sequences of Bm86 gene from state of Colima, Mexico. Last, we used the model to predict the epitope immunogenic scores under different experimental conditions for the 26 112 peptides obtained from these sequences. The model may become a useful tool for epitope selection toward vaccine design. The theoretical-experimental results on Bm86 protein may help the future design of a new vaccine based on this protein.

  11. Thermal regimes of major volcanic centers: Magnetotelluric constraints

    Energy Technology Data Exchange (ETDEWEB)

    Hermance, J.F.


    The interpretation of geophysical/electromagnetic field data has been used to study dynamical processes in the crust beneath three of the major tectono-volcanic features in North America: the Long Valley/Mono Craters Volcanic Complex in eastern California, the Cascades Volcanic Belt in Oregon, and the Rio Grande Rift in the area of Socorro, New Mexico. Primary accomplishments have been in the area of creating and implementing a variety of 2-D generalized inverse computer codes, and the application of these codes to fields studies on the basin structures and he deep thermal regimes of the above areas. In order to more fully explore the space of allowable models (i.e. those inverse solutions that fit the data equally well), several distinctly different approaches to the 2-D inverse problem have been developed: (1) an overdetermined block inversion; (2) an overdetermined spline inverstion; (3) a generalized underdetermined total inverse which allows one to tradeoff certain attributes of their model, such as minimum structure (flat models), roughness (smooth models), or length (small models). Moreover, we are exploring various approaches for evaluating the resolution model parameters for the above algorithms. 33 refs.

  12. A Field Trip Guide to the Petrology of Quaternary Volcanism on the Yellowstone Plateau (United States)

    Vazquez, Jorge A.; Stelten, Mark; Bindeman, Ilya N.; Cooper, Kari M


    The Yellowstone Plateau is one of the largest manifestations of silicic volcanism on Earth, and marks the youngest focus of magmatism associated with the Yellowstone Hot Spot. The earliest products of Yellowstone Hot Spot volcanism are from ~17 million years ago, but may be as old as ~32 Ma, and include contemporaneous eruption of voluminous mafic and silicic magmas, which are mostly located in the region of northwestern Nevada and southeastern Oregon. Since 17 Ma, the main locus of Yellowstone Hot Spot volcanism has migrated northeastward producing numerous silicic caldera complexes that generally remain active for ~2–4 million years, with the present-day focus being the Yellowstone Plateau. Northeastward migration of volcanism associated with the Yellowstone Hot Spot resulted in the formation of the Snake River Plain, a low relief physiographic feature extending ~750 kilometers from northern Nevada to eastern Idaho. Most of the silicic volcanic centers along the Snake River Plain have been inundated by younger basalt volcanism, but many of their ignimbrites and lava flows are exposed in the extended regions at the margins of the Snake River Plain. 

  13. A field trip guide to the petrology of Quaternary volcanism on the Yellowstone Plateau (United States)

    Vazquez, Jorge A.; Stelten, Mark; Bindeman, Ilya N.; Cooper, Kari


    The Yellowstone Plateau is one of the largest manifestations of silicic volcanism on Earth, and marks the youngest focus of magmatism associated with the Yellowstone Hot Spot. The earliest products of Yellowstone Hot Spot volcanism are from ~17 million years ago, but may be as old as ~32 Ma, and include contemporaneous eruption of voluminous mafic and silicic magmas, which are mostly located in the region of northwestern Nevada and southeastern Oregon. Since 17 Ma, the main locus of Yellowstone Hot Spot volcanism has migrated northeastward producing numerous silicic caldera complexes that generally remain active for ~2–4 million years, with the present-day focus being the Yellowstone Plateau. Northeastward migration of volcanism associated with the Yellowstone Hot Spot resulted in the formation of the Snake River Plain, a low relief physiographic feature extending ~750 kilometers from northern Nevada to eastern Idaho. Most of the silicic volcanic centers along the Snake River Plain have been inundated by younger basalt volcanism, but many of their ignimbrites and lava flows are exposed in the extended regions at the margins of the Snake River Plain. 

  14. Insights into Highland Patera Volcanism using Mars Express HRSC Data (United States)

    Williams, D. A.; Greeley, R.; Zuschneid, W.; Werner, S.; Neukum, G.; Gwinner, K.; Hauber, E.; Crown, D. A.; Gregg, T. K.; Raitala, J.


    We have used images obtained by the High Resolution Stereo Camera (HRSC) on the ESA Mars Express orbiter to assess geologic activity at two of Mars' highland volcanoes: Hadriaca Patera and Tyrrhena Patera. HRSC images cover wide swaths at consistent lighting conditions and resolutions, making them ideal resources for assessing surfaces ages using crater statistics. Additionally, multi-channel HRSC images are processed to produce Digital Terrain Models (DTMs) that are of greater spatial resolution than MOLA-derived DTMs, which are useful to assess regional and local topographic variations. Crater size-frequency analyses and cratering model age estimates show both Hadriaca and Tyrrhena Paterae have complex surfaces shaped by volcanic, fluvial, and eolian processes. These ancient shields were formed early in martian history, 3.7-4.0 Ga. At Hadriaca Patera, the earliest detectable caldera activity occurred at 3.5 Ga, followed by explosive volcanic and fluvial activity on the flanks at 3.3-3.4 Ga. Later caldera activity occurred at 2.2-2.5 Ga and again at 1.1-1.6 Ga. At Tyrrhena Patera, explosive volcanic activity and emplacement of pyroclastic deposits occurred 3.5-3.6 Ga, with later fluvial erosional activity at 1.9-2.0 Ga and again at 1.2-1.5 Ga. Slopes on Tyrrhena Patera are generally shallower (0.09-0.4 degrees) than those on Hadriaca Patera (up to 0.7 degrees). Hadriaca's north flank trends uphill, suggesting that Hadriaca Patera settled due to removal of material during formation of Dao Vallis. Further study is underway to use HRSC topographic data and computer modeling to better understand pyroclastic volcanism at these two volcanoes.

  15. Sectional methods for aggregation problems: application to volcanic eruptions (United States)

    Rossi, E.


    Particle aggregation is a general problem that is common to several scientific disciplines such as planetary formation, food industry and aerosol sciences. So far the ordinary approach to this class of problems relies on the solution of the Smoluchowski Coagulation Equations (SCE), a set of Ordinary Differential Equations (ODEs) derived from the Population Balance Equations (PBE), which basically describe the change in time of an initial grain-size distribution due to the interaction of "single" particles. The frequency of particles collisions and their sticking efficiencies depend on the specific problem under analysis, but the mathematical framework and the possible solutions to the ODEs seem to be somehow discipline-independent and very general. In this work we will focus on the problem of volcanic ash aggregation, since it represents an extreme case of complexity that can be relevant also to other disciplines. In fact volcanic ash aggregates observed during the fallouts are characterized by relevant porosities and they do not fit with simplified descriptions based on monomer-like structures or fractal geometries. In this work we propose a bidimensional approach to the PBEs which uses additive (mass) and non-additive (volume) internal descriptors in order to better characterize the evolution of volcanic ash aggregation. In particular we used sectional methods (fixed-pivot) to discretize the internal parameters space. This algorithm has been applied to a one dimensional volcanic plume model in order to investigate how the Total Grain Size Distribution (TGSD) changes throughout the erupted column in real scenarios (i.e. Eyjafjallajokull 2010, Sakurajima 2013 and Mt. Saint Helens 1980).

  16. Geologic Map of the Snegurochka Planitia Quadrangle (V-1): Implications for the Volcanic History of the North Polar Region of Venus (United States)

    Hurwitz, D. M.; Head, J. W.


    Geologic mapping of Snegurochka Planitia (V-1) reveals a complex stratigraphy of tectonic and volcanic features that can provide insight into the geologic history of Venus and Archean Earth [1,2], including 1) episodes of both localized crustal uplift and mantle downwelling, 2) shifts from local to regional volcanic activity, and 3) a shift back to local volcanic activity. We present our interpretations of the volcanic history of the region surrounding the north pole of Venus and explore how analysis of new data support our interpretations

  17. HASSET: a probability event tree tool to evaluate future volcanic scenarios using Bayesian inference (United States)

    Sobradelo, Rosa; Bartolini, Stefania; Martí, Joan


    Event tree structures constitute one of the most useful and necessary tools in modern volcanology for assessment of hazards from future volcanic scenarios (those that culminate in an eruptive event as well as those that do not). They are particularly relevant for evaluation of long- and short-term probabilities of occurrence of possible volcanic scenarios and their potential impacts on urbanized areas. In this paper, we introduce Hazard Assessment Event Tree (HASSET), a probability tool, built on an event tree structure that uses Bayesian inference to estimate the probability of occurrence of a future volcanic scenario and to evaluate the most relevant sources of uncertainty from the corresponding volcanic system. HASSET includes hazard assessment of noneruptive and nonmagmatic volcanic scenarios, that is, episodes of unrest that do not evolve into volcanic eruption but have an associated volcanic hazard (e.g., sector collapse and phreatic explosion), as well as unrest episodes triggered by external triggers rather than the magmatic system alone. Additionally, HASSET introduces the Delta method to assess precision of the probability estimates, by reporting a 1 standard deviation variability interval around the expected value for each scenario. HASSET is presented as a free software package in the form of a plug-in for the open source geographic information system Quantum Gis (QGIS), providing a graphically supported computation of the event tree structure in an interactive and user-friendly way. We also include further in-depth explanations for each node together with an application of HASSET to Teide-Pico Viejo volcanic complex (Spain).

  18. Field-trip guides to selected volcanoes and volcanic landscapes of the western United States (United States)



    The North American Cordillera is home to a greater diversity of volcanic provinces than any comparably sized region in the world. The interplay between changing plate-margin interactions, tectonic complexity, intra-crustal magma differentiation, and mantle melting have resulted in a wealth of volcanic landscapes.  Field trips in this guide book collection (published as USGS Scientific Investigations Report 2017–5022) visit many of these landscapes, including (1) active subduction-related arc volcanoes in the Cascade Range; (2) flood basalts of the Columbia Plateau; (3) bimodal volcanism of the Snake River Plain-Yellowstone volcanic system; (4) some of the world’s largest known ignimbrites from southern Utah, central Colorado, and northern Nevada; (5) extension-related volcanism in the Rio Grande Rift and Basin and Range Province; and (6) the eastern Sierra Nevada featuring Long Valley Caldera and the iconic Bishop Tuff.  Some of the field trips focus on volcanic eruptive and emplacement processes, calling attention to the fact that the western United States provides opportunities to examine a wide range of volcanological phenomena at many scales.The 2017 Scientific Assembly of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) in Portland, Oregon, was the impetus to update field guides for many of the volcanoes in the Cascades Arc, as well as publish new guides for numerous volcanic provinces and features of the North American Cordillera. This collection of guidebooks summarizes decades of advances in understanding of magmatic and tectonic processes of volcanic western North America. These field guides are intended for future generations of scientists and the general public as introductions to these fascinating areas; the hope is that the general public will be enticed toward further exploration and that scientists will pursue further field-based research.

  19. Volcanic caves of East Africa - an overview

    Directory of Open Access Journals (Sweden)

    Jim W. Simons


    Full Text Available Numerous Tertiary to recent volcanoes are located in East Africa. Thus, much of the region is made up volcanic rock, which hosts the largest and greatest variety of East Africas caves. Exploration of volcanic caves has preoccupied members of Cave Exploration Group of East Africa (CEGEA for the past 30 years. The various publications edited by CEGEA are in this respect a treasure troves of speleological information. In the present paper an overview on the most important volcanic caves and areas are shortly reported.

  20. Mafic and related complexes in Galicia: an excursion guide

    NARCIS (Netherlands)

    Arps, C.E.S.; Calsteren, van P.W.C.; Hilgen, J.D.; Kuijper, R.P.; Tex, den E.


    In Galicia occur several polymetamorphic complexes that contain mafic and ultramafic rocks. Mafic volcanics and gabbros are situated in or near the complexes. An episode of metamorphism and granitization encompassed the generation of the volcanics and gabbros. Gravity surveys revealed the existence

  1. Volcanic activity at Tvashtar Catena, Io (United States)

    Milazzo, M.P.; Keszthelyi, L.P.; Radebaugh, J.; Davies, A.G.; Turtle, E.P.; Geissler, P.; Klaasen, K.P.; Rathbun, J.A.; McEwen, A.S.


    Galileo's Solid State Imager (SSI) observed Tvashtar Catena four times between November 1999 and October 2001, providing a unique look at a distinctive high latitude volcanic complex on Io. The first observation (orbit I25, November 1999) resolved, for the first time, an active extraterrestrial fissure eruption; the brightness temperature was at least 1300 K. The second observation (orbit I27, February 2000) showed a large (??? 500 km 2) region with many, small, hot, regions of active lava. The third observation was taken in conjunction with Cassini imaging in December 2000 and showed a Pele-like, annular plume deposit. The Cassini images revealed an ???400 km high Pele-type plume above Tvashtar Catena. The final Galileo SSI observation of Tvashtar (orbit I32, October 2001), revealed that obvious (to SSI) activity had ceased, although data from Galileo's Near Infrared Mapping Spectrometer (NIMS) indicated that there was still significant thermal emission from the Tvashtar region. In this paper, we primarily analyze the style of eruption during orbit I27 (February 2000). Comparison with a lava flow cooling model indicates that the behavior of the Tvashtar eruption during I27 does not match that of simple advancing lava flows. Instead, it may be an active lava lake or a complex set of lava flows with episodic, overlapping eruptions. The highest reliable color temperature is ???1300 K. Although higher temperatures cannot be ruled out, they do not need to be invoked to fit the observed data. The total power output from the active lavas in February 2000 was at least 1011 W. ?? 2005 Elsevier Inc. All rights reserved.

  2. Active Volcanic Plumes on Io (United States)


    This color image, acquired during Galileo's ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon (see inset at upper right), erupting over a caldera (volcanic depression) named Pillan Patera after a South American god of thunder, fire and volcanoes. The plume seen by Galileo is 140 kilometers (86 miles) high and was also detected by the Hubble Space Telescope. The Galileo spacecraft will pass almost directly over Pillan Patera in 1999 at a range of only 600 kilometers (373 miles).The second plume, seen near the terminator (boundary between day and night), is called Prometheus after the Greek fire god (see inset at lower right). The shadow of the 75-kilometer (45- mile) high airborne plume can be seen extending to the right of the eruption vent. The vent is near the center of the bright and dark rings. Plumes on Io have a blue color, so the plume shadow is reddish. The Prometheus plume can be seen in every Galileo image with the appropriate geometry, as well as every such Voyager image acquired in 1979. It is possible that this plume has been continuously active for more than 18 years. In contrast, a plume has never been seen at Pillan Patera prior to the recent Galileo and Hubble Space Telescope images.North is toward the top of the picture. The resolution is about 6 kilometers (3.7 miles) per picture element. This composite uses images taken with the green, violet and near infrared filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The images were obtained on June 28, 1997, at a range of more than 600,000 kilometers (372,000 miles).The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http

  3. Volcanic Ash Advisory Database, 1983-2003 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanic ash is a significant hazard to aviation and can also affect global climate patterns. To ensure safe navigation and monitor possible climatic impact, the...

  4. Palaeoclimate: Volcanism caused ancient global warming (United States)

    Meissner, Katrin J.; Bralower, Timothy J.


    A study confirms that volcanism set off one of Earth's fastest global-warming events. But the release of greenhouse gases was slow enough for negative feedbacks to mitigate impacts such as ocean acidification. See Letter p.573

  5. Submarine silicic volcanism: Processes and products

    Digital Repository Service at National Institute of Oceanography (India)

    Kalangutkar, N.G.; Iyer, S.D.

    The occurrence of submarine silicic volcanics is rare at the mid-oceanic ridges, abyssal depths, seamounts and fracture zones. Hydrothermal processes are active in submarine silicic environments and are associated with host ores of Cu, Au, Ag, Pb...

  6. Volcanism and associated hazards: the Andean perspective

    Directory of Open Access Journals (Sweden)

    R. I. Tilling


    Full Text Available Andean volcanism occurs within the Andean Volcanic Arc (AVA, which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth's longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These segments are separated by volcanically inactive gaps that are inferred to indicate regions where the dips of the subducting plates are too shallow to favor the magma generation needed to sustain volcanism. The Andes host more volcanoes that have been active during the Holocene (past 10 000 years than any other volcanic region in the world, as well as giant caldera systems that have produced 6 of the 47 largest explosive eruptions (so-called "super eruptions" recognized worldwide that have occurred from the Ordovician to the Pleistocene.

    The Andean region's most powerful historical explosive eruption occurred in 1600 at Huaynaputina Volcano (Peru. The impacts of this event, whose eruptive volume exceeded 11 km3, were widespread, with distal ashfall reported at distances >1000 km away. Despite the huge size of the Huaynaputina eruption, human fatalities from hazardous processes (pyroclastic flows, ashfalls, volcanogenic earthquakes, and lahars were comparatively small owing to the low population density at the time. In contrast, lahars generated by a much smaller eruption (<0.05 km3 in 1985 of Nevado del Ruiz (Colombia killed about 25 000 people – the worst volcanic disaster in the Andean region as well as the second worst in the world in the 20th century. The Ruiz tragedy has been attributed largely to ineffective communications of hazards information and indecisiveness by government officials, rather than any major deficiencies in scientific data. Ruiz's disastrous outcome, however, together with responses to subsequent

  7. Early volcanic history of the Rabaul area (United States)

    McKee, Chris O.; Duncan, Robert A.


    We conducted an extensive program of 40Ar-39Ar age determinations on a suite of 27 volcanic rock samples from key stratigraphic units at Rabaul, Papua New Guinea in order to improve understanding of the early eruption history of the multiple volcanic systems present in the area. Analyses of whole rock, plagioclase and groundmass separates yielded statistically significant ages for 24 samples. Replicate analyses (groundmass, plagioclase) for 17 of the samples provided concordant ages. The oldest systems in the Rabaul area (>1 Ma to ≈300 ka) are in the south, associated with the caldera-like Varzin Depression, and in the north, at the stratovolcanoes Watom and Tovanumbatir. The earliest known activity of the Rabaul system occurred between about 330 and 200 ka and involved emplacement of lava flows and scoria deposits. Major explosive activity at the Rabaul system commenced at about 200 ka and produced a sequence of dacitic ignimbrites that culminated with the emplacement of the large-volume Malaguna Pyroclastics at about 160 ka. Calderas may have been formed as a consequence of the large volumes of tephra produced during some of these eruptions. Products of the early activity are found in the northern and northeastern walls of Rabaul Caldera and on the northeastern flank of Tovanumbatir. This leads to the conclusion that the source of the early activity at Rabaul probably was located in the northern part of the present caldera complex. A shift in the focus of activity at the Rabaul system took place between about 160 and 125 ka. All of the younger (<125 ka) major pyroclastic formations, including the Karavia Welded Tuff, the Barge Tunnel Ignimbrite and the Latlat Pyroclastics, which make up the bulk of the exposure in the southern and western walls of Rabaul Caldera, were erupted from a source or sources in the south-central part of the complex. The stratovolcanoes Palangiangia and Kabiu, which flank the northeastern part of the complex, had commenced activity by

  8. Shape measurements of volcanic particles by CAMSIZER


    Lo Castro, Maria Deborah; Andronico, Daniele; Nunnari, Giuseppe; Spata, Alessandro; Torrisi, Alessio


    The shape of volcanic particles is an important parameter holding information related to physical and geochemical processes. The study of particle shape may help improving knowledge on the main eruptive processes (fragmentation, transport and sedimentation) during explosive activity. In general, volcanic ash is formed by different components, namely juvenile, lithic and crystal particles, each one characterized by peculiar morphology. Moreover, quantifying the shape of pyroclasts is needed by...

  9. About the Mechanism of Volcanic Eruptions

    CERN Document Server

    Nechayev, Andrei


    A new approach to the volcanic eruption theory is proposed. It is based on a simple physical mechanism of the imbalance in the system "magma-crust-fluid". This mechanism helps to explain from unified positions the different types of volcanic eruptions. A criterion of imbalance and magma eruption is derived. Stratovolcano and caldera formation is analyzed. High explosive eruptions of the silicic magma is discussed

  10. Age and petrogenetic constraints on the Lower Glassy Ignimbrite of the Mount Somers Volcanic Group, New Zealand

    DEFF Research Database (Denmark)

    van der Meer, Quinten; Waight, Tod Earle; Whitehouse, Martin


    The Mount Somers Volcanic Group (MSVG) forms a large (~18000 km2) calc-alkaline volcanic complex on New Zealand’s Eastern Province. U-Pb SIMS spot ages on zircon from the lower glassy ignimbrite in Rakaia Gorge reveal a bimodal distribution of 99.0 ± 0.5 and 96.3 ± 0.5 Ma (2σ). These ages...

  11. Medical effects of volcanic eruptions (United States)

    Baxter, Peter J.


    Excluding famine and tsunamis, most deaths in volcanic eruptions have been from pyroclastic flows and surges (nuées ardentes) and wet debris flows (lahars). Information on the causes of death and injury in eruptions is sparse but the available literature is summarised for the benefit of volcanologists and emergency planners. In nuées, thermal injury may be at least as important as asphyxia in causing immediate deaths. The high temperature of the gases and entrained particles readily causes severe burns to the skin and the air passages and the presence of both types of injury in an individual may combine to increase the delayed mortality risk from respiratory complications or from infection of burns. Trauma from missiles or body displacement is also common, but the role of asphyxiant or irritant gases, and steam, remains unclear. The ratio of dead: injured is much higher than in other natural disasters. At the periphery of a nuée being protected inside buildings which remain intact appears to greatly increase the chances of survival. In lahars, infected wounds and crush injury are the main delayed causes of death, and the scope for preventive measures, other than evacuation, is small. The evidence from Mount St. Helens, 1980, and other major eruptions indicates that, although mortality is high within the main zone of devastation and in the open, emergency planning should concentrate on the periphery of a nuée where preventive measures are feasible and could save many lives in densely populated areas.

  12. Mercury content in volcanic soils across Europe and its relationship with soil properties

    Energy Technology Data Exchange (ETDEWEB)

    Pena-Rodriguez, Susana; Fernandez-Calvino, David; Arias-Estevez, Manuel; Novoa-Munoz, Juan Carlos [Vigo Univ., Ourense (Spain). Area de Edafoloxia e Quimica Agricola; Pontevedra-Pombal, Xabier; Taboada, Teresa; Martinez-Cortizas, Antonio; Garcia-Rodeja, Eduardo [Universidad de Santiago, Coruna (Spain). Dept. Edafoloxia e Quimica Agricola


    Volcanoes are a natural source of Hg, whose deposition can occur in neighbouring soils. This study examines the role of soil compounds in the geochemical behaviour of total Hg (Hg{sub T}) in volcanic soils. An estimation of Hg from lithological origin is also assessed to ascertain the relevance of other sources in Hg{sub T} accumulated in volcanic soils. Twenty soil profiles developed from volcanic materials and located across European volcanic regions were selected for this study. The general characterisation of soils included total C, N and S content and Al and Fe distribution determined using traditional methods. The total content of major and trace elements was determined using X-ray fluorescence spectrometry (XRF). The total Hg content of soil samples was measured with atomic absorption spectroscopy using a solid sample Hg analyser. Lithogenic Hg was calculated in the uppermost soil considering Al, Ti and Zr as conservative reference elements. Several statistical analyses (Pearson correlations, Mann-Whitney tests, stepwise multiple regressions and analysis of variance) were carried to ascertain the role of soil parameters and characteristics in the Hg accumulation in volcanic soils. The total Hg ranged from 3.0 to 640 ng g{sup -1} and it tended to diminish with soil depth except in some soils where the lithological discontinuities resulted in high values of Hg{sub T} in the Bw horizons. More than 75% of the Hg{sub T} variance could be attributed to distinct contents of organic matter, Al- and Fe-humus complexes and inorganic non-crystalline Al and Fe compounds in ''andic'', ''vitric'' and ''non-andic'' horizons. The degree of pedogenetic soil evolution notably influenced the Hg{sub T} soil content. Lithogenic Hg (1.6-320 ng g{sup -1}) was correlated with Al-humus complexes and clay content, suggesting the relevance of pedogenetic processes, whereas exogenic Hg (1.4-180 ng g{sup -1}) was correlated

  13. Árboles y arbustos tropicales nativos productores de néctar y polen en el estado de Colima, México

    Directory of Open Access Journals (Sweden)

    L. Román


    Full Text Available El objetivo de este estudio fue identificar las principales especies de árboles y arbustos nativos de interés apícola en el estado de Colima, su distribución ecológica y mes de floración. El trabajo consideró una revisión bibliográfica, recorridos de campo en forma mensual a las diferentes comunidades ecológicas del estado, así como la recuperación del conocimiento tradicional de productores y técnicos de la zona de estudio; asimismo, se realizaron colectas de ejemplares para su identificación taxonómica en el herbario del Instituto de Botánica de la Universidad de Guadalajara (IBUG. Los resultados mostraron el potencial apícola de la flora nativa del estado, con 140 especies en total; de los cuales, 120 fueron árboles y 20 arbustos, representados por 45 familias; predominaron las especies de la familia Fabaceae (Leguminosae con un 21.43%. Por su utilidad apícola, las de mayor número correspondió a las nectaríferas (58%, seguidas de las nectarífera- poliníferas (33% y poliníferas (9%. La mayoría de los árboles florece durante los meses de marzo a mayo, y en los arbustos la floración predomina en los meses de octubre a diciembre. Asimismo, el mayor número de especies de árbo- les se encuentra dentro de la selva mediana subcaducifolia y baja caducifolia; y en el caso de arbustos, en la selva baja caducifolia y bosques de encino. Existe diversidad y abundancia de especies que favorece el desarrollo apícola en el estado, así como una floración diferenciada que permite tener alimento para las abejas la mayor parte del año.

  14. Ground subsidence and associated ground fracturing in urban areas: InSAR monitoring of active tectonic structures (Ciudad Guzman, Colima Graben - Mexico) (United States)

    Bignami, C.; Brunori, C.; Zucca, F.; Groppelli, G.; Norini, G.; Hernandez, N. D.; Stramondo, S.


    This study focuses on the observation of a creeping phenomenon that produces subsidence of the Zapotlan basin and ground fracturing in correspondence of the Ciudad Guzmàn (Jalisco - Mexico). The September 21, 2012, the Ciudad Guzmàn has been struck by a phenomenon of ground fracturing of about 1.5 km of length. This event caused the deformation of the roads and the damage of 30 houses, of which eight have been declared uninhabitable. The alignment of fractures is coincident with the escarpments produced in September 19, 1985, in the Ciudad Guzman urban area, when a strong earthquake, magnitude 8.1, struck the Mexican area, causing the deaths of at least 10,000 people and serious damage in Mexico City. In Ciudad Guzmán, about 60% of the buildings were destroyed, with about 50 loss of life. The city is located in the Zapotlan basin (northern Colima graben), a wide tectonic depression where the depth of the infilling sediments is about 1 km. This subsidence cannot be measured outside the urbanized area, but it can be considered as a deformation mechanism of the central part of the basin. In order to detect and mapping the spatio-temporal features of the processes that led to this event, we applied InSAR multi-temporal techniques to analyze a dataset of ENVISAT satellite SAR images, acquired in a time span between 2003-2010. InSAR techniques detect a subsidence of the north-western part of Ciudad Guzmàn of about 15 mm/yr in the time interval 2003-2010. The displacement occurred in September 21, 2012, was detected using two RadarSAT2 acquisitions (2012-03-22 and 2013-03-17). The explanation of surface movements based on interferometric results, ground data and geological field observations, allowed confirming surface effect due to the overexploitation of the aquifers and highlights a subsidence due to anthropogenic causes coupled to buried tectonic structures.

  15. Quantification of the CO2 emitted from volcanic lakes in Pico Island (Azores) (United States)

    Andrade, César; Cruz, José; Viveiros, Fátima; Branco, Rafael


    This study shows the results of the diffuse CO2 degassing surveys performed in lakes from Pico volcanic Island (Azores archipelago, Portugal). Detailed flux measurements using the accumulation chamber method were made at six lakes (Capitão, Caiado, Paul, Rosada, Peixinho and Negra) during two field campaigns, respectively, in winter (February 2016) and late summer (September 2016). Pico is the second largest island of the Azores archipelago with an area of 444.8 km2; the oldest volcanic unit is dated from about 300,000 years ago. The edification of Pico was mainly due to Hawaiian and Strombolian type volcanic activity, resulting in pahoehoe and aa lava flows of basaltic nature, as well as scoria and spatter cones. Three main volcanic complexes are identified in the island, namely (1) the so-called Montanha Volcanic Complex, corresponding to a central volcano located in the western side of the island that reaches a maximum altitude of 2351 m, (2) the São Roque-Piedade Volcanic Complex, and (3) the Topo-Lajes Volcanic Complex, this last one corresponding to the remnants of a shield volcano located in the south coast. The studied lakes are spread along the São Roque-Piedade Volcanic Complex at altitudes between 785 m and 898 m. Three are associated with depressions of undifferentiated origin (Caiado, Peixinho, Negra), two with depressions of tectonic origin (Capitão, Paul), while Rosada lake is located inside a scoria cone crater. The lakes surface areas vary between 1.25x10-2 and 5.38x10-2 km2, and the water column maximum depth is 7.9 m (3.5-7.9 m). The water storage ranges between 3.6x104 to 9.1x104 m3, and the estimated residence time does not exceed 1.8x10-1 years. A total of 1579 CO2 flux measurements were made during both surveys (868 in summer and 711 in the winter campaign), namely 518 in Caiado lake (293; 225), 358 in Paul (195; 163), 279 in Capitão (150, 129), 200 in Rosada (106, 94), 171 in Peixinho (71, 100) and 53 measurements in Negra lake. Negra

  16. On the Role of Climate Forcing by Volcanic Sulphate and Volcanic Ash

    Directory of Open Access Journals (Sweden)

    Baerbel Langmann


    Full Text Available There is overall agreement that volcanic sulphate aerosols in the stratosphere can reduce solar radiation reaching the earth’s surface for years, thereby reducing surface temperatures, affecting global circulation patterns and generally the global climate system. However, the response of the climate system after large volcanic eruptions is not fully understood and global climate models have difficulties to reproduce the observed variability of the earth system after large volcanic eruptions until now. For geological timescales, it has been suggested that, in addition to the stratospheric climate forcing by volcanic sulphate aerosols, volcanic ash affects climate by modifying the global carbon cycle through iron fertilising the surface ocean and stimulating phytoplankton growth. This process has recently also been observed after the eruption of the volcano Kasatochi on the Aleutian Islands in summer 2008. To trigger future research on the effect of volcanic ash on the climate system via ocean iron fertilisation, this review paper describes the formation processes and atmospheric life cycles of volcanic sulphate and volcanic ash, contrasts their impact on climate, and emphasises current limitations in our understanding.

