Reconstruction of caldera collapse and resurgence processes in the offshore sector of the Campi Flegrei caldera (Italy)

Science.gov (United States)

Steinmann, Lena; Spiess, Volkhard; Sacchi, Marco

2015-04-01

Large collapse calderas are associated with exceptionally explosive volcanic eruptions, which are capable of triggering a global catastrophe second only to that from a giant meteorite impact. Therefore, active calderas have attracted significant attention in both scientific communities and governmental institutions worldwide. One prime example of a large collapse caldera can be found in southern Italy, more precisely in the northern Bay of Naples within the Campi Flegrei Volcanic Area. The Campi Flegrei caldera covers an area of approximately 200 km² defined by a quasi-circular depression, half onland, half offshore. It is still under debate whether the caldera formation was related to only one ignimbritic eruption namely the Neapolitan Yellow Tuff (NYT) eruption at 15 ka or if it is a nested-caldera system related to the NYT and the Campanian Ignimbrite eruption at 39 ka. During the last 40 years, the Campi Flegrei caldera has experienced episodes of unrest involving significant ground deformation and seismicity, which have nevertheless not yet led to an eruption. Besides these short-term episodes of unrest, long-term ground deformation with rates of several tens of meters within a few thousand years can be observed in the central part of the caldera. The source of both short-term and long-term deformation is still under debate and possibly related to a shallow hydrothermal system and caldera resurgence attributed to a deeper magma chamber, respectively. Understanding the mechanisms for unrest and eruptions is of paramount importance as a future eruption of the Campi Flegrei caldera would expose more than 500,000 people to the risk of pyroclastic flows. This study is based on a dense grid (semi-3D) of high-resolution multi-channel seismic profiles acquired in the offshore sector of the Campi Flegrei caldera. The seismic lines show evidence for the escape of fluids and/or gases along weak zones such as faults, thereby supporting the existence of a hydrothermal

Searching for patterns in caldera unrest

Science.gov (United States)

Sandri, Laura; Acocella, Valerio; Newhall, Chris

2017-07-01

The ultimate goal of volcanology is forecasting eruptions. This task is particularly challenging at calderas, where unrest is frequent, affects wider areas and its evidence is often masked by the activity of hydrothermal systems. A recent study has compiled a database on caldera unrest, derived from seismicity, geodetic, gravity, and geochemical monitoring data at calderas worldwide, from 1988 to 2014. Here we exploit this database, searching for the most recurring features of unrest and, in turn, its possible dynamics. In particular, we focus on (a) the duration of unrest at calderas; (b) recurring patterns in unrest; (c) unrest episodes culminating in eruptions, including time-predictability or size-predictability and a multivariate regression analysis. Our analysis indicates that preeruptive unrest is shorter than noneruptive unrest, particularly with open or semiplugged calderas, calderas with mafic or mixed composition of past eruptive products, or unrest driven by mafic magma; conversely, lack of data on preeruptive unrest driven by felsic magma and/or at felsic or plugged calderas prevents an analysis of these specific subsets. In addition, 72% of preeruptive unrest lasts reliable to characterize preeruptive unrest. Our analysis suggests that magma may withstand only a limited period of "eruptability," before becoming stored in the upper crust.

Geomorphological classification of post-caldera volcanoes in the Buyan-Bratan caldera, North Bali, Indonesia

Science.gov (United States)

Okuno, Mitsuru; Harijoko, Agung; Wayan Warmada, I.; Watanabe, Koichiro; Nakamura, Toshio; Taguchi, Sachihiro; Kobayashi, Tetsuo

2017-12-01

A landform of the post-caldera volcanoes (Lesung, Tapak, Sengayang, Pohen, and Adeng) in the Buyan-Bratan caldera on the island of Bali, Indonesia can be classified by topographic interpretation. The Tapak volcano has three craters, aligned from north to south. Lava effused from the central crater has flowed downward to the northwest, separating the Tamblingan and Buyan Lakes. This lava also covers the tip of the lava flow from the Lesung volcano. Therefore, it is a product of the latest post-caldera volcano eruption. The Lesung volcano also has two craters, with a gully developing on the pyroclastic cone from the northern slope to the western slope. Lava from the south crater has flowed down the western flank, beyond the caldera rim. Lava distributed on the eastern side from the south also surrounds the Sengayang volcano. The Adeng volcano is surrounded by debris avalanche deposits from the Pohen volcano. Based on these topographic relationships, Sengayang volcano appears to be the oldest of the post-caldera volcanoes, followed by the Adeng, Pohen, Lesung, and Tapak volcanoes. Coarse-grained scoria falls around this area are intercalated with two foreign tephras: the Samalas tephra (1257 A.D.) from Lombok Island and the Penelokan tephra (ca. 5.5 kBP) from the Batur caldera. The source of these scoria falls is estimated to be either the Tapak or Lesung volcano, implying that at least two volcanoes have erupted during the Holocene period.

The isotopic composition of ore lead of the Creede mining district and vicinity, San Juan Mountains, Colorado: Text of a talk presented at the San Juan Mountains symposium to honor Thomas A. Steven; Rocky Mountain Section meeting of the Geological Society of America, May 2, 1987, Boulder, Colorado

Science.gov (United States)

Foley, N.K.; Barton, P.B.; Bethke, P.M.; Doe, B.R.

1988-01-01

Galenas from the major Creede veins and their northern extensions are remarkably homogeneous in Pb-isotopic composition and are too radiogenic to have been derived from any magma comparable in composition to the principal volcanic rocks. This pattern was identified by Doe et al. in 1979 who proposed that the lead was derived from the Precambrian basement. The homogeneity of the ore leads, however, requires a uniform reservoir; an unlikely prospect for lead from the Precambrian basement. We report on 16 new analyses of geographically and paragenetically dispersed galenas from the Creede district and other areas as far as 11 km to the north. The lead values range from 18.972 to 19.060 for 206Pb/204Pb, from 15.591 to 15.671 for 207Pb/204Pb, and from 37.781 to 37.921 for 208Pb/204Pb. These ranges overlap those previously reported for the main ore zone.

Thermally-assisted Magma Emplacement Explains Restless Calderas

Science.gov (United States)

Amoruso, A.; Crescentini, L.; D'Antonio, M.; Acocella, V.

2017-12-01

Many calderas show repeated unrest over centuries. Though probably induced by magma, this unique behaviour is not understood and its dynamics remains elusive. To better understand these restless calderas, we interpret deformation data and build thermal models of Campi Flegrei, Italy, which is the best-known, yet most dangerous calderas, lying to the west of Naples and restless since the 1950s at least.Our elaboration of the geodetic data indicates that the inflation and deflation of magmatic sources at the same location explain most deformation, at least since the build-up of the last 1538 AD eruption. However, such a repeated magma emplacement requires a persistently hot crust.Our thermal models show that the repeated emplacement was assisted by the thermal anomaly created by magma that was intruded at shallow depth 3 ka before the last eruption and, in turn, contributed to maintain the thermal anomaly itself. This may explain the persistence of the magmatic sources promoting the restless behaviour of the Campi Flegrei caldera; moreover, it explains the crystallization, re-melting and mixing among compositionally distinct magmas recorded in young volcanic rocks.Available information at other calderas highlights similarities to Campi Flegrei, in the pattern and cause of unrest. All monitored restless calderas have either geodetically (Yellowstone, Aira Iwo-Jima, Askja, Fernandina and, partly, Long Valley) or geophysically (Rabaul, Okmok) detected sill-like intrusions inducing repeated unrest. Some calderas (Yellowstone, Long Valley) also show stable deformation pattern, where inflation insists on and mimics the resurgence uplift. The common existence of sill-like sources, also responsible for stable deformation patterns, in restless calderas suggests close similarities to Campi Flegrei. This suggests a wider applicability of our model of thermally-assisted sill emplacement, to be tested by future studies to better understand not only the dynamics of restless

Location of silicic caldera formation in arc settings

Energy Technology Data Exchange (ETDEWEB)

Hughes, Gwyneth R; Mahood, Gail A [Department of Geological and Environmental Sciences, Stanford University, 450 Serra, Mall, Building 320, Stanford, CA 94305-2115 (United States)

2008-10-01

Silicic calderas are the surface expressions of silicic magma chambers, and thus their study may yield information about what tectonic and crustal features favor the generation of evolved magma. The goal of this study is to determine whether silicic calderas in arc settings are preferentially located behind the volcanic front. After a global analysis of young, arc-related calderas, we find that silicic calderas at continental margins do form over a wide area behind the front, as compared to other types of arc volcanoes.

Krakatau caldera deposits: revisited and verification by geophysical means

Directory of Open Access Journals (Sweden)

Izumi Yokoyama

2014-10-01

Full Text Available  One of the differences between volcanic craters and calderas is that the latter bottoms are flatways filled with caldera deposit with lower density in comparison to country rocks. The 1883 Krakatau eruption affords us important knowledge on caldera formation even if it was not observed with modern sophisticated instruments. First, volcanic activities of the Krakatau Islands before and after the 1883 eruption are reexamined: previous suppositions involving a caldera-forming eruption of the proto-Krakatau prior to 1883 proved to be unsupported by the bathymetric topographies and gravity anomalies on and around the Krakatau Islands. Then, Anak Krakatau is interpreted as a parasitic cone of the main Krakatau volcano. As supplementary knowledge to discussion of caldera deposits, the results of drillings at several calderas in Japan and Mexico are introduced. Mass deficiency of the caldera deposit at Krakatau caldera is estimated by the gravity anomaly observed there and converted to probable volume with suitable density. For quantitative examination of the subsurface structure beneath the Krakatau complex, spatial distributions of seismic S-wave attenuation and Vp/Vs ratios have been already studied by temporary seismological observations and their results have been published. The high ratios of Vp/Vs observed approximately at Krakatau caldera may be attributable to the caldera deposit that is low density and contain much water. As additional remarks, a zone having both the characters, S-wave attenuation and zones of relatively high Vp/Vs ratio, may be a probable magma reservoir centering at a depth of about 10 km.

Multi-scale, multi-method geophysical investigations of the Valles Caldera

Science.gov (United States)

Barker, J. E.; Daneshvar, S.; Langhans, A.; Okorie, C.; Parapuzha, A.; Perez, N.; Turner, A.; Smith, E.; Carchedi, C. J. W.; Creighton, A.; Folsom, M.; Bedrosian, P.; Pellerin, L.; Feucht, D. W.; Kelly, S.; Ferguson, J. F.; McPhee, D.

2017-12-01

In 2016, the Summer of Applied Geophysical Experience (SAGE) program, in cooperation with the National Park Service, began a multi-year investigation into the structure and evolution of the Valles Caldera in northern New Mexico. The Valles Caldera is a 20-km wide topographic depression in the Jemez Mountains volcanic complex that formed during two massive ignimbrite eruptions at 1.65 and 1.26 Ma. Post-collapse volcanic activity in the caldera includes the rise of Redondo peak, a 1 km high resurgent dome, periodic eruptions of the Valles rhyolite along an inferred ring fracture zone, and the presence of a geothermal reservoir beneath the western caldera with temperatures in excess of 300°C at a mere 2 km depth. Broad sediment-filled valleys associated with lava-dammed Pleistocene lakes occupy much of the northern and southeastern caldera. SAGE activities to date have included collection of new gravity data (>120 stations) throughout the caldera, a transient electromagnetic (TEM) survey of Valle Grande, reprocessing of industrial magnetotelluric (MT) data collected in the 1980s, and new MT data collection both within and outside of the caldera. Gravity modeling provides constraints on the pre-Caldera structure, estimates of the thickness of Caldera fill, and reveals regional structural trends reflected in the geometry of post-Caldera collapse. At a more local scale, TEM-derived resistivity models image rhyolite flows radiating outward from nearby vents into the lacustrine sediments filling Valle Grande. Resistivity models along a 6-km long profile also provide hints of structural dismemberment along the inferred Valles and Toledo ring fracture zones. Preliminary MT modeling at the caldera scale reveals conductive caldera fill, the resistive crystalline basement, and an enigmatic mid-crustal conductor likely related to magmatic activity that post-dates caldera formation.

Post-supereruption recovery at Toba Caldera.

Science.gov (United States)

Mucek, Adonara E; Danišík, Martin; de Silva, Shanaka L; Schmitt, Axel K; Pratomo, Indyo; Coble, Matthew A

2017-05-16

Large calderas, or supervolcanoes, are sites of the most catastrophic and hazardous events on Earth, yet the temporal details of post-supereruption activity, or resurgence, remain largely unknown, limiting our ability to understand how supervolcanoes work and address their hazards. Toba Caldera, Indonesia, caused the greatest volcanic catastrophe of the last 100 kyr, climactically erupting ∼74 ka. Since the supereruption, Toba has been in a state of resurgence but its magmatic and uplift history has remained unclear. Here we reveal that new 14 C, zircon U-Th crystallization and (U-Th)/He ages show resurgence commenced at 69.7±4.5 ka and continued until at least ∼2.7 ka, progressing westward across the caldera, as reflected by post-caldera effusive lava eruptions and uplifted lake sediment. The major stratovolcano north of Toba, Sinabung, shows strong geochemical kinship with Toba, and zircons from recent eruption products suggest Toba's climactic magma reservoir extends beneath Sinabung and is being tapped during eruptions.

Thermally-assisted Magma Emplacement Explains Restless Calderas.

Science.gov (United States)

Amoruso, Antonella; Crescentini, Luca; D'Antonio, Massimo; Acocella, Valerio

2017-08-11

Many calderas show repeated unrest over centuries. Though probably induced by magma, this unique behaviour is not understood and its dynamics remains elusive. To better understand these restless calderas, we interpret deformation data and build thermal models of Campi Flegrei caldera, Italy. Campi Flegrei experienced at least 4 major unrest episodes in the last decades. Our results indicate that the inflation and deflation of magmatic sources at the same location explain most deformation, at least since the build-up of the last 1538 AD eruption. However, such a repeated magma emplacement requires a persistently hot crust. Our thermal models show that this repeated emplacement was assisted by the thermal anomaly created by magma that was intruded at shallow depth ~3 ka before the last eruption. This may explain the persistence of the magmatic sources promoting the restless behaviour of the Campi Flegrei caldera; moreover, it explains the crystallization, re-melting and mixing among compositionally distinct magmas recorded in young volcanic rocks. Our model of thermally-assisted unrest may have a wider applicability, possibly explaining also the dynamics of other restless calderas.

Inequalities in the Japanese Workplace : Gender, Political Creed, and the Right to Life

OpenAIRE

ウィリアムズ, ノエル

2001-01-01

Much of my recent research in the area of fundamental rights in the Japanese and comparative contexts has been concerned with the issue of equality. In this paper we look at the issue of equality in the Japanese workplace, concentrating on the company organization. Three aspects in particular are discussed. First, gender inequality ; second, the issue of workers and their political creed ; third, the inequality of the right to life of workers.

Gravity-height correlations for unrest at calderas

Science.gov (United States)

Berrino, G.; Rymer, H.; Brown, G. C.; Corrado, G.

1992-11-01

Calderas represent the sites of the world's most serious volcanic hazards. Although eruptions are not frequent at such structures on the scale of human lifetimes, there are nevertheless often physical changes at calderas that are measurable over periods of years or decades. Such calderas are said to be in a state of unrest, and it is by studying the nature of this unrest that we may begin to understand the dynamics of eruption precursors. Here we review combined gravity and elevation data from several restless calderas, and present new data on their characteristic signatures during periods of inflation and deflation. We find that unless the Bouguer gravity anomaly at a caldera is extremely small, the free-air gradient used to correct gravity data for observed elevation changes must be the measured or calculated gradient, and not the theoretical gradient, use of which may introduce significant errors. In general, there are two models that fit most of the available data. The first involves a Mogi-type point source, and the second is a Bouguer-type infinite horizontal plane source. The density of the deforming material (usually a magma chamber) is calculated from the gravity and ground deformation data, and the best fitting model is, to a first approximation, the one producing the most realistic density. No realistic density is obtained where there are real density changes, or where the data do not fit the point source or slab model. We find that a point source model fits most of the available data, and that most data are for periods of caldera inflation. The limited examples of deflation from large silicic calderas indicate that the amount of mass loss, or magma drainage, is usually much less than the mass gain during the preceding magma intrusion. In contrast, deflationary events at basaltic calderas formed in extensional tectonic environments are associated with more significant mass loss as magma is injected into the associated fissure swarms.

Post-collapse evolution of a coastal caldera system: Insights from a 3D multichannel seismic survey from the Campi Flegrei caldera (Italy)

Science.gov (United States)

Steinmann, Lena; Spiess, Volkhard; Sacchi, Marco

2018-01-01

In this study we present the first 3D high-resolution multichannel seismic dataset from a (partly) submerged caldera setting, the Campi Flegrei caldera (CFc). Our work aims at examining the spatial and temporal evolution of the CFc since the last caldera-forming event, the Neapolitan Yellow Tuff (NYT, 15 ka) eruption. The main objectives are to investigate the caldera's shallow ( 200 m) outer caldera ring-fault zone. The seismic data revealed that the NYT collapse occurred exclusively along the inner caldera ring-fault and that the related NYT caldera depression is filled with on average 61 m of sediment deposited between 15 and 8.6 ka. The geometry of the inner ring-fault, consisting of four fault segments, seems to be strongly influenced by regional NW-SE and NE SW-trending faults. Furthermore, we found that the ring-faults have acted as pathway for the recent (Bank (10.3-9.5 ka), Nisida Island ( 3.98 ka), and Capo Miseno (3.7 ka) eruptions, yielding DRE values of 0.15 km3, 0.1 km3, and 0.08 km3, respectively, and an explosive magnitude of at least moderate-large scale (VEI 3). Our findings highlight that eruption volumes may be underestimated by 3 to 4 times if the submerged portion of a (partly) submerged caldera is not considered, implying severe consequences for the hazard and risk evaluation. The spatial response of the post-collapse (< 15 ka) depositional environment to volcanic activity, deformational processes and sea-level variations is presented in a comprehensive 3D evolutionary model.