  17. Volcanic Ash Impacts on Air Traffic from the 2009 Mt. Redoubt Eruption (United States)

    Murray, J. J.; Matus, A. V.; Hudnall, L. A.; Krueger, A. J.; Haynes, J. A.; Pippin, M. R.


    The dispersion of volcanic ash during the March 2009 eruption of Mt. Redoubt created the potential for major problems for aviation. Mt. Redoubt is located 110 km west-southwest of Alaska Airlines hub in Anchorage. It last erupted in 1990 and caused an estimated $101 million cost to the aviation industry (Waythomas, 1998). This study was conducted to assist in improving warning systems, policy and procedures for addressing the impact of volcanic ash on aviation. The study had two primary components. First, the altitude and extent of SO2 dispersion was determined through analysis of synoptic meteorological conditions and satellite imagery. Second, impacts on aviation from the volcanic ash dispersion were investigated. OMI SO2 column measurements were employed to assess the altitude and extent of SO2 dispersion of volcanic ash. To accomplish this, OMI data were assimilated with CALIPSO backscatter profiles, geopotential height plots, and HYSPLIT forward model trajectories. Volcanic Ash Advisories were compared to airport and pilot reports to assess aviation impacts. The eruption produced a complex dispersion of volcanic ash. Volcanic ash altitudes estimated for 23 March 2009 indicate that the majority of the plume remained at approximately 8 km, although reports indicate that the initial plume may have reached as high as18 km (60,000 ft). A low pressure system which passed over the eruption area appears to have entrained most of the ash at approximately 8 km, however the CALIPSO satellite indicates that dispersion also extended to 10 km and 16 km. Atmospheric patterns suggest dispersion at approximately 3 km near Hudson Bay. Analysis of 25 March 2009 indicates that much of the ash plume was dispersed at higher altitudes, where CALIPSO data locates the stratospheric ash plume at approximately 14 km above mean sea level. By the time the eruptions had subsided in April, Alaska Airlines had cancelled 295 flights and disrupted the flights of over 20,000 passengers. This

  18. Volcanic Ash Activates the NLRP3 Inflammasome in Murine and Human Macrophages

    Directory of Open Access Journals (Sweden)

    David E. Damby


    Full Text Available Volcanic ash is a heterogeneous mineral dust that is typically composed of a mixture of amorphous (glass and crystalline (mineral fragments. It commonly contains an abundance of the crystalline silica (SiO2 polymorph cristobalite. Inhalation of crystalline silica can induce inflammation by stimulating the NLRP3 inflammasome, a cytosolic receptor complex that plays a critical role in driving inflammatory immune responses. Ingested material results in the assembly of NLRP3, ASC, and caspase-1 with subsequent secretion of the interleukin-1 family cytokine IL-1β. Previous toxicology work suggests that cristobalite-bearing volcanic ash is minimally reactive, calling into question the reactivity of volcanically derived crystalline silica, in general. In this study, we target the NLRP3 inflammasome as a crystalline silica responsive element to clarify volcanic cristobalite reactivity. We expose immortalized bone marrow-derived macrophages of genetically engineered mice and primary human peripheral blood mononuclear cells (PBMCs to ash from the Soufrière Hills volcano as well as representative, pure-phase samples of its primary componentry (volcanic glass, feldspar, cristobalite and measure NLRP3 inflammasome activation. We demonstrate that respirable Soufrière Hills volcanic ash induces the activation of caspase-1 with subsequent release of mature IL-1β in a NLRP3 inflammasome-dependent manner. Macrophages deficient in NLRP3 inflammasome components are incapable of secreting IL-1β in response to volcanic ash ingestion. Cellular uptake induces lysosomal destabilization involving cysteine proteases. Furthermore, the response involves activation of mitochondrial stress pathways leading to the generation of reactive oxygen species. Considering ash componentry, cristobalite is the most reactive pure-phase with other components inducing only low-level IL-1β secretion. Inflammasome activation mediated by inhaled ash and its potential relevance in

  19. Volcanic ash activates the NLRP3 inflammasome in murine and human macrophages (United States)

    Damby, David; Horwell, Claire J.; Baxter, Peter J.; Kueppers, Ulrich; Schnurr, Max; Dingwell, Donald B.; Duewell, Peter


    Volcanic ash is a heterogeneous mineral dust that is typically composed of a mixture of amorphous (glass) and crystalline (mineral) fragments. It commonly contains an abundance of the crystalline silica (SiO2) polymorph cristobalite. Inhalation of crystalline silica can induce inflammation by stimulating the NLRP3 inflammasome, a cytosolic receptor complex that plays a critical role in driving inflammatory immune responses. Ingested material results in the assembly of NLRP3, ASC, and caspase-1 with subsequent secretion of the interleukin-1 family cytokine IL-1β. Previous toxicology work suggests that cristobalite-bearing volcanic ash is minimally reactive, calling into question the reactivity of volcanically derived crystalline silica, in general. In this study, we target the NLRP3 inflammasome as a crystalline silica responsive element to clarify volcanic cristobalite reactivity. We expose immortalized bone marrow-derived macrophages of genetically engineered mice and primary human peripheral blood mononuclear cells (PBMCs) to ash from the Soufrière Hills volcano as well as representative, pure-phase samples of its primary componentry (volcanic glass, feldspar, cristobalite) and measure NLRP3 inflammasome activation. We demonstrate that respirable Soufrière Hills volcanic ash induces the activation of caspase-1 with subsequent release of mature IL-1β in a NLRP3 inflammasome-dependent manner. Macrophages deficient in NLRP3 inflammasome components are incapable of secreting IL-1β in response to volcanic ash ingestion. Cellular uptake induces lysosomal destabilization involving cysteine proteases. Furthermore, the response involves activation of mitochondrial stress pathways leading to the generation of reactive oxygen species. Considering ash componentry, cristobalite is the most reactive pure-phase with other components inducing only low-level IL-1β secretion. Inflammasome activation mediated by inhaled ash and its potential relevance in chronic pulmonary

  20. Volcanic Supersites as cross-disciplinary laboratories (United States)

    Provenzale, Antonello; Beierkuhnlein, Carl; Giamberini, Mariasilvia; Pennisi, Maddalena; Puglisi, Giuseppe


    Volcanic Supersites, defined in the frame of the GEO-GSNL Initiative, are usually considered mainly for their geohazard and geological characteristics. However, volcanoes are extremely challenging areas from many other points of view, including environmental and climatic properties, ecosystems, hydrology, soil properties and biogeochemical cycling. Possibly, volcanoes are closer to early Earth conditions than most other types of environment. During FP7, EC effectively fostered the implementation of the European volcano Supersites (Mt. Etna, Campi Flegrei/Vesuvius and Iceland) through the MED-SUV and FUTUREVOLC projects. Currently, the large H2020 project ECOPOTENTIAL (2015-2019, 47 partners, contributes to GEO/GEOSS and to the GEO ECO Initiative, and it is devoted to making best use of remote sensing and in situ data to improve future ecosystem benefits, focusing on a network of Protected Areas of international relevance. In ECOPOTENTIAL, remote sensing and in situ data are collected, processed and used for a better understanding of the ecosystem dynamics, analysing and modelling the effects of global changes on ecosystem functions and services, over an array of different ecosystem types, including mountain, marine, coastal, arid and semi-arid ecosystems, and also areas of volcanic origin such as the Canary and La Reunion Islands. Here, we propose to extend the network of the ECOPOTENTIAL project to include active Volcanic Supersites, such as Mount Etna and other volcanic Protected Areas, and we discuss how they can be included in the framework of the ECOPOTENTIAL workflow. A coordinated and cross-disciplinary set of studies at these sites should include geological, biological, ecological, biogeochemical, climatic and biogeographical aspects, as well as their relationship with the antropogenic impact on the environment, and aim at the global analysis of the volcanic Earth Critical Zone - namely, the upper layer of the Earth

  1. Volcanic Alert System (VAS) developed during the (2011-2013) El Hierro (Canary Islands) volcanic process (United States)

    Ortiz, Ramon; Berrocoso, Manuel; Marrero, Jose Manuel; Fernandez-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Garcia, Alicia


    In volcanic areas with long repose periods (as El Hierro), recently installed monitoring networks offer no instrumental record of past eruptions nor experience in handling a volcanic crisis. Both conditions, uncertainty and inexperience, contribute to make the communication of hazard more difficult. In fact, in the initial phases of the unrest at El Hierro, the perception of volcanic risk was somewhat distorted, as even relatively low volcanic hazards caused a high political impact. The need of a Volcanic Alert System became then evident. In general, the Volcanic Alert System is comprised of the monitoring network, the software tools for the analysis of the observables, the management of the Volcanic Activity Level, and the assessment of the threat. The Volcanic Alert System presented here places special emphasis on phenomena associated to moderate eruptions, as well as on volcano-tectonic earthquakes and landslides, which in some cases, as in El Hierro, may be more destructive than an eruption itself. As part of the Volcanic Alert System, we introduce here the Volcanic Activity Level which continuously applies a routine analysis of monitoring data (particularly seismic and deformation data) to detect data trend changes or monitoring network failures. The data trend changes are quantified according to the Failure Forecast Method (FFM). When data changes and/or malfunctions are detected, by an automated watchdog, warnings are automatically issued to the Monitoring Scientific Team. Changes in the data patterns are then translated by the Monitoring Scientific Team into a simple Volcanic Activity Level, that is easy to use and understand by the scientists and technicians in charge for the technical management of the unrest. The main feature of the Volcanic Activity Level is its objectivity, as it does not depend on expert opinions, which are left to the Scientific Committee, and its capabilities for early detection of precursors. As a consequence of the El Hierro

  2. Late Cretaceous volcanism in south-central New Mexico: Conglomerates of the McRae and Love Ranch Formations

    Energy Technology Data Exchange (ETDEWEB)

    Chapman-Fahey, J.L.; McMillan, N.J.; Mack, G.H.; Seager, W.R. (New Mexico State Univ., Las Cruces, NM (United States). Dept. of Geological Sciences)


    Evidence to support Late Cretaceous volcanism in south central New Mexico is restricted to a small area of 75-Ma-old andesitic rocks at Copper Flats near Hillsboro, and volcanic clasts in the McRae (Late Cretaceous/Paleocene ) and Love Ranch (Paleocene/Eocene). Formations located in the Jornada del Muerto basin east and northeast of the Caballo Mountains. Major and trace element data and petrographic analysis of 5 samples from Copper Flats lavas and 40 samples of volcanic clasts from the McRae and Love Ranch conglomerates will be used to reconstruct the Cretaceous volcanic field. The McRae Formation consists of two members: the lower Jose Creek and the upper Hall Lake. The lowermost Love Ranch Formation is unconformable in all places on the Hall Lake Member. Stratigraphic variations in clast composition from volcanic rocks in the lower Love Ranch Formation to Paleozoic and Precambrian clasts in the upper Love Ranch Formation reflect the progressive unroofing of the Laramide Rio Grande Uplift. Volcanic clasts in the McRae and Love Ranch Formations were derived from the west and south of the depositional basin, but the source area for McRae clasts is less well constrained. Stratigraphic, chemical, and petrographic data will be used to reconstruct the volcanic complex and more clearly define magma genesis and metasomatism associated with Laramide deformation.

  3. The issue of trust and its influence on risk communication during a volcanic crisis (United States)

    Haynes, Katharine; Barclay, Jenni; Pidgeon, Nick


    This paper investigates trust in the scientists, government authorities and wider risk management team during the ongoing volcanic crisis in Montserrat, WI. Identifying the most trusted communicator and how trust in information can be enhanced are considered important for improving the efficacy of volcanic risk communication. Qualitative interviews, participant observations and a quantitative survey were utilised to investigate the views and attitudes of the public, authorities and scientists. Trust was found to be dynamic, influenced by political factors made more complex by the colonial nature of Montserrat’s governance and the changing level of volcanic activity. The scientists were viewed by the authorities as a highly trusted expert source of volcanic information. Mistrust among some of the local authorities towards the scientists and British Governor was founded in the uncertainty of the volcanic situation and influenced by differences in levels of acceptable risk and suspicions about integrity (e.g. as a consequence of employment by the British Government). The public viewed friends and relatives as the most trusted source for volcanic information. High trust in this source allowed competing messages to reinforce beliefs of lower risk than were officially being described. The scientists were the second most trusted group by the public and considered significantly more competent, reliable, caring, fair and open than the authorities. The world press was the least trusted, preceded closely by the British Governor’s Office and Montserratian Government officials. These results tally well with other empirical findings suggesting that government ministers and departments are typically distrusted as sources of risk-related information. These findings have implications for risk communication on Montserrat and other volcanic crises. The importance and potential effectiveness of scientists as communicators, because of, and despite, the existence of political

  4. Impact of tectonic and volcanism on the Neogene evolution of isolated carbonate platforms (SW Indian Ocean) (United States)

    Courgeon, S.; Jorry, S. J.; Jouet, G.; Camoin, G.; BouDagher-Fadel, M. K.; Bachèlery, P.; Caline, B.; Boichard, R.; Révillon, S.; Thomas, Y.; Thereau, E.; Guérin, C.


    Understanding the impact of tectonic activity and volcanism on long-term (i.e. millions years) evolution of shallow-water carbonate platforms represents a major issue for both industrial and academic perspectives. The southern central Mozambique Channel is characterized by a 100 km-long volcanic ridge hosting two guyots (the Hall and Jaguar banks) and a modern atoll (Bassas da India) fringed by a large terrace. Dredge sampling, geophysical acquisitions and submarines videos carried out during recent oceanographic cruises revealed that submarine flat-top seamounts correspond to karstified and drowned shallow-water carbonate platforms largely covered by volcanic material and structured by a dense network of normal faults. Microfacies and well-constrained stratigraphic data indicate that these carbonate platforms developed in shallow-water tropical environments during Miocene times and were characterized by biological assemblages dominated by corals, larger benthic foraminifera, red and green algae. The drowning of these isolated carbonate platforms is revealed by the deposition of outer shelf sediments during the Early Pliocene and seems closely linked to (1) volcanic activity typified by the establishment of wide lava flow complexes, and (2) to extensional tectonic deformation associated with high-offset normal faults dividing the flat-top seamounts into distinctive structural blocks. Explosive volcanic activity also affected platform carbonates and was responsible for the formation of crater(s) and the deposition of tuff layers including carbonate fragments. Shallow-water carbonate sedimentation resumed during Late Neogene time with the colonization of topographic highs inherited from tectonic deformation and volcanic accretion. Latest carbonate developments ultimately led to the formation of the Bassas da India modern atoll. The geological history of isolated carbonate platforms from the southern Mozambique Channel represents a new case illustrating the major

  5. Role of volcanism in climate and evolution

    Energy Technology Data Exchange (ETDEWEB)

    Axelrod, D.I.


    Several major episodes of Tertiary explosive volcanism coincided with sharply lowered temperature as inferred from oxygen-isotope composition of foraminiferal tests in deep-sea cores. At these times, fossil floras in the western interior recorded significant changes. Reductions in taxa that required warmth occurred early in the Paleogene. Later, taxa that demand ample summer rain were reduced during a progressive change reflecting growth of the subtropic high. Other ecosystem changes that appear to have responded to volcanically induced climatic modifications include tachytely in Equidae (12 to 10 m.y. B.P.), rapid evolution of grasses (7 to 5 m.y. B.P.), evolution of marine mammals, and plankton flucuations. Although Lake Cretaceous extinctions commenced as epeiric seas retreated, the pulses of sharply lowered temperature induced by explosive volcanism, together with widespread falls of volcanic ash, may have led to extinction of dinosaurs, ammonites, cycadeoids, and other Cretaceous taxa. earlier, as Pangaea was assembled, Permian extinctions resulted not only from the elimination of oceans, epeiric seas, and shorelines, and the spread of more-continental climates, bu also from the climatic effects of major pulses of global volcanism and Gondwana glaciation.

  6. Magnetic minerals from volcanic Ultisols as heterogeneous Fenton catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Aravena, S., E-mail:; Pizarro, C.; Rubio, M. A. [USACH, Facultad de Quimica y Biologia (Chile); Cavalcante, L. C. D. [Universidade Federal do Piaui, Centro de Ciencias da Natureza (Brazil); Garg, V. K. [Universidade de Brasilia, Instituto de Fisica (Brazil); Pereira, M. C.; Fabris, J. D. [ICEx-UFMG, Departamento de Quimica (Brazil)


    This study was devoted to the evaluation of the effectiveness of Fenton catalysts, based on magnetically-concentrated portions of iron oxide-rich sand fractions from two magnetic Ultisols, derived from volcanic materials of southern Chile. The samples were labeled according to the municipality where the sample sites are geographically located, namely Metrenco and Collipulli, and were characterized with Moessbauer spectroscopy at 298 K and saturation magnetization ({sigma}) measurements. Moessbauer data revealed a complex magnetic hyperfine structure for these magnetic portions from both soil-sand materials, suggesting relatively complex mineral assemblages. The monitored rate of H{sub 2}O{sub 2} decomposition via heterogeneous Fenton reaction revealed that materials from the Collipulli soil are more efficient Fenton catalyst than are those from the Metrenco soil. The reasons for these differences are from now on being explored on basis of a more detailed chemical investigation of these samples.

  7. Active Volcanic Eruptions on Io (United States)


    Six views of the volcanic plume named Prometheus, as seen against Io's disk and near the bright limb (edge) of the satellite by the SSI camera on the Galileo spacecraft during its second (G2) orbit of Jupiter. North is to the top of each frame. To the south-southeast of Prometheus is another bright spot that appears to be an active plume erupting from a feature named Culann Patera. Prometheus was active 17 years ago during both Voyager flybys, but no activity was detected by Voyager at Culann. Both of these plumes were seen to glow in the dark in an eclipse image acquired by the imaging camera during Galileo's first (G1) orbit, and hot spots at these locations were detected by Galileo's Near-Infrared Mapping Spectrometer.The plumes are thought to be driven by heating sulfur dioxide in Io's subsurface into an expanding fluid or 'geyser'. The long-lived nature of these eruptions requires that a substantial supply of sulfur dioxide must be available in Io's subsurface, similar to groundwater. Sulfur dioxide gas condenses into small particles of 'snow' in the expanding plume, and the small particles scatter light and appear bright at short wavelengths. The images shown here were acquired through the shortest-wavelength filter (violet) of the Galileo camera. Prometheus is about 300 km wide and 75 km high and Culann is about 150 km wide and less than 50 km high. The images were acquired on September 4, 1996 at a range of 2,000,000 km (20 km/pixel resolution). Prometheus is named after the Greek fire god and Culann is named after the Celtic smith god.The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL Background information and educational context for the images can

  8. National volcanic ash operations plan for aviation (United States)

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    The National Aviation Weather Program Strategic Plan (1997) and the National Aviation Weather Initiatives (1999) both identified volcanic ash as a high-priority informational need to aviation services. The risk to aviation from airborne volcanic ash is known and includes degraded engine performance (including flameout), loss of visibility, failure of critical navigational and operational instruments, and, in the worse case, loss of life. The immediate costs for aircraft encountering a dense plume are potentially major—damages up to $80 million have occurred to a single aircraft. Aircraft encountering less dense volcanic ash clouds can incur longer-term costs due to increased maintenance of engines and external surfaces. The overall goal, as stated in the Initiatives, is to eliminate encounters with ash that could degrade the in-flight safety of aircrews and passengers and cause damage to the aircraft. This goal can be accomplished by improving the ability to detect, track, and forecast hazardous ash clouds and to provide adequate warnings to the aviation community on the present and future location of the cloud. To reach this goal, the National Aviation Weather Program established three objectives: (1) prevention of accidental encounters with hazardous clouds; (2) reduction of air traffic delays, diversions, or evasive actions when hazardous clouds are present; and (3) the development of a single, worldwide standard for exchange of information on airborne hazardous materials. To that end, over the last several years, based on numerous documents (including an OFCMsponsored comprehensive study on aviation training and an update of Aviation Weather Programs/Projects), user forums, and two International Conferences on Volcanic Ash and Aviation Safety (1992 and 2004), the Working Group for Volcanic Ash (WG/VA), under the OFCM-sponsored Committee for Aviation Services and Research, developed the National Volcanic Ash Operations Plan for Aviation and Support of the

  9. Late Pleistocene-Holocene Volcanism of the Mexico Basin and Assessment of Volcanic Hazards in One of the World’s Largest Cities (United States)

    Layer, P. W.; Macías, J.; Arce, J.; García, F.


    The Mexico City metropolitan area is home to more than 22 million people living in sight of, or living on, several volcanoes that either are currently active or show evidence of Late Pleistocene-Holocene activity (e.g., pyroclastic flows, debris avalanches and lahars). The volcanic rocks are located in five main belts or ranges: Sierra Nevada, Sierra de las Cruces, Sierra Guadalupe, Sierra de Santa Catarina, and the Chichinautzin Volcanic Field which surround the Mexico Basin and belong to the Trans-Mexican Volcanic Belt, preserving approx. 14 Ma of geologic history. Much attention has been devoted to the youngest of the volcanoes such as Popocatépetl in the Sierra Nevada which resumed activity in 1994-present and Chichinautzin which includes the 1600 year bp Xitle volcano. Surprisingly, the pre-Holocene history is not well constrained in the Mexico City area, due of the lack of detailed mapping coupled with high precision geochronology. Our new 40Ar/39Ar and petrologic data and detailed mapping focus on the earliest history of these volcanic systems and their temporal, spatial and geochemical evolution. For example, data from Tlaloc and Telapón volcanoes in the Sierra Nevada show at least two significant periods of edifice building (1.0 to 1.5 Ma and 0 to 400 ka) with an apparent long period of quiescence that clearly suggests that volcanism in the region did not migrate from north to south but that it has a more complex evolution that continues to pose a serious threat to the population of Mexico City. In addition, a 450 ka age, based on dome and pumice dating, constrains the timing of a major sector collapse of Iztaccíhuatl volcano that produced a Mt. St. Helens - sized debris avalanche deposit towards the present metropolitan area of the City of Puebla. In the Sierra de las Cruces Range, volcanic centers do show a north-south age progression from ~5 Ma, cumulating with the Zempoala edifice collapse approximately 900 ka, producing lahars and block and ash

  10. Variabilidad de cepas de Hirsutella thompsonii, a partir de ácaros fitófagos en tres sistemas terrestres del estado de Colima, México Variability of Hirsutella thompsonii strains, isolated from phytophagous mites from three terrestrial systems in the State of Colima, México

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    José Luis Rosas-Acevedo


    Full Text Available Entre 1999 y 2004 se obtuvieron diez cepas del hongo Hirsutella thompsonii Fisher, a partir de ácaros infectados, en 9 localidades de 3 de los 11 sistemas terrestres que tiene el estado de Colima, México: Llanura Costera de Tecomán, Llanura Costera de Cuyutlán y Valle del río Armería. De las 10 cepas, 5 pertenecen a la variedad thompsonii que es de crecimiento micelial mullido, ligeramente elevado, de color gris a gris verdoso, y 5 a la variedad sinematosa Samson, McCoy y O'Donnell, de apariencia plana y coloración blanco a amarillo. Los hospedantes fueron araña roja (Tetranychus urticae Koch, eriófidos (Aceria guerreronis Keifer y Phyllocoptruta oleivora Ashmead y brevipálpidos (Brevipalpus phoenicis Geijkes sobre cítricos como hospedero de 8 de los 10 aislamientos. De ellos, sólo la cepa HtM130 de H. thompsonii var. thompsonii presentó formación de exudados en la fase esporulativa, característica que le da mayor potencial de manejo en estrategias para el control de ácaros fitopatógenos. El tipo de crecimiento y la coloración de las cepas no se correlacionan con el sistema terrestre donde se encontraron, ni con las condiciones climáticas imperantes en ellos. La presente contribución demuestra la importancia de valorar la presencia de enemigos naturales autóctonos para garantizar un mejor establecimiento bajo las condiciones agroclimáticas de la región donde se pretenda utilizarlos, y antes de introducir microorganismos comerciales o aislamientos de otros sitios para no afectar los sistemas naturales de regulación.Between 1999 and 2004, ten strains of the fungus Hirsutella thompsonii Fisher were isolated from infected acari, in 9 localities of 3 of the 11 terrestrial systems found in the state of Colima, Mexico: Coastal Plain of Tecomán, Coastal Plain of Cuyutlán and Valley of the Armería river. Of the 10 strains, 5 belong to var. thompsonii, whose growth is fluffed mycelial, slightly tall, gray to greenish gray, and 5

  11. A new way to detect volcanic plumes (United States)

    Larson, Kristine M.


    of volcanic plumes, especially ash-laden ones, is important both for public health and aircraft safety. A variety of geophysical tools and satellite data are used to monitor volcanic eruptions and to predict the movement of ash. However, satellite-based methods are restricted by time of day and weather, while radars are often unavailable because of cost/portability. Here a method is proposed to detect volcanic plumes using GPS signal strength data. The strengths and limitations of the method are assessed using GPS data collected during the 2008 and 2009 eruptions of the Okmok and Mt. Redoubt volcanoes. Plume detections using this GPS technique are consistent with independently collected seismic and radar data.

  12. Ozone depletion following future volcanic eruptions (United States)

    Eric Klobas, J.; Wilmouth, David M.; Weisenstein, Debra K.; Anderson, James G.; Salawitch, Ross J.


    While explosive volcanic eruptions cause ozone loss in the current atmosphere due to an enhancement in the availability of reactive chlorine following the stratospheric injection of sulfur, future eruptions are expected to increase total column ozone as halogen loading approaches preindustrial levels. The timing of this shift in the impact of major volcanic eruptions on the thickness of the ozone layer is poorly known. Modeling four possible climate futures, we show that scenarios with the smallest increase in greenhouse gas concentrations lead to the greatest risk to ozone from heterogeneous chemical processing following future eruptions. We also show that the presence in the stratosphere of bromine from natural, very short-lived biogenic compounds is critically important for determining whether future eruptions will lead to ozone depletion. If volcanic eruptions inject hydrogen halides into the stratosphere, an effect not considered in current ozone assessments, potentially profound reductions in column ozone would result.

  13. Constraining volcanic inflation at Three Sisters Volcanic Field in Oregon, USA, through microgravity and deformation modeling (United States)

    Zurek, Jeffrey; William-Jones, Glyn; Johnson, Dan; Eggers, Al


    Microgravity data were collected between 2002 and 2009 at the Three Sisters Volcanic Complex, Oregon, to investigate the causes of an ongoing deformation event west of South Sister volcano. Three different conceptual models have been proposed as the causal mechanism for the deformation event: (1) hydraulic uplift due to continual injection of magma at depth, (2) pressurization of hydrothermal systems and (3) viscoelastic response to an initial pressurization at depth. The gravitational effect of continual magma injection was modeled to be 20 to 33 μGal at the center of the deformation field with volumes based on previous deformation studies. The gravity time series, however, did not detect a mass increase suggesting that a viscoelactic response of the crust is the most likely cause for the deformation from 2002 to 2009. The crust, deeper than 3 km, in the Three Sisters region was modeled as a Maxwell viscoelastic material and the results suggest a dynamic viscosity between 1018 to 5 × 1019 Pa s. This low crustal viscosity suggests that magma emplacement or stall depth is controlled by density and not the brittle ductile transition zone. Furthermore, these crustal properties and the observed geochemical composition gaps at Three Sisters can be best explained by different melt sources and limited magma mixing rather than fractional crystallization. More generally, low intrusion rates, low crustal viscosity, and multiple melt sources could also explain the whole rock compositional gaps observed at other arc volcanoes.

  14. Tropical Volcanic Soils From Flores Island, Indonesia

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    Full Text Available Soils that are developed intropical region with volcanic parent materials have many unique properties, and high potential for agricultural use.The purpose of this study is to characterize the soils developed on volcanic materials from Flores Island, Indonesia,and to examine if the soils meet the requirements for andic soil properties. Selected five soils profiles developed fromandesitic volcanic materials from Flores Island were studied to determine their properties. They were compared intheir physical, chemical and mineralogical characteristics according to their parent material, and climatic characteristicdifferent. The soils were developed under humid tropical climate with ustic to udic soil moisture regimes withdifferent annual rainfall. The soils developed from volcanic ash parent materials in Flores Island showed differentproperties compared to the soils derived from volcanic tuff, even though they were developed from the sameintermediary volcanic materials. The silica contents, clay mineralogy and sand fractions, were shown as the differences.The different in climatic conditions developed similar properties such as deep solum, dark color, medium texture, andvery friable soil consistency. The soils have high organic materials, slightly acid to acid, low to medium cationexchange capacity (CEC. The soils in western region have higher clay content and showing more developed than ofthe eastern region. All the profiles meet the requirements for andic soil properties, and classified as Andisols order.The composition of sand mineral was dominated by hornblende, augite, and hypersthenes with high weatherablemineral reserves, while the clay fraction was dominated by disordered kaolinite, and hydrated halloysite. The soilswere classified into subgroup as Thaptic Hapludands, Typic Hapludands, and Dystric Haplustands

  15. Volcanic air pollution hazards in Hawaii (United States)

    Elias, Tamar; Sutton, A. Jeff


    Noxious sulfur dioxide gas and other air pollutants emitted from Kīlauea Volcano on the Island of Hawai‘i react with oxygen, atmospheric moisture, and sunlight to produce volcanic smog (vog) and acid rain. Vog can negatively affect human health and agriculture, and acid rain can contaminate household water supplies by leaching metals from building and plumbing materials in rooftop rainwater-catchment systems. U.S. Geological Survey scientists, along with health professionals and local government officials are working together to better understand volcanic air pollution and to enhance public awareness of this hazard.