Magma storage in a strike-slip caldera.

Science.gov (United States)

Saxby, J; Gottsmann, J; Cashman, K; Gutiérrez, E

2016-07-22

Silicic calderas form during explosive volcanic eruptions when magma withdrawal triggers collapse along bounding faults. The nature of specific interactions between magmatism and tectonism in caldera-forming systems is, however, unclear. Regional stress patterns may control the location and geometry of magma reservoirs, which in turn may control the spatial and temporal development of faults. Here we provide new insight into strike-slip volcano-tectonic relations by analysing Bouguer gravity data from Ilopango caldera, El Salvador, which has a long history of catastrophic explosive eruptions. The observed low gravity beneath the caldera is aligned along the principal horizontal stress orientations of the El Salvador Fault Zone. Data inversion shows that the causative low-density structure extends to ca. 6 km depth, which we interpret as a shallow plumbing system comprising a fractured hydrothermal reservoir overlying a magmatic reservoir with vol% exsolved vapour. Fault-controlled localization of magma constrains potential vent locations for future eruptions.

Lithium deposits hosted in intracontinental rhyolite calderas

Science.gov (United States)

Benson, T. R.; Coble, M. A.; Mahood, G. A.

2017-12-01

Lithium (Li) is classified as a technology-critical element due to the increasing demand for Li-ion batteries, which have a high power density and a relatively low cost that make them optimal for energy storage in mobile electronics, the electrical power grid, and hybrid and electric vehicles. Given that many projections for Li demand exceed current economic reserves and the market is dominated by Australia and Chile, discovery of new domestic Li resources will help diversify the supply chain and keep future technology costs down. Here we show that lake sediments preserved within intracontinental rhyolite calderas have the potential to host Li deposits on par with some of the largest Li brine deposits in the world. We compare Li concentrations of rhyolite magmas formed in a variety of tectonic settings using in situ SHRIMP-RG measurements of homogenized quartz-hosted melt inclusions. Rhyolite magmas that formed within thick, felsic continental crust (e.g., Yellowstone and Hideaway Park, United States) display moderate to extreme Li enrichment (1,500 - 9,000 ppm), whereas magmas formed in thin crust or crust comprised of accreted arc terranes (e.g., Pantelleria, Italy and High Rock, Nevada) contain Li concentrations less than 500 ppm. When the Li-enriched magmas erupt to form calderas, the cauldron depression serves as an ideal catchment within which meteoric water that leached Li from intracaldera ignimbrite, nearby outflow ignimbrite, and caldera-related lavas can accumulate. Additional Li is concentrated in the system through near-neutral, low-temperature hydrothermal fluids circulated along ring fractures as remnant magma solidifies and degasses. Li-bearing hectorite and illite clays form in this alteration zone, and when preserved in the geological record, can lead to a large Li deposit like the 2 Mt Kings Valley Li deposit in the McDermitt Caldera, Nevada. Because more than 100 large Cenozoic calderas occur in the western United States that formed on eruption

Stable Isotopes of Tilted Ignimbrite Calderas in Nevada

Science.gov (United States)

John, D. A.; Watts, K. E.; Hofstra, A. H.; Colgan, J. P.; Henry, C.; Bindeman, I. N.

2013-12-01

Mid-Tertiary calderas are exceptionally well exposed in tilted fault blocks of the northern Great Basin, facilitating detailed evolutionary models of their magmatic-hydrothermal systems. The 29.4 Ma Job Canyon caldera, the oldest of 3 overlapping calderas in the Stillwater Range, west-central Nevada, is tilted ~90° exposing a 10-km-thick section of the crust. Large parts of the >7 km-diameter caldera system, including >2 km thickness of intracaldera rhyolitic tuff, lower parts of an ~2 km thick sequence of post-caldera intermediate lavas, and the upper 500 m of the resurgent granodioritic IXL pluton, were pervasively altered to propylitic, argillic, and sericitic assemblages. Sparse quartz×calcite veins cut the tuff. δ18O values of altered whole rock samples range from +4.8 to -9.1‰ but are mostly -6 to -9‰ at paleodepths >2 km. Calculated magmatic δ18O and δD values range from +6.4 to 8.2‰ and ~-70‰, respectively. Calculated fluid compositions using temperatures from fluid inclusions and mineral assemblages are δ18OH2O=-9.5 to -15‰ and δDH2O=-125 to -135‰ (chlorite) and -70 to -80‰ (epidote). Chlorite-whole rock data suggest fluids that were derived from moderately 18O-exchanged meteoric water. Fault blocks in north-central Nevada expose a >5 km upper crustal cross section through the 12-17 x 20 km, 34 Ma Caetano caldera, including >3 km thickness intracaldera rhyolitic Caetano Tuff. Asymmetric caldera subsidence left a depression >1 km deep partly filled with a lake. Magma resurgence and emplacement of shallow granite porphyry plutons drove a hydrothermal system that altered >120 km2 of the caldera to depths >1.5 km. Alteration was focused in an early granite porphyry intrusion and surrounding upper Caetano Tuff and lacustrine sediments. Early pervasive quartz-kaolinite-pyrite alteration grades outward and downward into more restricted quartz-illite/smectite-pyrite alteration. Hematite, quartz, and barite veins and hydrothermal breccias cut

Geology and structure of the Malpaso caldera and El Ocote ignimbrite, Aguascalientes, Mexico

International Nuclear Information System (INIS)

Nieto-Obregon, Jorge; Aguirre-DIaz, Gerardo

2008-01-01

A new caldera, named Malpaso, is reported west of the city of Aguascalientes, Mexico. The Malpaso caldera is a volcano-tectonic depression, highly fractured and faulted, and was filled by voluminous pyroclastic products related to the caldera collapse. Due to these characteristics it as a graben caldera. It is truncated by younger normal faults of the Calvillo and Aguascalientes grabens. In this work we present a summary of the geologic and structural observations on this caldera, as well as a description of the main caldera product, the high-grade El Ocote ignimbrite.

Geology and structure of the Malpaso caldera and El Ocote ignimbrite, Aguascalientes, Mexico

Energy Technology Data Exchange (ETDEWEB)

Nieto-Obregon, Jorge [Facultad de IngenierIa, UNAM, Coyoacan, 04510, Mexico D.F. (Mexico); Aguirre-DIaz, Gerardo [Centro de Geociencias, UNAM, Campus Juriquilla, 76220, Queretaro, Qro. (Mexico)], E-mail: nieto@servidor.unam.mx, E-mail: ger@geociencias.unam.mx

2008-10-01

A new caldera, named Malpaso, is reported west of the city of Aguascalientes, Mexico. The Malpaso caldera is a volcano-tectonic depression, highly fractured and faulted, and was filled by voluminous pyroclastic products related to the caldera collapse. Due to these characteristics it as a graben caldera. It is truncated by younger normal faults of the Calvillo and Aguascalientes grabens. In this work we present a summary of the geologic and structural observations on this caldera, as well as a description of the main caldera product, the high-grade El Ocote ignimbrite.

New Seismic Monitoring Station at Mohawk Ridge, Valles Caldera

Energy Technology Data Exchange (ETDEWEB)

Roberts, Peter Morse [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-09-20

Two new broadband digital seismic stations were installed in the Valles Caldera in 2011 and 2012. The first is located on the summit of Cerros del Abrigo (station code CDAB) and the second is located on the flanks of San Antonio Mountain (station code SAMT). Seismic monitoring stations in the caldera serve multiple purposes. These stations augment and expand the current coverage of the Los Alamos Seismic Network (LASN), which is operated to support seismic and volcanic hazards studies for LANL and northern New Mexico (Figure 1). They also provide unique continuous seismic data within the caldera that can be used for scientific studies of the caldera’s substructure and detection of very small seismic signals that may indicate changes in the current and evolving state of remnant magma that is known to exist beneath the caldera. Since the installation of CDAB and SAMT, several very small earthquakes have already been detected near San Antonio Mountain just west of SAMT (Figure 2). These are the first events to be seen in that area. Caldera stations also improve the detection and epicenter determination quality for larger local earthquakes on the Pajarito Fault System east of the Preserve and the Nacimiento Uplift to the west. These larger earthquakes are a concern to LANL Seismic Hazards assessments and seismic monitoring of the Los Alamos region, including the VCNP, is a DOE requirement. Currently the next closest seismic stations to the caldera are on Pipeline Road (PPR) just west of Los Alamos, and Peralta Ridge (PER) south of the caldera. There is no station coverage near the resurgent dome, Redondo Peak, in the center of the caldera. Filling this “hole” is the highest priority for the next new LASN station. We propose to install this station in 2018 on Mohawk Ridge just east of Redondito, in the same area already occupied by other scientific installations, such as the MCON flux tower operated by UNM.

Post-eruptive flooding of Santorini caldera and implications for tsunami generation

Science.gov (United States)

Nomikou, P.; Druitt, T. H.; Hübscher, C.; Mather, T. A.; Paulatto, M.; Kalnins, L. M.; Kelfoun, K.; Papanikolaou, D.; Bejelou, K.; Lampridou, D.; Pyle, D. M.; Carey, S.; Watts, A. B.; Weiß, B.; Parks, M. M.

2016-01-01

Caldera-forming eruptions of island volcanoes generate tsunamis by the interaction of different eruptive phenomena with the sea. Such tsunamis are a major hazard, but forward models of their impacts are limited by poor understanding of source mechanisms. The caldera-forming eruption of Santorini in the Late Bronze Age is known to have been tsunamigenic, and caldera collapse has been proposed as a mechanism. Here, we present bathymetric and seismic evidence showing that the caldera was not open to the sea during the main phase of the eruption, but was flooded once the eruption had finished. Inflow of water and associated landsliding cut a deep, 2.0–2.5 km3, submarine channel, thus filling the caldera in less than a couple of days. If, as at most such volcanoes, caldera collapse occurred syn-eruptively, then it cannot have generated tsunamis. Entry of pyroclastic flows into the sea, combined with slumping of submarine pyroclastic accumulations, were the main mechanisms of tsunami production. PMID:27824353

How summit calderas collapse on basaltic volcanoes: new insights from the April 2007 caldera collapse of Piton de la Fournaise volcano

Energy Technology Data Exchange (ETDEWEB)

Michon, Laurent; Catry, Thibault; Merle, Olivier [Laboratoire GeoSciences Reunion, Universite de la Reunion, Institut de Physique du Globe de Paris, CNRS, UMR 7154 - Geologie des Systemes Volcaniques, 15 avenue Rene Cassin, 97715 Saint Denis (France); Villeneuve, Nicolas [Institut de Recherche pour le Developpement, US 140, BP172, 97492 Sainte-Clotilde cedex (France)], E-mail: laurent.michon@univ-reunion.fr

2008-10-01

In April 2007, Piton de la Fournaise volcano experienced a caldera collapse during its largest historical eruption. We present here the resulting deformation and a synthesis of the seismicity recorded during recent caldera collapses. It allows us to propose a unifying mechanism that explains the pulsating collapse dynamics.

Remote sensing of geologic mineral occurrences for the Colorado mineral belt using LANDSAT data

Science.gov (United States)

Carpenter, R. H. (Principal Investigator); Trexler, D. W.

1976-01-01

The author has identified the following significant results. LANDSAT imagery was examined as a practical and productive tool for mineral exploration along the Colorado Mineral Belt. An attempt was made to identify all large, active and/or abandoned mining districts on the imagery which initially were discovered by surface manifestations. A number of strong photolinements, circular features, and color anomalies were identified. Some of these form a part of the structural and igneous volcanic framework in which mineral deposits occur. No specific mineral deposits such as veins or porphyries were identified. Promising linear and concentric features were field checked at several locations. Some proved to be fault zones and calderas; others were strictly topographic features related to stream or glacial entrenchment. The Silverton Caldera region and the Idaho Springs-Central City district were chosen and studied as case histories to evaluate the application of LANDSAT imagery to mineral exploration. Evidence of specific mineralization related to ore deposits in these two areas were observed only on low level photography.

A kuroko-type polymetallic sulfide deposit in a submarine silicic caldera

Science.gov (United States)

Iizasa; Fiske; Ishizuka; Yuasa; Hashimoto; Ishibashi; Naka; Horii; Fujiwara; Imai; Koyama

1999-02-12

Manned submersible studies have delineated a large and actively growing Kuroko-type volcanogenic massive sulfide deposit 400 kilometers south of Tokyo in Myojin Knoll submarine caldera. The sulfide body is located on the caldera floor at a depth of 1210 to 1360 meters, has an area of 400 by 400 by 30 meters, and is notably rich in gold and silver. The discovery of a large Kuroko-type polymetallic sulfide deposit in this arc-front caldera raises the possibility that the numerous unexplored submarine silicic calderas elsewhere might have similar deposits.

Kaguyak dome field and its Holocene caldera, Alaska Peninsula

Science.gov (United States)

Fierstein, J.; Hildreth, W.

2008-01-01

Kaguyak Caldera lies in a remote corner of Katmai National Park, 375??km SW of Anchorage, Alaska. The 2.5-by-3-km caldera collapsed ~ 5.8 ?? 0.2??ka (14C age) during emplacement of a radial apron of poorly pumiceous crystal-rich dacitic pyroclastic flows (61-67% SiO2). Proximal pumice-fall deposits are thin and sparsely preserved, but an oxidized coignimbrite ash is found as far as the Valley of Ten Thousand Smokes, 80??km southwest. Postcaldera events include filling the 150-m-deep caldera lake, emplacement of two intracaldera domes (61.5-64.5% SiO2), and phreatic ejection of lakefloor sediments onto the caldera rim. CO2 and H2S bubble up through the lake, weakly but widely. Geochemical analyses (n = 148), including pre-and post-caldera lavas (53-74% SiO2), define one of the lowest-K arc suites in Alaska. The precaldera edifice was not a stratocone but was, instead, nine contiguous but discrete clusters of lava domes, themselves stacks of rhyolite to basalt exogenous lobes and flows. Four extracaldera clusters are mid-to-late Pleistocene, but the other five are younger than 60??ka, were truncated by the collapse, and now make up the steep inner walls. The climactic ignimbrite was preceded by ~ 200??years by radial emplacement of a 100-m-thick sheet of block-rich glassy lava breccia (62-65.5% SiO2). Filling the notches between the truncated dome clusters, the breccia now makes up three segments of the steep caldera wall, which beheads gullies incised into the breccia deposit prior to caldera formation. They were probably shed by a large lava dome extruding where the lake is today.

Seismic constraints on caldera dynamics from the 2015 Axial Seamount eruption.

Science.gov (United States)

Wilcock, William S D; Tolstoy, Maya; Waldhauser, Felix; Garcia, Charles; Tan, Yen Joe; Bohnenstiehl, DelWayne R; Caplan-Auerbach, Jacqueline; Dziak, Robert P; Arnulf, Adrien F; Mann, M Everett

2016-12-16

Seismic observations in volcanically active calderas are challenging. A new cabled observatory atop Axial Seamount on the Juan de Fuca ridge allows unprecedented real-time monitoring of a submarine caldera. Beginning on 24 April 2015, the seismic network captured an eruption that culminated in explosive acoustic signals where lava erupted on the seafloor. Extensive seismic activity preceding the eruption shows that inflation is accommodated by the reactivation of an outward-dipping caldera ring fault, with strong tidal triggering indicating a critically stressed system. The ring fault accommodated deflation during the eruption and provided a pathway for a dike that propagated south and north beneath the caldera's east wall. Once north of the caldera, the eruption stepped westward, and a dike propagated along the extensional north rift. Copyright © 2016, American Association for the Advancement of Science.

Piston to funnel - successive growth of a collapsed caldera during the Miyakejima 2000 eruption

International Nuclear Information System (INIS)

Geshi, Nobuo

2008-01-01

We present an analysis of caldera evolution at Miyakejima in 2000. The caldera changed its structure from piston to funnel subsidence during its growth. The successive subsidence of the central block induced landslides at the caldera wall, which successively enlarged the diameter of the caldera.

Piston to funnel - successive growth of a collapsed caldera during the Miyakejima 2000 eruption

Energy Technology Data Exchange (ETDEWEB)

Geshi, Nobuo [Geological Survey of Japan, AIST, 1-1-1 Higashi, Tsukuba Ibaraki 305-8567 (Japan)], E-mail: geshi-nob@aist.go.jp

2008-10-01

We present an analysis of caldera evolution at Miyakejima in 2000. The caldera changed its structure from piston to funnel subsidence during its growth. The successive subsidence of the central block induced landslides at the caldera wall, which successively enlarged the diameter of the caldera.

Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption.