  16. Tellurium in active volcanic environments: Preliminary results (United States)

    Milazzo, Silvia; Calabrese, Sergio; D'Alessandro, Walter; Brusca, Lorenzo; Bellomo, Sergio; Parello, Francesco


    Tellurium is a toxic metalloid and, according to the Goldschmidt classification, a chalcophile element. In the last years its commercial importance has considerably increased because of its wide use in solar cells, thermoelectric and electronic devices of the last generation. Despite such large use, scientific knowledge about volcanogenic tellurium is very poor. Few previous authors report result of tellurium concentrations in volcanic plume, among with other trace metals. They recognize this element as volatile, concluding that volcanic gases and sulfur deposits are usually enriched with tellurium. Here, we present some results on tellurium concentrations in volcanic emissions (plume, fumaroles, ash leachates) and in environmental matrices (soils and plants) affected by volcanic emissions and/or deposition. Samples were collected at Etna and Vulcano (Italy), Turrialba (Costa Rica), Miyakejima, Aso, Asama (Japan), Mutnovsky (Kamchatka) at the crater rims by using common filtration techniques for aerosols (polytetrafluoroethylene filters). Filters were both eluted with Millipore water and acid microwave digested, and analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Volcanic ashes emitted during explosive events on Etna and Copahue (Argentina) were analyzed for tellurium bulk composition and after leaching experiments to evaluate the soluble fraction of tellurium. Soils and leaves of vegetation were also sampled close to active volcanic vents (Etna, Vulcano, Nisyros, Nyiragongo, Turrialba, Gorely and Masaya) and investigated for tellurium contents. Preliminary results showed very high enrichments of tellurium in volcanic emissions comparing with other volatile elements like mercury, arsenic, thallium and bismuth. This suggests a primary transport in the volatile phase, probably in gaseous form (as also suggested by recent studies) and/or as soluble salts (halides and/or sulfates) adsorbed on the surface of particulate particles and ashes. First

  17. Volcanic Pipe of the Namuaiv Mountain

    Directory of Open Access Journals (Sweden)

    Vladimir K. Karzhavin


    Full Text Available This research was aimed at reconstructing thermodynamic conditions required for the studied mineral assemblages to be created and exist in nature. The results of the investigations confirm to the recent ideas about an important, even leading, role of temperature, pressure and dioxide carbon in diamond formation in volcanic pipers. The results of this theoretical research allows assuming that one of the reasons for the absence of diamonds in the Namuaiv Mountain volcanic pipe may lie in the increased content of water and oxidizing environmental conditions of their formation

  18. Assessing Volcanic Risk in Saudi Arabia (United States)

    Lindsay, Jan Marie; Rashad Moufti, Mohammed


    The Kingdom of Saudi Arabia has numerous large monogenetic volcanic fields, known locally as "harrats." The largest of these, Harrat Rahat (Figure 1), produced a basaltic fissure eruption in 1256 C.E. with lava flows traveling within 20 kilometers of the city Al-Madinah, which currently has a population of 1.5 million plus an additional 3 million pilgrims annually. With more than 950 visible vents and periodic seismic swarms, an understanding of the risk of future eruptions in this volcanic field is vital.

  19. Emplacement Scenarios for Volcanic Domes on Venus (United States)

    Glaze, Lori S.; Baloga, Steve M.; Stofan, Ellen R.


    One key to understanding the history of resurfacing on Venus is better constraints on the emplacement timescales for the range of volcanic features visible on the surface. A figure shows a Magellan radar image and topography for a putative lava dome on Venus. 175 such domes have been identified with diameters ranging from 19 - 94 km, and estimated thicknesses as great as 4 km. These domes are thought to be volcanic in origin and to have formed by the flow of viscous fluid (i.e., lava) on the surface.

  20. AVAL - The ASTER Volcanic Ash Library (United States)

    Williams, D.; Ramsey, M. S.


    Volcanic ash is a rich data source for understanding the causal mechanisms behind volcanic eruptions. Petrologic and morphometric information can provide direct information on the characteristics of the parent magma. Understanding how erupted ash interacts with the atmosphere can help quantify the effect that explosive volcanism has on the local to regional climate, whereas a measure of the particle size distribution enables more accurate modeling of plume propagation. Remote sensing is regularly employed to monitor volcanic plumes using a suite of high temporal/low spatial resolution sensors. These methods employ radiative transfer modeling with assumptions of the transmissive properties of infrared energy through the plume to determine ash density, particle size and sulfur dioxide content. However, such approaches are limited to the optically-transparent regions, and the low spatial resolution data are only useful for large-scale trends. In a new approach, we are treating the infrared-opaque regions of the plume in a similar way to a solid emitting surface. This allows high spatial resolution orbital thermal infrared data from the dense proximal plume to be modeled using a linear deconvolution approach coupled with a spectral library to extract the particle size and petrology. The newly created ASTER Volcanic Ash Library (AVAL) provides the end member spectral suite, and is comprised of laboratory emission measurements of volcanic ash taken from a variety of different volcanic settings, to obtain a wide range of petrologies. These samples have been further subdivided into particle size fractions to account for spectral changes due to diffraction effects. Once mapped to the ASTER sensor's spectral resolution, this library is applied to image data and the plume deconvolved to estimate composition and particle size. We have analyzed eruptions at the Soufrière Hills Volcano, Montserrat, Chaitén and Puyehue-Cordón Caulle, both Chile, and Eyjafjallajökull, Iceland





    This thesis is a palaeoenviromnental investigation into possible non-climatic effects on the environment from volcanic ash fall and toxic emissions outside the blast zone of a volcanic eruption. These effects are determined from palynological and geochemical changes following tephra fall at a range of sites across the North Island of New Zealand which were located at increasing distances from the main volcanic source, the Taupo Volcanic Zone. These sites collectively covered a wid...

  2. Multiphase flow modeling and simulation of explosive volcanic eruptions (United States)

    Neri, Augusto

    Recent worldwide volcanic activity, such as eruptions at Mt. St. Helens, Washington, in 1980, Mt. Pinatubo, Philippines, in 1991, as well as the ongoing eruption at Montserrat, West Indies, highlighted again the complex nature of explosive volcanic eruptions as well as the tremendous risk associated to them. In the year 2000, about 500 million people are expected to live under the shadow of an active volcano. The understanding of pyroclastic dispersion processes produced by explosive eruptions is, therefore, of primary interest, not only from the scientific point of view, but also for the huge worldwide risk associated with them. The thesis deals with an interdisciplinary research aimed at the modeling and simulation of explosive volcanic eruptions by using multiphase thermo-fluid-dynamic models. The first part of the work was dedicated to the understanding and validation of recently developed kinetic theory of two-phase flow. The hydrodynamics of fluid catalytic cracking particles in the IIT riser were simulated and compared with lab experiments. Simulation results confirm the validity of the kinetic theory approach. Transport of solids in the riser is due to dense clusters. On a time-average basis the bottom of the riser and the walls are dense, in agreement with IIT experimental data. The low frequency of oscillation (about 0.2 Hz) is also in agreement with data. The second part of the work was devoted to the development of transient two-dimensional multiphase and multicomponent flow models of pyroclastic dispersion processes. In particular, the dynamics of ground-hugging high-speed and high-temperature pyroclastic flows generated by the collapse of volcanic columns or by impulsive discrete explosions, was investigated. The model accounts for the mechanical and thermal non-equilibrium between a multicomponent gas phase and N different solid phases representative of pyroclastic particles of different sizes. Pyroclastic dispersion dynamics describes the formation

  3. Compositional Differences between Felsic Volcanic rocks from the ...

    African Journals Online (AJOL)

    Pliocene felsic rift margin and Quaternary rift center volcanic rocks from the northern Main Ethiopian Rift (MER) exhibit contrasts in major and trace element contents and Sr-Nd isotopic ratios. Quaternary rift center felsic volcanic rocks are mainly peralkaline trachytes and rhyolites, whereas Pliocene felsic rift margin volcanic ...

  4. Improving volcanic ash forecasts with ensemble-based data assimilation

    NARCIS (Netherlands)

    Fu, Guangliang


    The 2010 Eyjafjallajökull volcano eruption had serious consequences to civil aviation. This has initiated a lot of research on volcanic ash forecasting in recent years. For forecasting the volcanic ash transport after eruption onset, a volcanic ash transport and diffusion model (VATDM) needs to be

  5. Deccan volcanism, the KT mass extinction and dinosaurs

    Indian Academy of Sciences (India)


    Oct 29, 2009 ... Recent advances in Deccan volcanic studies indicate three volcanic phases with the phase-1 at 67.5 Ma followed by a 2 m.y. period of quiescence. Phase-2 marks the main Deccan volcanic eruptions in Chron 29r near the end of the Maastrichtian and accounts for ∼80% of the entire 3500 m thick Deccan ...

  6. Implications of volcanic erratics in Quaternary deposits of North Greenland

    DEFF Research Database (Denmark)

    Funder, Svend Visby; Larsen, Ole


    Erratic boulders, petrographically similar to the volcanics exposed around Kap Washington, are found on islands and along the coast much further to the east. Isotopic measurements on two such boulders show that these volcanic rocks are of the same age as the Kap Washington volcanics. The regional...

  7. The Elusive Evidence of Volcanic Lightning. (United States)

    Genareau, K; Gharghabi, P; Gafford, J; Mazzola, M


    Lightning strikes are known to morphologically alter and chemically reduce geologic formations and deposits, forming fulgurites. A similar process occurs as the result of volcanic lightning discharge, when airborne volcanic ash is transformed into lightning-induced volcanic spherules (LIVS). Here, we adapt the calculations used in previous studies of lightning-induced damage to infrastructure materials to determine the effects on pseudo-ash samples of simplified composition. Using laboratory high-current impulse experiments, this research shows that within the lightning discharge channel there is an ideal melting zone that represents roughly 10% or less of the total channel radius at which temperatures are sufficient to melt the ash, regardless of peak current. The melted ash is simultaneously expelled from the channel by the heated, expanding air, permitting particles to cool during atmospheric transport before coming to rest in ash fall deposits. The limited size of this ideal melting zone explains the low number of LIVS typically observed in volcanic ash despite the frequent occurrence of lightning during explosive eruptions.

  8. Amazonian volcanism inside Valles Marineris on Mars

    Czech Academy of Sciences Publication Activity Database

    Brož, Petr; Hauber, E.; Wray, J. J.; Michael, G.


    Roč. 473, September (2017), s. 122-130 ISSN 0012-821X Institutional support: RVO:67985530 Keywords : Mars * Valles Marineris * volcanism * scoria cone * hydrothermal activity Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 4.409, year: 2016

  9. Geochemistry and petrogenesis of anorogenic basic volcanic ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    anorogenic setting for the basic rocks of Kundal area is suggested, which is in conformity with the similar setting for Malani Igneous Suite. 1. Introduction. The Malani magmatism is characterized by sub- volcanic setting, volcano-plutonic ring structures, anorogenic (A-type), high heat producing magma- tism and controlled by ...

  10. Assessing quality in volcanic ash soils (United States)

    Terry L. Craigg; Steven W. Howes


    Forest managers must understand how changes in soil quality resulting from project implementation affect long-term productivity and watershed health. Volcanic ash soils have unique properties that affect their quality and function; and which may warrant soil quality standards and assessment techniques that are different from other soils. We discuss the concept of soil...

  11. Halogen Chemistry in Volcanic Plumes (Invited) (United States)

    Roberts, Tjarda


    Volcanoes release vast amounts of gases and particles in the atmosphere. Volcanic halogens (HF, HCl, HBr, HI) are co-emitted alongside SO2, and observations show rapid formation of BrO and OClO in the plume as it disperses into the troposphere. The development of 1D and Box models (e.g. PlumeChem) that simulate volcanic plume halogen chemistry aims to characterise how volcanic reactive halogens form and quantify their atmospheric impacts. Following recent advances, these models can broadly reproduce the observed downwind BrO/SO2 ratios using "bromine-explosion" chemistry schemes, provided they use a "high-temperature initialisation" to inject radicals (OH, Cl, Br and possibly NOx) which "kick-start" the low-temperature chemistry cycles that convert HBr into reactive bromine (initially as Br2). The modelled rise in BrO/SO2 and subsequent plateau/decline as the plume disperses downwind reflects cycling between reactive bromine, particularly Br-BrO, and BrO-HOBr-BrONO2. BrCl is produced when aerosol becomes HBr-depleted. Recent model simulations suggest this mechanism for reactive chlorine formation can broadly account for OClO/SO2 reported at Mt Etna. Predicted impacts of volcanic reactive halogen chemistry include the formation of HNO3 from NOx and depletion of ozone. This concurs with HNO3 widely reported in volcanic plumes (although the source of NOx remains under question), as well as observations of ozone depletion reported in plumes from several volcanoes (Mt Redoubt, Mt Etna, Eyjafjallajokull). The plume chemistry can transform mercury into more easily deposited and potentially toxic forms, for which observations are limited. Recent incorporation of volcanic halogen chemistry in a 3D regional model of degassing from Ambrym (Vanuatu) also predicts how halogen chemistry causes depletion of OH to lengthen the SO2 lifetime, and highlights the potential for halogen transport from the troposphere to the stratosphere. However, the model parameter-space is vast and

  12. MED SUV TASK 6.3 Capacity building and interaction with decision makers: Improving volcanic risk communication through volcanic hazard tools evaluation, Campi Flegrei Caldera case study (Italy) (United States)

    Nave, Rosella; Isaia, Roberto; Sandri, Laura; Cristiani, Chiara


    In the communication chain between scientists and decision makers (end users), scientific outputs, as maps, are a fundamental source of information on hazards zoning and the related at risk areas definition. Anyway the relationship between volcanic phenomena, their probability and potential impact can be complex and the geospatial information not easily decoded or understood by not experts even if decision makers. Focusing on volcanic hazard the goal of MED SUV WP6 Task 3 is to improve the communication efficacy of scientific outputs, to contribute in filling the gap between scientists and decision-makers. Campi Flegrei caldera, in Neapolitan area has been chosen as the pilot research area where to apply an evaluation/validation procedure to provide a robust evaluation of the volcanic maps and its validation resulting from end users response. The selected sample involved are decision makers and officials from Campanian Region Civil Protection and municipalities included in Campi Flegrei RED ZONE, the area exposed to risk from to pyroclastic currents hazard. Semi-structured interviews, with a sample of decision makers and civil protection officials have been conducted to acquire both quantitative and qualitative data. The tested maps have been: the official Campi Flegrei Caldera RED ZONE map, three maps produced by overlapping the Red Zone limit on Orthophoto, DTM and Contour map, as well as other maps included a probabilistic one, showing volcanological data used to border the Red Zone. The outcomes' analysis have assessed level of respondents' understanding of content as displayed, and their needs in representing the complex information embedded in volcanic hazard. The final output has been the development of a leaflet as "guidelines" that can support decision makers and officials in understanding volcanic hazard and risk maps, and also in using them as a communication tool in information program for the population at risk. The same evaluation /validation process

  13. International Database of Volcanic Ash Impacts (United States)

    Wallace, K.; Cameron, C.; Wilson, T. M.; Jenkins, S.; Brown, S.; Leonard, G.; Deligne, N.; Stewart, C.


    Volcanic ash creates extensive impacts to people and property, yet we lack a global ash impacts catalog to organize, distribute, and archive this important information. Critical impact information is often stored in ephemeral news articles or other isolated resources, which cannot be queried or located easily. A global ash impacts database would improve 1) warning messages, 2) public and lifeline emergency preparation, and 3) eruption response and recovery. Ashfall can have varying consequences, such as disabling critical lifeline infrastructure (e.g. electrical generation and transmission, water supplies, telecommunications, aircraft and airports) or merely creating limited and expensive inconvenience to local communities. Impacts to the aviation sector can be a far-reaching global issue. The international volcanic ash impacts community formed a committee to develop a database to catalog the impacts of volcanic ash. We identify three user populations for this database: 1) research teams, who would use the database to assist in systematic collection, recording, and storage of ash impact data, and to prioritize impact assessment trips and lab experiments 2) volcanic risk assessment scientists who rely on impact data for assessments (especially vulnerability/fragility assessments); a complete dataset would have utility for global, regional, national and local scale risk assessments, and 3) citizen science volcanic hazard reporting. Publication of an international ash impacts database will encourage standardization and development of best practices for collecting and reporting impact information. Data entered will be highly categorized, searchable, and open source. Systematic cataloging of impact data will allow users to query the data and extract valuable information to aid in the development of improved emergency preparedness, response and recovery measures.

  14. Cooling Rates of Lunar Volcanic Glass Beads (United States)

    Hui, Hejiu; Hess, Kai-Uwe; Zhang, Youxue; Peslier, Anne; Lange, Rebecca; Dingwell, Donald; Neal, Clive


    It is widely accepted that the Apollo 15 green and Apollo 17 orange glass beads are of volcanic origin. The diffusion profiles of volatiles in these glass beads are believed to be due to degassing during eruption (Saal et al., 2008). The degree of degassing depends on the initial temperature and cooling rate. Therefore, the estimations of volatiles in parental magmas of lunar pyroclastic deposits depend on melt cooling rates. Furthermore, lunar glass beads may have cooled in volcanic environments on the moon. Therefore, the cooling rates may be used to assess the atmospheric condition in an early moon, when volcanic activities were common. The cooling rates of glasses can be inferred from direct heat capacity measurements on the glasses themselves (Wilding et al., 1995, 1996a,b). This method does not require knowledge of glass cooling environments and has been applied to calculate the cooling rates of natural silicate glasses formed in different terrestrial environments. We have carried out heat capacity measurements on hand-picked lunar glass beads using a Netzsch DSC 404C Pegasus differential scanning calorimeter at University of Munich. Our preliminary results suggest that the cooling rate of Apollo 17 orange glass beads may be 12 K/min, based on the correlation between temperature of the heat capacity curve peak in the glass transition range and glass cooling rate. The results imply that the parental magmas of lunar pyroclastic deposits may have contained more water initially than the early estimations (Saal et al., 2008), which used higher cooling rates, 60-180 K/min in the modeling. Furthermore, lunar volcanic glass beads could have been cooled in a hot gaseous medium released from volcanic eruptions, not during free flight. Therefore, our results may shed light on atmospheric condition in an early moon.

  15. U–Pb geochronology and geochemistry of late Palaeozoic volcanism in Sardinia (southern Variscides

    Directory of Open Access Journals (Sweden)

    L. Gaggero


    Full Text Available The latest Carboniferous to lower Permian volcanism of the southern Variscides in Sardinia developed in a regional continental transpressive and subsequent transtensile tectonic regime. Volcanism produced a wide range of intermediate–silicic magmas including medium- to high-K calc-alkaline andesites, dacites, and rhyolites. A thick late Palaeozoic succession is well exposed in the four most representative Sardinian continental basins (Nurra, Perdasdefogu, Escalaplano, and Seui–Seulo, and contains substantial stratigraphic, geochemical, and geochronological evidence of the area's complex geological evolution from the latest Carboniferous to the beginning of the Triassic. Based on major and trace element data and LA-ICP-MS U–Pb zircon dating, it is possible to reconstruct the timing of post-Variscan volcanism. This volcanism records active tectonism between the latest Carboniferous and Permian, and post-dates the unroofing and erosion of nappes in this segment of the southern Variscides. In particular, igneous zircon grains from calc-alkaline silicic volcanic rocks yielded ages between 299 ± 1 and 288 ± 3 Ma, thereby constraining the development of continental strike-slip faulting from south (Escalaplano Basin to north (Nurra Basin. Notably, andesites emplaced in medium-grade metamorphic basement (Mt. Cobingius, Ogliastra show a cluster of older ages at 332 ± 12 Ma. Despite the large uncertainty, this age constrains the onset of igneous activity in the mid-crust. These new radiometric ages constitute: (1 a consistent dataset for different volcanic events; (2 a precise chronostratigraphic constraint which fits well with the biostratigraphic data and (3 insights into the plate reorganization between Laurussia and Gondwana during the late Palaeozoic evolution of the Variscan chain.

  16. Geochemistry and geochronology of Hangay Dome volcanic rocks: exploring the source of high topography and volcanism in an intracontinental setting (United States)

    Ancuta, L. D.; Carlson, R. W.; Idleman, B. D.; Zeitler, P. K.


    . Flow stratigraphy clearly shows the presence of substantial paleotopography that has been completely blanketed by flows, and a complex history of incision spanning the duration of volcanism. A plume source for the volcanism unlikely, given the basalt geochemistry, the lack of a large flood basalt province, and the lack of a discernable hot spot track. Large-scale slab-like delamination of the lower lithosphere also seems unlikely given the significant duration and diffuse nature of the magmatic activity. Geodynamic processes consistent with the high topography in the Hangay, the long duration of volcanism, and the sub-lithosphereic EM-1 isotopic signature include shear driven asthenospheric upwelling, thermal blanketing of the asthenosphere by thick crust, several small scale lithospheric drips or a small-scale edge-driven convection cell in the upper mantle.

  17. Genesis of petroduric and petrocalcic horizons in Latinamerica volcanic soils (United States)

    Quantin, Paul


    -arid climate. A complex soil profile of petrocalcic Phaeozem, derived from 4 pyroclastic layers, shows among its successive horizons: in layer 3 the 'upper cangahua' with petrocalcic features and in layer 4 the 'lower cangahua' with hard fragipan properties. The features of the petrocalcic cangahua differ from a Mexican fragipan (Hidalgo & al 1997) by: a hard calcrete, higher alkalinity, stability in water after HCl and NaOH treatment, 2-4% of 'free silica'. The macro and micro-morphology shows: the laminar calcite crust, at the top of cangahua, with alternate micrite-sparite layers; downwards, microcalcite infillings in the voids of a prismatic structure, invading the groundmass by epigenesis of clay sheets, together whith microcrystalline opal. From these data this scenario is inferred: after a former weathering of volcanic glass to form a clayey matrix, as well amorphous silica and microcalcite coatings and infillings, then a second process, perhaps due to drier climate, produced the laminar crust formation, by invasion of microcalcite in the matrix. Conclusion. The petrocalcic horizon in Ecuador was produced by two processes: from a former phase of weathering giving a fragic horizon to a second producing the accumulation of calcite and some opal over and inside the matrix, due to climate change. The petroduric horizon in Mexico, is the product of a very complex soil transformation, from a former clayey Nitisol, through four successive processes: clay eluviation-illuviation, alternate redoximorphy, clay degradation, finally a progressive silicification over and inside the groundmass, probably due to pedoclimate change. References F. Elsass, D. Dubroeucq & M. Thiry. 2000. Clay Minerals, 35, 477-489. C. Hidalgo, P. Quantin & F. Elsass. 1997. Memorias del III Simposio Internacional sobre Suelos volcanicos endurecidos (Quito 1996), p. 65-72. - P. Quantin & C. Zebrowski. 1997. idem, p. 29-47.- J.P. Rossignol & P. Quantin. 1997. idem, p. 73-82.

  18. Using Spatial Density to Characterize Volcanic Fields on Mars (United States)

    Richardson, J. A.; Bleacher, J. E.; Connor, C. B.; Connor, L. J.


    We introduce a new tool to planetary geology for quantifying the spatial arrangement of vent fields and volcanic provinces using non parametric kernel density estimation. Unlike parametricmethods where spatial density, and thus the spatial arrangement of volcanic vents, is simplified to fit a standard statistical distribution, non parametric methods offer more objective and data driven techniques to characterize volcanic vent fields. This method is applied to Syria Planum volcanic vent catalog data as well as catalog data for a vent field south of Pavonis Mons. The spatial densities are compared to terrestrial volcanic fields.

  19. Volcanic geomorphosites and geotourism in Las Cañadas del Teide National Park, Tenerife, Canary Islands, Spain (United States)

    Dóniz-Paéz, Javier; Becerra-Ramírez, Rafael; González-Cárdenas, Elena; Rodriguez, Fátima


    Geomorphosites and geoturism studies are increasing for the high scientific, societal, cultural, and aesthetic values of the relief. Volcanic areas are exciting targets for such studies for their geodiversity. The aim of these study is an inventory of volcanic geomorphosites and its relationship to geotourism. Las Cañadas del Teide National Park (LCTNP) is a volcanic complex area located in the central part of Tenerife island (Canary Islands, Spain). This area is a volcanic paradise rich in spectacular landforms: stratovolcanoes, calderas, cinder cones, craters, pahoehoe, aa, block and balls lavas, gullies, etc. The national park is registered in the world heritage list (UNESCO) in 2007 as a natural site. The LCTNP receives more than 2,5 million tourists per year and it has 21 main pahts and 14 secondary ones. For the selection of the geomophosites the LCTNP was divided into four geomorphological units (Teide-Pico Viejo stratovolcanoes, Las Cañadas Caldera wall, the bottom of Las Cañadas and the basaltic volcanic field) and each one of them is selected the most representative geomorphosites by its geodiversity, because of its geomorphological heritage, its landscapes and its tourist potential with the paths. All selected geomorphosites are within areas where public use is allowed in the park. The inventory classifies the 23 geomorphosites in two main categories: (a) direct volcanic with 17 geomorphosites (stratovolcanoes, domes, cinder cones, pahoehoe, aa and bloc lava flows, etc.) and (b) eroded volcanic landforms with 6 (wall of Las Cañadas caldera, talusees, foodplains, etc.). The Teide-Pico Viejo unit is which has more geomorphosites with 8 and the Las Cañadas wall unit possessing less with 5. The assessment evaluates the scientific, cultural/historical, and use values and helps to define priorities in site management. These geomorphosites demonstrate the volcanic history and processes of the LCTNP.

  20. Insight of the fusion behavior of volcanic ash: Implications for Volcanic ash Hazards to Aircraft Safety (United States)

    Song, Wenjia; Hess, Kai-Uwe; Küppers, Ulrich; Scheu, Bettina; Cimarelli, Corrado; Lavallée, Yan; Sohyun, Park; Gattermann, Ulf; Müller, Dirk; Dingwell, Donald Bruce


    The interaction of volcanic ash with jet turbines during via ingestion of ash into engines operating at supra-volcanic temperatures is widely recognized as a potentially fatal hazard for jet aircraft. In the past 12 years, more than 60 modern jet airplanes, mostly jumbo jets, have been damaged by drifting clouds of volcanic ash that have contaminated air routes and airport facilities. Seven of these encounters are known to have caused in flight loss of engine power to jumbo jets carrying a total of more than 2000 passengers. The fusibility of volcanic ash is believed to impact strongly its deposition in the hotter parts of jet engines. Despite this, explicit investigation of ash sintering using standardized techniques is in its infancy. Volcanic ash may vary widely in its physical state and chemical composition between and even within explosive volcanic eruptions. Thus a comparative study of the fusibility of ash which involves a standard recognized techniques would be highly desirable. In this work, nine samples of fine ash, deposited from co-pyroclastic offrom nine different volcanoes which cover a broad range of chemical composition, were investigated. Eight of them were collected from 2001-2009 eruptions. Because of the currently elevated level of eruptive activity and its potential hazards to aircraft safety and the remaining one sample was collected from a 12,121 ± 114 yr B.P. eruption. We used the method of accessing the behavior of deposit-forming impurities in high temperature boiler plants on the basis of observations of the change in shape and size of a cylindrical coal ash to study the fusion phenomena as well as determine the volcanic ash melting behavior by defining four characteristic temperatures (shrinkage temperature, deformation temperature, hemispherical temperature, and flow temperature) by means of heating microscope instrument and different thermal analysis methods. Here, we find that there are similar sticking ability and flow behavior of

  1. Magma chamber processes in central volcanic systems of Iceland

    DEFF Research Database (Denmark)

    Þórarinsson, Sigurjón Böðvar; Tegner, Christian


    New field work and petrological investigations of the largest gabbro outcrop in Iceland, the Hvalnesfjall gabbro of the 6-7 Ma Austurhorn intrusive complex, have established a stratigraphic sequence exceeding 800 m composed of at least 8 macrorhythmic units. The bases of the macrorhythmic units...... olivine basalts from Iceland that had undergone about 20% crystallisation of olivine, plagioclase and clinopyroxene and that the macrorhythmic units formed from thin magma layers not exceeding 200-300 m. Such a "mushy" magma chamber is akin to volcanic plumbing systems in settings of high magma supply...... rate including the mid-ocean ridges and present-day magma chambers over the Iceland mantle plume. The Austurhorn central volcano likely formed in an off-rift flank zone proximal to the Iceland mantle plume during a major rift relocation....

  2. Frictional melting dynamics in the upper conduit: A chemical answer to a complex physical question (United States)

    Henton De Angelis, S.; Lavallee, Y.; Kendrick, J. E.; Hornby, A.; von Aulock, F. W.; Clesham, S.; Hirose, T.; Perugini, D.


    During volcanic eruptions the generation of frictional heat along the walls of the shallow conduit leads to melting of the rocks along the slip interface. Frictional melting has previously been described as a process out of thermodynamic equilibrium, but upon slip and mingling of the melt batches, homogeneity can be achieved, and may have an h important rheological control on the dynamics of slip. To test melt homogenization in the frictional melt zones of volcanic conduits we performed constant-rate slip experiments under controlled stress conditions using a high-velocity rotary shear apparatus. Volcanic dome samples from three different volcanoes (Volcán De Colima, Soufrière Hills Volcano and Santiaguito Volcano) were investigated. Each sample was subjected to a stress of 1 MPa and slip rate of 1 m/s. For each sample set 5 experiments were conducted: 1) experiment stopped at the onset of melting; 2) experiment stopped on the formation of a full melt layer; 3) experiment stopped after 5m of slip at steady state conditions; 4) experiment stopped after 10m of slip at steady state conditions; 5) experiment stopped after 15m of slip at steady state conditions. We analyzed the resulting proto-melt zones using micron sized X-ray spectroscopy in the high-brightness synchrotron beamline I18 (at Diamond Light Source UK). Particular focus was given to the concentration variance analysis of Rare Earth Elements as their mobilities can be used to precisely quantify the degree and timescale of homogenisation involved during frictional melting. This study refines our understanding of the chemical process of melting and mixing which carry important consequences for the rheological control on the physical dynamics of slip.

  3. In-flight dynamics of volcanic ballistic projectiles (United States)

    Taddeucci, J.; Alatorre-Ibargüengoitia, M. A.; Cruz-Vázquez, O.; Del Bello, E.; Scarlato, P.; Ricci, T.


    Centimeter to meter-sized volcanic ballistic projectiles from explosive eruptions jeopardize people and properties kilometers from the volcano, but they also provide information about the past eruptions. Traditionally, projectile trajectory is modeled using simplified ballistic theory, accounting for gravity and drag forces only and assuming simply shaped projectiles free moving through air. Recently, collisions between projectiles and interactions with plumes are starting to be considered. Besides theory, experimental studies and field mapping have so far dominated volcanic projectile research, with only limited observations. High-speed, high-definition imaging now offers a new spatial and temporal scale of observation that we use to illuminate projectile dynamics. In-flight collisions commonly affect the size, shape, trajectory, and rotation of projectiles according to both projectile nature (ductile bomb versus brittle block) and the location and timing of collisions. These, in turn, are controlled by ejection pulses occurring at the vent. In-flight tearing and fragmentation characterize large bombs, which often break on landing, both factors concurring to decrease the average grain size of the resulting deposits. Complex rotation and spinning are ubiquitous features of projectiles, and the related Magnus effect may deviate projectile trajectory by tens of degrees. A new relationship is derived, linking projectile velocity and size with the size of the resulting impact crater. Finally, apparent drag coefficient values, obtained for selected projectiles, mostly range from 1 to 7, higher than expected, reflecting complex projectile dynamics. These new perspectives will impact projectile hazard mitigation and the interpretation of projectile deposits from past eruptions, both on Earth and on other planets.

  4. Volcanic field elongation, vent distribution and tectonic evolution of continental rift: The Main Ethiopian Rift example (United States)

    Mazzarini, Francesco; Le Corvec, Nicolas; Isola, Ilaria; Favalli, Massimiliano


    Magmatism and faulting operate in continental rifts and interact at a variety of scales, however their relationship is complex. The African rift, being the best example for both active continental rifting and magmatism, provides the ideal location to study the interplay between the two mechanisms. The Main Ethiopian Rift (MER), which connects the Afar depression in the north with the Turkana depression and Kenya Rift to the south, consists of two distinct systems of normal faults and its floor is scattered with volcanic fields formed by tens to several hundreds monogenetic, generally basaltic, small volcanoes and composite volcanoes and small calderas. The distribution of vents defines the overall shape of the volcanic field. Previous work has shown that the distribution of volcanic vents and the shape of a field are linked to its tectonic environment and its magmatic system. In order to distinguish the impact of each mechanism, we analyzed four volcanic fields located at the boundary between the central and northern MER, three of them (Debre Zeyit, Wonji and Kone) grew in the rift valley and one (Akaki) on the western rift shoulder. The elongation and shape of the fields were analyzed based on their vent distribution using the Principal Component Analysis (PCA), the Vent-to-Vent Distance (VVD), and the two dimensional symmetric Gaussian kernel density estimate methods. We extracted from these methods several parameters characterizing the spatial distribution of points (e.g., eccentricity (e), eigenvector index (evi), angular dispersion (Da)). These parameters allow to define at least three types of shape for volcanic fields: strong elongate (line and ellipse), bimodal/medium elongate (ellipse) and dispersed (circle) shapes. Applied to the natural example, these methods well differentiate each volcanic field. For example, the elongation of the field increases from shoulder to rift axis inversely to the angular dispersion. In addition, the results show that none of

  5. [Effects of volcanic eruptions on human health in Iceland. Review]. (United States)

    Gudmundsson, Gunnar; Larsen, Guðrun


    Volcanic eruptions are common in Iceland and have caused health problems ever since the settlement of Iceland. Here we describe volcanic activity and the effects of volcanic gases and ash on human health in Iceland. Volcanic gases expelled during eruptions can be highly toxic for humans if their concentrations are high, irritating the mucus membranes of the eyes and upper respiratory tract at lower concentrations. They can also be very irritating to the skin. Volcanic ash is also irritating for the mucus membranes of the eyes and upper respiratory tract. The smalles particles of volcanic ash can reach the alveoli of the lungs. Described are four examples of volcanic eruptions that have affected the health of Icelanders. The eruption of Laki volcanic fissure in 1783-1784 is the volcanic eruption that has caused the highest mortality and had the greatest effects on the well-being of Icelanders. Despite multiple volcanic eruptions during the last decades in Iceland mortality has been low and effects on human health have been limited, although studies on longterm effects are lacking. Studies on the effects of the Eyjafjallajökul eruption in 2010 on human health showed increased physical and mental symptoms, especially in those having respiratory disorders. The Directorate of Health in Iceland and other services have responded promptly to recurrent volcanic eruptions over the last few years and given detailed instructions on how to minimize the effects on the public health. Key words: volcanic eruptions, Iceland, volcanic ash, volcanic gases, health effects, mortality. Correspondence: Gunnar Guðmundsson,

  6. Combining probabilistic hazard assessment with cost-benefit analysis to support decision making in a volcanic crisis from the Auckland Volcanic Field, New Zealand (United States)

    Sandri, Laura; Jolly, Gill; Lindsay, Jan; Howe, Tracy; Marzocchi, Warner


    One of the main challenges of modern volcanology is to provide the public with robust and useful information for decision-making in land-use planning and in emergency management. From the scientific point of view, this translates into reliable and quantitative long- and short-term volcanic hazard assessment and eruption forecasting. Because of the complexity in characterizing volcanic events, and of the natural variability of volcanic processes, a probabilistic approach is more suitable than deterministic modeling. In recent years, two probabilistic codes have been developed for quantitative short- and long-term eruption forecasting (BET_EF) and volcanic hazard assessment (BET_VH). Both of them are based on a Bayesian Event Tree, in which volcanic events are seen as a chain of logical steps of increasing detail. At each node of the tree, the probability is computed by taking into account different sources of information, such as geological and volcanological models, past occurrences, expert opinion and numerical modeling of volcanic phenomena. Since it is a Bayesian tool, the output probability is not a single number, but a probability distribution accounting for aleatory and epistemic uncertainty. In this study, we apply BET_VH in order to quantify the long-term volcanic hazard due to base surge invasion in the region around Auckland, New Zealand's most populous city. Here, small basaltic eruptions from monogenetic cones pose a considerable risk to the city in case of phreatomagmatic activity: evidence for base surges are not uncommon in deposits from past events. Currently, we are particularly focussing on the scenario simulated during Exercise Ruaumoko, a national disaster exercise based on the build-up to an eruption in the Auckland Volcanic Field. Based on recent papers by Marzocchi and Woo, we suggest a possible quantitative strategy to link probabilistic scientific output and Boolean decision making. It is based on cost-benefit analysis, in which all costs

  7. A New Way to estimate volcanic hazards and present multi-hazard maps (United States)

    Germa, A.; Connor, C.; Connor, L.; Malservisi, R.


    To understand long term hazards in distributed volcanic systems, we are developing a research framework to relate statistical models of spatial intensity (vents per unit area), volume intensity (erupted volume per unit area) and volume-flux intensity (erupted volume per unit time and area) to conceptual models of the subsurface processes of magma storage and transport. The distribution of mapped vents and volumes erupted from these vents are used to develop nonparametric (kernel density) statistical models for distributed volcanic systems. Using radiometric age determinations of vents and erupted units, we then estimate the recurrence rate of volcanism and associated uncertainty using a Monte Carlo approach. The outputs of Monte Carlo simulation of recurrence rates allow us to produce dynamic statistical maps that reveal the spatio-temporal evolution of volcanic activity within the field studied. To further improve our research framework, we have implemented solutions to differential equations governing magma production and transport to model subsurface processes of magma ascent. This behavior can be statistically approximated by modeling the flow of a viscous fluid within a homogeneous porous medium using Darcy's law with variable conductivity dependent on flow rate and lithospheric stresses (Bonafede and Boschi, 1992; Bonafede and Cenni, 1998). Using this continuous formulation, additional complexities that influence magma migration such as complex sources, magma generation, magma rheology, tectonic stresses, and/or anisotropic/heterogeneous behavior of the porous medium, can be simply implemented by varying the choice of source and conductivity parameters. In this way we can explore physical processes that may give rise to heterogeneous flux in numerical models and relate these outputs to observed vent distributions and volume flux at the surface. Overall, data extracted from our research framework should link statistical models of volcano distribution with the

  8. Sustaining Volcanism of the Klyuchevskoy Group (United States)

    Nikulin, A.; Levin, V. L.; Carr, M. J.; Herzberg, C. T.; West, M. E.


    A primary control on the geographic position of volcanic arcs is the depth of fluid release from the subducting plate beneath the arc. Volcanoes of the Klyuchevskoy Group in Eastern Russia comprise the most active volcanic arc system in the world with the depth of the subducting Pacific plate beneath the arc estimated at 180-200km, greatly in excess of the global average. We attribute this deviation to a presence of a secondary melt generation source beneath this arc and present geophysical, geochemical and petrological evidence in support of this hypothesis. We present seismological constraints based on receiver function migration on the upper mantle structure beneath the Klyuchevskoy Group. We identify a sharply bounded low-velocity seismic feature at ~110 km depth separated from the subducting Pacific Plate. Analysis of open-access geochemical databases yields a previously unnoted bi-modal distribution of Zr/Nb concentrations in the Klyuchevskoy Group lavas. If the Zr/Nb ratio has some sensitivity for the depth to the slab, as it appears to in Central America, the observed bi-modal distribution of Zr/Nb values within lavas of the Klyuchevskoy Group may be associated with two sources, a deep source and a shallower source with higher Zr/Nb. Results of petrological modeling of melting conditions inferred from unfractionated basalt indicate melting pressures consistent with a source at a depth shallower than the estimated depth to the subducting plate. Inferred pressures of initial melting indicate a depth of about 70 to 90 km depth, roughly consistent with the position of the low -velocity seismic anomaly. We hypothesize that this upper mantle structure may serve as a second source of melts driving volcanism of the Klyuchevskoy Group. Presence of such source may explain both the extraordinary productivity of this volcanic arc and its unusual location.

  9. Volcanic disasters and incidents: A new database (United States)

    Witham, C. S.


    A new database on human mortality and morbidity, and civil evacuations arising from volcanic activity is presented. The aim is to quantify the human impacts of volcanic phenomena during the 20th Century. Data include numbers of deaths, injuries, evacuees and people made homeless, and the nature of the associated volcanic phenomena. The database has been compiled from a wide range of sources, and discrepancies between these are indicated where they arise. The quality of the data varies according to the source and the impacts reported. Data for homelessness are particularly poor and effects from ashfall and injuries appear to be under-reported. Of the 491 events included in the database, ˜53% resulted in deaths, although the total death toll of 91,724 is dominated by the disasters at Mt Pelée and Nevado del Ruiz. Pyroclastic density currents account for the largest proportion of deaths, and lahars for the most injuries incurred. The Philippines, Indonesia, and Southeast Asia, as a region, were the worst affected, and middle-income countries experienced greater human impacts than low or high-income countries. Compilation of the database has highlighted a number of problems with the completeness and accuracy of the existing CRED EM-DAT disaster database that includes volcanic events. This database is used by a range of organisations involved with risk management. The new database is intended as a resource for future analysis and will be made available via the Internet. It is hoped that it will be maintained and expanded.

  10. Central San Juan caldera cluster: Regional volcanic framework (United States)

    Lipman, Peter W.


    Eruption of at least 8800 km3 of dacitic-rhyolitic magma as 9 major ash-slow sheets (individually 150-5000 km3) was accompanied by recurrent caldera subsidence between 28.3 and about 26.5 Ma in the central San Juan Mountains, Colorado. Voluminous andesitic-decitic lavas and breccias were erupted from central volcanoes prior to the ash-flow eruptions, and similar lava eruptions continued within and adjacent to the calderas during the period of explosive volcanism, making the central San Juan caldera cluster an exceptional site for study of caldera-related volcanic processes. Exposed calderas vary in size from 10 to 75 km in maximum diameter, the largest calderas being associated with the most voluminous eruptions. After collapse of the giant La Garita caldera during eruption if the Fish Canyon Tuff at 17.6 Ma, seven additional explosive eruptions and calderas formed inside the La Garita depression within about 1 m.y. Because of the nested geometry, maximum loci of recurrently overlapping collapse events are inferred to have subsided as much as 10-17 km, far deeper than the roof of the composite subvolcanic batholith defined by gravity data, which represents solidified caldera-related magma bodies. Erosional dissection to depths of as much as 1.5 km, although insufficient to reach the subvolcanic batholith, has exposed diverse features of intracaldera ash-flow tuff and interleaved caldera-collapse landslide deposits that accumulated to multikilometer thickness within concurrently subsiding caldera structures. The calderas display a variety of postcollapse resurgent uplift structures, and caldera-forming events produced complex fault geometries that localized late mineralization, including the epithermal base- and precious-metal veins of the well-known Creede mining district. Most of the central San Juan calderas have been deeply eroded, and their identification is dependent on detailed geologic mapping. In contrast, the primary volcanic morphology of the

  11. Fracturing Fluid Leak-off for Deep Volcanic Rock in Zhungeer Basin: Mechanism and Control Method

    Directory of Open Access Journals (Sweden)

    Huang Bo


    Full Text Available The deep volcanic reservoir in Zhungeer Basin is buried in over 4000m depth, which is characterized by complex lithology (breccia, andesite, basalt, etc., high elastic modulus and massive natural fractures. During hydraulic fracturing, hydraulic fracture will propagate and natural fractures will be triggered by the increasing net pressure. However, the extension of fractures, especially natural fractures, would aggravate the leak-off effect of fracturing fluid, and consequently decrease the fracturing success rate. 4 out of 12 fracturing wells in the field have failed to add enough proppants due to fluid loss. In order to increase the success rate and efficiency of hydraulic fracturing for deep volcanic reservoir, based on theoretical and experimental method, the mechanism of fracturing fluid leak-off is deeply studied. We propose a dualistic proppant scheme and employ the fluid loss reducer to control the fluid leak-off in macro-fractures and micro-fractures respectively. The proposed technique remarkably improved the success rate in deep volcanic rock fracturing. It bears important theoretical value and practical significance to improve the hydraulic fracturing design for deep volcanic reservoir.

  12. Reference dataset of volcanic ash physicochemical and optical properties for atmospheric measurement retrievals and transport modelling (United States)

    Vogel, Andreas; Durant, Adam; Sytchkova, Anna; Diplas, Spyros; Bonadonna, Costanza; Scarnato, Barbara; Krüger, Kirstin; Kylling, Arve; Kristiansen, Nina; Stohl, Andreas


    Explosive volcanic eruptions emit up to 50 wt.% (total erupted mass) of fine ash particles (quantitative assessment of measurement uncertainties of ash properties to provide realistic ash forecast uncertainty. Currently, information on volcanic ash physicochemical and optical properties is derived from a small number of somewhat dated publications. In this study, we provide a reference dataset for physical (size distribution and shape), chemical (bulk vs. surface chemistry) and optical properties (complex refractive index in the UV-vis-NIR range) of a representative selection of volcanic ash samples from 10 different volcanic eruptions covering the full variability in silica content (40-75 wt.% SiO2). Through the combination of empirical analytical methods (e.g., image analysis, Energy Dispersive Spectroscopy, X-ray Photoelectron Spectroscopy, Transmission Electron Microscopy and UV/Vis/NIR/FTIR Spectroscopy) and theoretical models (e.g., Bruggeman effective medium approach), it was possible to fully capture the natural variability of ash physicochemical and optical characteristics. The dataset will be applied in atmospheric measurement retrievals and atmospheric transport modelling to determine the sensitivity to uncertainty in ash particle characteristics.

  13. Exploratory Data Analysis Using a Dedicated Visualization App: Looking for Patterns in Volcanic Activity (United States)

    van Manen, S. M.; Chen, S.


    Here we present an App designed to visualize and identify patterns in volcanic activity during the last ten years. It visualizes VEI (volcanic explosivity index) levels, population size, frequency of activity, and geographic region, and is designed to address the issue of oversampling of data. Often times, it is difficult to access a large set of data that can be scattered at first glance and hard to digest without visual aid. This App serves as a model that solves this issue and can be applied to other data. To enable users to quickly assess the large data set it breaks down the apparently chaotic abundance of information into categories and graphic indicators: color is used to indicate the VEI level, size for population size within 5 km of a volcano, line thickness for frequency of activity, and a grid to pinpoint a volcano's latitude. The categories and layers within them can be turned on and off by the user, enabling them to scroll through and compare different layers of data. By visualising the data this way, patterns began to emerge. For example, certain geographic regions had more explosive eruptions than others. Another good example was that low frequency larger impact volcanic eruptions occurred more irregularly than smaller impact volcanic eruptions, which had a more stable frequencies. Although these findings are not unexpected, the easy to navigate App does showcase the potential of data visualization for the rapid appraisal of complex and abundant multi-dimensional geoscience data.

  14. Runout of the Socompa volcanic debris avalanche, Chile : a mechanical explanation for low basal shear resistance


    Davies, T.; McSaveney, M.; Kelfoun, Karim


    We propose a mechanical explanation for the low basal shear resistance (about 50 kPa) previously used to simulate successfully the complex, well-documented deposit morphology and lithological distribution produced by emplacement of the 25 km(3) Socompa volcanic debris avalanche deposit, Chile. Stratigraphic evidence for intense basal comminution indicates the occurrence of dynamic rock fragmentation in the basal region of this large granular mass flow, and we show that such fragmentation gene...

  15. Volcanic alert system (VAS) developed during the 2011-2014 El Hierro (Canary Islands) volcanic process (United States)

    García, Alicia; Berrocoso, Manuel; Marrero, José M.; Fernández-Ros, Alberto; Prates, Gonçalo; De la Cruz-Reyna, Servando; Ortiz, Ramón


    The 2011 volcanic unrest at El Hierro Island illustrated the need for a Volcanic Alert System (VAS) specifically designed for the management of volcanic crises developing after long repose periods. The VAS comprises the monitoring network, the software tools for analysis of the monitoring parameters, the Volcanic Activity Level (VAL) management, and the assessment of hazard. The VAS presented here focuses on phenomena related to moderate eruptions, and on potentially destructive volcano-tectonic earthquakes and landslides. We introduce a set of new data analysis tools, aimed to detect data trend changes, as well as spurious signals related to instrumental failure. When data-trend changes and/or malfunctions are detected, a watchdog is triggered, issuing a watch-out warning (WOW) to the Monitoring Scientific Team (MST). The changes in data patterns are then translated by the MST into a VAL that is easy to use and understand by scientists, technicians, and decision-makers. Although the VAS was designed specifically for the unrest episodes at El Hierro, the methodologies may prove useful at other volcanic systems.

  16. UNAVCO Conference explores advances in volcanic geodesy (United States)

    Stein, Seth; Hamburger, Michael; Meertens, Charles; Dixon, Timothy; Owen, Susan

    Volcanic eruptions are among Earth's most spectacular surface phenomena. However, attempts to understand their basic physics face the challenge that the key processes occur at great depth and are difficult to observe. Thus volcanologists have been interested for years in using ground deformation measurements to study active volcanoes and predict their behavior during extended volcanic crises, such as the dramatic six weeks in 1980 between the initial and major eruptions of Mt. Saint Helens.The advent of new technologies in recent years—in particular the Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (INSAR)—has shown potential for significant advances in volcano studies. Progress in this direction was explored at a conference organized by the University Navstar Consortium (UNAVCO) on September 15-17, 1999, with financial support from the National Science Foundation (NSF), NASA, and the U.S. Geological Survey (USGS). The meeting aimed to assess the status of various geodetic technologies and their potential to address crucial scientific and social needs in volcanic science and monitoring, as well as to develop recommendations on ways to spur further progress in these areas.

  17. Amazonian volcanism inside Valles Marineris on Mars (United States)

    Brož, Petr; Hauber, Ernst; Wray, James J.; Michael, Gregory


    The giant trough system of Valles Marineris is one of the most spectacular landforms on Mars, yet its origin is still unclear. Although often referred to as a rift, it also shows some characteristics that are indicative of collapse processes. For decades, one of the major open questions was whether volcanism was active inside the Valles Marineris. Here we present evidence for a volcanic field on the floor of the deepest trough of Valles Marineris, Coprates Chasma. More than 130 individual edifices resemble scoria and tuff cones, and are associated with units that are interpreted as lava flows. Crater counts indicate that the volcanic field was emplaced sometime between ∼0.4 Ga and ∼0.2 Ga. The spatial distribution of the cones displays a control by trough-parallel subsurface structures, suggesting magma ascent in feeder dikes along trough-bounding normal faults. Spectral data reveal an opaline-silica-rich unit associated with at least one of the cones, indicative of hydrothermal processes. Our results point to magma-water interaction, an environment of astrobiological interest, perhaps associated with late-stage activity in the evolution of Valles Marineris, and suggest that the floor of Coprates Chasma is promising target for the in situ exploration of Mars.

  18. Geothermal and volcanism in west Java (United States)

    Setiawan, I.; Indarto, S.; Sudarsono; Fauzi I, A.; Yuliyanti, A.; Lintjewas, L.; Alkausar, A.; Jakah


    Indonesian active volcanoes extend from Sumatra, Jawa, Bali, Lombok, Flores, North Sulawesi, and Halmahera. The volcanic arc hosts 276 volcanoes with 29 GWe of geothermal resources. Considering a wide distribution of geothermal potency, geothermal research is very important to be carried out especially to tackle high energy demand in Indonesia as an alternative energy sources aside from fossil fuel. Geothermal potency associated with volcanoes-hosted in West Java can be found in the West Java segment of Sunda Arc that is parallel with the subduction. The subduction of Indo-Australian oceanic plate beneath the Eurasian continental plate results in various volcanic products in a wide range of geochemical and mineralogical characteristics. The geochemical and mineralogical characteristics of volcanic and magmatic rocks associated with geothermal systems are ill-defined. Comprehensive study of geochemical signatures, mineralogical properties, and isotopes analysis might lead to the understanding of how large geothermal fields are found in West Java compared to ones in Central and East Java. The result can also provoke some valuable impacts on Java tectonic evolution and can suggest the key information for geothermal exploration enhancement.

  19. Venus volcanism: Initial analysis from Magellan data (United States)

    Head, J.W.; Campbell, D.B.; Elachi, C.; Guest, J.E.; Mckenzie, D.P.; Saunders, R.S.; Schaber, G.G.; Schubert, G.


    Magellan images confirm that volcanism is widespread and has been fundamentally important in the formation and evolution of the crust of Venus. High-resolution imaging data reveal evidence for intrusion (dike formation and cryptodomes) and extrusion (a wide range of lava flows). Also observed are thousands of small shield volcanoes, larger edifices up to several hundred kilometers in diameter, massive outpourings of lavas, and local pyroclastic deposits. Although most features are consistent with basaltic compositions, a number of large pancake-like domes are morphologically similar to rhyolite-dacite domes on Earth. Flows and sinuous channels with lengths of many hundreds of kilometers suggest that extremely high effusion rates or very fluid magmas (perhaps komatiites) may be present. Volcanism is evident in various tectonic settings (coronae, linear extensional and compressional zones, mountain belts, upland rises, highland plateaus, and tesserae). Volcanic resurfacing rates appear to be low (less than 2 km3/yr) but the significance of dike formation and intrusions, and the mode of crustal formation and loss remain to be established.

  20. Volcanic Glasses as Habitat for Microfossils: Evidence from the Early Paleoproterozoic Pillow Lavas of Karelia and their Modern Analogues in the Mid-Atlantic Ridge (United States)

    Adtafieva, M. M.; Rozanov, A. Yu; Sharkov, E. V.; Chistyakov, A. V.; Bogina, M. M.; Hoover, R. B.


    Microbial complexes were identified in the volcanic glasses from the ancient (2.4-Ga-old basaltic pillow-lavas of Karelia) and modern (pillow lavas of Mid-Atlantic ridge) volcanic rocks. It was shown that that their microbial colonization is likely to occur by the same mechanism. Thus, well preserved pillow lavas, which occupy a spacious fields in the Archean and Early Paleoproterozoic greenstone belts, are promising object for search of the earliest traces of life on Earth.

  1. Global volcanic emissions: budgets, plume chemistry and impacts (United States)

    Mather, T. A.


    Over the past few decades our understanding of global volcanic degassing budgets, plume chemistry and the impacts of volcanic emissions on our atmosphere and environment has been revolutionized. Global volcanic emissions budgets are needed if we are to make effective use of regional and global atmospheric models in order to understand the consequences of volcanic degassing on global environmental evolution. Traditionally volcanic SO2 budgets have been the best constrained but recent efforts have seen improvements in the quantification of the budgets of other environmentally important chemical species such as CO2, the halogens (including Br and I) and trace metals (including measurements relevant to trace metal atmospheric lifetimes and bioavailability). Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents and during electrical discharges in ash-rich volcanic plumes. These reactive trace species have important consequences for gas plume chemistry and impacts, for example, in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate. There are still many challenges and open questions to be addressed in this fascinating area of science.

  2. La pesquería de tiburones oceánicos-costeros en los litorales de Colima, Jalisco y Michoacán

    Directory of Open Access Journals (Sweden)

    Angélica Cruz


    Full Text Available La pesquería de tiburón es una de las más importantes en el Pacífico mexicano, en la actualidad no se cuentan con los datos de la composición específica de las capturas de las diferentes flotas. En el presente trabajo se describen aspectos biológicos-pesqueros de las especies de tiburón, capturadas por la flota palangrera de mediana altura del puerto de Manzanillo, en un periodo anual de abril 2006-abril 2007, los muestreos se realizaron mensualmente a bordo de estas embarcaciones. La composición de las capturas estuvo representada por nueve especies (n=1 962, de las cuales Carcharhinus falciformis (Bibron, 1839 (88.12% sostiene esta pesquería y en segundo lugar Prionace glauca (Linnaeus, 1758 (8.21%. Las especies poco frecuentes fueron Sphyrna zygaena (Linnaeus, 1758 con (1.78%, Alopias pelagicus (Nakamura, 1935 (0.82%, Carcharhinus longimanus (Poey, 1861 (0.45%, Alopias superciliosus (Lowe, 1839 (0.35%, Carcharhinus leucas (Valenciennes, 1839 (0.1%, Carcharhinus limbatus (Valenciennes, 1839 (0.1% é Isurus oxyrinchus (Rafinesque, 1810 (0.05%. La fecundidad estimada para C. falciformis fue de 3-7 crías/hembra con tallas de 30-45cm LT; 40.57+2.03cm LT y P. glauca con 5-52 crías/hembra, con tallas de 5-18.6cm LT; 11.61±0.21cm LT. Por lo tanto se asume que C. falciformis presenta un ciclo concurrente y P. glauca probablemente un ciclo bianual consecutivo.Fishery of oceanic and coastal sharks in Colima, Jalisco and Michoacán. Shark fishery is one of the most important activities in the Mexican Pacific coast, nevertheless, there is few data available about the specific captures done by the fleet along the coast. This study describes fishery biology aspects of the shark species catched by the semi-industrial long-line fleet of Manzanillo. Monthly samplings were made on board of these vessels during an annual period from April 2006 to April 2007. Captured species composition (n=1 962 organisms was represented by nine species. The one

  3. Analysis of concentration patterns in volcanic rocks: Insights into dynamics of highly explosive volcanic eruptions (United States)

    Perugini, D.; Petrelli, M.; Poli, G.


    In this contribution we present new data resulting from the analysis of concentration patterns of mixed juvenile fragments ejected by a highly explosive volcanic eruption that occurred on Salina Island (Aeolian Islands, Italy) and our aim is to identify the fluid-dynamic regime characterizing the magma mixing process. Concentration patterns are studied by calculating the power spectrum of concentration variability along transects crossing the magma mixing structures. Results indicate that the slope of power spectrum has an average value of about -5/3, according to Kolmogorov law of turbulence, and suggest that the magma mixing process, in the studied conditions, can be approximated by considering the passive scalar mixing hypothesis in homogeneous isotropic turbulent flow. These results represent a first step towards a better understanding of magma mixing processes associated to highly explosive volcanic eruptions and this first step is taken by studying concentration patterns in volcanic rocks by coupling petrological and non-linear dynamics methods.

  4. Caldera volcanoes of the Taupo Volcanic Zone, New Zealand (United States)

    Wilson, C. J. N.; Rogan, A. M.; Smith, I. E. M.; Northey, D. J.; Nairn, I. A.; Houghton, B. F.


    The Taupo volcanic zone (TVZ) has been active since 2 Ma and has erupted >104 km3 of dominantly rhyolitic magma during the last 1 m.y. Most of the volcanism is concentrated in a 125×60 km area forming the central TVZ and is expressed largely as six major caldera volcanoes, Rotorua, Okataina, Kapenga, Mangakino, Maroa, and Taupo, marked by localized collapse of the underlying basement and clustering of known or inferred vent sites. These centers have activity spans from 150 to 600 ka and have each erupted at least 300 to 1000 km3 of magma. All centers except Rotorua are known or inferred to have had complex histories of multiple caldera collapse, which have occurred alongside general basement collapse within the TVZ accompanying regional extension. Deep-seated NE trending basement lineations and/or faults have influenced vent sites at Okataina, Maroa, and Taupo. Welded ignimbrites are prominent in the pre-140 ka record; their absence since then is attributed to the effects of surface water on eruption styles rather than to a change in eruptive behavior. Volcanism from the centers has been overwhelmingly rhyolitic (>97% SiO2 69-77 wt%) with minor high-A1 basalt and dacite and traces of andesite, mostly as lithic fragments in ignimbrites from Okataina and Mangakino. Although insignificant in volume, the basalt is important as a low-Si end-member in mixing relationships with the rhyolite (at one extreme generating the dacites) and occasionally as a trigger for the rhyolitic eruptions. The current average rhyolite magma eruption rate from the central TVZ is ˜0.27 m3 s-1, equally divided between Okataina and Taupo, a figure close to the long-term average for the last 1.1 Ma. However, geothermal heat flow data imply that a further 1.4-1.8 m3 s-1 of magma may be intruded within the crust. The ratio of inferred intruded material to erupted material is higher at centers where lava extrusions are volumetrically significant (Okataina, Maroa), and this is correlated with

  5. Volcanic ash plume identification using polarization lidar: Augustine eruption, Alaska (United States)

    Sassen, Kenneth; Zhu, Jiang; Webley, Peter W.; Dean, K.; Cobb, Patrick


    During mid January to early February 2006, a series of explosive eruptions occurred at the Augustine volcanic island off the southern coast of Alaska. By early February a plume of volcanic ash was transported northward into the interior of Alaska. Satellite imagery and Puff volcanic ash transport model predictions confirm that the aerosol plume passed over a polarization lidar (0.694 mm wavelength) site at the Arctic Facility for Atmospheric Remote Sensing at the University of Alaska Fairbanks. For the first time, lidar linear depolarization ratios of 0.10 – 0.15 were measured in a fresh tropospheric volcanic plume, demonstrating that the nonspherical glass and mineral particles typical of volcanic eruptions generate strong laser depolarization. Thus, polarization lidars can identify the volcanic ash plumes that pose a threat to jet air traffic from the ground, aircraft, or potentially from Earth orbit.

  6. Supervolcanoes Within an Ancient Volcanic Province in Arabia Terra, Mars (United States)

    Michalski, Joseph. R.; Bleacher, Jacob E.