Science.gov (United States)

Di Vito, Mauro A; Acocella, Valerio; Aiello, Giuseppe; Barra, Diana; Battaglia, Maurizio; Carandente, Antonio; Del Gaudio, Carlo; de Vita, Sandro; Ricciardi, Giovanni P; Ricco, Ciro; Scandone, Roberto; Terrasi, Filippo

2016-08-25

Calderas are collapse structures related to the emptying of magmatic reservoirs, often associated with large eruptions from long-lived magmatic systems. Understanding how magma is transferred from a magma reservoir to the surface before eruptions is a major challenge. Here we exploit the historical, archaeological and geological record of Campi Flegrei caldera to estimate the surface deformation preceding the Monte Nuovo eruption and investigate the shallow magma transfer. Our data suggest a progressive magma accumulation from ~1251 to 1536 in a 4.6 ± 0.9 km deep source below the caldera centre, and its transfer, between 1536 and 1538, to a 3.8 ± 0.6 km deep magmatic source ~4 km NW of the caldera centre, below Monte Nuovo; this peripheral source fed the eruption through a shallower source, 0.4 ± 0.3 km deep. This is the first reconstruction of pre-eruptive magma transfer at Campi Flegrei and corroborates the existence of a stationary oblate source, below the caldera centre, that has been feeding lateral eruptions for the last ~5 ka. Our results suggest: 1) repeated emplacement of magma through intrusions below the caldera centre; 2) occasional lateral transfer of magma feeding non-central eruptions within the caldera. Comparison with historical unrest at calderas worldwide suggests that this behavior is common.

National uranium resource evaluation, Montrose Quadrangle, Colorado

International Nuclear Information System (INIS)

Goodknight, C.S.; Ludlam, J.R.

1981-06-01

The Montrose Quadrangle in west-central Colorado was evaluated to identify and delineate areas favorable for the occurrence of uranium deposits according to National Uranium Resource Evaluation program criteria. General surface reconnaissance and geochemical sampling were conducted in all geologic environments in the quadrangle. Preliminary data from aerial radiometric and hydrogeochemical and stream-sediment reconnaissance were analyzed and brief followup studies were performed. Twelve favorable areas were delineated in the quadrangle. Five favorable areas contain environments for magmatic-hydrothermal uranium deposits along fault zones in the Colorado mineral belt. Five areas in parts of the Harding and Entrada Sandstones and Wasatch and Ohio Creek Formations are favorable environments for sandstone-type uranium deposits. The area of late-stage rhyolite bodies related to the Lake City caldera is a favorable environment for hydroauthigenic uranium deposits. One small area is favorable for uranium deposits of uncertain genesis. All near-surface Phanerozoic sedimentary rocks are unfavorable for uranium deposits, except parts of four formations. All near-surface plutonic igneous rocks are unfavorable for uranium deposits, except five areas of vein-type deposits along Tertiary fault zones. All near-surface volcanic rocks, except one area of rhyolite bodies and several unevaluated areas, are unfavorable for uranium. All near-surface Precambrian metamorphic rocks are unfavorable for uranium deposits. Parts of two wilderness areas, two primitive areas, and most of the subsurface environment are unevaluated

Caldera resurgence driven by magma viscosity contrasts.

Science.gov (United States)

Galetto, Federico; Acocella, Valerio; Caricchi, Luca

2017-11-24

Calderas are impressive volcanic depressions commonly produced by major eruptions. Equally impressive is the uplift of the caldera floor that may follow, dubbed caldera resurgence, resulting from magma accumulation and accompanied by minor eruptions. Why magma accumulates, driving resurgence instead of feeding large eruptions, is one of the least understood processes in volcanology. Here we use thermal and experimental models to define the conditions promoting resurgence. Thermal modelling suggests that a magma reservoir develops a growing transition zone with relatively low viscosity contrast with respect to any newly injected magma. Experiments show that this viscosity contrast provides a rheological barrier, impeding the propagation through dikes of the new injected magma, which stagnates and promotes resurgence. In explaining resurgence and its related features, we provide the theoretical background to account for the transition from magma eruption to accumulation, which is essential not only to develop resurgence, but also large magma reservoirs.

Petrological cycles and caldera-forming events

Science.gov (United States)

Bachmann, O.; Deering, C. D.

2012-12-01

Many caldera-forming events can be framed within broad petrological cycles; volcanic stratigraphy typically defines a trend from mafic to more silicic magmas with time, culminating in the catastrophic evacuation of an upper crustal reservoir filled with the silicic magma, followed by a return to the eruption of more mafic magmas shortly after caldera collapse. Understanding how such cycles develop has clear implications for characterizing the current state of an active system. Here, we focus on a detailed examination of the well-exposed Quaternary Kos-Nisyros eruptive sequence (eastern Aegean arc) to frame a potential model for such cycles. On the basis of zircon U/Th/Pb ages, building the upper crustal magma chamber large enough to induce caldera collapse required at least a few hundred thousand years. This timeframe is necessary not only for the accumulation of large amounts of viscous, gas-rich silicic magma, but also to heat the upper crust sufficiently to allow the developing reservoir to be maintained above the solidus. In the Kos-Nisyros volcanic center, small eruptions precede the caldera-forming event and mark this period of thermal maturation as the system transitions from intermediate to silicic magma, reaching the most-evolved state only shortly prior to the caldera-forming event, the Kos Plateau Tuff (> 60 km3 of volatile-rich, high-silica rhyolite). The Kos Plateau Tuff was then followed by small-volume eruptions of more mafic magma (basaltic andesite, andesite, and dacites) that are characterized by a drier mineral assemblage. With time, the system transitioned back to cold, wet, high-SiO2 rhyolite. We suggest that the changes in magma composition and mineralogy following the caldera-forming event are due to a near-complete crystallization of the non-erupted mush in the upper crustal reservoir as it is abruptly decompressed during eruption. This rapid crystallization (1) leads to the formation of a porphyritic texture in the crystalline residual - a

‘BIG, HARD and UP!’ A healthy creed for men to live by?

Directory of Open Access Journals (Sweden)

Stephan Van der Watt

2016-06-01

Full Text Available The social construction of reality is influenced extensively by the mass media. Commercialised images of masculinity, including discourses to interpret it, are continuously reflected and/or created by sources of mass media, in a myriad of ways. These images are subjectively loaded, but still effectively communicate to us, and even entice and persuade us. It furthermore wields extensive power over men – especially over their self-images, passions, and egos. In this article, dominating images and discourses concerning manhood and male identity – particularly those displayed in men’s health magazines (MHM – were critically examined. This was done through a thematic analysis of 123 issues (spanning more than 10 years of MHM cover pages. The investigation showed that MHM is infused with traditional masculine ideology. Moreover, MHM fails to confront discourses that endorse hegemonic masculinity, for the sake of holistic health. It was suggested that a sober, precautionary, health strategy should challenge men to critically engage with MHM’s reigning creed: ‘big, hard and up’. This creed incites a utilitarian view of sexuality within a culture of performance-driven masculinity, which subsequently fuels anxieties that can lead to unhealthy issues, such as body image dissatisfaction. From a pastoral care perspective, it was asserted that (specifically Christian men need to search for alternative ways to instigate their capacity to experience and facilitate authentic intimacy, in order to work toward the social construction of more balanced and healthy discourses on male identity.   Keywords:Masculinity/Masculinities; Men's Health; Male Sexuality; Embodiment; Pastoral Care Perspective

The Magmatic Plumbing System of the Campi Flegrei Caldera.

Science.gov (United States)

Lucia, C.; Ilenia, A.; Massimo, D.; Valeria, D.; Mauro, D.; Giovanni, O.

2006-12-01

The Campi Flegrei caldera is a nested and resurgent structure generated by at least two major collapses. Large sectors of the structural boundary of both calderas resulted from partial reactivation of pre-existing faults generated by regional tectonism. Its magmatic system is still active with the last eruption occurring in 1538 A.D. (Monte Nuovo), widespread fumaroles and hot springs activity, and the unrest episodes in the last 35 years, with a maximum net uplift of about 3.5 m in the Pozzuoli area. The definition of the history of the magmatic feeding system of this caldera, in terms of composition, time- scale and depth of crystallization, relation between composition of the erupted magma and structural position of the vent, and magma chamber processes, is of extreme importance for a better understanding of the dynamic conditions of the present day magma chamber and for evaluating of the extent to which the behavior of the magmatic system can be predicted. The Campi Flegrei caldera magmatic plumbing system is characterized by deep and shallow reservoirs. Campi Flegrei magmas originated in a subduction modified mantle source, stagnate at mid crustal level (20- 10 km depth), where they differentiated and are contaminated with the continental crust. From the "deep reservoir" shoshonitic to latitic magmas rise towards the surface along the NE aligned regional fault reactivated during the caldera collapse, whereas trachytic magmas rise mostly along faults and fractures bordering the resurgent block and the southern part of the Campi Flegrei caldera. Repeated arrival of trachytic to phonolitic magmas form shallow reservoirs at 4-3 km depth, in which differentiation and mixing processes occur before and during the eruption.

14C ages for the ejecta from Kutcharo and Mashu calderas, eastern Hokkaido, Japan

International Nuclear Information System (INIS)

Yamamoto, Takahiro; Ito, Jun-ichi; Nakagawa, Mitsuhiro; Hasegawa, Takeshi; Kishimoto, Hiroshi

2010-01-01

Eruption ages of the ejecta from Kutcharo and Mashu calderas were systematically determined by 14 C dating. 16 charred samples were newly obtained from the Mashu and Nakashumbetsu Tephra Formations around the calderas and dated by AMS and β-counting methods. Examined units are Ma-d, Ma-e, Ma-f, Ma-j, Ma-k, Ma-l and Ml-a in the Mashu ejecta and 6 Nakashumbetsu tephra layers including Kutcharo Pumice Flow Deposit I (KpI), which is the youngest caldera-forming product from Kutcharo caldera. Results of the 14 C dating range from 3,660 ±40 yBP to 36,080±1,300 yBP, and are consistent with the tephrostratigraphy. Calendar age for KpI was newly calculated at almost 40 ka and this age shows there was about 70,000 years recurrence interval between KpI and KpIV caldera-forming eruptions. Mashu caldera has appeared on the eastern part of Kutcharo caldera immediately after the KpI eruption, and calendar age for its main caldera-forming eruption were determined at ca. BC 5,600. (author)

Geophysical expression of caldera related volcanism, structures and mineralization in the McDermitt volcanic field

Science.gov (United States)

Rytuba, J. J.; Blakely, R. J.; Moring, B.; Miller, R.

2013-12-01

The High Rock, Lake Owyhee, and McDermitt volcanic fields, consisting of regionally extensive ash flow tuffs and associated calderas, developed in NW Nevada and SE Oregon following eruption of the ca. 16.7 Ma Steens flood basalt. The first ash flow, the Tuff of Oregon Canyon, erupted from the McDermitt volcanic field at 16.5Ma. It is chemically zoned from peralkaline rhyolite to dacite with trace element ratios that distinguish it from other ash flow tuffs. The source caldera, based on tuff distribution, thickness, and size of lithic fragments, is in the area in which the McDermitt caldera (16.3 Ma) subsequently formed. Gravity and magnetic anomalies are associated with some but not all of the calderas. The White Horse caldera (15.6 Ma), the youngest caldera in the McDermitt volcanic field has the best geophysical expression, with both aeromagnetic and gravity lows coinciding with the caldera. Detailed aeromagnetic and gravity surveys of the McDermitt caldera, combined with geology and radiometric surveys, provides insight into the complexities of caldera collapse, resurgence, post collapse volcanism, and hydrothermal mineralization. The McDermitt caldera is among the most mineralized calderas in the world, whereas other calderas in these three Mid Miocene volcanic fields do not contain important hydrothermal ore deposits, despite having similar age and chemistry. The McDermitt caldera is host to Hg, U, and Li deposits and potentially significant resources of Ga, Sb, and REE. The geophysical data indicate that post-caldera collapse intrusions were important in formation of the hydrothermal systems. An aeromagnetic low along the E caldera margin reflects an intrusion at a depth of 2 km associated with the near-surface McDermitt-hot-spring-type Hg-Sb deposit, and the deeper level, high-sulfidation Ga-REE occurrence. The Li deposits on the W side of the caldera are associated with a series of low amplitude, small diameter aeromagnetic anomalies that form a continuous

Asymmetric growth of collapsed caldera by oblique subsidence during the 2000 eruption of Miyakejima, Japan

Science.gov (United States)

Geshi, Nobuo

2009-04-01

Oblique development of the ring faults reflecting the structural heterogeneities inside the volcano formed many asymmetric structures of Miyakejima 2000 AD caldera. The asymmetry includes (a) offset location of the ring faults with respect to the associated shallow magma chamber, (b) unequal outward migration of the caldera wall 600 m at the southeastern rim but only 200 m at the northwestern rim, (c) development of tilted terrace only at the southeastern caldera margin, (d) eruption sites and fumaroles being confined to the southern part of the caldera. Geophysical data, including ground deformation and seismic activity, indicates the offset of the location of the magma chamber about 2 km south of the caldera center on the surface. The ring faults propagated from the deflating magma chamber obliquely about 30 degrees toward the summit. The oblique subsidence of the cylindrical block formed a wider instable zone, particularly in the southeastern side of the ring fault that enhanced the larger outward migration of the caldera rim and also caused the formation of the outer half-ring fault bordering the tilting slope at the southern part. Ascending pass of the buoyant magma along the tilted ring faults was concentrated in the southern half of the caldera and consequently the distributions of the eruption sites and fumaroles are localized in the southern-half part of the caldera. The structure of the Miyakejima 2000 caldera with complete development of the ring faults, its high roof aspect ratio and oblique subsidence is clearly distinguishable from trapdoor-type caldera. The oblique development of the ring faults can be controlled by the mechanical contrast between the solidified conduits and surrounding fragile volcanic edifice. Asymmetric development of the Miyakejima caldera shows that the collapsed calderas are potential indicators of the heterogeneous structures inside of the volcano, particularly in the case of small-size caldera.

Pre-eruptive conditions of the phonolitic magma from the El Abrigo caldera-forming eruption (Las Canadas caldera, Tenerife, Canary Islands)

International Nuclear Information System (INIS)

Marti, J; Andujar, J; Costa, F; Wolff, J A; Carroll, M R

2008-01-01

We have performed phase equilibrium experiments to determine the pre-eruptive conditions of the largest phonolitic caldera-forming eruption (∼20 km3 of DRE) that occurred on Tenerife (Canary Islands). The Abrigo ignimbrite was erupted during the last caldera-forming episode (ca. 190 ka), from the Canadas caldera. Comparison of the natural and experimental phase proportions and compositions indicates that the phonolite at the roof of the Abrigo magma reservoir was at 130 ± 50 MPa (corresponding to ca. 4 - 5 km below the surface), 825 ± 25 oC, with 3 ± 1 wt% dissolved H2O and fO2 at the Ni-NiO buffer ? 1 log unit. This shows that the magma that produced the largest ignimbrite on Tenerife was stored at relatively shallow depths but was water-undersaturated, and its eruption was probably triggered by input of fresh mafic magma.

Pre-eruptive conditions of the phonolitic magma from the El Abrigo caldera-forming eruption (Las Canadas caldera, Tenerife, Canary Islands)

Energy Technology Data Exchange (ETDEWEB)

Marti, J; Andujar, J; Costa, F [Institute of Earth Sciences ' Jaume Almera' , CSIC, C/ Lluis Sole I Sabaris, s/n Barcelona, 08028 Spain (Spain); Wolff, J A [School of Earth and Environmental Sciences, Washington State University, Pullman, WA 99164-2812 (United States); Carroll, M R [Dipartimento di Scienze della Terra, Via Gentile III da Varano, Universita di Camerino, 62032 MC (Italy)], E-mail: jawolff@mail.wsu.edu, E-mail: Michael.carroll@unicam.it

2008-10-01

We have performed phase equilibrium experiments to determine the pre-eruptive conditions of the largest phonolitic caldera-forming eruption ({approx}20 km3 of DRE) that occurred on Tenerife (Canary Islands). The Abrigo ignimbrite was erupted during the last caldera-forming episode (ca. 190 ka), from the Canadas caldera. Comparison of the natural and experimental phase proportions and compositions indicates that the phonolite at the roof of the Abrigo magma reservoir was at 130 {+-} 50 MPa (corresponding to ca. 4 - 5 km below the surface), 825 {+-} 25 oC, with 3 {+-} 1 wt% dissolved H2O and fO2 at the Ni-NiO buffer ? 1 log unit. This shows that the magma that produced the largest ignimbrite on Tenerife was stored at relatively shallow depths but was water-undersaturated, and its eruption was probably triggered by input of fresh mafic magma.

Chapter 1. Valles Caldera National Preserve land use history

Science.gov (United States)

Kurt F. Anschuetz

2007-01-01

The land use history of the Valles Caldera National Preserve (VCNP) extends back over thousands of years. Few known archaeological properties in the Valles Caldera date to the Paleoindian period (10000/9500–5500 B.C.). These finds include the recent discovery, during ongoing archaeological studies (Dr. Bob Parmeter, personal communication, VCNP, Los Alamos, 2005), of...

Exploration of Geothermal Natural Resources from Menengai Caldera at Naruku, Kenya

Science.gov (United States)

Patlan, E.; Wamalwa, A.; Thompson, L. E.; Kaip, G.; Velasco, A. A.

2011-12-01

The Menengai Caldera, a large, dormant volcano, lies near the city of Naruku, Kenya (0.20°S, 36.07°E) and presents a significant natural geothermal energy resource that will benefit local communities. Kenya continues to explore and exploit its only major energy resource: geothermal energy. The Geothermal Development Company (GDC) of Kenya and University of Texas at El Paso (UTEP) have initially deployed seven seismic stations to address the volcanic hazards and associated processes that occurs through the analysis of data collection from seismic sensors that record ground motion. Seven more sensors are planned to be deployed in Aug. 2011. In general, the internal state and activity of the caldera is an important component to the understanding of porosity of the fault system, which is derived from the magma movement of the hot spot, and for the exploitation of geothermal energy. We analyze data from March to May 2011 to investigate the role of earthquakes and faults in controlling the caldera processes, and we find 15 events occurred within the caldera. We will utilize the double difference earthquake location algorithm (HypoDD) to analyze the local events in order to find active faulting of the caldera and the possible location of the magma chamber. For future work, we will combine the exiting data with the new seismic station to image the location of the caldera magma chamber.