    Several irregularly shaped craters located within Arabia Terra, Mars represent a new type of highland volcanic construct and together constitute a previously unrecognized martian igneous province. Similar to terrestrial supervolcanoes, these low-relief paterae display a range of geomorphic features related to structural collapse, effusive volcanism, and explosive eruptions. Extruded lavas contributed to the formation of enigmatic highland ridged plains in Arabia Terra. Outgassed sulfur and erupted fine-grained pyroclastics from these calderas likely fed the formation of altered, layered sedimentary rocks and fretted terrain found throughout the equatorial region. Discovery of a new type of volcanic construct in the Arabia volcanic province fundamentally changes the picture of ancient volcanism and climate evolution on Mars. Other eroded topographic basins in the ancient Martian highlands that have been dismissed as degraded impact craters should be reconsidered as possible volcanic constructs formed in an early phase of widespread, disseminated magmatism on Mars.

  7. Petrographic features of Middle-Late Triassic volcanic rocks of the Transdanubian Range and their comparison to contemporaneous volcanic rocks of the Southern Alps (United States)

    Farics, Éva; Józsa, Sándor; Haas, János


    , rhyolite, sandstone, siltstone - in a glassy groundmass); dacite/rhyolite tuff (juvenile glass shards and pumice as well as pseudomorphs after feldspar, subordinate quartz, pseudomorphs after pyroxene and biotite). The rocks are strongly altered by K-metasomatism. For this reason we can define in most cases andesite as K-trachyte, microdiorite as K-syenite. We may compare the petrographic features of the volcanic rocks of the NE part of the Transdanubian Range to the volcanic complex of Predazzo and dyke rocks of Latemar, Western Dolomites. The most important similarity is the presence of basalt, andesite, trachyte, latite and rhyolite lava rocks, as well as dolerite/gabbro, diorite and aplite dyke rocks in both regions. However, the volcanic rocks in Predazzo and Latemar are more varied and extended than in the Transdanubian Range. Some rock types do not occur in the Transdanubian region, for example basanite, monzonite, pyroxenite, nefelin-sodalite-syenite, granite and pegmatite. We can conclude that there is a definite similarity in the petrographic characteristics of the Middle to Late Triassic volcanic rocks of the two areas, but further comparative geochemical and geochronological studies are needed for a comprehensive evaluation of the similarities and differences and for better understanding the history of the volcanic activity.

  8. Galileo SSI Observations of Volcanic Activity at Tvashtar Catena, Io (United States)

    Milazzo, M. P.; Keszthely, L. P.; Radebaugh, J.; Davies, A. G.; Turtle, E. P.; Geissler, P.; Klaasen, K. P.; McEwen, A. S.


    Introduction: We report on the analysis of the Galileo SSI's observations of the volcanic activity at Tvashtar Catena, Io as discussed by Milazzo et al. Galileo's Solid State Imager (SSI) observed Tvashtar Catena (63 deg N, 120 deg W) four times between November 1999 and October 2001, providing a unique look at the distinctive high latitude volcanism on Io. The November 1999 observation spatially resolved, for the first time, an active extraterrestrial fissure eruption. The brightness temperature of the lavas at the November 1999 fissure eruption was 1300 K. The second observation (orbit I27, February 2000) showed a large (approx. 500 sq km) region with many, small spots of hot, active lava. The third observation was taken in conjunction with a Cassini observation in December 2000 and showed a Pele-like plume deposition ring, while the Cassini images revealed a 400 km high Pele-type plume above the Catena. The final Galileo SSI observation of Tvashtar was acquired in October 2001, and all obvious (to SSI) activity had ceased, although data from Galileo's Near Infrared Mapping Spectrometer (NIMS) indicated that there was still significant thermal emission from the Tvashtar region. We have concentrated on analyzing the style of eruption during orbit I27 (February 2000). Comparison with a lava flow cooling model indicates that the behavior of the Tvashtar eruption during I27 does not match that of "simple" advancing lava flows. Instead, it may be an active lava lake or a complex set of lava flows with episodic, overlapping (in time and space) eruptions.

  9. Late Cretaceous intraplate silicic volcanism in the Lake Chad region: incipient continental rift volcanism vs. Cameroon Line volcanism (United States)

    Shellnutt, G.; Lee, T. Y.; Torng, P. K.; Yang, C. C.


    The crustal evolution of west-central Africa during the Cretaceous was directly related to plate motion associated with the opening of the central Atlantic Ocean. Late Cretaceous (~66 Ma) to recent magmatism related to the Cameroon Line stretches from Northern Cameroon (i.e. Golda Zuelva) to the Gulf of Guinea (i.e. Pagalu) and is considered to be due to mantle-crust interaction. The volcanic rocks at Hadjer el Khamis, west-central Chad, are considered to be amongst the oldest volcanic rocks of the Cameroon Line but their relationship is uncertain because they erupted during a period of a regional extension associated with the opening of the Late Cretaceous (~75 Ma) Termit basin. The silicic volcanic rocks can be divided into a peraluminous group and a peralkaline group with both rock types having similar chemical characteristics as within-plate granitoids. In situ U/Pb zircon dating yielded a mean 206Pb/238U age of 74.4 ± 1.3 Ma and indicates the rocks erupted ~10 million years before the next oldest eruption attributed to the Cameroon Line. The Sr isotopes (i.e. ISr = 0.7050 to 0.7143) show a wide range but the Nd isotopes (i.e. 143Nd/144Ndi = 0.51268 to 0.51271) are more uniform and indicate that the rocks were derived from a moderately depleted mantle source. Major and trace elemental modeling show that the silicic rocks likely formed by shallow fractionation of a mafic parental magma where the peraluminous rocks experienced crustal contamination and the peralkaline rocks did not. The silicic rocks are more isotopically similar to Late Cretaceous basalts in the Doba and Bongor basins (i.e. ISr = 0.7040 to 0.7060; 143Nd/144Ndi = 0.51267 to 0.51277) of southern Chad than to rocks of the Cameroon Line (i.e. ISr = 0.7026 to 0.7038; 143Nd/144Ndi = 0.51270 to 0.51300). Given the age and isotopic compositions, it is likely that the silicic volcanic rocks of the Lake Chad area are related to Late Cretaceous extensional tectonics rather than to Cameroon Line magmatism.

  10. Post-caldera volcanism: In situ measurement of U-Pb age and oxygen isotope ratio in Pleistocene zircons from Yellowstone caldera (United States)

    Bindeman, I.N.; Valley, J.W.; Wooden, J.L.; Persing, H.M.


    The Yellowstone Plateau volcanic field, the site of some of the largest known silicic volcanic eruptions, is the present location of NE-migrating hotspot volcanic activity. Most volcanic rocks in the Yellowstone caldera (0.6 Ma), which formed in response to the climactic eruption of 1000 km3 of Lava Creek Tuff (LCT), have unusually low oxygen isotope ratios. Ion microprobe analysis of both U-Pb age and ??18O in zircons from these low-??18O lavas reveals evidence of complex inheritance and remelting. A majority of analyzed zircons from low-??18O lavas erupted inside the Yellowstone caldera have cores that range in age from 2.4 to 0.7 Ma, significantly older than their eruption ages (0.5-0.4 Ma). These ages and the high-??18O cores indicate that these lavas are largely derived from nearly total remelting of normal-??18O Huckleberry Ridge Tuff (HRT) and other pre-LCT volcanic rocks. A post-HRT low-??18O lava shows similar inheritance of HRT-age zircons. The recycling of volcanic rocks by shallow remelting can change the water content and eruptive potential of magma. This newly proposed mechanism of intracaldera volcanism is best studied by combining in situ analysis of oxygen and U-Pb isotope ratios of individual crystals. ?? 2001 Elsevier Science B.V. All rights reserved.

  11. Post-caldera volcanism: in situ measurement of U-Pb age and oxygen isotope ratio in Pleistocene zircons from Yellowstone caldera (United States)

    Bindeman, Ilya N.; Valley, John W.; Wooden, J. L.; Persing, Harold M.


    The Yellowstone Plateau volcanic field, the site of some of the largest known silicic volcanic eruptions, is the present location of NE-migrating hotspot volcanic activity. Most volcanic rocks in the Yellowstone caldera (0.6 Ma), which formed in response to the climactic eruption of 1000 km3 of Lava Creek Tuff (LCT), have unusually low oxygen isotope ratios. Ion microprobe analysis of both U-Pb age and δ18O in zircons from these low-δ18O lavas reveals evidence of complex inheritance and remelting. A majority of analyzed zircons from low-δ18O lavas erupted inside the Yellowstone caldera have cores that range in age from 2.4 to 0.7 Ma, significantly older than their eruption ages (0.5-0.4 Ma). These ages and the high-δ18O cores indicate that these lavas are largely derived from nearly total remelting of normal-δ18O Huckleberry Ridge Tuff (HRT) and other pre-LCT volcanic rocks. A post-HRT low-δ18O lava shows similar inheritance of HRT-age zircons. The recycling of volcanic rocks by shallow remelting can change the water content and eruptive potential of magma. This newly proposed mechanism of intracaldera volcanism is best studied by combining in situ analysis of oxygen and U-Pb isotope ratios of individual crystals.

  12. The impact of volcanic tephra on weathering and soil development of Icelandic Histosols, SE Iceland (United States)

    Bonatotzky, Theresa; Ottner, Franz; Gísladóttir, Guðrún


    A mixture of poorly decomposed plant remains, crystalline volcanic material and intense aeolian deposition sets Icelandic Histosols apart from other Histosols in the northern hemisphere. They exhibit a unique combination of histic (organic) and andic soil characteristics. Allophane, imogolite and ferrihydrite are common minerals in Icelandic soils while layer silicates are rare. The volcanically active area south of Vatnajökull has received numerous tephra deposits of varying thickness during Holocene. Two distinct tephra layers, the light coloured rhyolitic tephra from the Öræfajökull eruption in AD 1362 and a black basaltic tephra from a Veiðivötn fissure eruption within the Bárðarbunga volcanic system in AD 1477, are well preserved in the soils. This provides a unique opportunity to study weathering behaviour of tephra deposits of different composition and to examine their contrasting mineralogy and impact on soils south of Vatnajökull glacier. The investigated soils can be classified as Histosols with plant residues as parent material and influenced by volcanic ejecta (tephra) and aeolian material. Low pH (H2O) and high organic matter (OM) content are the two dominating factors influencing their weathering behaviour. The soil organic carbon (SOC) content was found to between 16 - 31%. As OM inhibits the formation of amorphous secondary minerals, the clay content in Icelandic soils is generally low while Al-humus complexes are predominant. The soil horizons developed from rhyolitic and basaltic tephra both show differences. Investigations of the mineralogy show small evidence of weathering in the basaltic V1477 tephra, whereas the rhyolitic volcanic ejecta has hardly altered since its formation.

  13. Taos Plateau Volcanic Project: A Vehicle for Integration of Concepts in Igneous Petrology (United States)

    Henry, D.; Dutrow, B.


    Integrating concepts of igneous petrology is generally a challenge, but can be effective in the context of a project based on actual field, geochemical and geochronological data. The final lab project in the igneous portion of petrology involves a series of volcanic and associated rock samples that were collected from the Taos Plateau Volcanic Field, New Mexico, USA. Samples were collected over an area of several tens of km2 throughout the Plateau and represent a spatially and temporally correlated rock suite related to continental rifting. Rift-related magmatism encompasses much of the diversity of terrestrial magma types. Compositions of mafic magmas range from tholeiite to some of the most silica-undersaturated magmas found on the continents. Large effusive eruptions from fissures are typical of some rifts, whereas others may be dominated by central vent cones or even silicic caldera complexes. The injection of mantle-derived magma in extending crust may have a profound effect on the rheology of the crust and, therefore, the style of deformation associated with extension. Most of these aspects of rift volcanism and a wide range of mafic to silicic magma compositions are represented in the Rio Grande rift and the volcanic rocks of the Taos Plateau. In addition, much published data exists for whole rock and trace element geochemistry as well as geochronology. Rock samples and associated information are presented so that the student must integrate multiple lines of evidence, petrographic, petrologic, geochemical and geochronological data in a geospatial framework, to establish a geologic history of the region. The student must also draw on skills learned in mineralogy and structural geology furthering core geoscience education. Subsequent to the petrology course, the students visit the Taos Plateau Volcanic Field during their required field camp, thus reinforcing the linkage between the classroom setting and geologic reality.

  14. Local seismic hazard assessment in explosive volcanic settings by 3D numerical analyses (United States)

    Razzano, Roberto; Pagliaroli, Alessandro; Moscatelli, Massimiliano; Gaudiosi, Iolanda; Avalle, Alessandra; Giallini, Silvia; Marcini, Marco; Polpetta, Federica; Simionato, Maurizio; Sirianni, Pietro; Sottili, Gianluca; Vignaroli, Gianluca; Bellanova, Jessica; Calamita, Giuseppe; Perrone, Angela; Piscitelli, Sabatino


    This work deals with the assessment of local seismic response in the explosive volcanic settings by reconstructing the subsoil model of the Stracciacappa maar (Sabatini Volcanic District, central Italy), whose pyroclastic succession records eruptive phases ended about 0.09 Ma ago. Heterogeneous characteristics of the Stracciacappa maar (stratification, structural setting, lithotypes, and thickness variation of depositional units) make it an ideal case history for understanding mechanisms and processes leading to modifications of amplitude-frequency-duration of seismic waves generated at earthquake sources and propagating through volcanic settings. New geological map and cross sections, constrained with recently acquired geotechnical and geophysical data, illustrate the complex geometric relationships among different depositional units forming the maar. A composite interfingering between internal lacustrine sediments and epiclastic debris, sourced from the rim, fills the crater floor; a 45 meters thick continuous coring borehole was drilled in the maar with sampling of undisturbed samples. Electrical Resistivity Tomography surveys and 2D passive seismic arrays were also carried out for constraining the geological model and the velocity profile of the S-waves, respectively. Single station noise measurements were collected in order to define natural amplification frequencies. Finally, the nonlinear cyclic soil behaviour was investigated through simple shear tests on the undisturbed samples. The collected dataset was used to define the subsoil model for 3D finite difference site response numerical analyses by using FLAC 3D software (ITASCA). Moreover, 1D and 2D numerical analyses were carried out for comparison purposes. Two different scenarios were selected as input motions: a moderate magnitude (volcanic event) and a high magnitude (tectonic event). Both earthquake scenarios revealed significant ground motion amplification (up to 15 in terms of spectral acceleration

  15. Transform Tectonics and Non-Volcanic Oceanic Islands


    Palmiotto, Camilla


    Oceanic islands can be divided, according to their origin, in volcanic and tectonic. Volcanic islands are due to excess volcanism. Tectonic islands are mainly formed due to vertical tectonic motions of blocks of oceanic lithosphere along transverse ridges flanking transform faults at slow and ultraslow mid-ocean ridges. Vertical tectonic motions are due to a reorganization of the geometry of the transform plate boundary, with the transition from a transcurrent tectonics to a transtensive and/...

  16. Role of volcanic forcing on future global carbon cycle


    J. F. Tjiputra; O. H. Otterå


    Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller but more frequent eruptions, such as Pinatubo, would hav...

  17. Volatile Transport by Volcanic Plumes on Earth, Venus and Mars (United States)

    Glaze, Lori S.; Self, Stephen; Baloga, Steve; Stofan, Ellen R.


    Explosive volcanic eruptions can produce sustained, buoyant columns of ash and gas in the atmosphere (Fig. 1). Large flood basalt eruptions may also include significant explosive phases that generate eruption columns. Such eruptions can transport volcanic volatiles to great heights in the atmosphere. Volcanic eruption columns can also redistribute chemical species within the atmosphere by entraining ambient atmosphere at low altitudes and releasing those species at much higher altitudes.

  18. Los volcanes del Sistema Volcánico Transversal

    Directory of Open Access Journals (Sweden)

    Esperanza Yarza de la Torre


    Full Text Available Si hizo la selección de textos referentes a algunos de los volcanes que integran el Sistema Volcánico Transversal. Publicado en: Yarza de De la Torre, E. (1992, "Los volcanes del Sistema Volcánico Transversal", Volcanes de México, 4a ed. corregida y aumentada, Instituto de Geografía, UNAM, México, pp. 82-83, 89-136.

  19. Los volcanes del Sistema Volcánico Transversal


    Esperanza Yarza de la Torre


    Si hizo la selección de textos referentes a algunos de los volcanes que integran el Sistema Volcánico Transversal. Publicado en: Yarza de De la Torre, E. (1992), "Los volcanes del Sistema Volcánico Transversal", Volcanes de México, 4a ed. corregida y aumentada, Instituto de Geografía, UNAM, México, pp. 82-83, 89-136.

  20. Characteristics and Similarities of Lava Suites from Jorullo and La Pilita Volcanoes, Volcanic Front of the Westernmost Trans-Mexican Volcanic Belt (United States)

    Roberge, J.; Delgado Granados, H.


    The monogenetic volcanic field of Michoacán-Guanajuato is at the westernmost part of the Trans-Mexican Volcanic Belt. This is the region where the influence of the Cocos plate starts under the subduction system beneath North America. Jorullo volcano had eruptive activity between 1759-1774 and La Pilita within the Holocene. The eruption of Jorullo and the products from La Pilita were first treated in the incredible work of Luhr and Carmichael (1985), however nothing else has been done on those lava flows since. We have visited the lava flows from Jorullo and La Pilita volcanoes in January 2007 and many new observations were made. Two flows were emitted from the north cone, the age of these lavas is debatable and apparently are older than Jorullo. Also a big older flow is running from the southern base of the main Jorullo cone. So far, this big flow had been ignored in the literature and we found that it is texturally very similar to the La Pilita flow. In this work we present geochemical and textural analyses of over 20 lava flows samples from Jorullo, and 3 lava samples from La Pilita. These data are then compared with samples from the large flow south of Jorullo to constrain his origin and chronology. The origin of this big flow maybe the proof that Jorullo is in fact a volcanic complex, and it was active before the 1959 eruption. This implies that Jorullo may not be a monogenetic volcano.

  1. Experimental Constraints on the Respiratory Health Hazard Posed by Crystalline Silica-bearing Volcanic Ash (United States)

    Damby, D. E.; Horwell, C. J.; Baxter, P. J.


    Since volcanic ash from the 1980 eruption of Mount St Helens, USA, impacted on a million inhabitants in the Pacific Northwest, it is known that a substantial fraction of volcanic ejecta is respirable and therefore capable of being a human health hazard. Exacerbation of airway problems, such as asthma and chronic bronchitis, due to an increase in ambient particulate matter following the eruption, was an expected finding; however, a significant amount of cristobalite, a toxic mineral, in the ash was unforeseen and led to repeated toxicological testing of the ash to establish the hazard posed to human health. Those results together with studies on cristobalite-bearing ash from other major eruptions suggest that volcanic cristobalite is minimally reactive relative to pure phase standards. This finding adheres to a well-established thesis on the variable pathogenicity of crystalline silica, whereby intrinsic characteristics and extrinsic modifications of the crystalline silica govern reactivity. Indeed, chemical impurities (up to 4 wt% aluminum) and substantial structural defects have been implicated in the reduced potency of volcanic cristobalite. However, whilst not overtly toxic, volcanic ash exposure can initiate a sample-dependent inflammatory response in macrophages, a cell type that provides a first line of defense against inhaled particles. Inflammation plays a pivotal role in crystal-driven disease progression and can be observed in patients with particle-induced lung disease. We demonstrate that ash can induce inflammation by stimulating the NLRP3 inflammasome, a cytosolic receptor complex that drives the inflammatory response to several endo- and exogenous crystalline materials. The impact of inflammasome activation mediated by inhaled ash particles and its potential relevance in chronic pulmonary diseases was confirmed in primary human cells; however, it is not yet known whether the response resolves in vivo. The NLRP3 inflammasome as an ash

  2. Melting Behavior of Volcanic Ash relevant to Aviation Ash Hazard (United States)

    Song, W.; Hess, K.; Lavallee, Y.; Cimarelli, C.; Dingwell, D. B.


    Volcanic ash is one of the major hazards caused by volcanic eruptions. In particular, the threat to aviation from airborne volcanic ash has been widely recognized and documented. In the past 12 years, more than 60 modern jet airplanes, mostly jumbo jets, have been damaged by drifting clouds of volcanic ash that have contaminated air routes and airport facilities. Seven of these encounters are known to have caused in-flight loss of engine power to jumbo jets carrying a total of more than 2000 passengers. The primary cause of engine thrust loss is that the glass in volcanic ash particles is generated at temperatures far lower than the temperatures in the combustion chamber of a jet engine ( i.e. > 1600 oC) and when the molten volcanic ash particles leave this hottest section of the engine, the resolidified molten volcanic ash particles will be accumulated on the turbine nozzle guide vanes, which reduced the effective flow of air through the engine ultimately causing failure. Thus, it is essential to investigate the melting process and subsequent deposition behavior of volcanic ash under gas turbine conditions. Although few research studies that investigated the deposition behavior of volcanic ash at the high temperature are to be found in public domain, to the best our knowledge, no work addresses the formation of molten volcanic ash. In this work, volcanic ash produced by Santiaguito volcano in Guatemala in November 8, 2012 was selected for study because of their recent activity and potential hazard to aircraft safety. We used the method of accessing the behavior of deposit-forming impurities in high temperature boiler plants on the basis of observations of the change in shape and size of a cylindrical coal ash to study the sintering and fusion phenomena as well as determine the volcanic ash melting behavior by using characteristic temperatures by means of hot stage microscope (HSM), different thermal analysis (DTA) and Thermal Gravimetric Analysis (TGA) to

  3. The Martian highland paterae: Evidence for explosive volcanism on Mars (United States)

    Crown, David A.; Greeley, Ronald


    The Martian surface exhibits numerous volcanic landforms displaying great diversity in size, age, and morphology. Most research regarding Martian volcanology has centered around effusive basaltic volcanism, including analyses of individual lava flows, extensive lava plains, and large shield volcanoes. These studies were hindered by a lack of definitive morphologic criteria for the remote identification of ash deposits. Knowledge of the abundances, ages, and geologic settings of explosive volcanic deposits on Mars is essential to a comprehensive understanding of the evolution of the Martian surface, with implications for the evolution of the lithosphere and atmosphere as well as the histories of specific volcanic centers and provinces.

  4. Effect of volcanic tuff on the characteristics of cement mortar

    Directory of Open Access Journals (Sweden)

    Jehad Al-Zou'by


    Full Text Available This paper examines how Jordanian volcanic tuff aggregates affect the characteristics of cement mortar. Five mortar mixes were prepared by replacing normal aggregate (standard sand with volcanic tuff aggregate in ratios of 0, 25, 50, 75, and 100% (M1 to M5, respectively. Compressive strength, flexural strength, and unit weight were tested at mortar ages of 3, 7, 28, and 56 days. The results revealed improved compressive and flexural strength, which were maximal for the M3 sample. Unit weight decreased as the ratio of volcanic tuff increased. Based on these results, adding Jordanian volcanic tuff in the appropriate ratio will improve these mortar characteristics.

  5. Structural significance of the south Tyrrhenian volcanism (United States)

    Gaudiosi, G.; Musacchio, G.; Ventura, G.; de Astis, G.


    The southern part of the Tyrrhenian Sea represents a transition from ocenic- (the Tyrrhenian Sea) to continental-domain (the Calabrian Arc) and is affected by active calkalkaline to potassic volcanism (the Eolian Islands). Active extensional tectonics, coupled with the general upwelling of northern Sicily and Calabria continental crust, coexists with active subduction of the Ionian Plate beneath the Calabrian Arc. This has been interpreted as the result of the detachment of the slab beneath the Calbrian Arc. Present-day tectonics is characterized by NE-SW normal faults and NNW- SSE dextral oblique-slip faults. The normal faults form the major peri- Tyrrhenian basins. Refraction and high resolution onshore-offshore wide-angle-reflection profiles, as well as potential field modeling, provide a 3D image of the Moho. Short wave-length undulations characterize the Moho beneath the Aeolian Arch. The major upraise is about 6 km, beneath the Aeolian active volcanic area, and affects all the crustal boundaries. Another sharp crustal thinning is observed beneath the gulf of Patti at the south-eastern edge of the Tyrrhenian basin. We suggest that the graben-like structure, occurring along the Salina-Lipari-Vulcano islands and oriented at high angles to the trench, is lithospheric and can be followed down to Moho depths. NNW-SSE dextral oblique-slip faults, like the Tindari Letojanni fault system, control the Salina-Lipari-Vulcano portion of the Aeolian volcanism and connect the oceanic crust of the Marsili Basin to the Malta Escarpment, through the Etna volcano. Across this lineament seismicity changes from mostly shallow to the west, to deep intra- slab to the east.

  6. Volcanic hazard assessment at Deception Island (United States)

    Bartolini, S.; Sobradelo, R.; Geyer, A.; Martí, J.


    Deception Island is the most active volcano of the South Shetland Islands (Antarctica) with more than twenty eruptions recognised over the past two centuries. The island was formed on the expansion axis of the Central Bransfield Strait and its evolution consists of constructive and destructive phases. A first a shield phase was followed by the construction of a central edifice and formation of the caldera with a final monogenetic volcanism along the caldera rim. The post-caldera magma composition varies from andesitic-basaltic to dacitic. The activity is characterised by monogenetic eruptions of low volume and short duration. The eruptions show a variable degree of explosivity, strombolian or phreatomagmatic, with a VEI 2 to 4, which have generated a wide variety of pyroclastic deposits and lavas. It is remarkable how many phases of phreatic explosive eruptions are associated to the emission of large ballistic blocks. Tephra record preserved in the glacier ice of Livingston Island or in marine sediments show the explosive power of the phreatomagmatic phases and the wide dispersal of its finest products in a great variety of directions of the prevailing winds. Also it is important to highlight the presence of different lahar deposits associated with some of these eruptions. In this contribution we present the guidelines to conduct a short-term and long-term volcanic hazard assessment at Deception Island. We apply probabilistic methods to estimate the susceptibility, statistical techniques to determine the eruption recurrence and eruptive scenario, and reproduce the effects of historical eruptions too. Volcanic hazard maps and scenarios are obtained using a Voris-based model tool (Felpeto et al., 2007) in a free Geographical Information System (GIS), a Quantum GIS.

  7. Peralkaline ash flow tuffs and calderas of the McDermitt volcanic field, southeast Oregon and north central Nevada. (United States)

    Rytuba, J.J.; McKee, E.H.


    This volcanic field covers an area of 20 000 km2 and consists of seven large-volume ash-flow sheets that vented 16.1-15 m.y. ago. The volcanic field is characterized by peralkaline, high-silica rhyolite, and all but one of the sheets are comendites. Each ash-flow sheet resulted in the formation of a large collapse caldera. Thickening of the ash-flow sheets, monoclinal warping outside the caldera ring-fault and tilting-in towards the caldera of blocks bounded by curvilinear faults all indicate regional subsidence prior to caldera collapse. The McDermitt caldera complex is highly mineralized; it contains ore deposits of Hg, Sb, Cs, Li and U. The peralkaline tuffs have high contents of these elements and were the source rocks from which metals were leached by hydrothermal systems developed during the last stage of caldera-related volcanism. (Following abstract) -W.H.B.

  8. Hubble Captures Volcanic Eruption Plume From Io (United States)


    The Hubble Space Telescope has snapped a picture of a 400-km-high (250-mile-high) plume of gas and dust from a volcanic eruption on Io, Jupiter's large innermost moon.Io was passing in front of Jupiter when this image was taken by the Wide Field and Planetary Camera 2 in July 1996. The plume appears as an orange patch just off the edge of Io in the eight o'clock position, against the blue background of Jupiter's clouds. Io's volcanic eruptions blasts material hundreds of kilometers into space in giant plumes of gas and dust. In this image, material must have been blown out of the volcano at more than 2,000 mph to form a plume of this size, which is the largest yet seen on Io.Until now, these plumes have only been seen by spacecraft near Jupiter, and their detection from the Earth-orbiting Hubble Space Telescope opens up new opportunities for long-term studies of these remarkable phenomena.The plume seen here is from Pele, one of Io's most powerful volcanos. Pele's eruptions have been seen before. In March 1979, the Voyager 1 spacecraft recorded a 300-km-high eruption cloud from Pele. But the volcano was inactive when the Voyager 2 spacecraft flew by Jupiter in July 1979. This Hubble observation is the first glimpse of a Pele eruption plume since the Voyager expeditions.Io's volcanic plumes are much taller than those produced by terrestrial volcanos because of a combination of factors. The moon's thin atmosphere offers no resistance to the expanding volcanic gases; its weak gravity (one-sixth that of Earth) allows material to climb higher before falling; and its biggest volcanos are more powerful than most of Earth's volcanos.This image is a contrast-enhanced composite of an ultraviolet image (2600 Angstrom wavelength), shown in blue, and a violet image (4100 Angstrom wavelength), shown in orange. The orange color probably occurs because of the absorption and/or scattering of ultraviolet light in the plume. This light from Jupiter passes through the plume and is

  9. Volcanism/tectonics working group summary

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    Kovach, L.A. [Nuclear Regulatory Commission, Washington, DC (United States); Young, S.R. [Center for Nuclear Waste Regulatory Analyses, San Antonio, TX (United States)


    This article is a summary of the proceedings of a group discussion which took place at the Workshop on the Role of Natural Analogs in Geologic Disposal of High-Level Nuclear Waste in San Antonio, Texas on July 22-25, 1991. The working group concentrated on the subject of the impacts of earthquakes, fault rupture, and volcanic eruption on the underground repository disposal of high-level radioactive wastes. The tectonics and seismic history of the Yucca Mountain site in Nevada is discussed and geologic analogs to that site are described.

  10. Automatic classification of seismo-volcanic signatures (United States)

    Malfante, Marielle; Dalla Mura, Mauro; Mars, Jérôme; Macedo, Orlando; Inza, Adolfo; Métaxian, Jean-Philippe


    The prediction of volcanic eruptions and the evaluation of their associated risks is still a timely and open issue. For this purpose, several types of signals are recorded in the proximity of volcanoes and then analysed by experts. Typically, seismic signals that are considered as precursor or indicator of an active volcanic phase are detected and manually classified. In this work, we propose an architecture for automatic classification of seismo-volcanic waves. The system we propose is based on supervised machine learning. Specifically, a prediction model is built from a large dataset of labelled examples by the means of a learning algorithm (Support Vector Machine or Random Forest). Four main steps are involved: (i) preprocess the signals, (ii) from each signal, extract features that are useful for the classes discrimination, (iii) use an automatic learning algorithm to train a prediction model and (iv) classify (i.e., assign a semantic label) newly recorded and unlabelled examples. Our main contribution lies in the definition of the feature space used to represent the signals (i.e., in the choice of the features to extract from the data). Feature vectors describe the data in a space of lower dimension with respect to the original one. Ideally, signals are separable in the feature space depending on their classes. For this work, we consider a large set of features (79) gathered from an extensive state of the art in both acoustic and seismic fields. An analysis of this feature set shows that for the application of interest, 11 features are sufficient to discriminate the data. The architecture is tested on 4725 seismic events recorded between June 2006 and September 2011 at Ubinas, the most active volcano of Peru. Six main classes of signals are considered: volcanic tremors (TR), long period (LP), volcano-tectonic (VT), explosion (EXP), hybrids (HIB) and tornillo (TOR). Our model reaches above 90% of accuracy, thereby validating the proposed architecture and the

  11. A method for multi-hazard mapping in poorly known volcanic areas: an example from Kanlaon (Philippines) (United States)

    Neri, M.; Le Cozannet, G.; Thierry, P.; Bignami, C.; Ruch, J.


    Hazard mapping in poorly known volcanic areas is complex since much evidence of volcanic and non-volcanic hazards is often hidden by vegetation and alteration. In this paper, we propose a semi-quantitative method based on hazard event tree and multi-hazard map constructions developed in the frame of the FP7 MIAVITA project. We applied this method to the Kanlaon volcano (Philippines), which is characterized by poor geologic and historical records. We combine updated geological (long-term) and historical (short-term) data, building an event tree for the main types of hazardous events at Kanlaon and their potential frequencies. We then propose an updated multi-hazard map for Kanlaon, which may serve as a working base map in the case of future unrest. The obtained results extend the information already contained in previous volcanic hazard maps of Kanlaon, highlighting (i) an extensive, potentially active ~5 km long summit area striking north-south, (ii) new morphological features on the eastern flank of the volcano, prone to receiving volcanic products expanding from the summit, and (iii) important riverbeds that may potentially accumulate devastating mudflows. This preliminary study constitutes a basis that may help local civil defence authorities in making more informed land use planning decisions and in anticipating future risk/hazards at Kanlaon. This multi-hazard mapping method may also be applied to other poorly known active volcanoes.

  12. Lower Pliensbachian caldera volcanism in high-obliquity rift systems in the western North Patagonian Massif, Argentina (United States)

    Benedini, Leonardo; Gregori, Daniel; Strazzere, Leonardo; Falco, Juan I.; Dristas, Jorge A.


    In the Cerro Carro Quebrado and Cerro Catri Cura area, located at the border between the Neuquén Basin and the North Patagonian Massif, the Garamilla Formation is composed of four volcanic stages: 1) andesitic lava-flows related to the beginning of the volcanic system; 2) basal massive lithic breccias that represent the caldera collapse; 3) voluminous, coarse-crystal rich massive lava-like ignimbrites related to multiple, steady eruptions that represent the principal infill of the system; and, finally 4) domes, dykes, lava flows, and lava domes of rhyolitic composition indicative of a post-collapse stage. The analysis of the regional and local structures, as well as, the architectures of the volcanic facies, indicates the existence of a highly oblique rift, with its principal extensional strain in an NNE-SSW direction (˜N10°). The analyzed rocks are mainly high-potassium dacites and rhyolites with trace and RE elements contents of an intraplate signature. The age of these rocks (189 ± 0.76 Ma) agree well with other volcanic sequences of the western North Patagonian Massif, as well as, the Neuquén Basin, indicating that Pliensbachian magmatism was widespread in both regions. The age is also coincident with phase 1 of volcanism of the eastern North Patagonia Massif (188-178 Ma) represented by ignimbrites, domes, and pyroclastic rocks of the Marifil Complex, related to intraplate magmatism.

  13. State-of-the-art for evaluating the potential impact of tectonism and volcanism on a radioactive waste repository

    Energy Technology Data Exchange (ETDEWEB)


    Most estimates of the time required for safe isolation of radioactive wastes from the biosphere range from 100,000 to 1,000,000 years. For such long time spans, it is necessary to assess the potential effects of geologic processes such as volcanism and tectonic activity on the integrity of geologic repositories. Predictions of geologic phenomena can be based on probabilistic models, which assume a random distribution of events. The necessary historic and geologic records are rarely available to provide an adequate data base for such predictions. The observed distribution of volcanic and tectonic activity is not random, and appears to be controlled by extremely complex deterministic processes. The advent of global plate tectonic theory in the past two decades has been a giant step toward understanding these processes. At each potential repository site, volcanic and tectonic processes should be evaluated to provide the most thorough possible understanding of those deterministic processes. Based on this knowledge, judgements will have to be made as to whether or not the volcanic and tectonic processes pose unacceptable risk to the integrity of the repository. This report describes the potential hazards associated with volcanism and tectonism, and the means for evaluating these processes.

  14. Silicon isotopes in allophane as a proxy for mineral formation in volcanic soils

    Energy Technology Data Exchange (ETDEWEB)

    Opfergelt, S., E-mail: [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN (United Kingdom)] [Earth and Life Institute, Universite catholique de Louvain, Croix du Sud 2/10, 1348 Louvain-la-Neuve (Belgium); Georg, R.B. [Trent University, Worsfold Water Quality Centre, 1600 West Bank Dr., Peterborough, Ontario (Canada); Burton, K.W. [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN (United Kingdom); Guicharnaud, R. [Agricultural University of Iceland, Keldnaholt 112, Reykjavik (Iceland); Siebert, C. [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN (United Kingdom); Gislason, S.R. [Institute of Earth Sciences, University of Iceland, Sturlugata 7, 101 Reykjavik (Iceland); Halliday, A.N. [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN (United Kingdom)


    Highlights: > The fate of dissolved Si in volcanic soils strongly depends on Al availability. > Lighter {delta}{sup 30}Si ratios in allophane relative to the basalt reflect weathering processes. > Heavier {delta}{sup 30}Si ratios in allophane indicate Si precipitation as Al is humus-complexed. > Allophane {delta}{sup 30}Si ratios could be useful in paleo-environmental reconstruction. - Abstract: Weathering of basaltic ash in volcanic areas produces andosols, rich in allophane and ferrihydrite. Since the rate of mineral formation is very useful in climate and geochemical modelling, this study investigates Si isotope compositions of allophane as a proxy for mineral formation. Allophane formed in contrasting conditions in five Icelandic soil profiles displays silicon isotope signatures lighter than the basalt in less weathered soils (-0.64 {+-} 0.15 per mille), and heavier in more weathered organic-rich soils (+0.23 {+-} 0.10 per mille). The fate of the dissolved Si in those volcanic soils strongly depends on Al availability. In organic-rich soils, most of Al is humus-complexed, and the results support that Si precipitates as opaline silica by super-saturation, leaving an isotopically heavier dissolved Si pool to form allophane with uncomplexed Al. This study highlights that Si isotopes can be useful to record successive soil processes involved in mineral formation, which is potentially useful in environmental paleo-reconstruction.

  15. Laboratory simulations of volcanic ash charging and conditions for volcanic lightning on Venus (United States)

    Airey, Martin; Warriner-Bacon, Elliot; Aplin, Karen


    Lightning may be important in the emergence of life on Earth and elsewhere, as significant chemical reactions occur in the superheated region around the lightning channel. This, combined with the availability of phosphates in volcanic clouds, suggests that volcanic lightning could have been the catalyst for the formation of biological compounds on the early Earth [1]. In addition to meteorological lightning, volcanic activity also generates electrical discharges within charged ash plumes, which can be a significant contributor to atmospheric electricity on geologically active planets. The physical properties of other planetary atmospheres, such as that of Venus, have an effect on the processes that lead to the generation of volcanic lightning. Volcanism is known to have occurred on Venus in the past, and recent observations made by ESA's Venus Express satellite have provided evidence for currently active volcanism [2-4], and lightning discharges [e.g. 5]. Venusian lightning could potentially be volcanic in origin, since no meteorological mechanisms are known to separate charge effectively in its clouds [6]. The hunt for further evidence for lightning at Venus is ongoing, for example by means of the Lightning and Airglow Camera (LAC) [7] on Akatsuki, the current JAXA mission at Venus. Our laboratory experiments simulate ash generation and measure electrical charging of the ash under typical atmospheric conditions on Earth and Venus. The study uses a 1 litre chamber, which, when pressurised and heated, can simulate the high-pressure, high-temperature, carbon dioxide-dominated atmosphere of Venus at 10 km altitude ( 5 MPa, 650 K). A key finding of previous work [8] is that ash plume-forming eruptions are more likely to occur at higher altitudes such as these on Venus. The chamber contains temperature/pressure monitoring and logging equipment, a rock collision apparatus (based on [9]) to generate the charged rock fragments, and charge measurement electrodes connected

  16. Variations in magmatic processes along the East Greenland volcanic margin (United States)

    Voss, Max; Schmidt-Aursch, Mechita C.; Jokat, Wilfried


    Seismic velocities and the associated thicknesses of rifted and igneous crust provide key constraints on the rifting history, the differentiation between non-volcanic and volcanic rifted margins, the driving force of magmatism at volcanic margins, that is, active or passive upwelling and the temperature anomaly in the lithosphere. This paper presents two new wide-angle seismic transects of the East Greenland margin and combines the velocity models with a compilation of 30-wide-angle seismic velocity models from several publications along the entire East Greenland margin. Compiled maps show the depth to basement, depth to Moho, crustal thickness and thickness of high velocity lower crust (HVLC; with velocities above 7.0 km s-1). First, we present two new wide-angle seismic transects, which contribute to the compilation at the northeast Greenland margin and over the oceanic crust between Shannon Island and the Greenland Fracture Zone. Velocity models, produced by ray tracing result in total traveltime rms-misfits of 100-120 milliseconds and χ2 values of 3.7 and 2.3 for the northern and southern profiles with respect to the data quality and structural complexity. 2-D gravity modelling is used to verify the structural and lithologic constraints. The northernmost profile, AWI-20030200, reveals a magma starved break-up and a rapidly thinning oceanic crust until magnetic anomaly C21 (47.1 Ma). The southern seismic transect, AWI-20030300, exhibits a positive velocity anomaly associated with the Shannon High, and a basin of up to 15 km depth beneath flood basalts between Shannon Island and the continent-ocean boundary. Break-up is associated with minor crustal thickening and a rapidly decreasing thickness of oceanic crust out to anomaly C21. The continental region is proposed to be only sparsely penetrated by volcanism and not underplated by magmatic material at all compared to the vast amount of magmatism further south. Break-up is proposed to have occurred at the seaward

  17. Rates of volcanic deposition, facies changes and movements in a dynamic basin: the Nuussuaq Basin, West Greenland, around the C27n-C26r transition

    DEFF Research Database (Denmark)

    Pedersen, A. K.; Larsen, L. M.; Riisager, P.


    The initial stages of Palaeogene volcanism in the Nuussuaq Basin in West Greenland were characterized by eruption of basaltic and picritic magmas through sediments of Cretaceous to early Paleocene age into a marine or lowlying coastal environment. Recent magnetostratigraphic work has recognized......, subsidence c. 25 m ka−1. If the volcanism evolved continuously at this high aggradation rate, all of the Vaigat Formation could have erupted in 70 ka. However, the complex geological record indicates a much longer total duration, and the volcanism must have had an intermittent character....... the C27n-C26r transition (estimated duration less than 10 ka and here assumed to be 5 ka) as a c. 170 m thick zone within a succession of thin picritic lava flows. Multimodel photogrammetry combined with chemical and lithological analysis of the volcanic rocks has allowed detailed 3D analysis...

  18. Volcanic plumes fast detection: a methodological proposal for an integrated approach (United States)

    Bernabeo, R. Alberto; Tositti, Laura; Brattich, Erika


    The behaviour of erupting volcanoes ranges from the quiet, steady effusion of lava to highly explosive eruptions. Therefore volcanic eruptions may present a direct threat to the safety of aircraft in flight and major operational difficulties at aerodromes and in airspaces located downwind the resulting volcanic ash cloud, in particular when eruptions are of high intensity and/or prolonged. Since volcanic ash clouds and gases are not displayed on either airborne or ATC radar and are extremely difficult to identify at night, pilots must rely on reports from air traffic controllers and from other pilots to determine the location of an ash cloud or gases. As a result, there is a clear need to develop extra tools enabling the timely on-board sensing of volcanic plumes for the sake of safety purposes. Large scale eruptions may eject many cubic kilometres of glass particles and pulverized rock (volcanic ash) as well as corrosive/hazardous gases high into the atmosphere, potentially over a wide area for timescales ranging from hours to weeks or even months. Volcanic ash consists mostly of sharp-edged, hard glass particles and pulverized rock. It is very abrasive and, being largely composed of siliceous materials, has a melting temperature below the operating temperature of modern turbine engines at cruise thrust. A volcanic plume in fact contains a complex mixture of water vapour, sulphur dioxide (producing sulphuric acid as a result of gas-to particle conversions reaction catalysed by iron in cloud droplets), chlorine and other halogens, and trace elements which are highly reactive and may interact with the mineral particles to produce corrosive effects hazardous to both airframes and human health. Remotely piloted aircraft system (RPAS) or Unmanned aerial vehicles (UAV) are slowly becoming efficient platforms - with dedicated miniaturized sensors that can be used in scientific/commercial remote sensing applications - and are of fundamental support to the planning

  19. The largest deep-ocean silicic volcanic eruption of the past century. (United States)

    Carey, Rebecca; Soule, S Adam; Manga, Michael; White, James; McPhie, Jocelyn; Wysoczanski, Richard; Jutzeler, Martin; Tani, Kenichiro; Yoerger, Dana; Fornari, Daniel; Caratori-Tontini, Fabio; Houghton, Bruce; Mitchell, Samuel; Ikegami, Fumihiko; Conway, Chris; Murch, Arran; Fauria, Kristen; Jones, Meghan; Cahalan, Ryan; McKenzie, Warren


    The 2012 submarine eruption of Havre volcano in the Kermadec arc, New Zealand, is the largest deep-ocean eruption in history and one of very few recorded submarine eruptions involving rhyolite magma. It was recognized from a gigantic 400-km 2 pumice raft seen in satellite imagery, but the complexity of this event was concealed beneath the sea surface. Mapping, observations, and sampling by submersibles have provided an exceptionally high fidelity record of the seafloor products, which included lava sourced from 14 vents at water depths of 900 to 1220 m, and fragmental deposits including giant pumice clasts up to 9 m in diameter. Most (>75%) of the total erupted volume was partitioned into the pumice raft and transported far from the volcano. The geological record on submarine volcanic edifices in volcanic arcs does not faithfully archive eruption size or magma production.

  20. Numerical models of caldera-scale volcanic eruptions on Earth, Venus, and Mars

    Energy Technology Data Exchange (ETDEWEB)

    Kieffer, S.W. [Univ. of British Columbia, British Columbia (Canada)


    Volcanic eruptions of gassy magmas on Earth, Venus, and Mars produce plumes with markedly different fluid dynamics regimes. In large part the differences are caused by the differing atmospheric pressures and ratios of volcanic vent pressure to atmospheric pressure. For each of these planets, numerical simulations of an eruption of magma containing 4 weight percent gas were run on a workstation. On Venus the simulated eruption of a pressure-balanced plume formed a dense fountain over the vent and continuous pyroclastic flows. On Earth and Mars, simulated pressure-balanced plumes produced ash columns, ash falls, and possible small pyroclastic flows. An overpressured plume, illustrated for Mars, exhibited a complex supersonic velocity structure and internal shocks. 31 refs., 7 figs., 2 tabs.

  1. Analysis of GOSAT XCO2 in explosive volcanic plumes (United States)

    Popp, Christoph; Andrews, Benjamin J.; Carn, Simon A.; Chance, Kelly; Cottrell, Elizabeth; Schwandner, Florian M.


    In this study, we analyze columnar averaged dry air mole fraction of CO2 (XCO2) in volcanic gas plumes after major eruptions using space-borne near-infrared measurements from the Japanese Greenhouse gas Observing SATellite (GOSAT). Volcanic emissions are assumed to dominate the flux from the deep Earth to the surface but those global emissions as well as the partitioning between eruptive and non-eruptive emissions are to date highly uncertain. Satellite measurements are an indispensable complement to ground-based measurements of volcanic CO2 emissions because they are performed globally and regularly and they therefore have the potential to significantly broaden our knowledge of volcanic CO2 releases. However, the remote sensing of volcanic CO2 is challenging for various reasons, including the increasingly high atmospheric background, relatively coarse spatial resolution and/or sampling, and scattering effects of aerosols and clouds. We mined existing standard product level 2 GOSAT XCO2 data sets for a volcanic CO2 signal in the gas plumes of the largest volcanic eruptions since GOSAT's launch in 2009. These eruptions include the Volcanic Explosivity Index (VEI) 4 events of Sarychev Peak (Kuril Islands, Russia) in June 2009, Nabro (Ethiopia) in June 2011, and Puyehue-Cordon Caulle (Chile) in June 2011. GOSAT background and plume soundings are distinguished using corresponding Ozone Monitoring Instrument (OMI) SO2 retrievals taking advantage of the usually low atmospheric SO2 background abundance. A volcanic CO2 signal in the GOSAT products can subsequently be found by comparing GOSAT XCO2 for the plume and background soundings. Possible XCO2 enhancements in the volcanic plumes are converted to an estimated CO2 release of the investigated eruptions. Based on this analysis, the current capabilities and added value of GOSAT TANSO-FTS to detect and quantify CO2 emissions from explosive volcanism are outlined.

  2. Nano-volcanic Eruption of Silver. (United States)

    Lin, Shih-Kang; Nagao, Shijo; Yokoi, Emi; Oh, Chulmin; Zhang, Hao; Liu, Yu-Chen; Lin, Shih-Guei; Suganuma, Katsuaki


    Silver (Ag) is one of the seven metals of antiquity and an important engineering material in the electronic, medical, and chemical industries because of its unique noble and catalytic properties. Ag thin films are extensively used in modern electronics primarily because of their oxidation-resistance. Here we report a novel phenomenon of Ag nano-volcanic eruption that is caused by interactions between Ag and oxygen (O). It involves grain boundary liquation, the ejection of transient Ag-O fluids through grain boundaries, and the decomposition of Ag-O fluids into O2 gas and suspended Ag and Ag2O clusters. Subsequent coating with re-deposited Ag-O and the de-alloying of O yield a conformal amorphous Ag coating. Patterned Ag hillock arrays and direct Ag-to-Ag bonding can be formed by the homogenous crystallization of amorphous coatings. The Ag "nano-volcanic eruption" mechanism is elaborated, shedding light on a new mechanism of hillock formation and new applications of amorphous Ag coatings.

  3. Mantle updrafts and mechanisms of oceanic volcanism (United States)

    Anderson, Don L.; Natland, James H.


    Convection in an isolated planet is characterized by narrow downwellings and broad updrafts-consequences of Archimedes' principle, the cooling required by the second law of thermodynamics, and the effect of compression on material properties. A mature cooling planet with a conductive low-viscosity core develops a thick insulating surface boundary layer with a thermal maximum, a subadiabatic interior, and a cooling highly conductive but thin boundary layer above the core. Parts of the surface layer sink into the interior, displacing older, colder material, which is entrained by spreading ridges. Magma characteristics of intraplate volcanoes are derived from within the upper boundary layer. Upper mantle features revealed by seismic tomography and that are apparently related to surface volcanoes are intrinsically broad and are not due to unresolved narrow jets. Their morphology, aspect ratio, inferred ascent rate, and temperature show that they are passively responding to downward fluxes, as appropriate for a cooling planet that is losing more heat through its surface than is being provided from its core or from radioactive heating. Response to doward flux is the inverse of the heat-pipe/mantle-plume mode of planetary cooling. Shear-driven melt extraction from the surface boundary layer explains volcanic provinces such as Yellowstone, Hawaii, and Samoa. Passive upwellings from deeper in the upper mantle feed ridges and near-ridge hotspots, and others interact with the sheared and metasomatized surface layer. Normal plate tectonic processes are responsible both for plate boundary and intraplate swells and volcanism.

  4. Forecasting volcanic explosions based on seismic quiescence (United States)

    Roman, D.; La Femina, P.; Rodgers, M.; Geirsson, H.; Tenorio, V.


    Volcanic eruptions are generally forecast based on strong increases in monitoring parameters such as seismicity or gas emissions above a relatively low background level. Because of this, forecasting individual explosions during an ongoing eruption, or at persistently restless volcanoes, is difficult as seismicity, gas emissions, and other indicators of unrest are already in a heightened state. Therefore, identification of short-term precursors to individual explosions at volcanoes already in heightened states of unrest, and an understanding of explosion trigger mechanisms, is important for the reduction of volcanic risk worldwide. Seismic and visual observations at Telica Volcano, Nicaragua, demonstrate that a) episodes of seismic quiescence reliably preceded explosions during an eruption in May 2011 and b) the duration of precursory quiescence and the energy released in the ensuing explosion were strongly correlated. Precursory seismic quiescence is interpreted as the result of sealing of shallow gas pathways, leading to pressure accumulation and eventual catastrophic failure of the system, culminating in an explosion. Longer periods of sealing and pressurization lead to greater energy release in the ensuing explosion. Near-real-time observations of seismic quiescence at restless or erupting volcanoes can thus be useful for both timely eruption warnings and for forecasting the energy of impending explosions.

  5. The scientific management of volcanic crises (United States)

    Marzocchi, Warner; Newhall, Christopher; Woo, Gordon


    Sound scientific management of volcanic crises is the primary tool to reduce significantly volcanic risk in the short-term. At present, a wide variety of qualitative or semi-quantitative strategies is adopted, and there is not yet a commonly accepted quantitative and general strategy. Pre-eruptive processes are extremely complicated, with many degrees of freedom nonlinearly coupled, and poorly known, so scientists must quantify eruption forecasts through the use of probabilities. On the other hand, this also forces decision-makers to make decisions under uncertainty. We review the present state of the art in this field in order to identify the main gaps of the existing procedures. Then, we put forward a general quantitative procedure that may overcome the present barriers, providing guidelines on how probabilities may be used to take rational mitigation actions. These procedures constitute a crucial link between science and society; they can be used to establish objective and transparent decision-making protocols and also clarify the role and responsibility of each partner involved in managing a crisis.

  6. Payenia volcanic province, southern Mendoza, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina; Holm, Paul Martin; Llambias, Eduardo Jorge


    to the low thickness of the lithospheric mantle and preheating of the lower crust by earlier Mio-Pliocene volcanism. Rare earth element modelling of mantle melting calls for enriched source compositions and a beginning of melting within the garnet stability field for all Payenia basalts. The Río Colorado......The Pleistocene to Holocene Payenia volcanic province is a backarc region of 60,000 km2 in Mendoza, Argentina, which is dominated by transitional to alkaline basalts and trachybasalts. We present major and trace element compositions of 139 rocks from this area of which the majority are basaltic...... rocks with 4 to 12 wt.% MgO and 44 to 50 wt.% SiO2. The southern Payenia province is dominated by intraplate basalts and the trace element patterns of the Río Colorado and Payún Matrú lavas suggest little or no influence from subducted slab components. The mantle source of these rocks is similar to some...

  7. A great volcanic eruption around AD 1300 recorded in lacustrine ...

    Indian Academy of Sciences (India)

    Hekla, Iceland, 1341. Note: We referred to Lavigne et al. (2013) for the AD 1257 Samalas volcanic eruption. in eolian dust (Liu et al. 2014). Thus, the Sr and Nd isotope values clearly show that volcanic ash is the primary contributor of the Ti, Al and. Fe2O3 content anomaly at ∼AD 1300. Isotope com- position analysis is ...

  8. Monitoring gas emissions can help forecast volcanic eruptions (United States)

    Kern, Christoph; Maarten de Moor,; Bo Galle,


    As magma ascends in active volcanoes, dissolved volatiles partition from melt into a gas phase, rise, and are released into the atmosphere from volcanic vents. The major components of high-temperature volcanic gas are typically water vapor, carbon dioxide, and sulfur dioxide. 

  9. Abiogenic Organic Polymers in Products of Modern Volcanism

    Directory of Open Access Journals (Sweden)

    V. I. Silaev


    Full Text Available For the first time, the particles of organic polymers have been found in the products of modern volcanism in Kamchatka. They are probably of abiotic origin, which makes it possible to interpret the results of studies from the perspective of volcanic-atmospheric-oceanic hypothesis about the origin of life on the Earth by A. I. Oparin–J. Haldane.

  10. geochemistry of the potassic basalts from the bufumbira volcanic

    African Journals Online (AJOL)


    ABSTRACT. Bufumbira volcanic field is the southernmost of the four Ugandan small Pleistocene to Recent volcanic fields within the western branch of the East African rift system. The rocks consist of silica undersaturated and vesicular basalts with numerous primary structures. The rocks consist of basanites, leucitites ...

  11. Explosive Volcanic Activity at Extreme Depths: Evidence from the Charles Darwin Volcanic Field, Cape Verdes (United States)

    Kwasnitschka, T.; Devey, C. W.; Hansteen, T. H.; Freundt, A.; Kutterolf, S.


    Volcanic eruptions on the deep sea floor have traditionally been assumed to be non-explosive as the high-pressure environment should greatly inhibit steam-driven explosions. Nevertheless, occasional evidence both from (generally slow-) spreading axes and intraplate seamounts has hinted at explosive activity at large water depths. Here we present evidence from a submarine field of volcanic cones and pit craters called Charles Darwin Volcanic Field located at about 3600 m depth on the lower southwestern slope of the Cape Verdean Island of Santo Antão. We examined two of these submarine volcanic edifices (Tambor and Kolá), each featuring a pit crater of 1 km diameter, using photogrammetric reconstructions derived from ROV-based imaging followed by 3D quantification using a novel remote sensing workflow, aided by sampling. The measured and calculated parameters of physical volcanology derived from the 3D model allow us, for the first time, to make quantitative statements about volcanic processes on the deep seafloor similar to those generated from land-based field observations. Tambor cone, which is 2500 m wide and 250 m high, consists of dense, probably monogenetic medium to coarse-grained volcaniclastic and pyroclastic rocks that are highly fragmented, probably as a result of thermal and viscous granulation upon contact with seawater during several consecutive cycles of activity. Tangential joints in the outcrops indicate subsidence of the crater floor after primary emplacement. Kolá crater, which is 1000 m wide and 160 m deep, appears to have been excavated in the surrounding seafloor and shows stepwise sagging features interpreted as ring fractures on the inner flanks. Lithologically, it is made up of a complicated succession of highly fragmented deposits, including spheroidal juvenile lapilli, likely formed by spray granulation. It resembles a maar-type deposit found on land. The eruption apparently entrained blocks of MORB-type gabbroic country rocks with

  12. Detection and Classification of Volcanic Earthquakes/Tremors in Central Anatolian Volcanic Province (United States)

    Kahraman, Metin; Arda Özacar, A.; Bülent Tank, S.; Uslular, Göksu; Kuşcu, Gonca; Türkelli, Niyazi


    Central Anatolia has been characterized by active volcanism since 10 Ma which created the so called Central Anatolia Volcanic Province (CAVP) where a series of volcanoes are located along the NE-SW trend. The petrological investigations reveal that the magma source in the CAVP has both subduction and asthenospheric signature possibly due to tearing of ongoing northward subduction of African plate along Aegean and Cyprus arcs. Recently, a temporary seismic array was deployed within the scope of Continental Dynamics: Central Anatolian Tectonics (CD-CAT) project and provided a unique opportunity to study the deep seismic signature of the CAVP. Passive seismic imaging efforts and magnetotellurics (MT) observations revealed low velocity and high conductivity zones supporting the presence of localized partial melt bodies beneath the CAVP at varying depths, especially around Mt. Hasan which exhibits both geological and archeological evidences for its eruption around 7500 B.C. In Central Anatolia, local seismicity detected by the CD-CAT array coincides well with the active faults zones. However, active or potentially active volcanoes within CAVP are characterized by the lack of seismic activity. In this study, seismic data recorded by permanent stations of Regional Earthquake-Tsunami Monitoring Center were combined with temporary seismic data collected by the CD-CAT array to improve sampling density across the CAVP. Later, the continuous seismic waveforms of randomly selected time intervals were manually analyzed to identify initially undetected seismic sources which have signal characters matching to volcanic earthquakes/tremors. For candidate events, frequency spectrums are constructed to classify the sources according to their physical mechanisms. Preliminary results support the presence of both volcano-tectonic (VT) and low-period (LT) events within the CAVP. In the next stage, the spectral and polarization analyses techniques will be utilized to the entire seismic

  13. Correlating geochemistry, tectonics, and volcanic volume along the Central American volcanic front (United States)

    Bolge, Louise L.; Carr, Michael J.; Milidakis, Katherine I.; Lindsay, Fara N.; Feigenson, Mark D.


    The Central American volcanic front consists of several distinct volcanic lineaments or segments, separated by right steps and/or changes in strike. Each volcanic line is rotated slightly counterclockwise from the strike of the inclined seismic zone. Right stepping volcanic lines, oblique to the strike of the slab, create a sawtooth pattern in the depth to the slab. Zr/Nb is the first geochemical signature with consistent large offsets at the right steps in the volcanic front. Moreover, Zr/Nb mirrors the sawtooth variation in depth to the slab; within a segment it increases from SE to NW, and at the right steps, separating segments, it abruptly decreases. Unfortunately, there is no simple negative correlation between Zr/Nb and depth to the slab because Zr/Nb also has a regional variation, similar to previously documented regional variations in slab tracers in Central America (e.g., Ba/La, U/Th, and 87Sr/86Sr). Within a segment, Zr/Nb decreases with increasing depth to slab. This can be explained in two ways: a Nb retaining mineral, e.g., amphibole, in the subducting slab is breaking down gradually with increasing depth causing more Nb to be released and consequently a smaller Nb depletion in deeper melts; alternatively, all melts have the same initial Nb depletion which is then diluted by acquiring Nb from the surrounding mantle wedge as melts rise and react. Deeper melts have longer paths and therefore more reaction with the mantle wedge diluting the initial Nb depletion. Within each volcanic segment there is variation in eruptive volume. The largest volcanoes generally occur in the middle of the segments, and the smaller volcanoes tend to be located at the ends. Connecting the largest volcanoes in each segment suggests an axis of maximum productivity. This is likely the surface projection of the center of the melt aggregation zone. The largest volcanoes tap the entire melt zone. Those with shallow depths to the slab tap just the front part of the melt zone and

  14. Ash production by attrition in volcanic conduits and plumes. (United States)

    Jones, T J; Russell, J K


    Tephra deposits result from explosive volcanic eruption and serve as indirect probes into fragmentation processes operating in subsurface volcanic conduits. Primary magmatic fragmentation creates a population of pyroclasts through volatile-driven decompression during conduit ascent. In this study, we explore the role that secondary fragmentation, specifically attrition, has in transforming primary pyroclasts upon transport in volcanic conduits and plumes. We utilize total grain size distributions from a suite of natural and experimentally produced tephra to show that attrition is likely to occur in all explosive volcanic eruptions. Our experimental results indicate that fine ash production and surface area generation is fast (eruption column stability, tephra dispersal, aggregation, volcanic lightening generation, and has concomitant effects on aviation safety and Earth's climate.