Magnetic study of the Furnas caldera (Azores

Directory of Open Access Journals (Sweden)

J. M. Torta

1997-06-01

Full Text Available A local ground magnetic study of the Furnas caldera (S. Miguel Island, Azores has provided new insight into the magnetic structure of this volcano. Analysis of the data comprised removal of the IGRF, reduction to the pole, pseudogravity integration and upward continuation. Also, a spectral method was applied to estimate the depth to the magnetic sources, as well as a 2.5D forward modelling technique. Magnetic properties obtained at the laboratory for some representative sample rocks were considered in the modelling process. The most relevant features are the existence of an important negative anomaly inside the caldera and of an intense positive anomaly to the south of the coast. The former points out a decrease in the magnetization of the caldera filling materials with respect to the surrounding rocks, which could be explained as the result of post-eruption processes such as hydrothermal alteration. This is expected as Furnas has an active hydrothermal system probably related with a magmatic reservoir at high temperature. The positive anomaly suggests the existence of a strongly-magnetized body beneath the south coast.

Structural controls on diffuse degassing in the Las Cañadas caldera, Tenerife, Canary Islands

Science.gov (United States)

Galindo, I.; Soriano, C.; Martí, J.; Pérez, N.

2003-04-01

The Las Cañadas caldera is an elliptical depression located in the central part of the Tenerife Island. The active Teide stratovolcano stands in the centre of the depression, which is limited to the south by the caldera wall, up to 500 m high above the caldera floor. Mapping most of the caldera wall at 1:5000 has provided new insights on its stratigraphy, structure, and geological evolution. Three major ENE-WSW normal faults have been mapped on the caldera wall in the area comprised between El Llano de Ucanca and Los Azulejos, where an intense hydrothermal alteration affects the lower stratigraphic levels of the caldera wall. Hydrothermal alteration is rather distinctive in this area, showing bluish to greenish colours. Most of the phonolitic cone sheets and radial dykes of the caldera wall do not show distinctive hydrothermal features, as do show the phonolitic pyroclastic rocks and lavas of the lower parts of the caldera wall. This suggests the main episodes of dyke intrusion in the Las Cañadas caldera postdate hydrothermal alteration. ENE-WSW normal faults involve dyke swarms and rocks of the upper stratigraphic levels of the caldera wall, and show displacements of up to 100 m. Unfortunately the upper possible age of these faults is poorly constrained since no contact relationship has been observed between fault planes and the rocks of the uppermost stratigraphic levels of the caldera wall. The rocks of the caldera wall adjacent to the faults are intensely fractured at the macro and mesoscale. In addition to field mapping, a soil gas survey was carried out at the caldera depression. Soil CO2 efflux and H2 concentration were measured reaching values of 12 gm-2d-1 and 4 ppmV, respectively. Spatial distribution of these species showed that positive anomalies coincide with the surface expression of the three major faults and their adjacent intensely fractured zone. The high CO2 and H2 values and their coincidence with major normal faults suggests that degassing in

Influences of magma chamber ellipticity on ring fracturing and eruption at collapse calderas

International Nuclear Information System (INIS)

Holohan, Eoghan P; Walsh, John J; Vries, Benjamin van Wyk de; Troll, Valentin R; Walter, Thomas R

2008-01-01

Plan-view ellipticity of a pre-caldera magma reservoir, and its influence on the development of caldera ring fracturing and eruptive behaviour, have not previously been subjected to dedicated evaluation. We experimentally simulated caldera collapse into elliptical magma chambers and found that collapse into highly-elliptical chambers produced a characteristic pattern of ring-fault localization and lateral propagation. Although results are preliminary, the general deformation pattern for elliptical resurgence shows strong similarities to elliptical collapse. Ring faults accommodating uplift again initiate around the chamberos short axis and are reverse, but dip inward. Field and geophysical observations at several elliptical calderas of varying scale (e.g. Long Valley, Katmai, and Rabaul calderas) are consistent with a control from elliptical magma chamber geometry on ring fracturing and eruption, as predicted from our experiments.

Influences of magma chamber ellipticity on ring fracturing and eruption at collapse calderas

Energy Technology Data Exchange (ETDEWEB)

Holohan, Eoghan P; Walsh, John J [Fault Analysis Group, School of Geological Sciences, University College Dublin, Belfield, Dublin 4 (Ireland); Vries, Benjamin van Wyk de [Laboratoire Magmas et Volcans, 5 rue Kessler, 63038 Clermont-Ferrand (France); Troll, Valentin R [Department of Earth Sciences, Uppsala University, SE-752 36, Uppsala (Sweden); Walter, Thomas R [GFZ Potsdam, Telegrafenberg, Potsdam, D-14473 (Germany)], E-mail: Eoghan.Holohan@ucd.ie

2008-10-01

Plan-view ellipticity of a pre-caldera magma reservoir, and its influence on the development of caldera ring fracturing and eruptive behaviour, have not previously been subjected to dedicated evaluation. We experimentally simulated caldera collapse into elliptical magma chambers and found that collapse into highly-elliptical chambers produced a characteristic pattern of ring-fault localization and lateral propagation. Although results are preliminary, the general deformation pattern for elliptical resurgence shows strong similarities to elliptical collapse. Ring faults accommodating uplift again initiate around the chamberos short axis and are reverse, but dip inward. Field and geophysical observations at several elliptical calderas of varying scale (e.g. Long Valley, Katmai, and Rabaul calderas) are consistent with a control from elliptical magma chamber geometry on ring fracturing and eruption, as predicted from our experiments.

GPS time series at Campi Flegrei caldera (2000-2013

Directory of Open Access Journals (Sweden)

Prospero De Martino

2014-05-01

Full Text Available The Campi Flegrei caldera is an active volcanic system associated to a high volcanic risk, and represents a well known and peculiar example of ground deformations (bradyseism, characterized by intense uplift periods, followed by subsidence phases with some episodic superimposed mini-uplifts. Ground deformation is an important volcanic precursor, and, its continuous monitoring, is one of the main tool for short time forecast of eruptive activity. This paper provides an overview of the continuous GPS monitoring of the Campi Flegrei caldera from January 2000 to July 2013, including network operations, data recording and processing, and data products. In this period the GPS time series allowed continuous and accurate tracking of ground deformation of the area. Seven main uplift episodes were detected, and during each uplift period, the recurrent horizontal displacement pattern, radial from the “caldera center”, suggests no significant change in deformation source geometry and location occurs. The complete archive of GPS time series at Campi Flegrei area is reported in the Supplementary materials. These data can be usefull for the scientific community in improving the research on Campi Flegrei caldera dynamic and hazard assessment.

Caldera deformation in Kyushu island (SW Japan) through InSAR data

Science.gov (United States)

Nobile, Adriano; Pepe, Susi; Ruch, Joel; Trippanera, Daniele; Casu, Francesco; Castaldo, Raffaele; Tizzani, Pietro; Aoki, Yosuke; Geshi, Nobuo; Acocella, Valerio; Sansosti, Eugenio; Siniscalchi, Valeria; Borgstrom, Sven; Zoffoli, Simona

2014-05-01

Calderas are the surface expression of a long-lived and complex magmatic system, often hosting a shallower hydrothermal system. Most monitored calderas have experienced some forms of unrest, even though only a part of these unrest episodes has culminated in an eruption. This study focuses on surface deformation analysis using InSAR from 1993 to 2013 at two large active calderas, Aso and Aira, located on Kyushu Island (Japan). Despite being closely monitored, our knowledge on the deformation history of both calderas with regard to their activity is poor. ERS, ENVISAT, ALOS and COSMO-SkyMed SAR images have been processed to obtain mean velocity deformation maps and time series through the SBAS technique. Results are then inverted using the simulated annealing technique to evaluate the deformation source parameters. Aso caldera hosts several vents in its central portion. One of these, the Naka Dake crater is the only currently active and erupted 7 times since 1993. From January 1996 to November 1998, after the important 1994 - 1995 eruption, we observed a subsidence of ~1.2 cm/yr at the center of the caldera. Analytical models suggest a deflating source (with various possible shapes) at 5-7 km of depth, implying a magmatic nature for the deformation. Inversion results are consistent with available seismic and GPS data. Aira Caldera hosts the Sakurajima volcano along its southern rim, with a persistent eruptive activity since 1950s. From June 2006 to March 2011, we observed a broad uplift of ~1.5 cm along most of the caldera rim. Analytical inversion of both the entire dataset and a cross-correlated dataset suggests a deformation source at the caldera center, at a depth of 5-9 km (depending on the source shape), implying a magmatic nature of the deformation. Inversion results are in agreement with GPS and InSAR data inversions for other periods of activity. This research has been partially performed within the frame of Italian Space Agency (ASI) and Japan Aerospace

Scaling properties of planetary calderas and terrestrial volcanic eruptions

Directory of Open Access Journals (Sweden)

L. Sanchez

2012-11-01

Full Text Available Volcanism plays an important role in transporting internal heat of planetary bodies to their surface. Therefore, volcanoes are a manifestation of the planet's past and present internal dynamics. Volcanic eruptions as well as caldera forming processes are the direct manifestation of complex interactions between the rising magma and the surrounding host rock in the crust of terrestrial planetary bodies. Attempts have been made to compare volcanic landforms throughout the solar system. Different stochastic models have been proposed to describe the temporal sequences of eruptions on individual or groups of volcanoes. However, comprehensive understanding of the physical mechanisms responsible for volcano formation and eruption and more specifically caldera formation remains elusive. In this work, we propose a scaling law to quantify the distribution of caldera sizes on Earth, Mars, Venus, and Io, as well as the distribution of calderas on Earth depending on their surrounding crustal properties. We also apply the same scaling analysis to the distribution of interevent times between eruptions for volcanoes that have the largest eruptive history as well as groups of volcanoes on Earth. We find that when rescaled with their respective sample averages, the distributions considered show a similar functional form. This result implies that similar processes are responsible for caldera formation throughout the solar system and for different crustal settings on Earth. This result emphasizes the importance of comparative planetology to understand planetary volcanism. Similarly, the processes responsible for volcanic eruptions are independent of the type of volcanism or geographical location.

Magma transfer at Campi Flegrei caldera (Italy) before the 1538 AD eruption

Science.gov (United States)

Di Vito, Mauro A.; Acocella, Valerio; Aiello, Giuseppe; Barra, Diana; Battaglia, Maurizio; Carandente, Antonio; Del Gaudio, Carlo; de Vita, Sandro; Ricciardi, Giovanni; Rico, Ciro; Scandone, Roberto; Terrasi, Filippo

2017-04-01

Defining and understanding the shallow transfer of magma at volcanoes is crucial to forecast eruptions, possibly the ultimate goal of volcanology. This is particularly challenging at felsic calderas experiencing unrest, which typically includes significant changes in seismicity, deformation and degassing rates. Caldera unrest is particularly frequent, affects wide areas and often does not culminate in an eruption. Moreover its evidence is usually complicated by the presence of a hydrothermal system. As a result, forecasting any eruption and vent-opening sites within a caldera is very difficult. The Campi Flegrei caldera (CFc), in the densely inhabited area of Naples (Italy), is commonly considered one of the most dangerous active volcanic systems. CFc is a 12 km wide depression hosting two nested calderas formed during the eruptions of the Campanian Ignimbrite ( 39 ka) and the Neapolitan Yellow Tuff ( 15 ka). In the last 5 ka, resurgence, with uplift >60 m close to the central part of the caldera, was accompanied by volcanism between 4.8 and 3.8 ka. After 3 ka of quiescence, increasing seismicity and uplift preceded the last eruption at Monte Nuovo in 1538 for several decades. The most recent activity culminated in four unrest episodes between 1950-1952, 1969-1972, 1982-1984 and 2005-Present, with a cumulative uplift at Pozzuoli of 4.5 m; the present unrest episode has been interpreted as being magma-driven. These unrest episodes are considered the most evident expression of a longer-term (centuries or more) restless activity. The post-1980 deformation largely results from a magmatic oblate or sill-like source at 4 km depth below Pozzuoli. Despite the restless activity of CFc, the recent unrest episodes did not culminate in eruption, so that any possibility to define the pre-eruptive shallow transfer of magma remains elusive. Indeed, this definition is a crucial step in order to identify and understand pre-eruptive processes, and thus to make any forecast. To fill

The caldera of Volcan Fernandina: a remote sensing study of its structure and recent activity

Science.gov (United States)

Rowland, Scott K.; Munro, Duncan C.

1992-12-01

Air photographs taken in 1946, 1960, and 1982, together with SPOT HVR-1 images obtained in April and October of 1988, are used to characterize recent activity in and around the caldera of Fernandina Volcano, West Galapagos Islands. The eruptive and collapse events during this time span appear to be distributed in a NW-SE band across the summit and caldera. On the flanks of the volcano, subtle topographic ridges indicate that this is a long-term preferred orientation of extra-caldera activity as well (although radial and arcuate fissures are found on all sectors). The caldera is formed from the coalescence of multiple collapse features that are also distributed along a NW-SE direction, and these give the caldera its elongate and scalloped outline. The NW and SE benches consist of lavas that ponded in once-separated depressions that have been incorporated into the caldera by more recent collapse. The volume of individual eruptions within the caldera over the observed 42 years appears to be small (˜4x106 m3) in comparison to the volumes of individual flows exposed in the caldera walls (˜120 150x106 m3). Field observations (in 1989) of lavas exposed in the caldera walls and their cross-cutting relationships show that there have been at least three generations of calderas, and that at times each was completely filled. An interplay between a varying supply rate to the volcano and a regional stress regime is suggested to be the cause of long-term spatial and volumetric variations in activity. When supply is high, the caldera is filled in relative to collapse and dikes tend to propagate in all directions through the edifice. At other times (such as the present) supply is relatively low; eruptions are small, the caldera is far from being filled in, and dike propagation is influenced by an extra-volcano stress regime.

Carbonatite ring-complexes explained by caldera-style volcanism.

Science.gov (United States)

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

2013-01-01

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.

Gas Chemistry of Submarine Hydrothermal Venting at Maug Caldera, Mariana Arc

Science.gov (United States)

Embley, R. W.; Lupton, J. E.; Butterfield, D. A.; Lilley, M. D.; Evans, L. J.; Olson, E. J.; Resing, J. A.; Buck, N.; Larson, B. I.; Young, C.

2014-12-01

Maug volcano consists of 3 islands that define the perimeter of a submerged caldera that was formed by an explosive eruption. The caldera reaches a depth of ~225 meters, and has a prominent central cone or pinnacle that ascends within 20 meters of the sea surface. Our exploration of Maug began in 2003, when a single hydrocast in the caldera detected a strong suspended particle and helium plume reaching a maximum of δ3He = 250% at ~180 meters depth, clearly indicating hydrothermal activity within the caldera. In 2004 we returned armed with the ROPOS ROV, and two ROPOS dives discovered and sampled low temperature (~4 °C) diffuse venting associated with bacterial mats on the NE flank of the central pinnacle at 145 m depth. Samples collected with titanium gas tight bottles were badly diluted with ambient seawater but allowed an estimate of end-member 3He/4He of 7.3 Ra. Four vertical casts lowered into the caldera in 2004 all had a strong 3He signal (δ3He = 190%) at 150-190 meters depth. A recent expedition in 2014 focused on the shallow (~10 m) gas venting along the caldera interior. Scuba divers were able to collect samples of the gas bubbles using evacuated SS bottles fitted with plastic funnels. The gas samples had a consistent ~170 ppm He, 8 ppmNe, 60% CO2, 40%N2, and 0.8% Ar, and an end-member 3He/4He ratio of 6.9 Ra. This 3He/4He ratio falls within the range for typical arc volcanoes. The rather high atmospheric component (N2, Ar, Ne) in these samples is not contamination but appears to be derived from subsurface exchange between the ascending CO2 bubbles and air saturated seawater. A single vertical cast in 2014 had a maximum δ3He = 55% at 140 m depth, much lower than in 2003 and 2004. This decrease is possibly due to recent flushing of the caldera by a storm event, or may reflect a decrease in the deep hydrothermal activity. This area of shallow CO2 venting in Maug caldera is of particular interest as a natural laboratory for studying the effects of ocean

Hydrothermal activity in the Tulancingo-Acoculco Caldera Complex, central Mexico. Exploratory studies

Energy Technology Data Exchange (ETDEWEB)

Lopez-Hernandez, Aida [Gerencia de Proyectos Geotermoelectricos, CFE, Alejandro Volta 655, 58290 Morelia, Michoacan (Mexico); Centro de Geociencias, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Queretaro, Qro., 76230 (Mexico); Garcia-Estrada, Gerardo; Palma-Guzman, Hugo; Quijano-Leon, Jose L. [Gerencia de Proyectos Geotermoelectricos, CFE, Alejandro Volta 655, 58290 Morelia, Michoacan (Mexico); Aguirre-Diaz, Gerardo; Gonzalez-Partida, Eduardo [Centro de Geociencias, Universidad Nacional Autonoma de Mexico, Campus Juriquilla, Queretaro, Qro., 76230 (Mexico)

2009-09-15

Mineral alteration and fluid inclusion studies of drill cuttings and core samples indicate that the sedimentary basement rocks and the volcanic rocks associated with Tulancingo-Acoculco Caldera Complex have been the site of two distinct and major hydrothermal events. The complex, located in the eastern portion of the Trans-Mexican Volcanic Belt, is formed by the Pliocene Tulancingo Caldera and the younger (Pleistocene) Acoculco Caldera, which developed within the older depression. The volcanic rocks are underlain by Cretaceous sedimentary rocks of the Sierra Madre Oriental. The earliest important hydrothermal event occurred during the emplacement of Mid-Tertiary granitic intrusions that metamorphosed the sedimentary rocks; these intrusives are not exposed at the surface. However, granitic rocks were encountered at the bottom of exploratory borehole EAC-1, drilled within the Caldera Complex. The second main event occurred during the formation of the Tulancingo and Acoculco Calderas. Both episodes lead to secondary mineralization that reduced the permeability of the reservoir rocks. A possible third hydrothermal event may be associated with the recent magmatic activity within the Acoculco Caldera.Thermal logs from well EAC-1 display a conductive thermal gradient with maximum temperatures exceeding 300 C at 2000 m depth. Although there are no active thermal springs in the area, there is extensive fossil surface hydrothermal alteration and cold gas discharges with high He{sup 3}/He{sup 4} ratios. (author)

Storage, Ascent, and Release of Silicic Magma in Caldera-forming Eruptions

Science.gov (United States)

Myers, Madison Logan

The mechanisms and timescales associated with the triggering of caldera-forming eruptions remain ambiguous and poorly constrained. Do such eruptions start vigorously, then escalate, or can there be episodicity? Are they triggered through internal processes (e.g. recharge, buoyancy), or can external modulations play an important role? Key to answering these questions is the ability to reconstruct the state of the magma body immediately prior to eruption. My dissertation research seeks to answer these questions through detailed investigation of four voluminous caldera-forming eruptions: (1) 650 km3, 0.767 Ma Bishop Tuff, Long Valley, (2) 530 km3, 25.4 ka Oruanui eruption, Taupo, (3) 2,500 km3, 2.08 Ma Huckleberry Ridge Tuff, Yellowstone and (4) 250 km3, 26.91 Ma Cebolla Creek Tuff, Colorado. The main techniques I applied integrated glass geochemistry (major, trace and volatile), diffusion modeling, and detailed field sampling. In chapters two, three, and four these methods are applied to the initial fall deposits of three supereruptions (Bishop, Oruanui and Huckleberry Ridge) that preserve field-evidence for different opening behaviors. These behaviors range from continuous deposition of fall deposits and ignimbrite (Bishop), to repetitive start/stop behavior, with time breaks between eruptive episodes on the order of weeks to months (Oruanui, Huckleberry Ridge). To reconstruct the timescales of opening activity and relate this to conduit processes, I used two methods that exploit diffusion of volatiles through minerals and melt, providing estimates for the rate at which magmas ascended to the surface. This knowledge is then integrated with the pre-eruptive configuration of the magma body, based on melt inclusion chemistry, to interpret what triggered these systems into unrest. Finally, in chapter five I take a different approach by integrating geochemical data for melt inclusions and phenocryst minerals to test whether the mechanism of heat and volatile recharge

Insights into the emplacement of upper-crustal plutons and their relationship to large silicic calderas, from field relationships, geochronology, and zircon trace element geochemistry in the Stillwater - Clan Alpine caldera complex, western Nevada, USA

Science.gov (United States)

Colgan, Joseph P.; John, David A.; Henry, Christopher D.; Watts, Kathryn E.

2018-01-01

Geologic mapping, new U-Pb zircon ages, and new and published 40Ar/39Ar sanidine ages document the timing and extent of Oligocene magmatism in the southern Stillwater Range and Clan Alpine Mountains of western Nevada, where Miocene extension has exposed at least six nested silicic calderas and underlying granitic plutons to crustal depths locally ≥ 9 km. Both caldera-forming rhyolitic tuffs and underlying plutons were emplaced in two episodes, one from about 30.4-28.2 Ma that included the Deep Canyon, Job Canyon, and Campbell Creek calderas and underlying plutons, and one from about 25.3-24.8 Ma that included the Louderback Mountains, Poco Canyon, and Elevenmile Canyon calderas and underlying plutons. In these two 1-2 m.y. periods, almost the entire Mesozoic upper crust was replaced by Oligocene intrusive and extrusive rocks to depths ≥ 9 km over an estimated total area of 1500 km2 (pre-extension). Zircon trace element geochemistry indicates that some plutonic rock can be solidified residual magma from the tuff eruptions. Most plutons are not solidified residual magma, although they directly underlie calderas and were emplaced along the same structures shortly after to as much as one million years after caldera formation. Magma chambers and plutons grew by floor subsidence accommodated by downward transfer of country rocks. If other Great Basin calderas are similar, the dense concentration of shallowly exposed calderas in central Nevada is underlain by a complexly zoned mid-Cenozoic batholith assembled in discrete pulses that coincided with formation of large silicic calderas up to 2500-5000 km3.

Graben calderas of the Sierra Madre Occidental: The case of Guanajuato, central Mexico

Science.gov (United States)

Aguirre-Diaz, G. J.; Tristán-González, M.; Labarthe-Hernández, G.; Marti, J.

2013-12-01

The Sierra Madre Occidental (SMO) volcanic province is characterized by voluminous silicic ignimbrites that reach an accumulated thickness of 500 to 1500 m. A single ignimbrite can reach up to 350 m thick in its outflow facies. This ignimbrite sequence formed mostly within 38-23 Ma, building up a total estimated volume of ca. 580,000 km3 making the SMO the largest ignimbrite province of the world. We have showed that several and probably most of the SMO ignimbrites were erupted from fissures associated to Basin and Range fault systems or grabens (Geology, 2003), thus naming these volcano-tectonic structures as graben calderas (Caldera Volcanism book, Elsevier, 2008). Generally, the sequence observed in graben calderas include, from oldest to youngest, alluvial fan deposits combined with lacustrine deposits, pyroclastic surge deposits and minor volume ignimbrites, a large-volume ignimbrite that could be massive or made of successive layers, and sometimes silicic lava domes and/or mafic fissural lavas both with vents aligned with the graben trend. Fallout deposits, plinian or non-plinian, are not observed in the sequence. Thus, onset of caldera collapse represented by the major ignimbrite must occur just after deposition of continental sediments within the graben domain. A similar volcano-tectonic development is observed in pull-apart grabens. Therefore, extensional or transtensional tectonics, before and during caldera collapse, and the emplacement of a subgraben shallow silicic magma chamber are the necessary conditions for the development of graben calderas. We describe here the case of the Guanajuato graben caldera, located in the central part of Mexico and in the southeastern portion of the SMO volcanic province. The caldera is part of the economically important mining district of Guanajuato, with 28 silver mines, some active since the 16th century. The caldera structure, a rectangle of 10 x 16 km, was controlled by NW and NE regional fault systems. Most ore

Long Valley Caldera-Mammoth Mountain unrest: The knowns and unknowns

Science.gov (United States)

Hill, David P.

2017-01-01

This perspective is based largely on my study of the Long Valley Caldera (California, USA) over the past 40 years. Here, I’ll examine the “knowns” and the “known unknowns” of the complex tectonic–magmatic system of the Long Valley Caldera volcanic complex. I will also offer a few brief thoughts on the “unknown unknowns” of this system.

The confirmation of a work hypothesis: a new caldera in the center of the Mexican Volcanic Belt; La confirmacion de una hipotesis de trabajo: una nueva caldera en el centro del Cinturon Volcanico Mexicano

Energy Technology Data Exchange (ETDEWEB)

Anguita Virella, Francisco; Pal Verma, Surendra; Milan, Marcos; Garcia Cacho, Luis; Samaniego M, Daniel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1991-12-31

After synthesizing the most relevant aspects of the current volcanology and the genesis process of the collapse calderas, a process is described on the location and confirmation of a new caldera (the Mazahua) in the central part of the Mexican Volcanic Belt (MVB). [Espanol] Tras sintetizar los aspectos mas destacados de la vulcanologia actual y el proceso de genesis de las calderas de colapso, se describe el proceso de localizacion y confirmacion de una nueva caldera (la Mazahua) en la parte central del Cinturon Volcanico Mexicano (CVM).

The confirmation of a work hypothesis: a new caldera in the center of the Mexican Volcanic Belt; La confirmacion de una hipotesis de trabajo: una nueva caldera en el centro del Cinturon Volcanico Mexicano

Energy Technology Data Exchange (ETDEWEB)

Anguita Virella, Francisco; Pal Verma, Surendra; Milan, Marcos; Garcia Cacho, Luis; Samaniego M, Daniel [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

1992-12-31

After synthesizing the most relevant aspects of the current volcanology and the genesis process of the collapse calderas, a process is described on the location and confirmation of a new caldera (the Mazahua) in the central part of the Mexican Volcanic Belt (MVB). [Espanol] Tras sintetizar los aspectos mas destacados de la vulcanologia actual y el proceso de genesis de las calderas de colapso, se describe el proceso de localizacion y confirmacion de una nueva caldera (la Mazahua) en la parte central del Cinturon Volcanico Mexicano (CVM).

National Uranium Resource Evaluation: Durango Quadrangle, Colorado

International Nuclear Information System (INIS)

Theis, N.J.; Madson, M.E.; Rosenlund, G.C.; Reinhart, W.R.; Gardner, H.A.

1981-06-01

The Durango Quadrangle (2 0 ), Colorado, was evaluated using National Uranium Resource Evaluation criteria to determine environments favorable for uranium deposits. General reconnaissance, geologic and radiometric investigations, was augmented by detailed surface examination and radiometric and geochemical studies in selected areas. Eight areas favorable for uranium deposits were delineated. Favorable geologic environments include roscoelite-type vanadium-uranium deposits in the Placerville and Barlow Creek-Hermosa Creek districts, sandstone uranium deposits along Hermosa Creek, and vein uranium deposits in the Precambrian rocks of the Needle Mountains area and in the Paleozoic rocks of the Tuckerville and Piedra River Canyon areas. The major portions of the San Juan volcanic field, the San Juan Basin, and the San Luis Basin within the quadrangle were judged unfavorable. Due to lack of information, the roscoelite belt below 1000 ft (300 m), the Eolus Granite below 0.5 mi (0.8 km), and the Lake City caldera are unevaluated. The Precambrian Y melasyenite of Ute Creek and the Animas Formation within the Southern Ute Indian Reservation are unevaluated due to lack of access

Insights into the emplacement of upper-crustal plutons and their relationship to large silicic calderas, from field relationships, geochronology, and zircon trace element geochemistry in the Stillwater – Clan Alpine caldera complex, western Nevada, USA

Science.gov (United States)

Colgan, Joseph P.; John, David A.; Henry, Christopher D.; Watts, Kathryn E.

2018-01-01

Geologic mapping, new U-Pb zircon ages, and new and published 40Ar/39Ar sanidine ages document the timing and extent of Oligocene magmatism in the southern Stillwater Range and Clan Alpine Mountains of western Nevada, where Miocene extension has exposed at least six nested silicic calderas and underlying granitic plutons to crustal depths locally ≥ 9 km. Both caldera-forming rhyolitic tuffs and underlying plutons were emplaced in two episodes, one from about 30.4–28.2 Ma that included the Deep Canyon, Job Canyon, and Campbell Creek calderas and underlying plutons, and one from about 25.3–24.8 Ma that included the Louderback Mountains, Poco Canyon, and Elevenmile Canyon calderas and underlying plutons. In these two 1–2 m.y. periods, almost the entire Mesozoic upper crust was replaced by Oligocene intrusive and extrusive rocks to depths ≥ 9 km over an estimated total area of ~ 1500 km2 (pre-extension). Zircon trace element geochemistry indicates that some plutonic rock can be solidified residual magma from the tuff eruptions. Most plutons are not solidified residual magma, although they directly underlie calderas and were emplaced along the same structures shortly after to as much as one million years after caldera formation. Magma chambers and plutons grew by floor subsidence accommodated by downward transfer of country rocks. If other Great Basin calderas are similar, the dense concentration of shallowly exposed calderas in central Nevada is underlain by a complexly zoned mid-Cenozoic batholith assembled in discrete pulses that coincided with formation of large silicic calderas up to 2500–5000 km3.

Giant caldera in the Arctic Ocean: Evidence of the catastrophic eruptive event.

Science.gov (United States)

Piskarev, Alexey; Elkina, Daria

2017-04-10

A giant caldera located in the eastern segment of the Gakkel Ridge could be firstly seen on the bathymetric map of the Arctic Ocean published in 1999. In 2014, seismic and multibeam echosounding data were acquired at the location. The caldera is 80 km long, 40 km wide and 1.2 km deep. The total volume of ejected volcanic material is estimated as no less than 3000 km 3 placing it into the same category with the largest Quaternary calderas (Yellowstone and Toba). Time of the eruption is estimated as ~1.1 Ma. Thin layers of the volcanic material related to the eruption had been identified in sedimentary cores located about 1000 km away from the Gakkel Ridge. The Gakkel Ridge Caldera is the single example of a supervolcano in the rift zone of the Mid-Oceanic Ridge System.

Uplift, thermal unrest and magma intrusion at Yellowstone caldera.

Science.gov (United States)

Wicks, Charles W; Thatcher, Wayne; Dzurisin, Daniel; Svarc, Jerry

2006-03-02

The Yellowstone caldera, in the western United States, formed approximately 640,000 years ago when an explosive eruption ejected approximately 1,000 km3 of material. It is the youngest of a series of large calderas that formed during sequential cataclysmic eruptions that began approximately 16 million years ago in eastern Oregon and northern Nevada. The Yellowstone caldera was largely buried by rhyolite lava flows during eruptions that occurred from approximately 150,000 to approximately 70,000 years ago. Since the last eruption, Yellowstone has remained restless, with high seismicity, continuing uplift/subsidence episodes with movements of approximately 70 cm historically to several metres since the Pleistocene epoch, and intense hydrothermal activity. Here we present observations of a new mode of surface deformation in Yellowstone, based on radar interferometry observations from the European Space Agency ERS-2 satellite. We infer that the observed pattern of uplift and subsidence results from variations in the movement of molten basalt into and out of the Yellowstone volcanic system.

Long Valley Caldera 2003 through 2014: overview of low level unrest in the past decade

Science.gov (United States)

Wilkinson, Stuart K.; Hill, David P.; Langbein, John O.; Lisowski, Michael; Mangan, Margaret T.

2014-01-01

Long Valley Caldera is located in California along the eastern escarpment of the Sierra Nevada Range. The caldera formed about 760,000 years ago as the eruption of 600 km3 of rhyolite magma (Bishop Tuff) resulted in collapse of the partially evacuated magma chamber. Resurgent doming in the central part of the caldera occurred shortly afterwards, and the most recent eruptions inside the caldera occurred about 50,000 years ago. The caldera remains thermally active, with many hot springs and fumaroles, and has had significant deformation and seismicity since at least 1978. Periods of intense unrest in the 1980s to early 2000s are well documented in the literature (Hill and others, 2002; Ewert and others, 2010). In this poster, we extend the timeline forward, documenting seismicity and deformation over the past decade.

Maars to calderas: end-members on a spectrum of explosive volcanic depressions

Directory of Open Access Journals (Sweden)

Danilo M. Palladino

2015-07-01

Full Text Available We discuss maar-diatremes and calderas as end-members on a spectrum of negative volcanic landforms (depressions produced by explosive eruptions (note – we focus on calderas formed during explosive eruptions, recognizing that some caldera types are not related to such activity. The former are dominated by ejection of material during numerous discrete phreatomagmatic explosions, brecciation, and subsidence of diatreme fill, while the latter are dominated by subsidence over a partly evacuated magma chamber during sustained, magmatic volatile-driven discharge. Many examples share characteristics of both, including landforms that are identified as maars but preserve deposits from non-phreatomagmatic explosive activity, and ambiguous structures that appear to be coalesced maars but that also produced sustained explosive eruptions with likely magma reservoir subsidence. A convergence of research directions on issues related to magma-water interaction and shallow reservoir mechanics is an important avenue toward developing a unified picture of the maar-diatreme-caldera spectrum.

Long Valley caldera and the UCERF depiction of Sierra Nevada range-front faults

Science.gov (United States)

Hill, David P.; Montgomery-Brown, Emily K.

2015-01-01

Long Valley caldera lies within a left-stepping offset in the north-northwest-striking Sierra Nevada range-front normal faults with the Hilton Creek fault to the south and Hartley Springs fault to the north. Both Uniform California Earthquake Rupture Forecast (UCERF) 2 and its update, UCERF3, depict slip on these major range-front normal faults as extending well into the caldera, with significant normal slip on overlapping, subparallel segments separated by ∼10  km. This depiction is countered by (1) geologic evidence that normal faulting within the caldera consists of a series of graben structures associated with postcaldera magmatism (intrusion and tumescence) and not systematic down-to-the-east displacements consistent with distributed range-front faulting and (2) the lack of kinematic evidence for an evolving, postcaldera relay ramp structure between overlapping strands of the two range-front normal faults. The modifications to the UCERF depiction described here reduce the predicted shaking intensity within the caldera, and they are in accord with the tectonic influence that underlapped offset range-front faults have on seismicity patterns within the caldera associated with ongoing volcanic unrest.

The Acoculco caldera magmas: genesis, evolution and relation with the Acoculco geothermal system

Science.gov (United States)

Sosa-Ceballos, G.; Macías, J. L.; Avellán, D.