  15. Distinguishing high surf from volcanic long-period earthquakes (United States)

    Lyons, John; Haney, Matt; Fee, David; Paskievitch, John F.


    Repeating long-period (LP) earthquakes are observed at active volcanoes worldwide and are typically attributed to unsteady pressure fluctuations associated with fluid migration through the volcanic plumbing system. Nonvolcanic sources of LP signals include ice movement and glacial outburst floods, and the waveform characteristics and frequency content of these events often make them difficult to distinguish from volcanic LP events. We analyze seismic and infrasound data from an LP swarm recorded at Pagan volcano on 12–14 October 2013 and compare the results to ocean wave data from a nearby buoy. We demonstrate that although the events show strong similarity to volcanic LP signals, the events are not volcanic but due to intense surf generated by a passing typhoon. Seismo-acoustic methods allow for rapid distinction of volcanic LP signals from those generated by large surf and other sources, a critical task for volcano monitoring.

  16. Radon levels in the volcanic region of La Garrotxa, Spain

    Energy Technology Data Exchange (ETDEWEB)

    Baixeras, C. [Grup de Fisica de les Radiacions. Edifici Cc, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)]. E-mail:; Bach, J. [Unitat de Geodinamica Externa. Departament de Geologia. Edifici Cs, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Amgarou, K. [Grup de Fisica de les Radiacions. Edifici Cc, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Moreno, V. [Grup de Fisica de les Radiacions. Edifici Cc, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Font, Ll. [Grup de Fisica de les Radiacions. Edifici Cc, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)


    A preliminary survey in the city of Olot, the main town of the volcanic region of La Garrotxa, showed that dwellings built on volcanic formations present higher indoor radon levels than dwellings on non-volcanic materials. The soil of the area is not especially rich in radium. However, some of the volcanic materials present very high permeability and therefore radon entering the houses might have travelled over long distances. In this paper we present indoor radon values measured in a larger survey carried out during April-July 2004. The influence of the volcanic materials found in the preliminary survey has been confirmed. The results obtained suggest the possibility that radon comes from the degassification of mantle through active faults. The values obtained in working places do not constitute a relevant radiological risk for workers.

  17. Miocene to quaternary volcanism in eastern Kenya: Sequence and geochronology (United States)

    Brotzu, P.; Morbidelli, L.; Nicoletti, M.; Piccirillo, E. M.; Traversa, G.


    This paper presents the results of the first systematic geochronological study of widespread volcanic sequences in the region east of the Kenya Rift Valley between the Nyambeni Hills near the equator and the Hurri Hills-Dukana area close to the Ethiopian border. Volcanic activity in this area developed from Upper Miocene to Quaternary. Miocene activity (12-5 m.y.) was of fissure-type while the Plio-Quaternary volcanism was mainly of central type. This last volcanism occurred from early Pliocene (4.5 m.y.) to Recent (0.5 m.y.). The products of the two volcanic phases can be distinguished also from a compositional point of view. Previous stratigraphical interpretations are discussed on the basis of field and laboratory evidence.

  18. Volcanism on Io: New insights from global geologic mapping (United States)

    Williams, David A.; Keszthelyi, Laszlo P.; Crown, David A.; Yff, Jessica A.; Jaeger, Windy L.; Schenk, Paul M.; Geissler, Paul E.; Becker, Tammy L.


    bright flows are bright because they are sulfur flows, or because they are cold silicate flows covered in sulfur-rich particles from plume fallout. (3) We mapped 425 paterae (volcano-tectonic depressions), up from 417 previously identified by Radebaugh et al. (Radebaugh, J., Keszthelyi, L.P., McEwen, A.S., Turtle, E.P., Jaeger, W., Milazzo, M. [2001]. J. Geophys. Res. 106, 33005-33020). Although these features cover only 2.5% of Io's surface, they correspond to 64% of all detected hot spots; 45% of all hot spots are associated with the freshest dark patera floors, reflecting the importance of active silicate volcanism to Io's heat flow. (4) Mountains cover only ˜3% of the surface, although the transition from mountains to plains is gradational with the available imagery. 49% of all mountains are lineated and presumably layered, showing evidence of linear structures supportive of a tectonic origin. In contrast, only 6% of visible mountains are mottled (showing hummocks indicative of mass wasting) and 4% are tholi (domes or shields), consistent with a volcanic origin. (5) Initial analyses of the geographic distributions of map units show no significant longitudinal variation in the quantity of Io's mountains or paterae, in contrast to earlier studies. This is because we use the area of mountain and patera materials as opposed to the number of structures, and our result suggests that the previously proposed anti-correlation of mountains and paterae (Schenk, P., Hargitai, H., Wilson, R., McEwen, A., Thomas, P. [2001]. J. Geophys. Res. 106, 33201-33222; Kirchoff, M.R., McKinnon, W.B., Schenk, P.M. [2011]. Earth Planet. Sci. Lett. 301, 22-30) is more complex than previously thought. There is also a slight decrease in surface area of lava flows toward the poles of Io, perhaps indicative of variations in volcanic activity. (6) The freshest bright and dark flows make up about 29% of all of Io's flow fields, suggesting active emplacement is occurring in less than a third of Io

  19. Geochemical and Sr-Nd isotopic characteristics of Upper Cretaceous (calc-alkaline) and Miocene (alkaline) volcanic rocks: Elazığ, Eastern Taurides, Turkey (United States)

    Kürüm, Sevcan; Tanyıldızı, Özge


    The massive volcanic suite of Upper Cretaceous Elazığ Magmatic Complex, and Miocene basic volcanic rocks of crop out to the southern vicinity of Elazığ. The petrographical studies indicated that the massive volcanic suite of Upper Cretaceous are of basalt, spilitic basalt, basaltic andesite, andesite, trachite, dacite/ryolithe and dolerite in composition, and the Miocene volcanic rocks are basalt in composition. According to the geochemical data, which are conformable with the petrographical ones, Upper Cretaceous volcanic rocks are of low and medium-K contaning types and calc-alkalin in general, and enriched with respect to LILE and HREE contents. They also contain low Ti, have negative Nb and Ta anomaly and low 143Nd/147Nd and high 87Sr/86Sr ratios. Geochemical and isotopic data for the massive volcanic suite point out that these volcanic rocks were originated from an upper mantle source (lithospheric) which undergone fractional crystallisation and crustal contamination and enriched by these processes and metasomatized within a subduction zone. Miocene volcanic rocks are of high-K alkaline type, alkali basalt/basanite in composition and products of intraplate volcanism. These rocks are richer in some major oxide contents such as Na2O, K2O, MgO and trace element contents such as Nb, Sr, Zr compared to the massive volcanic rocks of Upper Cretaceous, and they are also enriched with respect to their LILE and HREE contents. The remarkable decrease from LREE towards HREE in the REE/Chondrite-normalized variation diagram indicates a magmatic differentiation process. The MgO and Ni ratios of Miocene volcanic rocks are not conformable with those of primitive basalt composition. However, all the chemical and isotopic (low 87Sr/86Sr ratio and positive (+) εNd values) data indicate that the source magma of these volcanic rocks was derived from a depleted garnet free magma (astenospheric mantle) and was modified once again by the post collosional geodynamical events and

  20. Volcanic sulfur dioxide index and volcanic explosivity index inferred from eruptive volume of volcanoes in Jeju Island, Korea: application to volcanic hazard mitigation (United States)

    Ko, Bokyun; Yun, Sung-Hyo


    Jeju Island located in the southwestern part of Korea Peninsula is a volcanic island composed of lavaflows, pyroclasts, and around 450 monogenetic volcanoes. The volcanic activity of the island commenced with phreatomagmatic eruptions under subaqueous condition ca. 1.8-2.0 Ma and lasted until ca. 1,000 year BP. For evaluating volcanic activity of the most recently erupted volcanoes with reported age, volcanic explosivity index (VEI) and volcanic sulfur dioxide index (VSI) of three volcanoes (Ilchulbong tuff cone, Songaksan tuff ring, and Biyangdo scoria cone) are inferred from their eruptive volumes. The quantity of eruptive materials such as tuff, lavaflow, scoria, and so on, is calculated using a model developed in Auckland Volcanic Field which has similar volcanic setting to the island. The eruptive volumes of them are 11,911,534 m3, 24,987,557 m3, and 9,652,025 m3, which correspond to VEI of 3, 3, and 2, respectively. According to the correlation between VEI and VSI, the average quantity of SO2 emission during an eruption with VEI of 3 is 2-8 × 103 kiloton considering that the island was formed under intraplate tectonic setting. Jeju Island was regarded as an extinct volcano, however, several studies have recently reported some volcanic eruption ages within 10,000 year BP owing to the development in age dating technique. Thus, the island is a dormant volcano potentially implying high probability to erupt again in the future. The volcanoes might have explosive eruptions (vulcanian to plinian) with the possibility that SO2 emitted by the eruption reaches stratosphere causing climate change due to backscattering incoming solar radiation, increase in cloud reflectivity, etc. Consequently, recommencement of volcanic eruption in the island is able to result in serious volcanic hazard and this study provides fundamental and important data for volcanic hazard mitigation of East Asia as well as the island. ACKNOWLEDGMENTS: This research was supported by a grant [MPSS

  1. Real Time Volcanic Cloud Products and Predictions for Aviation Alerts (United States)

    Krotkov, Nickolay A.; Habib, Shahid; da Silva, Arlindo; Hughes, Eric; Yang, Kai; Brentzel, Kelvin; Seftor, Colin; Li, Jason Y.; Schneider, David; Guffanti, Marianne; hide


    Volcanic eruptions can inject significant amounts of sulfur dioxide (SO2) and volcanic ash into the atmosphere, posing a substantial risk to aviation safety. Ingesting near-real time and Direct Readout satellite volcanic cloud data is vital for improving reliability of volcanic ash forecasts and mitigating the effects of volcanic eruptions on aviation and the economy. NASA volcanic products from the Ozone Monitoring Insrument (OMI) aboard the Aura satellite have been incorporated into Decision Support Systems of many operational agencies. With the Aura mission approaching its 10th anniversary, there is an urgent need to replace OMI data with those from the next generation operational NASA/NOAA Suomi National Polar Partnership (SNPP) satellite. The data provided from these instruments are being incorporated into forecasting models to provide quantitative ash forecasts for air traffic management. This study demonstrates the feasibility of the volcanic near-real time and Direct Readout data products from the new Ozone Monitoring and Profiling Suite (OMPS) ultraviolet sensor onboard SNPP for monitoring and forecasting volcanic clouds. The transition of NASA data production to our operational partners is outlined. Satellite observations are used to constrain volcanic cloud simulations and improve estimates of eruption parameters, resulting in more accurate forecasts. This is demonstrated for the 2012 eruption of Copahue. Volcanic eruptions are modeled using the Goddard Earth Observing System, Version 5 (GEOS-5) and the Goddard Chemistry Aerosol and Radiation Transport (GOCART) model. A hindcast of the disruptive eruption from Iceland's Eyjafjallajokull is used to estimate aviation re-routing costs using Metron Aviation's ATM Tools.

  2. Magnetic signature of the Sicily Channel volcanism (United States)

    Lodolo, E.; Civile, D.; Zanolla, C.; Geletti, R.


    Widespread Late Miocene to Quaternary volcanic activity is know to have occurred in the Sicily Channel continuing up to historical time. New magnetic anomaly data acquired in the Pantelleria Graben, one of the three main tectonic depressions forming the WNW-trending Sicily Channel rift system, integrated with available profiles, are used to identify and map volcanic bodies in this sector of the northern African margin. Some of these manifestations, both outcropping at the sea-floor or buried beneath a variable thickness of Plio-Quaternary sedimentary cover, have been imaged by seismic reflection profiles. Three main positive magnetic anomalies have been found: to the S-E of the Pantelleria Island, the largest emerged caldera of the Sicily Channel, along the eastern margin of the Nameless Bank, and at the north-western termination of the Linosa Graben. Only the anomaly located off the south-eastern coast of the Pantelleria Island, associated with a large outcropping body gradually buried beneath a substantially undisturbed Upper Pliocene-Quaternary sediments, aligns with the trend of the tectonic depression. 2-D geophysical models produced along seismic transects perpendicularly crossing the Pantelleria Graben have allowed to derive its deep crustal structure, and detect the presence of buried magmatic bodies which generate the anomalies. Marginal faults seem to have played a major role in focussing magma emplacement in this sector of the Sicily Channel. The other anomalies represent off-axis volcanic episodes and generally do not show evident magmatic manifestations at the sea-floor. These magnetic maxima seem to follow a NNE-SSW-trending belt extending from Linosa Island to the Nameless Bank, where pre-existing crustal anisotropies may have conditioned magma emplacement both at deep and shallow crustal levels. In general, data analysis has shown that there is a structural control on magma emplacement, with the major magmatic features located in specific locations

  3. Numerical modelling of collapsing volcanic edifices (United States)

    Costa, Ana; Marques, Fernando; Kaus, Boris


    The flanks of Oceanic Volcanic Edifice's (OVEs) can occasionally become unstable. If that occurs, they can deform in two different modes: either slowly along localization failure zones (slumps) or catastrophically as debris avalanches. Yet the physics of this process is incompletely understood, and the role of factors such as the OVE's strength (viscosity, cohesion, friction angle), dimensions, geometry, and existence of weak layers remain to be addressed. Here we perform numerical simulations to study the interplay between viscous and plastic deformation on the gravitational collapse of an OVE (diffuse deformation vs. localization of failure along discrete structures). We focus on the contribution of the edifice's strength parameters for the mode of deformation, as well as on the type of basement. Tests were performed for a large OVE (7.5 km high, 200 km long) and either purely viscous (overall volcano edifice viscosities between 1019-1023 Pa.s), or viscoplastic rheology (within a range of cohesion and friction angle values). Results show that (a) for a strong basement (no slip basal boundary condition), the deformation pattern suggests wide/diffuse "listric" deformation within the volcanic edifice, without the development of discrete plastic failure zones; (b) for a weak basement (free slip basal boundary condition), rapid collapse of the edifice through the propagation of plastic failure structures within the edifice occurs. Tests for a smaller OVE (4.5 km by 30 km) show that failure localization along large-scale listric structures occurs more readily for different combinations of cohesion and friction angles. In these tests, high cohesion values combined with small friction angles lead to focusing of deformation along a narrower band. Tests with a weak layer underlying part of the volcanic edifice base show deformation focused along discrete structures mainly dipping towards the distal sector of the volcano. These tests for a small OVE constitute a promising

  4. Geology of the Mid-Miocene Rooster Comb Caldera and Lake Owyhee Volcanic Field, eastern Oregon: Silicic volcanism associated with Grande Ronde flood basalt (United States)

    Benson, Thomas R.; Mahood, Gail A.


    The Lake Owyhee Volcanic Field (LOVF) of eastern Oregon consists of rhyolitic caldera centers and lava fields contemporaneous with and spatially related to Mid-Miocene Columbia River flood basalt volcanism. Previous studies delineated two calderas in the southeastern part of LOVF near Owyhee Reservoir, the result of eruptions of two ignimbrites, the Tuff of Leslie Gulch and the Tuff of Spring Creek. Our new interpretation is that these two map units are differentially altered parts of a single ignimbrite produced in a major phreatomagmatic eruption at ~ 15.8 Ma. Areas previously mapped as Tuff of Spring Creek are locations where the ignimbrite contains abundant clinoptilolite ± mordenite, which made it susceptible to erosion. The resistant intracaldera Tuff of Leslie Gulch has an alteration assemblage of albite ± quartz, indicative of low-temperature hydrothermal alteration. Our new mapping of caldera lake sediments and pre- and post-caldera rhyolitic lavas and intrusions that are chemically similar to intracaldera Tuff of Leslie Gulch point to a single ~ 20 × 25 km caldera, which we name the Rooster Comb Caldera. Erosion of the resurgently uplifted southern half of the caldera created dramatic exposures of intracaldera Tuff of Leslie Gulch cut by post-caldera rhyolite dikes and intrusions that are the deeper-level equivalents of lava domes and flows that erupted into the caldera lake preserved in exposures to the northeast. The Rooster Comb Caldera has features in common with more southerly Mid-Miocene calderas of the McDermitt Volcanic Field and High Rock Caldera Complex, including formation in a basinal setting shortly after flood basalt eruptions ceased in the region, and forming on eruption of peralkaline ignimbrite. The volcanism at Rooster Comb Caldera postdates the main activity at McDermitt and High Rock, but, like it, begins ~ 300 ky after flood basalt volcanism begins in the area, and while flood basalts don't erupt through the silicic focus, are

  5. Volcanism Studies: Final Report for the Yucca Mountain Project

    Energy Technology Data Exchange (ETDEWEB)

    Bruce M. Crowe; Frank V. Perry; Greg A. Valentine; Lynn M. Bowker


    This report synthesizes the results of volcanism studies conducted by scientists at the Los Alamos National Laboratory and collaborating institutions on behalf of the Department of Energy's Yucca Mountain Project. An assessment of the risk of future volcanic activity is one of many site characterization studies that must be completed to evaluate the Yucca Mountain site for potential long-term storage of high-level radioactive waste. The presence of several basaltic volcanic centers in the Yucca Mountain region of Pliocene and Quaternary age indicates that there is a finite risk of a future volcanic event occurring during the 10,000-year isolation period of a potential repository. Chapter 1 introduces the volcanism issue for the Yucca Mountain site and provides the reader with an overview of the organization, content, and significant conclusions of this report. The risk of future basaltic volcanism is the primary topic of concern including both events that intersect a potential repository and events that occur near or within the waste isolation system of a repository. Future volcanic events cannot be predicted with certainty but instead are estimated using formal methods of probabilistic volcanic hazard assessment (PVHA). Chapter 2 describes the volcanic history of the Yucca Mountain region (YMR) and emphasizes the Pliocene and Quaternary volcanic record, the interval of primary concern for volcanic risk assessment. The distribution, eruptive history, and geochronology of Plio-Quaternary basalt centers are described by individual center emphasizing the younger postcaldera basalt (<5 Ma). The Lathrop Wells volcanic center is described in detail because it is the youngest basalt center in the YMR. The age of the Lathrop Wells center is now confidently determined to be about 75 thousand years old. Chapter 3 describes the tectonic setting of the YMR and presents and assesses the significance of multiple alternative tectonic models. The Crater Flat volcanic zone is

  6. Airborne magnetic mapping of volcanic areas - state-of-the-art and future perspectives (United States)

    Supper, Robert; Paoletti, Valeria; Okuma, Shigeo


    Traditionally airborne magnetics surveys in volcanology are used for mapping regional geological features, fault zones and to develop a magnetic model of the volcanic subsurface. Within an Austrian-Italian-Japanese cooperation, several volcanic areas including Mt. Vesuvius, Ischia, Campi Flegreii and Aeolian Islands in Italy and Socorro Island in Mexico were mapped by high-resolution magnetic mapping during the last 15 years. In this paper, general conclusions from this long-term cooperation project on airborne magnetics in volcanic areas will be summarised. Basically the results showed the results from airborne magnetics could be used for three major purposes: 1. Developing a rough model for the magnetisation below the volcano down to several kilometres by applying advanced magnetic inversion algorithms helped to define the possible depth of the current or past magma chamber. Due to the complexity of the subsurface of volcanic areas, inversion of data was much dependent on constraints coming from other geoscientific disciplines. 2. After applying certain steps of reduction (topographic correction, field transformation) and a combination of source selective filtering, important regional structural trends could be derived from the alignment of the residual magnetic anomalies. 3. On the other hand during recent years, research has also focused on repeated measurements of the magnetic field of volcanic areas (differential in respect of time = differential magnetic measurements - DMM) using airborne sensors. Long-term temporal magnetic field variations in active volcanic areas can be caused by a changing size of the magma chamber or a general rise in temperature. This is caused by the fact that magnetization disappears, when a magnetic material is warmed up over a certain temperature (Curie- temperature). In consequence the resulting total magnetic field changes. Therefore, determining areas showing changes in the magnetic field could help to select areas where a

  7. Testing exposure of a jet engine to a dilute volcanic-ash cloud (United States)

    Guffanti, M.; Mastin, L. G.; Schneider, D. J.; Holliday, C. R.; Murray, J. J.


    An experiment to test the effects of volcanic-ash ingestion by a jet engine is being planned for 2014 by a consortium of U.S. Government agencies and engine manufacturers, under the auspices of NASA's Vehicle Integrated Propulsion Research Program. The experiment, using a 757-type engine, will be an on-ground, on-wing test carried out at Edwards Air Force Base, California. The experiment will involve the use of advanced jet-engine sensor technology for detecting and diagnosing engine health. A primary test objective is to determine the effect on the engine of many hours of exposure to ash concentrations (1 and 10 mg/cu m) representative of ash clouds many 100's to >1000 km from a volcanic source, an aviation environment of great interest since the 2010 Eyjafjallajökull, Iceland, eruption. A natural volcanic ash will be used; candidate sources are being evaluated. Data from previous ash/aircraft encounters, as well as published airborne measurements of the Eyjafjallajökull ash cloud, suggest the ash used should be composed primarily of glassy particles of andesitic to rhyolitic composition (SiO2 of 57-77%), with some mineral crystals, and a few tens of microns in size. Collected ash will be commercially processed less than 63 microns in size with the expectation that the ash particles will be further pulverized to smaller sizes in the engine during the test. For a nominally planned 80 hour test at multiple ash-concentration levels, the test will require roughly 500 kg of processed (appropriately sized) ash to be introduced into the engine core. Although volcanic ash clouds commonly contain volcanic gases such as sulfur dioxide, testing will not include volcanic gas or aerosol interactions as these present complex processes beyond the scope of the planned experiment. The viscous behavior of ash particles in the engine is a key issue in the experiment. The small glassy ash particles are expected to soften in the engine's hot combustion chamber, then stick to cooler

  8. The VUELCO project consortium: new interdisciplinary research for improved risk mitigation and management during volcanic unrest (United States)

    Gottsmann, J.


    Volcanic unrest is a complex multi-hazard phenomenon of volcanism. The fact that unrest may, but not necessarily must lead to an imminent eruption contributes significant uncertainty to short-term hazard assessment of volcanic activity world-wide. Although it is reasonable to assume that all eruptions are associated with precursory activity of some sort, the knowledge of the causative links between subsurface processes, resulting unrest signals and imminent eruption is, today, inadequate to deal effectively with crises of volcanic unrest. This results predominantly from the uncertainties in identifying the causative processes of unrest and as a consequence in forecasting its short-term evolution. However, key for effective risk mitigation and management during unrest is the early and reliable identification of changes in the subsurface dynamics of a volcano and their assessment as precursors to an impending eruption. The VUELCO project consortium has come together for a multi-disciplinary attack on the origin, nature and significance of volcanic unrest from the scientific contributions generated by collaboration of ten partners in Europe and Latin America. Dissecting the science of monitoring data from unrest periods at six type volcanoes in Italy, Spain, the West Indies, Mexico and Ecuador the consortium will create global strategies for 1) enhanced monitoring capacity and value, 2) mechanistic data interpretation and 3) identification of reliable eruption precursors; all from the geophysical, geochemical and geodetic fingerprints of unrest episodes. Experiments will establish a mechanistic understanding of subsurface processes capable of inducing unrest and aid in identifying key volcano monitoring parameters indicative of the nature of unrest processes. Numerical models will help establish a link between the processes and volcano monitoring data to inform on the causes of unrest and its short-term evolution. Using uncertainty assessment and new short

  9. Volcanic hazard assessment for the Canary Islands (Spain using extreme value theory

    Directory of Open Access Journals (Sweden)

    R. Sobradelo


    Full Text Available The Canary Islands are an active volcanic region densely populated and visited by several millions of tourists every year. Nearly twenty eruptions have been reported through written chronicles in the last 600 yr, suggesting that the probability of a new eruption in the near future is far from zero. This shows the importance of assessing and monitoring the volcanic hazard of the region in order to reduce and manage its potential volcanic risk, and ultimately contribute to the design of appropriate preparedness plans. Hence, the probabilistic analysis of the volcanic eruption time series for the Canary Islands is an essential step for the assessment of volcanic hazard and risk in the area. Such a series describes complex processes involving different types of eruptions over different time scales. Here we propose a statistical method for calculating the probabilities of future eruptions which is most appropriate given the nature of the documented historical eruptive data. We first characterize the eruptions by their magnitudes, and then carry out a preliminary analysis of the data to establish the requirements for the statistical method. Past studies in eruptive time series used conventional statistics and treated the series as an homogeneous process. In this paper, we will use a method that accounts for the time-dependence of the series and includes rare or extreme events, in the form of few data of large eruptions, since these data require special methods of analysis. Hence, we will use a statistical method from extreme value theory. In particular, we will apply a non-homogeneous Poisson process to the historical eruptive data of the Canary Islands to estimate the probability of having at least one volcanic event of a magnitude greater than one in the upcoming years. This is done in three steps: First, we analyze the historical eruptive series to assess independence and homogeneity of the process. Second, we perform a Weibull analysis of the

  10. The San Franciscan volcanic field, Arizona (United States)

    Robinson, Henry Hollister


    LOCATION OF AREAThe San Franciscan volcanic field, which takes its name from San Francisco Mountain, the largest volcano of the group, covers about 3,000 square miles in the north-central part of Arizona, as shown by the shaded space on the index map forming figure 1. The center of the field lies about 50 miles south of the Grand Canyon of the Colorado and the southern boundary is in part coterminous with that of the San Francisco Plateau, which forms the southwestern division of the great Colorado Plateau.The region is easily reached, for the main line of the Atchison, Topeka, & Santa Fe Railway traverses it from east to west for more than 60 miles. Flagstaff, a town of 1,500 inhabitants 10 miles south of the summit of San Francisco Mountain, is on the railroad, amid a branch line runs from Williams, 34 miles farther west, to the Grand Canyon. All the more important points of interest in the field may be reached without difficulty by wagon, and outfits may be obtained at Flagstaff.OUTLINE OF THE REPORTThis report deals primarily with the volcanic phenomena of the region as determined in the field and laboratory. Chapter I contains a brief description of the geography of the field and Chapter II is devoted largely to the sedimentary formations and structure. The rest of the report Chapters III to VI—treats entirely of the various features of the volcanoes and igneous rocks, both individually and collectively. Detailed descriptions of the volcanoes and lava fields are given in Chapter III; the volcanic history of the region and its correlation with the general history of the surrounding country are presented in Chapter IV. These two chapters will presumably suffice for the general reader who may desire to become acquainted with the broader volcanic features of the region. Chapter V (Petrography) is devoted entirely to the detailed description of the individual igneous rocks of the region, as represented by a selected set of type specimens. In Chapter VI (Petrology

  11. A Geochemical Investigation of Volcanic Rocks from the San Rafael Volcanic Field, Utah (United States)

    Koebli, D. J.; Germa, A.; Connor, C.; Atlas, Z. D.


    A Geochemical Investigation of Volcanic Rocks from the San Rafael Volcanic Field, Utah Authors: Danielle Koebli, Dr. Aurelie Germa, Dr. Zackary Atlas, Dr. Charles Connor The San Rafael Volcanic Field (SRVF), Utah, is a 4Ma volcanic field located in the northwestern section of the Colorado Plateau. Alkaline magmas intruded into Jurassic sandstones , known as the Carmel, Entrada, Curtis and Summerville sandstone formations, and formed comagmatic dikes, sills and conduits that became uniquely well exposed as country rocks were eroded. The two rock types that formed from the melts are shonkinite (45.88 wt% SiO2) and syenite (50.84wt% SiO2); with dikes being predominantly shonkinite and sills exhibiting vertical alternation of shonkinite and syenite, a result of liquid immiscibility. The aim of this study is to determine magma temperatures, and mineral compositions which will be used for determining physical conditions for magma crystallization. Research is being conducted using an Electron Probe Micro Analyzer (EPMA) for single crystal analysis, and data were plotted using PINGU software through VHub cyberinfrastructure. EPMA data supports hydrated magma theories due to the large amounts of biotite and hornblende mixed in with olivine, feldspar and pyroxene. The data is also indicative of a calcium-rich magma which is further supported by the amount of pyroxene and plagioclase in the sample. Moreover, there are trace amounts orthoclase, quartz and k-feldspar due to sandstone inclusions from the magma intruding into the country rocks. The olivine crystals present in the samples are all chemically similar, having high Mg (Fo80-Fo90), which, coupled with a lower Fe content indicate a hotter magma. Comparison of mineral and whole-rock compositions using MELTs program will allow us to calculate magma viscosity and density so that the physical conditions for magma crystallization can be determined.

  12. Inside the volcanic boiler room: knowledge exchange among stakeholders of volcanic unrest (United States)

    Gottsmann, Joachim; Christie, Ryerson; Bretton, Richard


    The knowledge of the causative links between subsurface processes, resulting monitoring signals and imminent eruption is incomplete. As a consequence, hazard assessment and risk mitigation strategies are subject to uncertainty. Discussion of unrest and pre-eruptive scenarios with uncertain outcomes are central during the discourse between a variety of stakeholders in volcanic unrest including scientists, emergency managers, policy makers and the public. Drawing from research within the EC FP7 VUELCO project, we argue that knowledge exchange amongst the different stakeholders of volcanic unrest evolves along three dimensions: 1) the identification of knowledge holders (including local communities) and their needs and expectations, 2) vehicles of communication and 3) trust. In preparing products that feed into risk assessment and management, scientists need to ensure that their deliverables are timely, accurate, clear, understandable and cater to the expectations of emergency managers. The means and content of communication amongst stakeholders need to be defined and adhered to. Finally, efficient and effective interaction between stakeholders is ideally based on mutual trust between those that generate knowledge and those that receive knowledge. For scientists, this entails contextualising volcanic hazard and risk in the framework of environmental and social values. Periods of volcanic quiescence are ideally suited to test established protocols of engagement between stakeholders in preparation for crises situations. The different roles of stakeholders and associated rules of engagement can be scrutinised and reviewed in antecessum rather than ad-hoc during a crisis situation to avoid issues related to distrust, loss of credibility and overall poor risk management. We will discuss these themes drawing from exploitation of research results from Mexico and Ecuador.