2017-12-01

The Acoculco Caldera Complex (ACC) is located at the eastern part of the Trans Mexican Volcanic Belt; México. This caldera complex have been active since 2.7 Ma through reactivations of the system or associated magmatism. Therefore the ACC is an excellent case scenario to investigate the relation between the magmatic heat supply and the evolution processes that modified magmatic reservoirs in a potential geothermal field. We investigated the origin and the magmatic processes (magma mixing, assimilation and crystallization) that modified the ACC rocks by petrography, major oxides-trace element geochemistry, and isotopic analysis. Magma mixing is considered as the heat supply that maintain active the magmatic system, whereas assimilation yielded insights about the depth at which processes occurred. In addition, we performed a series of hydrothermal experiments in order to constrain the storage depth for the magma tapped during the caldera collapse. Rocks from the ACC were catalogued as pre, syn and post caldera. The post caldera rocks are peralkaline rhyolites, in contrast to all other rocks that are subalkaline. Our investigation is focus to investigate if the collapse modified the plumbing system and the depth at which magmas stagnate and recorded the magmatic processes.

Physical volcanology of the mafic segment of the subaqueous New Senator caldera, Abitibi greenstone belt, Quebec, Canada

International Nuclear Information System (INIS)

Moore, Lyndsay N; Mueller, Wulf U

2008-01-01

Archean calderas provide valuable insight into internal geometries of subaqueous calderas. The New Senator caldera, Abitibi greenstone belt, Canada, is an Archean example of a subaqueous nested caldera with a basal stratigraphy dominated by gabbro-diorite dykes and sills, ponded magmas and basalt and andesite lava flows. The aim of our study is to focus on the use of physical volcanology to differentiate between the various mafic units found at the base of the New Senator caldera. Differentiation between these various mafic units is important from an exploration point of view because in modern subaqueous summit calders (e.g. Axial Seamount) margins of ponded magmas are often sites of VMS formation.

Physical volcanology of the mafic segment of the subaqueous New Senator caldera, Abitibi greenstone belt, Quebec, Canada

Energy Technology Data Exchange (ETDEWEB)

Moore, Lyndsay N; Mueller, Wulf U [Universite du Quebec a Chicoutimi, 555 boul. du l' Universite, Chicoutimi, Quebec, G7H2B1 (Canada)], E-mail: lyndsay.moore@uqac.ca

2008-10-01

Archean calderas provide valuable insight into internal geometries of subaqueous calderas. The New Senator caldera, Abitibi greenstone belt, Canada, is an Archean example of a subaqueous nested caldera with a basal stratigraphy dominated by gabbro-diorite dykes and sills, ponded magmas and basalt and andesite lava flows. The aim of our study is to focus on the use of physical volcanology to differentiate between the various mafic units found at the base of the New Senator caldera. Differentiation between these various mafic units is important from an exploration point of view because in modern subaqueous summit calders (e.g. Axial Seamount) margins of ponded magmas are often sites of VMS formation.

A Sr-isotopic comparison between thermal waters, rocks, and hydrothermal calcites, Long Valley caldera, California

Science.gov (United States)

Goff, F.; Wollenberg, H.A.; Brookins, D.C.; Kistler, R.W.

1991-01-01

The 87Sr/86Sr values of thermal waters and hydrothermal calcites of the Long Valley caldera geothermal system are more radiogenic than those of young intracaldera volcanic rocks. Five thermal waters display 87Sr/86Sr of 0.7081-0.7078 but show systematically lighter values from west to east in the direction of lateral flow. We believe the decrease in ratio from west to east signifies increased interaction of deeply circulating thermal water with relatively fresh volcanic rocks filling the caldera depression. All types of pre-, syn-, and post-caldera volcanic rocks in the west and central caldera have (87Sr/86Sr)m between about 0.7060 and 0.7072 and values for Sierra Nevada granodiorites adjacent to the caldera are similar. Sierran pre-intrusive metavolcanic and metasedimentary rocks can have considerably higher Sr-isotope ratios (0.7061-0.7246 and 0.7090-0.7250, respectively). Hydrothermally altered volcanic rocks inside the caldera have (87Sr/86Sr)m slightly heavier than their fresh volcanic equivalents and hydrothermal calcites (0.7068-0.7105) occupy a midrange of values between the volcanic/plutonic rocks and the Sierran metamorphic rocks. These data indicate that the Long Valley geothermal reservoir is first equilibrated in a basement complex that contains at least some metasedimentary rocks. Reequilibration of Sr-isotope ratios to lower values occurs in thermal waters as convecting geothermal fluids flow through the isotopically lighter volcanic rocks of the caldera fill. ?? 1991.

Caldera unrest detected with seawater temperature anomalies at Deception Island, Antarctic Peninsula

Science.gov (United States)

Berrocoso, M.; Prates, G.; Fernández-Ros, A.; Peci, L. M.; de Gil, A.; Rosado, B.; Páez, R.; Jigena, B.

2018-04-01

Increased thermal activity was detected to coincide with the onset of volcano inflation in the seawater-filled caldera at Deception Island. This thermal activity was manifested in pulses of high water temperature that coincided with ocean tide cycles. The seawater temperature anomalies were detected by a thermometric sensor attached to the tide gauge (bottom pressure sensor). This was installed where the seawater circulation and the locations of known thermal anomalies, fumaroles and thermal springs, together favor the detection of water warmed within the caldera. Detection of the increased thermal activity was also possible because sea ice, which covers the entire caldera during the austral winter months, insulates the water and thus reduces temperature exchange between seawater and atmosphere. In these conditions, the water temperature data has been shown to provide significant information about Deception volcano activity. The detected seawater temperature increase, also observed in soil temperature readings, suggests rapid and near-simultaneous increase in geothermal activity with onset of caldera inflation and an increased number of seismic events observed in the following austral summer.

Two-phase, reciprocal, double trapdoor collapse at Hannegan caldera, North Cascades, Washington, USA

Energy Technology Data Exchange (ETDEWEB)

Tucker, David S [Mount Baker Volcano Research Center Geology Department Western Washington University 516 High Street Bellingham, Washington 98225-9080 (United States)], E-mail: DaveTucker@mbvo.wwu.edu

2008-10-01

The intracaldera Hannegan volcanics were erupted during two collapse episodes of the Hannegan caldera in the North Cascade mountains of Washington State. The first eruption yielded a down-to-the-north trapdoor style collapse at 3.722 {+-} 0.020 Ma (40Ar/39Ar) that is bounded by a horseshoe-shaped ring fault. The second collapse, most probably also trapdoor style, followed a short period of sedimentation, and completed the elliptical ring fault around the southern margin of the caldera. Post caldera plutons, with U-Pb ages of 3.42 {+-} 0.10 and 3.36 {+-} 0.20 Ma, intruded the intracaldera ignimbrite.

Steady subsidence of a repeatedly erupting caldera through InSAR observations: Aso, Japan

KAUST Repository

Nobile, Adriano

2017-04-05

The relation between unrest and eruption at calderas is still poorly understood. Aso caldera, Japan, shows minor episodic phreatomagmatic eruptions associated with steady subsidence. We analyse the deformation of Aso using SAR images from 1993 to 2011 and compare it with the eruptive activity. Although the dataset suffers from limitations (e.g. atmospheric effects, coherence loss, low signal-to-noise ratio), we observe a steady subsidence signal from 1996 to 1998, which suggests an overall contraction of a magmatic source below the caldera centre, from 4 to 5 km depth. We propose that the observed contraction may have been induced by the release of the magmatic fluids feeding the eruptions. If confirmed by further data, this hypothesis suggests that degassing processes play a crucial role in triggering minor eruptions within open conduit calderas, such as at Aso. Our study underlines the importance of defining any eruptive potential also from deflating magmatic systems with open conduit.

Doubly stochastic models for volcanic hazard assessment at Campi Flegrei caldera

CERN Document Server

Bevilacqua, Andrea

2016-01-01

This study provides innovative mathematical models for assessing the eruption probability and associated volcanic hazards, and applies them to the Campi Flegrei caldera in Italy. Throughout the book, significant attention is devoted to quantifying the sources of uncertainty affecting the forecast estimates. The Campi Flegrei caldera is certainly one of the world’s highest-risk volcanoes, with more than 70 eruptions over the last 15,000 years, prevalently explosive ones of varying magnitude, intensity and vent location. In the second half of the twentieth century the volcano apparently once again entered a phase of unrest that continues to the present. Hundreds of thousands of people live inside the caldera and over a million more in the nearby city of Naples, making a future eruption of Campi Flegrei an event with potentially catastrophic consequences at the national and European levels.

Ground Deformation Related to Caldera Collapse and Ring-Fault Activity

KAUST Repository

Liu, Yuan-Kai

2018-05-01

Volcanic subsidence, caused by partial emptying of magma in the subsurface reservoir has long been observed by spaceborne radar interferometry. Monitoring long-term crustal deformation at the most notable type of volcanic subsidence, caldera, gives us insights of the spatial and hazard-related information of subsurface reservoir. Several subsiding calderas, such as volcanoes on the Galapagos islands have shown a complex ground deformation pattern, which is often composed of a broad deflation signal affecting the entire edifice and a localized subsidence signal focused within the caldera floor. Although numerical or analytical models with multiple reservoirs are proposed as the interpretation, geologically and geophysically evidenced ring structures in the subsurface are often ignored. Therefore, it is still debatable how deep mechanisms relate to the observed deformation patterns near the surface. We aim to understand what kind of activities can lead to the complex deformation. Using two complementary approaches, we study the three-dimensional geometry and kinematics of deflation processes evolving from initial subsidence to later collapse of calderas. Firstly, the analog experiments analyzed by structure-from-motion photogrammetry (SfM) and particle image velocimetry (PIV) helps us to relate the surface deformation to the in-depth structures. Secondly, the numerical modeling using boundary element method (BEM) simulates the characteristic deformation patterns caused by a sill-like source and a ring-fault. Our results show that the volcano-wide broad deflation is primarily caused by the emptying of the deep magma reservoir, whereas the localized deformation on the caldera floor is related to ring-faulting at a shallower depth. The architecture of the ring-fault to a large extent determines the deformation localization on the surface. Since series evidence for ring-faulting at several volcanoes are provided, we highlight that it is vital to include ring

Ground Deformation Related to Caldera Collapse and Ring-Fault Activity

KAUST Repository

Liu, Yuan-Kai

2018-01-01

Volcanic subsidence, caused by partial emptying of magma in the subsurface reservoir has long been observed by spaceborne radar interferometry. Monitoring long-term crustal deformation at the most notable type of volcanic subsidence, caldera, gives us insights of the spatial and hazard-related information of subsurface reservoir. Several subsiding calderas, such as volcanoes on the Galapagos islands have shown a complex ground deformation pattern, which is often composed of a broad deflation signal affecting the entire edifice and a localized subsidence signal focused within the caldera floor. Although numerical or analytical models with multiple reservoirs are proposed as the interpretation, geologically and geophysically evidenced ring structures in the subsurface are often ignored. Therefore, it is still debatable how deep mechanisms relate to the observed deformation patterns near the surface. We aim to understand what kind of activities can lead to the complex deformation. Using two complementary approaches, we study the three-dimensional geometry and kinematics of deflation processes evolving from initial subsidence to later collapse of calderas. Firstly, the analog experiments analyzed by structure-from-motion photogrammetry (SfM) and particle image velocimetry (PIV) helps us to relate the surface deformation to the in-depth structures. Secondly, the numerical modeling using boundary element method (BEM) simulates the characteristic deformation patterns caused by a sill-like source and a ring-fault. Our results show that the volcano-wide broad deflation is primarily caused by the emptying of the deep magma reservoir, whereas the localized deformation on the caldera floor is related to ring-faulting at a shallower depth. The architecture of the ring-fault to a large extent determines the deformation localization on the surface. Since series evidence for ring-faulting at several volcanoes are provided, we highlight that it is vital to include ring

Magmatism, ash-flow tuffs, and calderas of the ignimbrite flareup in the western Nevada volcanic field, Great Basin, USA

Science.gov (United States)

Christopher D. Henry,; John, David A.

2013-01-01

The western Nevada volcanic field is the western third of a belt of calderas through Nevada and western Utah. Twenty-three calderas and their caldera-forming tuffs are reasonably well identified in the western Nevada volcanic field, and the presence of at least another 14 areally extensive, apparently voluminous ash-flow tuffs whose sources are unknown suggests a similar number of undiscovered calderas. Eruption and caldera collapse occurred between at least 34.4 and 23.3 Ma and clustered into five ∼0.5–2.7-Ma-long episodes separated by quiescent periods of ∼1.4 Ma. One eruption and caldera collapse occurred at 19.5 Ma. Intermediate to silicic lavas or shallow intrusions commonly preceded caldera-forming eruptions by 1–6 Ma in any specific area. Caldera-related as well as other magmatism migrated from northeast Nevada to the southwest through time, probably resulting from rollback of the formerly shallow-dipping Farallon slab. Calderas are restricted to the area northeast of what was to become the Walker Lane, although intermediate and effusive magmatism continued to migrate to the southwest across the future Walker Lane.Most ash-flow tuffs in the western Nevada volcanic field are rhyolites, with approximately equal numbers of sparsely porphyritic (≤15% phenocrysts) and abundantly porphyritic (∼20–50% phenocrysts) tuffs. Both sparsely and abundantly porphyritic rhyolites commonly show compositional or petrographic evidence of zoning to trachydacites or dacites. At least four tuffs have volumes greater than 1000 km3, with one possibly as much as ∼3000 km3. However, the volumes of most tuffs are difficult to estimate, because many tuffs primarily filled their source calderas and/or flowed and were deposited in paleovalleys, and thus are irregularly distributed.Channelization and westward flow of most tuffs in paleovalleys allowed them to travel great distances, many as much as ∼250 km (original distance) to what is now the western foothills of the

Progressive approach to eruption at Campi Flegrei caldera in southern Italy.

Science.gov (United States)

Kilburn, Christopher R J; De Natale, Giuseppe; Carlino, Stefano

2017-05-15

Unrest at large calderas rarely ends in eruption, encouraging vulnerable communities to perceive emergency warnings of volcanic activity as false alarms. A classic example is the Campi Flegrei caldera in southern Italy, where three episodes of major uplift since 1950 have raised its central district by about 3 m without an eruption. Individual episodes have conventionally been treated as independent events, so that only data from an ongoing episode are considered pertinent to evaluating eruptive potential. An implicit assumption is that the crust relaxes accumulated stress after each episode. Here we apply a new model of elastic-brittle failure to test the alternative view that successive episodes promote a long-term accumulation of stress in the crust. The results provide the first quantitative evidence that Campi Flegrei is evolving towards conditions more favourable to eruption and identify field tests for predictions on how the caldera will behave during future unrest.

A short review of our current understanding of the development of ring faults during collapse caldera formation

Directory of Open Access Journals (Sweden)

Adelina eGeyer

2014-09-01

Full Text Available The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical and experimental studies. Nonetheless, even if there is a tendency to go for a general and comprehensive caldera dynamics model, some key aspects remain unclear, controversial or completely unsolved. This is the case of ring fault nucleation points and propagation and dip direction. Since direct information on calderas’ deeper structure comes mainly from partially eroded calderas or few witnessed collapses, ring faults layout at depth remains still uncertain. This has generated a strong debate over the detailed internal fault and fracture configuration of a caldera collapse and, in more detail, how ring faults initiate and propagate. We offer here a very short description of the main results obtained by those analogue and theoretical/mathematical models applied to the study of collapse caldera formation. We place special attention on those observations related to the nucleation and propagation of the collapse-controlling ring faults. This summary is relevant to understand the current state-of-the-art of this topic and it should be taken under consideration in future works dealing with collapse caldera dynamics.

Structural characteristics and collapse mechanism of the late Cretaceous Geumseongsan Caldera, SE Korea

Science.gov (United States)

Lee, S.; Cheon, Y.; Lee, Y.; Son, M.

2017-12-01

The Geumseongsan caldera provides an opportunity to understand the structural evolution of volcanic collapse and the role of paleostress. We focus on structural elements of the exhumed caldera floor to interpret the collapse mechanism. The caldera shows an NNW-trending elliptical shape (8×12 km). Basaltic and rhyolitic rocks are situated in the central high of the caldera, while pre-volcanic sedimentary rocks in the perimetric lowland of the volcanic rocks. Stratal attitudes change sharply from the outside to the inside of caldera bounded with a sub-vertical ring fault. The outside strata show a homocline toward SE about 15°, whereas the inside is divided into four structural domains (NE-, NW-, SE-, and SW-domains) based on the changing attitudes. The strata in NW- and SE-domains dip toward SE and NW, respectively, making an overall synclinal fold. While NE- and SW-domains comprise re-oriented, folded strata, which generally have NE- and SW-trending axes plunging toward the center. In addition, extensional and contractional structures occur distinctively in NW- and SE-domains and in NE- and SW-domains, respectively, indicating an axisymmetric deformation around NE-SW axis. The results indicate that higher horizontal mass movement toward the center occurred in NW- and SE-domains than in NE- and SW-domains while vertical mass movement was more active in the latter. This axisymmetric deformation could be produced by regional stress during the volcanic activity, which affected the collapse pattern of caldera floor. The regional stress field during the late Cretaceous is known as NW-SE horizontal maximum and NE-SW horizontal minimum stresses due to the oblique subduction of proto-Pacific Plate underneath Eurasian Plate. NNW-trending elliptical shape of the caldera is interpreted to have formed under the influence of this stresses, like a tension gash. The NW-SE maximum stress possibly acted to resist vertical displacement along the marginal fault of NW- and SE

Diffusive Soil Degassing of Radon and Carbon Dioxide at Ilopango Caldera, El Salvador, Central America

Science.gov (United States)

Ransom, L.; Lopez, D. L.; Hernandez, P.

2001-12-01

Ilopango Caldera lies 10 Km east of San Salvador, El Salvador and holds Ilopango Lake, the largest body of fresh water in El Salvador. There is currently no observed fumarolic activity within the caldera system. However, the last eruption occurred in 1880. In November - December, 1999, radon gas concentrations (pCi/l) were measured using a Pylon AB5 radon monitor, and flux of CO2 (g/m2/day) was determined using the accumulation chamber method at 106 sampling stations around the lake, along and across the caldera walls. Gas samples were also collected to determine the isotopic composition of C in CO2. CO2 fluxes did not show high values characteristic of other volcanic systems, values ranged from 0.7 to 9.2 g/m2/day with an average value of 3.9. These values are similar to the low values of the background population observed in nearby San Salvador volcano. Highest values are observed to the east and west of the lake. Isotopic values for C in soil gases do not show an important magmatic component. Radon concentrations present three distinct populations with the highest values occurring to the southwest. Thoron concentrations are higher close to the caldera walls than inside the caldera due to the possible higher rock fracturing in that region. Measurements taken in March 2001, after the January 13 and February 13, 2001 earthquakes did not show significant variations in CO2 fluxes. However, radon concentrations varied due to the high seismicity that lasted several months after these earthquakes. These results suggest that the magmatic system of Ilopango Caldera is not emitting high fluxes of CO2 to the atmosphere throughout the caldera soils. Subaquatic emissions of CO2 have not been evaluated. However, subaquatic hydrothermal discharges have not been identified at this calderic lake.

Trace Element Concentration and Speciation in Selected Mining-Contaminated Soils and Water in Willow Creek Floodplain, Colorado

Directory of Open Access Journals (Sweden)

R. Burt

2011-01-01

Full Text Available Long-term mining activities in the mountains around Creede, Colorado have resulted in significant contamination in soils and water in the Willow Creek floodplain. Total major and trace were determined for soils and water and sequential chemical extraction for soils. Objectives were to determine concentrations and potential reactivity of trace elements and investigate their relationship with other soil and water properties. Water trace elements showed significant variability among sites, ranging from 347 to 12108 μg/L. Relative trend showed (Zn > Sr > Ba > (Mn > W > Cd > (Sn > V ≈ Ni ≈ Cu > Co > (Ag. Soil trace elements showed significant short-range spatial variability, ranging from 2819 to 19274 mg/kg. Relative trend showed (Pb ≈ Zn > Mn > Ba > P > (As > Cu > Sr > V > Cd > Sb ≈ Ag > (Co ≈ Cr > Mo ≈ Sn ≈ Ni > (Be ≈ W > Se ≈ Hg. Predominant fractions were oxide, specifically-sorbed/carbonate bound, and residual. Water soluble and exchangeable fractions showed (Zn ≈ Cd > Pb and Cd > Zn > Pb, respectively. Mobility factors for highly contaminated soils showed Cd ≈ Zn > Pb > Cu > As.

Eruptive history, geochronology, and post-eruption structural evolution of the late Eocene Hall Creek Caldera, Toiyabe Range, Nevada

Science.gov (United States)

Colgan, Joseph P.; Henry, Christopher D.

2017-02-24

The magmatic, tectonic, and topographic evolution of what is now the northern Great Basin remains controversial, notably the temporal and spatial relation between magmatism and extensional faulting. This controversy is exemplified in the northern Toiyabe Range of central Nevada, where previous geologic mapping suggested the presence of a caldera that sourced the late Eocene (34.0 mega-annum [Ma]) tuff of Hall Creek. This region was also inferred to be the locus of large-magnitude middle Tertiary extension (more than 100 percent strain) localized along the Bernd Canyon detachment fault, and to be the approximate location of a middle Tertiary paleodivide that separated east and west-draining paleovalleys. Geologic mapping, 40Ar/39Ar dating, and geochemical analyses document the geologic history and extent of the Hall Creek caldera, define the regional paleotopography at the time it formed, and clarify the timing and kinematics of post-caldera extensional faulting. During and after late Eocene volcanism, the northern Toiyabe Range was characterized by an east-west trending ridge in the area of present-day Mount Callaghan, probably localized along a Mesozoic anticline. Andesite lava flows erupted around 35–34 Ma ponded hundreds of meters thick in the erosional low areas surrounding this structural high, particularly in the Simpson Park Mountains. The Hall Creek caldera formed ca. 34.0 Ma during eruption of the approximately 400 cubic kilometers (km3) tuff of Hall Creek, a moderately crystal-rich rhyolite (71–77 percent SiO2) ash-flow tuff. Caldera collapse was piston-like with an intact floor block, and the caldera filled with thick (approximately 2,600 meters) intracaldera tuff and interbedded breccia lenses shed from the caldera walls. The most extensive exposed megabreccia deposits are concentrated on or close to the caldera floor in the southwestern part of the caldera. Both silicic and intermediate post-caldera lavas were locally erupted within 400 thousand

76 FR 17444 - Notice of Inventory Completion: Colorado Historical Society (History Colorado), Denver, CO

Science.gov (United States)

2011-03-29

... Culture, Colorado Historical Society (History Colorado), 1560 Broadway, Suite 400, Denver, CO 80202...: Colorado Historical Society (History Colorado), Denver, CO AGENCY: National Park Service, Interior. ACTION... control of the Colorado Historical Society (History Colorado), Denver, CO. The human remains were removed...

Lithium enrichment in intracontinental rhyolite magmas leads to Li deposits in caldera basins.

Science.gov (United States)

Benson, Thomas R; Coble, Matthew A; Rytuba, James J; Mahood, Gail A

2017-08-16

The omnipresence of lithium-ion batteries in mobile electronics, and hybrid and electric vehicles necessitates discovery of new lithium resources to meet rising demand and to diversify the global lithium supply chain. Here we demonstrate that lake sediments preserved within intracontinental rhyolitic calderas formed on eruption and weathering of lithium-enriched magmas have the potential to host large lithium clay deposits. We compare lithium concentrations of magmas formed in a variety of tectonic settings using in situ trace-element measurements of quartz-hosted melt inclusions to demonstrate that moderate to extreme lithium enrichment occurs in magmas that incorporate felsic continental crust. Cenozoic calderas in western North America and in other intracontinental settings that generated such magmas are promising new targets for lithium exploration because lithium leached from the eruptive products by meteoric and hydrothermal fluids becomes concentrated in clays within caldera lake sediments to potentially economically extractable levels.Lithium is increasingly being utilized for modern technology in the form of lithium-ion batteries. Here, using in situ measurements of quartz-hosted melt inclusions, the authors demonstrate that preserved lake sediments within rhyolitic calderas have the potential to host large lithium-rich clay deposits.

Geochemical evolution of Ngorongoro Caldera, Northern Tanzania: Implications for crust magma interaction

Science.gov (United States)

Mollel, Godwin F.; Swisher, Carl C.; Feigenson, Mark D.; Carr, Michael J.

2008-07-01

Ngorongoro Caldera is the largest and best-preserved of nine Plio-Pleistocene volcanoes that make-up the Ngorongoro Volcanic Highlands (NVH) complex situated at the southern bifurcation of Gregory Rift, part of the East African Rift system of northern Tanzania. We report here, major and trace element abundances, Sr-Nd-Pb isotope analyses and 40Ar/ 39Ar laser incremental-heating and total fusion ages on lava and tephra sampled from stratigraphic sections exposed within the Ngorongoro Caldera. Major and trace elements measured on samples collected from the Ngorongoro Caldera wall indicate a stratified magma chamber whose silicic top and basaltic bottom was inverted by sequential eruptions. Samples from the lower part of the exposed Ngorongoro Caldera wall are high in silica, alkalis and HFSE (High Field Strength Elements). The Zr, Nb and Hf concentrations are highly correlated with each other and decrease up-section, indicative of the extent of magma evolution. Modeling of major, trace as well as Sr, Nd and Pb isotope data suggests that assimilation fractional crystallization processes were essential in producing the observed geochemical variations. The Sr and Nd isotope ratios from the Ngorongoro samples are widely dispersed ( 87Sr/ 86Sr = 0.70405 to 0.70801, 143Nd/ 144Nd = 0.512205 to 0.512623) and Pb isotope ratios are consistent with previous studies: 206Pb/ 204Pb = 18.73 to 19.37, 207Pb/ 204Pb = 15.64 to 15.69, 208Pb/ 204Pb = 39.52 to 39.55. Although Sr isotopic ratios are similar to Oceanic Island Basalt (OIB), the more radiogenic samples ( 87Sr/ 86Sr > 0.705) from the lower part of the section suggest crust-magma interaction; this is supported by Ce/Pb ratios (Ngorongoro Caldera wall section yield 40Ar/ 39Ar ages of 2.25 ± 0.02 Ma to 2.01 ± 0.02 Ma, constraining a duration of volcanism of the order of ~ 240 kyr. These ages suggest correlation of a normal to reverse geomagnetic polarity transition measured in the Ngorongoro Caldera wall section with the ~ 2

Finite-element modeling of magma chamber-host rock interactions prior to caldera collapse

Science.gov (United States)

Kabele, Petr; Žák, Jiří; Somr, Michael

2017-06-01

Gravity-driven failure of shallow magma chamber roofs and formation of collapse calderas are commonly accompanied by ejection of large volumes of pyroclastic material to the Earth's atmosphere and thus represent severe volcanic hazards. In this respect, numerical analysis has proven as a key tool in understanding the mechanical conditions of caldera collapse. The main objective of this paper is to find a suitable approach to finite-element simulation of roof fracturing and caldera collapse during inflation and subsequent deflation of shallow magma chambers. Such a model should capture the dominant mechanical phenomena, for example, interaction of the host rock with magma and progressive deformation of the chamber roof. To this end, a comparative study, which involves various representations of magma (inviscid fluid, nearly incompressible elastic, or plastic solid) and constitutive models of the host rock (fracture and plasticity), was carried out. In particular, the quasi-brittle fracture model of host rock reproduced well the formation of tension-induced radial and circumferential fractures during magma injection into the chamber (inflation stage), especially at shallow crustal levels. Conversely, the Mohr-Coulomb shear criterion has shown to be more appropriate for greater depths. Subsequent magma withdrawal from the chamber (deflation stage) results in further damage or even collapse of the chamber roof. While most of the previous studies of caldera collapse rely on the elastic stress analysis, the proposed approach advances modeling of the process by incorporating non-linear failure phenomena and nearly incompressible behaviour of magma. This leads to a perhaps more realistic representation of the fracture processes preceding roof collapse and caldera formation.

History of surface displacements at the Yellowstone Caldera, Wyoming, from leveling surveys and InSAR observations, 1923-2008

Science.gov (United States)

Dzurisin, Daniel; Wicks, Charles W.; Poland, Michael P.

2012-01-01

Modern geodetic studies of the Yellowstone caldera, Wyoming, and its extraordinary tectonic, magmatic, and hydrothermal systems date from an initial leveling survey done throughout Yellowstone National Park in 1923 by the U.S. Coast and Geodetic Survey. A repeat park-wide survey by the U.S. Geological Survey (USGS) and the University of Utah during 1975-77 revealed that the central part of the caldera floor had risen more than 700 mm since 1923, at an average rate of 14±1 mm/yr. From 1983 to 2007, the USGS conducted 15 smaller surveys of a single level line that crosses the northeast part of the caldera, including the area where the greatest uplift had occurred from 1923 to 1975-77. The 1983 and 1984 surveys showed that uplift had continued at an average rate of 22±1 mm/yr since 1975-77, but no additional uplift occurred during 1984-85 (-2±5 mm/yr), and during 1985-95 the area subsided at an average rate of 19±1 mm/yr. The change from uplift to subsidence was accompanied by an earthquake swarm, the largest ever recorded in the Yellowstone area (as of March 2012), starting in October 1985 and located near the northwest rim of the caldera. Interferometric synthetic aperture radar (InSAR) images showed that the area of greatest subsidence migrated from the northeast part of the caldera (including the Sour Creek resurgent dome) during 1992-93 to the southwest part (including the Mallard Lake resurgent dome) during 1993-95. Thereafter, uplift resumed in the northeast part of the caldera during 1995-96, while subsidence continued in the southwest part. The onset of uplift migrated southwestward, and by mid-1997, uplift was occurring throughout the entire caldera (essentially rim to rim, including both domes). Consistent with these InSAR observations, leveling surveys indicated 24±3 mm of uplift in the northeast part of the caldera during 1995-98. The beginning of uplift was coincident with or followed shortly after an earthquake swarm near the north caldera rim

Ring-fault activity at subsiding calderas studied from analogue experiments and numerical modeling

Science.gov (United States)

Liu, Y. K.; Ruch, J.; Vasyura-Bathke, H.; Jonsson, S.

2017-12-01

Several subsiding calderas, such as the ones in the Galápagos archipelago and the Axial seamount in the Pacific Ocean have shown a complex but similar ground deformation pattern, composed of a broad deflation signal affecting the entire volcanic edifice and of a localized subsidence signal focused within the caldera. However, it is still debated how deep processes at subsiding calderas, including magmatic pressure changes, source locations and ring-faulting, relate to this observed surface deformation pattern. We combine analogue sandbox experiments with numerical modeling to study processes involved from initial subsidence to later collapse of calderas. The sandbox apparatus is composed of a motor driven subsiding half-piston connected to the bottom of a glass box. During the experiments the observation is done by five digital cameras photographing from various perspectives. We use Photoscan, a photogrammetry software and PIVLab, a time-resolved digital image correlation tool, to retrieve time-series of digital elevation models and velocity fields from acquired photographs. This setup allows tracking the processes acting both at depth and at the surface, and to assess their relative importance as the subsidence evolves to a collapse. We also use the Boundary Element Method to build a numerical model of the experiment setup, which comprises contracting sill-like source in interaction with a ring-fault in elastic half-space. We then compare our results from these two approaches with the examples observed in nature. Our preliminary experimental and numerical results show that at the initial stage of magmatic withdrawal, when the ring-fault is not yet well formed, broad and smooth deflation dominates at the surface. As the withdrawal increases, narrower subsidence bowl develops accompanied by the upward propagation of the ring-faulting. This indicates that the broad deflation, affecting the entire volcano edifice, is primarily driven by the contraction of the

Tianmujian caldera. A potential area for locating rich and large uranium deposit

International Nuclear Information System (INIS)

Lin Ziyu; Xu Jinshan; Chen Mingzhuo; Jiang Jinyuan; Fan Honghai; Cheng Qi

2001-01-01

Based on the comprehensive analysis on geologic, remote sensing, gravimetric, magnetic and geochemical data, and the field geologic investigation, the author has preliminarily ascertained the formation and the distribution characteristics of the Tianmujian caldera, and recognized the porphyroclastic lava system which is extensively distributed in the area. The authors suggest that the Tianmujian volcanic basin experienced two evolution stages--the thermal uplifting and the formation of caldera, that large concealed uranium-rich granitic massif occurs in the area, and during the vertical evolution process the uranium showed its concentration in the lower part and depletion in the upper part, and large amount of ore-forming material moved upward along with the magmatic hydrothermals entering the caldera to form uranium deposit. In addition, it is clarified that the NE-NW rhombic-formed basement structural pattern is predominated by the NE-trending fault. At the same time, the important role of the basement faults in controlling the magmatic activities, in the formation of volcanic basins, as well as the formation of uranium mineralization is emphasized. On the basis of the above comprehensive analysis the authors suggest that the Tianmujian caldera is a quite favourable potential area for possessing the basic conditions necessary for the formation of rich and large uranium deposit including uranium 'source, migration, concentration, preservation' and favourable multiple metallogenic information is displayed in the Tianmujian area

Qualitative and Quantitative Assessment of Naturals Hazards in the Caldera of Mount Bambouto (West Cameroon)

Science.gov (United States)

Zangmo Tefogoum, G.; Kagou Dongmo, A.; Nkouathio, D. G.; Wandji, P.

2009-04-01

Mount Bambouto is polygenic stratovolcano of the Cameroon Volcanic Line, build between 21 Ma and 4,5Ma (Nkouathio et al., 2008). It is situated at about 200 km NE of mount Cameroon, at 09°55' and 10°15' East and, 05°25' and 05°50' Nord. This volcano covers an area of 500 Km2 and culminates at 2740 m at Meletan hill and bears a collapse caldera (13 x 8 km). Fissural, extrusive and explosive dynamism are responsible of the construction in three main stages this volcano including the edification of a sommital large rim caldera. Mount Bambouto structure gives rise to different natural hazards, of volcanological origin and meteorological origin. In the past time, landslides, floodings, firebush, blocks collapse took place in this area with catastrophic impact on the population. New research program had been carried out in the caldera concerning qualitative and quantitative evaluation of natural risks and catastrophes. The main factors of instability are rain, structure of the basement, slopes, lithology and anthropic activities; particularly, the occurrence of exceptional rainfall due to global change are relevant; this gives opportunity to draw landslides hazards zonation map of the Bambouto caldera which is the main risk in this area. We evaluate the financial potential of the caldera base on the average income of breeding, farming, school fees and the cost of houses and equipments for each family. The method of calculation revealed that, the yearly economy of the mounts Bambouto caldera represents about 2 billions FCFA. Some recommendations have been made in order to prevent and reduced the potential losses and the number of victims in particular by better land use planning. These help us to estimate the importance of destruction of the environment and biodiversity in case of catastrophes. We conclude that in the Bambouto caldera there is moderate to high probability that destructive phenomena due to landslides occurs within the upcoming years with enormous

Growth of intra-caldera lava domes controlled by various modes of caldera collapse, the Štiavnica volcano-plutonic complex, Western Carpathians

Czech Academy of Sciences Publication Activity Database

Tomek, Filip; Žák, J.; Holub, F. V.; Chlupáčová, M.; Verner, K.