  13. Holocene Volcanic Records in the Siple Dome Ice Cores (United States)

    Zielinski, G. A.; Dunbar, N. W.; Kurbatov, A. V.; Voisin, D. T.


    Using both the SO42- and Cl- time series and tephrochronological analyses, a highly detailed record of Holocene volcanism is being reconstructed from the Siple Dome A ice core. The volcanic glaciochemical record is being developed at a 2-4 year resolution for the last 10,000 years. Volcanic peaks were identified as those having a concentration of 2{σ } above the mean positive residual of the spline fit, as was done for the GISP2 volcanic record. We identified about 70 volcanic events for the mid-late Holocene. The largest sulfate signal (350 ppb) over the time period evaluated occurs at 2242 years ago. Large signals of volcanically enhanced sulfate in the ice core record also occur around 720 years ago (1280 C.E.;194-249 ppb)and 4710 years ago (378ppb). Ages for large equatorial or southern hemisphere volcanic eruptions are synchronous with identified sulfate peaks in the reconstructed volcanic record. However, the continuous scan for volcanic glass in these same samples yielded glass compositions more in-line with Antarctica volcanic zones (i.e., local eruptions). Nevertheless, our record provides important information on the atmospheric impact of volcanism in Antarctica geochemical cycles. The glass (i.e., tephra) found in various samples indicate that volcanoes within the McMurdo Volcanic Center (Victoria Land and the islands off its coast) including Mt. Melbourne, The Pleaides and Buckle Island appear to be the most active in Antarctica during the late Holocene. Rhyolitic shards of a composition not found in Antarctica also are present in some layers, although they are not overly abundant. The presence of dust with a Patagonian origin in East Antarctica ice cores as well as the nature of the Antarctica vortex indicate that material from this part of the southern hemisphere can reach various parts of Antarctica. Common circulation patterns around the Ross and Amundson Seas as well as the satellite trace of aerosols from the 1991 Cerro Hudson eruption, Argentina

  14. Detecting Volcanic Ash Plumes with GNSS Signals (United States)

    Rainville, N.; Larson, K. M.; Palo, S. E.; Mattia, M.; Rossi, M.; Coltelli, M.; Roesler, C.; Fee, D.


    Global Navigation Satellite Systems (GNSS) receivers are commonly placed near volcanic sites to measure ground deformation. In addition to the carrier phase data used to measure ground position, these receivers also record Signal to Noise ratio (SNR) data. Larson (2013) showed that attenuations in SNR data strongly correlate with ash emissions at a series of eruptions of Redoubt Volcano. This finding has been confirmed at eruptions for Tongariro, Mt Etna, Mt Shindake, and Sakurajima. In each of these detections, very expensive geodetic quality GNSS receivers were used. If low-cost GNSS instruments could be used instead, a networked array could be deployed and optimized for plume detection and tomography. The outputs of this sensor array could then be used by both local volcanic observatories and Volcano Ash Advisory Centers. Here we will describe progress in developing such an array. The sensors we are working with are intended for navigation use, and thus lack the supporting power and communications equipment necessary for a networked system. Reliably providing those features is major challenge for the overall sensor design. We have built prototypes of our Volcano Ash Plume Receiver (VAPR), with solar panels, lithium-ion batteries and onboard data storage for preliminary testing. We will present results of our field tests of both receivers and antennas. A second critical need for our array is a reliable detection algorithm. We have tested our algorithm on data from recent eruptions and have incorporated the noise characteristics of the low-cost GNSS receiver. We have also developed a simulation capability so that the receivers can be deployed to optimize vent crossing GNSS signals.

  15. Professional conduct of scientists during volcanic crises (United States)

    IAVCEI SubcommitteeCrisis Protocols; Newhall, Chris; Aramaki, Shigeo; Barberi, Franco; Blong, Russell; Calvache, Marta; Cheminee, Jean-Louis; Punongbayan, Raymundo; Siebe, Claus; Simkin, Tom; Sparks, Stephen; Tjetjep, Barry; Newhall, Chris

    Stress during volcanic crises is high, and any friction between scientists can distract seriously from both humanitarian and scientific effort. Friction can arise, for example, if team members do not share all of their data, if differences in scientific interpretation erupt into public controversy, or if one scientist begins work on a prime research topic while a colleague with longer-standing investment is still busy with public safety work. Some problems arise within existing scientific teams; others are brought on by visiting scientists. Friction can also arise between volcanologists and public officials. Two general measures may avert or reduce friction: (a) National volcanologic surveys and other scientific groups that advise civil authorities in times of volcanic crisis should prepare, in advance of crises, a written plan that details crisis team policies, procedures, leadership and other roles of team members, and other matters pertinent to crisis conduct. A copy of this plan should be given to all current and prospective team members. (b) Each participant in a crisis team should examine his or her own actions and contribution to the crisis effort. A personal checklist is provided to aid this examination. Questions fall generally in two categories: Are my presence and actions for the public good? Are my words and actions collegial, i.e., courteous, respectful, and fair? Numerous specific solutions to common crisis problems are also offered. Among these suggestions are: (a) choose scientific team leaders primarily for their leadership skills; (b) speak publicly with a single scientific voice, especially when forecasts, warnings, or scientific disagreements are involved; (c) if you are a would-be visitor, inquire from the primary scientific team whether your help would be welcomed, and, in general, proceed only if the reply is genuinely positive; (d) in publications, personnel evaluations, and funding, reward rather than discourage teamwork. Models are

  16. Electrochemical sensor monitoring of volcanic gases (United States)

    Roberts, Tjarda; Freshwater, Ray; Oppenheimer, Clive; Saffell, John; Jones, Rod; Griffiths, Paul; Braban, Christine; Mead, Iqbal


    Advances in instrumentation have fuelled a recent growth of interest in using portable sensor systems for environmental monitoring of pollution. Developments in wireless technology are enabling such systems to operate remotely and autonomously, generating a wealth of environmental data. We report here on the application of miniature Alphasense electrochemical sensors to the detection and characterisation of gases in volcanic plumes. A highly portable sensor system was developed to operate an array of 6 low cost electrochemical sensors to detect CO, H2, HCl, SO2, H2S and NO2 at 1 Hz. A miniature pump draws air over all sensors simultaneously (i.e. sensors arranged in parallel). The sensor output in these campaigns was logged on PDAs for real-time viewing, and later download (with a view to future data-streaming). The instrument was deployed at a number of volcanoes and was subject to extremely harsh conditions including highly acidic environments, low (Antarctic) temperatures, and transport over rough terrain. Analysis methods are demonstrated that consider calibration, cross-sensitivities of the sensors to multiple gases, differing sensor response times, temperature dependence, and background sensor drift with time. The analysis is applied to a range of plume field-measurements to extract gas concentrations ranging from 100's ppmv to sub-ppmv and to characterise the individual volcano emissions. Applications of similar sensor systems for real-time long-term monitoring of volcanic emissions (which may indicate and ultimately predict eruptive behavior), and UAV and balloon-borne plume sampling are now already being realised. This work focused on demonstrating the application of electrochemical sensors to monitoring of environmental pollution from volcanoes. Other applications for similar sensors include the near-source monitoring of industrial emissions, and of pollutant levels enhanced by traffic emissions in the urban environment.

  17. Intracaldera volcanism and sedimentation - Creede Caldera, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Heiken, G.; Krier, D.; Snow, M.G. [and others


    Within the Creede caldera, Colorado, many of the answers to its postcaldera volcanic and sedimentary history lie within the sequence of tuffaceous elastic sedimentary rocks and tuffs known as the Creede Formation. The Creede Formation and its interbedded ash deposits were sampled by research coreholes Creede 1 and 2, drilled during the fall of 1991. In an earlier study of the Creede Formation, based on surface outcrops and shallow mining company coreholes, Heiken and Krier concluded that the process of caldera structural resurgence was rapid and that a caldera lake had developed in an annulus ({open_quotes}moat{close_quotes}) located between the resurgent dome and caldera wall. So far we have a picture of intracaldera activity consisting of intermittent hydrovolcanic eruptions within a caldera lake for the lower third of the Creede Formation, and both magmatic and hydrovolcanic ash eruptions throughout the top two-thirds. Most of the ash deposits interbedded with the moat sedimentary rocks are extremely fine-grained. Ash fallout into the moat lake and unconsolidated ash eroded from caldera walls and the slopes of the resurgent dome were deposited over stream delta distributaries within relatively shallow water in the northwestern moat, and in deeper waters of the northern moat, where the caldera was intersected by a graben. Interbedded with ash beds and tuffaceous siltstones are coarse-grained turbidites from adjacent steep slopes and travertine from fissure ridges adjacent to the moat. Sedimentation rates and provenance for elastic sediments are linked to the frequent volcanic activity in and near the caldera; nearly all of the Creede Formation sedimentary rocks are tuffaceous.

  18. Density - Velocity Relationships in Explosive Volcanic Plumes (United States)

    Fisher, M. A.; Kobs-Nawotniak, S. E.


    Positively buoyant volcanic plumes rise until the bulk density of the plume is equal to the density of the ambient atmosphere. As ambient air mixes with the plume, it lowers the plume bulk density; thus, the plume is diluted enough to reach neutral density in a naturally stratified atmospheric environment. We produced scaled plumes in analogue laboratory experiments by injecting a saline solution with a tracer dye into distilled water, using a high-pressure injection system. We recorded each eruption with a CASIO HD digital camera and used ImageJ's FeatureJ Edge toolbox to identify individual eddies. We used an optical flow software based off the ImageJ toolbox FlowJ to determine the velocities along the edge of each eddy. Eddy densities were calculated by mapping the dye concentration to the RGB digital color value. We overlaid the eddy velocities over the densities in order to track the behavioral relationship between the two variables with regard to plume motion. As an eddy's bulk density decreases, the vertical velocity decreases; this is a result of decreased mass, and therefore momentum, in the eddy. Furthermore as the density rate of change increases, the eddy deceleration increases. Eddies are most dense at their top and least dense at their bottom. The less dense sections of the eddies have lower vertical velocities than the sections of the eddies with the higher densities, relating to the expanding radial size of an eddy as it rises and the preferential ingestion of ambient air at the base of eddies. Thus the mixing rate in volcanic plumes fluctuates not only as a function of height as described by the classic 1D entrainment hypothesis, but also as a function of position in an eddy itself.

  19. Volcanic glasses, their origins and alteration processes (United States)

    Friedman, I.; Long, W.


    Natural glass can be formed by volcanic processes, lightning (fulgarites) burning coal, and by meteorite impact. By far the most common process is volcanic - basically the glass is rapidly chilled molten rock. All natural glasses are thermodynamically unstable and tend to alter chemically or to crystallize. The rate of these processes is determined by the chemical composition of the magma. The hot and fluid basaltic melts have a structure that allows for rapid crystal growth, and seldom forms glass selvages greater than a few centimeters thick, even when the melt is rapidly cooled by extrusion in the deep sea. In contrast the cooler and very viscous rhyolitic magmas can yield bodies of glass that are tens of meters thick. These highly polymerized magmas have a high silica content - often 71-77% SiO2. Their high viscosity inhibits diffusive crystal growth. Basalt glass in sea water forms an alteration zone called palagonite whose thickness increases linearly with time. The rate of diffusion of water into rhyolitic glass, which follows the relationship - thickness = k (time) 1 2, has been determined as a function of the glass composition and temperature. Increased SiO2 increases the rate, whereas increased CaO, MgO and H2O decrease the rate. The activation energy of water diffusion varies from about 19 to 22 kcal/mol. for the glasses studied. The diffusion of alkali out of rhyolite glass occurs simultaneously with water diffusion into the glass. The rate of devitrification of rhyolitic glass is a function of the glass viscosity, which in turn is a function of water content and temperature. Although all of the aforementioned processes tend to destroy natural glasses, the slow rates of these processes, particularly for rhyolitic glass, has allowed samples of glass to persist for 60 million years. ?? 1984.

  20. Global volcanic earthquake swarm database and preliminary analysis of volcanic earthquake swarm duration

    Directory of Open Access Journals (Sweden)

    S. R. McNutt


    Full Text Available Global data from 1979 to 1989 pertaining to volcanic earthquake swarms have been compiled into a custom-designed relational database. The database is composed of three sections: 1 a section containing general information on volcanoes, 2 a section containing earthquake swarm data (such as dates of swarm occurrence and durations, and 3 a section containing eruption information. The most abundant and reliable parameter, duration of volcanic earthquake swarms, was chosen for preliminary analysis. The distribution of all swarm durations was found to have a geometric mean of 5.5 days. Precursory swarms were then separated from those not associated with eruptions. The geometric mean precursory swarm duration was 8 days whereas the geometric mean duration of swarms not associated with eruptive activity was 3.5 days. Two groups of precursory swarms are apparent when duration is compared with the eruption repose time. Swarms with durations shorter than 4 months showed no clear relationship with the eruption repose time. However, the second group, lasting longer than 4 months, showed a significant positive correlation with the log10 of the eruption repose period. The two groups suggest that different suites of physical processes are involved in the generation of volcanic earthquake swarms.

  1. Impact of volcanic processes on the cryospheric system of the Peteroa Volcano, Andes of southern Mendoza, Argentina (United States)

    Liaudat, Dario Trombotto; Penas, Pablo; Aloy, Gustavo


    Soil temperatures of the active Volcanic Complex Peteroa situated in the Cordillera Principal between Chile and Argentina at 35°15‧ S and 70°35‧ W (approximately) were monitored in the area, and local geomorphology (periglacial geomorphology, presence of permafrost, and cryoforms) was studied. The present contribution also resulted in a comparison of two consecutive analyses of the volcano peak carried out with special thermocameras (AGEMA TVH 550, FUR P660) in order to study the thermal range of different hot and cold sites selected in 2009. The thermocameras were used ascending by foot and also during flights with a Cessna 180. A night expedition to the volcanic avalanche caldera, at up to 3900 m asl (approximately), completed the monitoring activity of 2010. Hot zones were associated to present volcanism and cold zones to the presence of glacier ice and shadowy slopes with possible presence of permafrost. Identifying and mapping uncovered and covered ice was possible with the help of monitoring and geomorphological interpretation related to the upper englacement, which is severely affected by volcanism. Glaciers are retreating toward the north or approaching the rims of the volcanic avalanche caldera leaving islands of ice associated with superficial permafrost. The cryogenic area with slope permafrost was identified through active protalus and sedimentary cryogenic slopes. Craters have undergone considerable thermal changes in comparison to the year 2009; and new, much more vigorous fumaroles have appeared in hot areas detected in 2009 following a tendency toward the west. New subaquatic heat columns that appeared in crater 3, crater walls, and glaciated areas vanished, supplying cold water and thus contributing to the formation of a new lake in crater 4. A possible post-seismic shift of the volcanic activity may provide geodynamical evidence of the changes registered in other areas after the earthquake of 27 February 2010.

  2. Sustained effects of volcanic ash on biofilm stoichiometry, enzyme activity and community composition in North- Patagonia streams. (United States)

    Carrillo, Uara; Díaz-Villanueva, Verónica; Modenutti, Beatriz


    Volcanic eruptions are extreme perturbations that affect ecosystems. These events can also produce persistent effects in the environment for several years after the eruption, with increased concentrations of suspended particles and the introduction of elements in the water column. On 4th June 2011, the Puyehue-Cordón Caulle Volcanic Complex (40.59°S-72.11°W, 2200m.a.s.l.) erupted explosively in southern Chile. The area affected by the volcano was devastated; a thick layer of volcanic ash (up to 30cm) was deposited in areas 50 km east of the volcano towards Argentina. The aim of the present study was to evaluate the effect of volcanic ash deposits on stream ecosystems four years after the eruption, comparing biofilm stoichiometry, alkaline phosphatase activity, and primary producer's assemblage in streams which were severely affected by the volcano with unaffected streams. We confirmed in the laboratory that ash deposited in the catchment of affected streams still leach phosphorus (P) into the water four years after eruption. Results indicate that affected streams still receive volcanic particles and that these particles release P, thus stream water exhibits high P concentration. Biofilm P content was higher and the C:P ratio lower in affected streams compared to unaffected streams. As a consequence of less P in unaffected streams, the alkaline phosphatase activity was higher compared to affected streams. Cyanobacteria increased their abundances (99.9% of total algal biovolume) in the affected streams suggesting that the increase in P may positively affect this group. On the contrary, unaffected streams contained a diatom dominant biofilm. In this way, local heterogeneity was created between sub-catchments located within 30 km of each other. These types of events should be seen as opportunities to gather valuable ecological information about how severe disturbances, like volcanic eruptions, shape landscapes and lotic systems for several years after the event

  3. Geochemical Characteristics of Quaternary Rhyolitic Volcanism in Acigöl area, Cappadocia - Turkiye (United States)

    Evren Cubukcu, H.; Sen, Erdal; Aydar, Erkan


    Two of the oldest known Cappadocian ignimbrites (Kavak and Zelve ignimbrites, ~ 9 Ma) are thought to have been originated from a caldera located in the vicinity of Acıgöl (Nevşehir) area. During Upper Miocene, volcanism of the region is characterized by andesitic/adakitic lavas and domes, whereas Quaternary volcanism is represented by bimodal basaltic and rhyolitic products. Quaternary rhyolitic volcanism is represented by domes, dome complexes, associated lava flows, phreatomagmatic eruption centers and ignimbrite flows with fall deposits. Quaternary rhyolitic products are mostly aphyric with minute plagioclase + orthopyroxene + magnetite ± amphibole microphenocrystic assemblage with apatite and zircon as accessory phases. They exhibit a marked geochemical evolution towards more differentiated compositions through time. Rhyolites older than 75 ka (74 -75% SiO2) have higher Al2O3, Fe2O3, CaO content than their younger counterparts. Moreover, younger rhyolites are strongly depleted in Ba and Sr, have lower LREE and higher HREE contents with a sharp negative Eu anomaly. Chondrite normalized REE and primordial mantle normalized patterns of both compatible and incompatible elements suggest the crystal fractionation of a plagioclase dominant assemblage with scarce orthopyroxene and amphibole would yield the youngest rhyolitic compositions. Besides, evident temporal transition from meta/peraluminous towards mildly peralkaline whole rock compositions (Agpaitic Index: 0,91 - 0,96) of Quaternary rhyolites would be linked to the intraplate rifting of the Central Anatolia.

  4. Hazards posed by distal ash transport and sedimentation from extreme volcanic eruptions (United States)

    Sahagian, D. L.; Proussevitch, A. A.; White, C. M.; Klewicki, J.


    Volcanic ash injected into the upper troposphere and lower stratosphere poses a significant hazard to aviation and human security as a result of extreme, explosive eruptions. These have occurred in the recent geologic past, and are expected to occur again, now that modern society and its infrastructure is far more vulnerable than ever before. Atmospheric transport, dispersion, and sedimentation of Ash particles is controlled by fundamentally different processes than control other particles normally transported in the atmosphere due to their complex internal and external morphology. It is thus necessary to elucidate the fundamental processes of particle-fluid interactions in the upper troposphere and lower stratosphere, where most air traffic resides, and thereby enhance the capability of volcanic ash transport models to predict the ash concentration in distal regions that pose aviation and other hazards. Current Volcanic Ash Transport and Dispersion (VATD) models use simplistic stokes settling velocities for larger ash particles, and treat smaller ash particles (that are a large part of the hazard) merely as passive tracers. By incorporating the dynamics of fine ash particle-atmosphere interactions into existing VATD models provides the foundation for a much more accurate assessment framework applied to the hazard posed by specific future extreme eruptions, and thus dramatically reduce both the risk to air traffic and the cost of airport and flight closures, in addition to human health, water quality, agricultural, infrastructure hazards, as well as ice cap albedo and short term climate impacts.

  5. Ecological divergence combined with ancient allopatry in lizard populations from a small volcanic island. (United States)

    Suárez, N M; Pestano, J; Brown, R P


    Population divergence and speciation are often explained by geographical isolation, but may also be possible under high gene flow due to strong ecology-related differences in selection pressures. This study combines coalescent analyses of genetic data (11 microsatellite loci and 1 Kbp of mtDNA) and ecological modelling to examine the relative contributions of isolation and ecology to incipient speciation in the scincid lizard Chalcides sexlineatus within the volcanic island of Gran Canaria. Bayesian multispecies coalescent dating of within-island genetic divergence of northern and southern populations showed correspondence with the timing of volcanic activity in the north of the island 1.5-3.0 Ma ago. Coalescent estimates of demographic changes reveal historical size increases in northern populations, consistent with expansions from a volcanic refuge. Nevertheless, ecological divergence is also supported. First, the two morphs showed non-equivalence of ecological niches and species distribution modelling associated the northern morph with mesic habitat types and the southern morph with xeric habitat types. It seems likely that the colour morphs are associated with different antipredator strategies in the different habitats. Second, coalescent estimation of gene copy migration (based on microsatellites and mtDNA) suggest high rates from northern to southern morphs demonstrating the strength of ecology-mediated selection pressures that maintain the divergent southern morph. Together, these findings underline the complexity of the speciation process by providing evidence for the combined effects of ecological divergence and ancient divergence in allopatry. © 2014 John Wiley & Sons Ltd.

  6. Aeromagnetic survey of the Somma-Vesuvius volcanic area

    Directory of Open Access Journals (Sweden)

    A. Rapolla


    Full Text Available In this paper we present and discuss the results of a geophysical airborne survey carried out in the Somma-Vesuvius volcanic area, Southern Italy, in 1999. The helicopter-borne survey was aimed at giving new detailed insights into the distribution of the magnetization of the area and, therefore, into the volcanological characteristics of the region, enhancing the knowledge given by a previous low resolution survey carried out at a regional scale by Agip. The new survey was carried out by flying on a surface parallel to the topography of the area, along flight lines spaced 600 m apart. The obtained total field map is dominated by a large anomaly related to the Mt. Somma-Vesuvius complex itself and characterized by a roughly elliptical shape. High-frequency anomalies occur in the edifice and in the area east of it, partly produced by cultural noise due to the densely inhabited area. The compilation of the maps of the analytic signal and of the horizontal derivative of the field allowed the location of the lateral boundaries of the magnetic sources of the area and represents a first step toward the interpretation of the maps in terms of geological structures.

  7. Volcanic rocks cored on hess rise, Western Pacific Ocean (United States)

    Vallier, T.L.; Windom, K.E.; Seifert, K.E.; Thiede, Jorn


    Large aseismic rises and plateaus in the western Pacific include the Ontong-Java Plateau, Magellan Rise, Shatsky Rise, Mid-Pacific Mountains, and Hess Rise. These are relatively old features that rise above surrounding sea floors as bathymetric highs. Thick sequences of carbonate sediments overlie, what are believed to be, Upper Jurassic and Lower Cretaceous volcanic pedestals. We discuss here petrological and tectonic implications of data from volcanic rocks cored on Hess Rise. The data suggest that Hess Rise originated at a spreading centre in the late early Cretaceous (Aptian-Albian stages). Subsequent off-ridge volcanism in the late Albian-early Cenomanian stages built a large archipelago of oceanic islands and seamounts composed, at least in part, of alkalic rocks. The volcanic platform subsided during its northward passage through the mid-Cretaceousequatorial zone. Faulting and uplift, and possibly volcanism, occurred in the latest Cretaceous (Campanian-Maastrichtian stages). Since then, Hess Rise continued its northward movement and subsidence. Volcanic rocks from holes drilled on Hess Rise during IPOD Leg 62 (Fig. 1) are briefly described here and we relate the petrological data to the origin and evolution of that rise. These are the first volcanic rocks reported from Hess Rise. ?? 1980 Nature Publishing Group.

  8. Glass shards, pumice fragments and volcanic aerosol particles - diagenesis a recorder of volcanic activity? (United States)

    Obenholzner, J. H.; Schroettner, H.; Poelt, P.; Delgado, H.


    Detailed SEM/EDS studies of Triassic (Southern Alps, A, I, Sl) and Miocene (Mixteca Alta, Mexico) tuffs revealed that volcanic glass shards can be replaced by zeolites (analcite), chlorites and smectites preserving the shape of primary shards (1). The Triassic pyroclastic deposits have been incorporated in the pre-Alpine burial diagenesis, the Miocene pyroclastic deposits are bentonites. The volcanologist is impressed by the circumstances that million years old pyroclast relict textures can be sized. Shape parameters obtained by image analysis can be compared with much younger pyroclastic deposits (2). Both deposits have not been effected by shearing. The alteration of pumice fragments of Triassic age is not a simple replacement process. Intergrowth of different illites and chlorites and probably vesicle filling by SiO2 and subsequent overgrowth make a reconstruction sometimes difficult. These processes are accompanied by the formation of REE-, Y- and Zr-bearing minerals as well as with the alteration of zircons. Studies of recently erupted ash from Popocatepetl volcano reveal the presence of a variety of µm-sized contact-metamorphosed clasts being a part of the volcanic ash (3). Such clasts should be present in many older pyroclastic deposits, especially where volcanoes had been situated on massive sedimentary units providing contact metamorphism in the realm of a magma chamber or during magma ascent. Volcanic aerosol particles collected in 1997 from the passively degassing plume of Popocatepetl volcano revealed in FESEM/EDS analysis (H. Schroettner and P. Poelt) a wide spectrum of fluffy, spherical and coagulated spherical particles (µm-sized). Under pre-vacuum conditions they remained stable for ca. 3 years (3). In nature the fate of these particles in the atmosphere is unknown. Are there relicts in marine, lacustrine sediments and ice cores, which could be used as proxies of volcanic activity? (1) Obenholzner &Heiken,1999. Ann.Naturhist.Mus.Wien, 100 A, 13

  9. Petrogenesis and geodynamic significance of silicic volcanism in the western Trans-Mexican Volcanic Belt (United States)

    Petrone, C. M.; Ferrari, L.; Orozco, M. A.; Lopez Martinez, M.


    Silicic volcanism in the western Trans-Mexican Volcanic Belt (WTMVB) was defined a Pliocene ignimbrite flare-up associated with the rifting of the Jalisco block from mainland Mexico (Frey et al., 2007; GSAB). With the integration of new and published geochronologic, geochemical, and isotope data we revise this interpretation and propose a new petrogenetic model. The oldest silicic volcanism consists of large silicic domes and minor pyroclastic flows (~370 km3) emplaced to the north of Guadalajara above a thick succession of ~11 to 8.7 Ma basaltic lavas, which yielded Ar-Ar and obsidian FT ages of ~7.5 to 5 Ma. Shortly after (4.9 to 2.9 Ma) large amount of rhyolitic lavas and ash flow tuffs (~500 km3) were emplaced in a WNW-ESE trending belt from Guadalajara to Compostela. Rhyolitic domes and flows (~430 km3) were emplaced also in the Pleistocene mostly between Tequila and Guadalajara with the late Pleistocene La Primavera caldera (~35 km3) as the sole explosive volcanic episodes. As a whole, silicic volcanism occurred from Late Miocene to the Pleistocene, and was dominated by dome and lava flows. Most rhyolites have high LILE/HFSE values and negative spikes at Nb, P and Ti. They also show the same Ba/Nb and K/Rb values and slightly higher Rb/Sr ratios as the 11-8 Ma basalts. Rhyolite Sr isotope data (87Sr/86Sr init = 0.70371 - 070598) are only slightly more radiogenic than the 11-8 basalts (87Sr/86Sr init = 0.70349-0.70410), whereas Nd isotope ratios are indistinguishable from them. Sr and Nd isotope ratios of the rhyolites are also similar to the crust nearby, indicating that they can be compatible either with fractional crystallization (FC) of basalts or with crust assimilation/melting. However REE contents are too low to be the result of basalt FC. Isotope and REE data can be successfully modelled with an initial crustal melt which subsequently undergone fractional crystallization of feldspar and quartz. Late Miocene slab detachment and subsequent slab rollback

  10. Lidar detection of carbon dioxide in volcanic plumes (United States)

    Fiorani, Luca; Santoro, Simone; Parracino, Stefano; Maio, Giovanni; Del Franco, Mario; Aiuppa, Alessandro


    Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. Two differential absorption lidar instruments will be presented in this paper: BILLI (BrIdge voLcanic LIdar), based on injection seeded Nd:YAG laser, double grating dye laser, difference frequency mixing (DFM) and optical parametric amplifier (OPA), and VULLI (VULcamed Lidar), based on injection seeded Nd:YAG laser and optical parametric oscillator (OPO). The first one is funded by the ERC (European Research Council) project BRIDGE and the second one by the ERDF (European Regional Development Fund) project VULCAMED. While VULLI has not yet been tested in a volcanic site, BILLI scanned the gas emitted by Pozzuoli Solfatara (Campi Flegrei volcanic area, Naples, Italy) during a field campaign carried out from 13 to 17 October 2014. Carbon dioxide concentration maps were retrieved remotely in few minutes in the crater area. Lidar measurements were in good agreement with well-established techniques, based on different operating principles. To our knowledge, it is the first time that carbon dioxide in a volcanic plume is retrieved by lidar, representing the first direct measurement of this kind ever performed on an active volcano and showing the high potential of laser remote sensing in geophysical research.

  11. California's Vulnerability to Volcanic Hazards: What's at Risk? (United States)

    Mangan, M.; Wood, N. J.; Dinitz, L.


    California is a leader in comprehensive planning for devastating earthquakes, landslides, floods, and tsunamis. Far less attention, however, has focused on the potentially devastating impact of volcanic eruptions, despite the fact that they occur in the State about as frequently as the largest earthquakes on the San Andreas Fault Zone. At least 10 eruptions have occurred in the past 1,000 years—most recently in northern California (Lassen Peak 1914 to 1917)—and future volcanic eruptions are inevitable. The likelihood of renewed volcanism in California is about one in a few hundred to one in a few thousand annually. Eight young volcanoes, ranked as Moderate to Very High Threat [1] are dispersed throughout the State. Partially molten rock (magma) resides beneath at least seven of these—Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Long Valley Volcanic Region, Coso Volcanic Field, and Salton Buttes— causing earthquakes, toxic gas emissions, hydrothermal activity, and (or) ground deformation. Understanding the hazards and identifying what is at risk are the first steps in building community resilience to volcanic disasters. This study, prepared in collaboration with the State of California Governor's Office of Emergency Management and the California Geological Survey, provides a broad perspective on the State's exposure to volcano hazards by integrating mapped volcano hazard zones with geospatial data on at-risk populations, infrastructure, and resources. The study reveals that ~ 1