2016-01-01

Roč. 311, February 1 (2016), s. 183-197 ISSN 0377-0273 Institutional support: RVO:67985831 Keywords : andesite * anisotropy of magnetic susceptibility (AMS) * collapse caldera * lava dome * magma flow * stratovolcano Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.492, year: 2016

Long Valley Caldera Lake and reincision of Owens River Gorge

Science.gov (United States)

Hildreth, Wes; Fierstein, Judy

2016-12-16

Owens River Gorge, today rimmed exclusively in 767-ka Bishop Tuff, was first cut during the Neogene through a ridge of Triassic granodiorite to a depth as great as its present-day floor and was then filled to its rim by a small basaltic shield at 3.3 Ma. The gorge-filling basalt, 200 m thick, blocked a 5-km-long reach of the upper gorge, diverting the Owens River southward around the shield into Rock Creek where another 200-m-deep gorge was cut through the same basement ridge. Much later, during Marine Isotope Stage (MIS) 22 (~900–866 ka), a piedmont glacier buried the diversion and deposited a thick sheet of Sherwin Till atop the basalt on both sides of the original gorge, showing that the basalt-filled reach had not, by then, been reexcavated. At 767 ka, eruption of the Bishop Tuff blanketed the landscape with welded ignimbrite, deeply covering the till, basalt, and granodiorite and completely filling all additional reaches of both Rock Creek canyon and Owens River Gorge. The ignimbrite rests directly on the basalt and till along the walls of Owens Gorge, but nowhere was it inset against either, showing that the basalt-blocked reach had still not been reexcavated. Subsidence of Long Valley Caldera at 767 ka produced a steep-walled depression at least 700 m deeper than the precaldera floor of Owens Gorge, which was beheaded at the caldera’s southeast rim. Caldera collapse reoriented proximal drainages that had formerly joined east-flowing Owens River, abruptly reversing flow westward into the caldera. It took 600,000 years of sedimentation in the 26-km-long, usually shallow, caldera lake to fill the deep basin and raise lake level to its threshold for overflow. Not until then did reestablishment of Owens River Gorge begin, by incision of the gorge-filling ignimbrite.

Evolution and relationships between volcanism and tectonics in the central-eastern part of the Oligocene Borovitsa caldera (Eastern Rhodopes, Bulgaria)

Science.gov (United States)

Dhont, Damien; Yanev, Yotzo; Bardintzeff, Jacques-Marie; Chorowicz, Jean

2008-04-01

The nested Borovitsa caldera emplaced during the collision-related Paleogene volcanism in the Eastern Rhodopes. The pre-caldera succession consists in Priabonian to Early Oligocene sediments and lavas (absarokites, shoshonites, latites). The caldera filling corresponds to an acid volcanism Early Oligocene in age. The tectono-magmatic evolution of the caldera can be divided into six main stages. (1) Ignimbritic units (more than 1.5 km thick) with a trachydacitic to trachytic composition deposited. The K-Ar method yields an age of 34-33.5 Ma. The volcanic products are either strongly or not welded in the western and eastern parts of the caldera, respectively. (2) An initial Murga caldera, 7-10 km in diameter, collapsed. This event was accompanied by the intrusion of a circular body consisting of lenses-bearing rocks of trachyrhyodacitic to rhyolitic composition within the border faults. (3) The emission of pyroclastic rocks continued and a large sub-volcanic body (33 Ma) of trachydacitic to trachyrhyolitic composition intruded in the western part of the circular body. (4) The Borovitsa caldera (15 km × 34 km) collapsed. Rhyolitic and trachydacitic dykes dated at 32.5 Ma intruded along its border faults. (5) High-Si trachyrhyolitic-perlitic domes intruded in the eastern part of the Borovitsa caldera at 30-32 Ma and the Dushka caldera collapsed within the Borovitsa structure. (6) Dykes of various compositions (from shoshonite to rhyolite) and trachydacitic to rhyolitic sub-volcanic stocks finally intruded within the caldera and along its rims at 27.5-29.5 Ma. Observations on radar and optical satellite imagery allowed both a new mapping of the structural pattern in the Borovitsa caldera and the understanding of the relationships between faulting and volcanism in this area. Horse-tail features accommodating the right-lateral throw component at the termination of NW-SE and N-S right-lateral strike-slip faults are superimposed upon the Murga caldera and the eastern part

Monitoring super-volcanoes: geophysical and geochemical signals at Yellowstone and other large caldera systems.

Science.gov (United States)

Lowenstern, Jacob B; Smith, Robert B; Hill, David P

2006-08-15

Earth's largest calderas form as the ground collapses during immense volcanic eruptions, when hundreds to thousands of cubic kilometres of magma are explosively withdrawn from the Earth's crust over a period of days to weeks. Continuing long after such great eruptions, the resulting calderas often exhibit pronounced unrest, with frequent earthquakes, alternating uplift and subsidence of the ground, and considerable heat and mass flux. Because many active and extinct calderas show evidence for repetition of large eruptions, such systems demand detailed scientific study and monitoring. Two calderas in North America, Yellowstone (Wyoming) and Long Valley (California), are in areas of youthful tectonic complexity. Scientists strive to understand the signals generated when tectonic, volcanic and hydrothermal (hot ground water) processes intersect. One obstacle to accurate forecasting of large volcanic events is humanity's lack of familiarity with the signals leading up to the largest class of volcanic eruptions. Accordingly, it may be difficult to recognize the difference between smaller and larger eruptions. To prepare ourselves and society, scientists must scrutinize a spectrum of volcanic signals and assess the many factors contributing to unrest and toward diverse modes of eruption.

Geothermal hydrology of Valles Caldera and the southwestern Jemez Mountains, New Mexico

Science.gov (United States)

Trainer, Frank W.; Rogers, Robert J.; Sorey, M.L.

2000-01-01

The Jemez Mountains in north-central New Mexico are volcanic in origin and have a large central caldera known as Valles Caldera. The mountains contain the Valles geothermal system, which was investigated during 1970-82 as a source of geothermal energy. This report describes the geothermal hydrology of the Jemez Mountains and presents results of an earlier 1972-75 U.S. Geological Survey study of the area in light of more recent information. Several distinct types of thermal and nonthermal ground water are recognized in the Jemez Mountains. Two types of near-surface thermal water are in the caldera: thermal meteoric water and acid sulfate water. The principal reservoir of geothermal fluids is at depth under the central and western parts of the caldera. Nonthermal ground water in Valles Caldera occurs in diverse perched aquifers and deeper valley-fill aquifers. The geothermal reservoir is recharged by meteorically derived water that moves downward from the aquifers in the caldera fill to depths of 6,500 feet or more and at temperatures reaching about 330 degrees Celsius. The heated geothermal water rises convectively to depths of 2,000 feet or less and mixes with other ground water as it flows away from the geothermal reservoir. A vapor zone containing steam, carbon dioxide, and other gases exists above parts of the liquid-dominated geothermal zone. Two subsystems are generally recognized within the larger geothermal system: the Redondo Creek subsystem and the Sulphur Creek subsystem. The permeability in the Redondo Creek subsystem is controlled by stratigraphy and fault-related structures. Most of the permeability is in the high-angle, normal faults and associated fractures that form the Redondo Creek Graben. Faults and related fractures control the flow of thermal fluids in the subsystem, which is bounded by high-angle faults. The Redondo Creek subsystem has been more extensively studied than other parts of the system. The Sulphur Springs subsystem is not as well

History of the Magmatic Feeding System of the Campi Flegrei Caldera

Science.gov (United States)

Orsi, G.; Civetta, L.; Arienzo, I.; D'Antonio, M.; di Renzo, V.; di Vito, M. A.

2007-12-01

The definition of the magmatic feeding system of active volcanoes, in terms of composition, time-scale of crystallization, relation between composition of the erupted magma and structural position of vents, magma chamber processes and architecture, is of extreme importance for the hazard evaluation. The studies that are carried out for the definition of the magmatic systems include detailed mineralogical, geochemical and isotopic analyses (Sr, Nd, Pb). The Campi Flegrei caldera magmatic structure is characterized by deep and shallow magma chambers. In the deep reservoir (20-10 km depth) mantle derived magmas differentiate and are contaminated with continental crust. In the shallow reservoirs isotopically distinct magmas further differentiate, mix and mingle before the eruptions. These processes generated isotopically distinct components that were variably involved along different structures of the Campi Flegrei caldera during time. At Campi Flegrei caldera the relation between the structural position of the eruptive vent, for the last 14 ka of activity, and the isotopic composition of the emitted magma allow us to reconstruct the architecture of the magmatic feeding system and to infer the chemical and isotopic composition, and the magma chamber location and processes, of the future eruption, according to the position of the vent

Intra-caldera active fault: An example from the Mw 7.0 2016 Kumamoto, Japan, earthquake

Science.gov (United States)

Toda, S.; Murakami, T.; Takahashi, N.

2017-12-01

A NE-trending 30-km-long surface rupture with up to 2.4 m dextral slip emerged during the Mw=7.0 16 April 2016 Kumamoto earthquake along the previously mapped Futagawa and northern Hinagu fault systems. The 5-km-long portion of the northeast rupture end, which was previously unidentified, crossed somma and extended to the 20-km-diameter Aso Caldera, one of the major active volcanoes, central Kyushu. We here explore geologic exposures of interplays of active faulting and active volcanism, and then argue the Futagawa fault system has been influenced by the ring fault system associated with the caldera forming gigantic eruptions since 270 ka, last of which occurred 90 ka ejecting a huge amount of ignimbrite. To understand the interplays, together with the mapping of the 2016 rupture, we employed an UAV to capture numerous photos of the exposures along the canyon and developed 3D orthochromatic topographic model using PhotoScan. One-hundred-meter-deep Kurokawa River canyon by the Aso Caldera rim exposes two lava flow units of 50 ka vertically offset by 10 m by the Futatawa fault system. Reconstructions of the collapsed bridges across the Kurokawa River also reveal cross sections of a 30-meter-high tectonic bulge and 10-m-scale negative flower structure deformed by the frequent fault movements. We speculate two fault developing models across the Aso Caldera. One is that the NE edge of the Futagawa fault system was cut and reset by the caldera forming ring fault, which indicates the 3-km-long rupture extent within the Aso Caldera would be a product of the fault growth since the last Aso-4 eruption of 90 ka. It enables us to estimate the 33 mm/yr of the fault propagation speed. An alternative model is that subsurface rupture of the Kumamoto earthquake extended further to the NE rim, the other side of the caldera edge, which is partially supported by the geodetic and seismic inversions. With respect to the model, the clear surface rupture of the 2016 Kumamoto earthquake

Resurgent Toba – field, chronologic, and model constraints on time scales and mechanisms of resurgence at large calderas

Directory of Open Access Journals (Sweden)

Shanaka L De Silva

2015-06-01

Full Text Available New data reveal details of the post-caldera history at the Earth’s youngest resurgent supervolcano, Toba caldera in Sumatra. Resurgence after the caldera-forming ~74 ka Youngest Toba Tuff eruption uplifted the caldera floor as a resurgent dome, Samosir Island, capped with 100m of lake sediments. 14C age data from the uppermost datable sediments reveal that Samosir Island was submerged beneath lake level (~900m a.s.l ~33.7 ky. Since then, Samosir experienced 700m of uplift as a tilted block dipping to the west. Using 14C ages and elevations of sediment along a transect of Samosir reveal that minimum uplift rates were ~4.9 cm/yr from ~33.7 to 22.5 ka, but diminished to ~0.7 cm/yr after 22.5ka. Thermo-mechanical models informed by these rates reveal that detumescence does not produce the uplift nor the uplift rates estimated for Samosir. However, models calculating the effect of volume change of the magma reservoir within a temperature-dependent viscoelastic host rock reveal that a single pulse of ~475 km3 of magma produces a better fit to the uplift data than a constant flux. Reproducing the uplift rates require more sophisticated models. Motivation for resurgent uplift of the caldera floor is rebound of remnant magma as the system re-established magmastatic and isostatic equilibrium after the caldera collapse. Previous assertions that the caldera floor was apparently at 400m a.s.l or lower requires that uplift must have initiated between sometime between 33.7 ka and 74 ka at a minimum average uplift rate of ~1.1 cm/ year. The change in uplift rate from pre-33.7 ka to immediately post-33.7 ka suggests a role for deep recharge augmenting rebound. Average minimum rates of resurgent uplift at Toba are at least an order of magnitude slower than net rates of restlessness at currently active calderas. This connotes a distinction between resurgence and restlessness controlled by different processes, scales of process, and controlling variables.

Geology of the Mid-Miocene Rooster Comb Caldera and Lake Owyhee Volcanic Field, eastern Oregon: Silicic volcanism associated with Grande Ronde flood basalt

Science.gov (United States)

Benson, Thomas R.; Mahood, Gail A.

2016-01-01

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

Geologic field trip guide to Mount Mazama and Crater Lake Caldera, Oregon

Science.gov (United States)

Bacon, Charles R.; Wright, Heather M.

2017-08-08

Crater Lake partly fills one of the most spectacular calderas of the world—an 8 by 10 kilometer (km) basin more than 1 km deep formed by collapse of the Mount Mazama volcano during a rapid series of explosive eruptions ~7,700 years ago. Having a maximum depth of 594 meters (m), Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 square kilometers (km2) of pristine forested and alpine terrain, including the lake itself, and virtually all of Mount Mazama. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama’s climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest United States, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. In addition, many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama provide information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive processes revealed by

Application of electric and electromagnetic methods to the definition of the Campi Flegrei caldera (Italy

Directory of Open Access Journals (Sweden)

G. Cecere

2000-06-01

Full Text Available The results of an analysis of Dipolar Geoelectrical (DG, Magnetotelluric (MT and Self-Potential (SP data collected over the emerged portion of the Campi Flegrei (CF caldera (South Italy are presented. The DG and MT data are from previous surveys, while the SP data have been recently collected during a survey consisting of 265 pickup land sites. Although the emerged part of the CF caldera appears as a highly inhomogeneous structure, a few simple features have been highlighted through an integrated analysis of subsets of consistent data. A well resolved feature is the structural pattern of the caldera depression along a roughly E-W profile, deduced from a 2D combined interpretation of the MT and DG soundings. Resistivity dispersion effects have also been observed at both ends of this profile. They have been ascribed to the presence of hydrothermally altered zones related to the main fracture systems bordering the caldera. A pressure/temperature source body at a mean depth of about 5 km bsl under the Bay of Pozzuoli has been inferred from the analysis of the 3D SP tomography imaging.

Geologic Map of Mount Mazama and Crater Lake Caldera, Oregon

Science.gov (United States)

Bacon, Charles R.

2008-01-01

Crater Lake partly fills one of the most spectacular calderas of the world, an 8-by-10-km basin more than 1 km deep formed by collapse of the volcano known as Mount Mazama (fig. 1) during a rapid series of explosive eruptions about 7,700 years ago. Having a maximum depth of 594 m, Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 km2 of pristine forested and alpine terrain, including the lake itself, virtually all of Mount Mazama, and most of the area of the geologic map. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama's climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, greatly enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. Lastly, the many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama are a source of information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive

Caldera de recuperación de gases perdidos

OpenAIRE

Camacho Thielepape, Daniel José

2011-01-01

El objeto de este proyecto es describir las instalaciones de la caldera de recuperación de gases perdidos. Más concretamente, las instalaciones de una nueva Planta de Reciclado de Aceite Lubricante en el Campo de Gibraltar, ubicada en el Polígono Industrial del término municipal de San Roque (Cádiz).

78 FR 50095 - Notice of Inventory Completion: History Colorado, Formerly Colorado Historical Society, Denver, CO

Science.gov (United States)

2013-08-16

... Mountain Reservation, Colorado, New Mexico & Utah may proceed. History Colorado is responsible for....R50000] Notice of Inventory Completion: History Colorado, Formerly Colorado Historical Society, Denver, CO AGENCY: National Park Service, Interior. ACTION: Notice. [[Page 50096

Assessing volcanic hazard at the most populated caldera in the world: Campi Flegrei, Southern Italy

Science.gov (United States)

Somma, R.; de Natale, G.; Troise, C.; Kilburn, C.; Moretti, R.

2017-12-01

Naples and its hinterland in Southern Italy are one of the most urbanized areas in the world under threat from volcanic activity. The region lies within range of three active volcanic centers: Vesuvius, Campi Flegrei, and Ischia. The Campi Flegrei caldera, in particular, has been in unrest for six decades. The unrest followed four centuries of quiescence and has heightened concern about an increased potential for eruption. Innovative geochemical and geophysical analysis, combined with scientific drilling, are being used to investigate Campi Flegrei. Results highlight key directions for better understanding the mechanisms of caldera formation and the respective roles of magma intrusion and hydrothermal activity in determining the volcano's behavior. They also provide a framework for evaluating and mitigating the risk from this caldera and other large ones worldwide.

78 FR 19296 - Notice of Inventory Completion: History Colorado, formerly Colorado Historical Society, Denver, CO

Science.gov (United States)

2013-03-29

... Reservation, Colorado, New Mexico & Utah agreed to accept disposition of the human remains. In 2006, History....R50000] Notice of Inventory Completion: History Colorado, formerly Colorado Historical Society, Denver, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: History Colorado, formerly...

78 FR 30737 - Irish Potatoes Grown in Colorado; Reestablishment of Membership on the Colorado Potato...

Science.gov (United States)

2013-05-23

... FR] Irish Potatoes Grown in Colorado; Reestablishment of Membership on the Colorado Potato...: This final rule reestablishes the membership on the Colorado Potato Administrative Committee, Area No... Irish potatoes grown in Colorado. This action modifies the Committee membership structure by amending...

Zeolitization of intracaldera sediments and rhyolitic rocks in the 1.25 Ma lake of Valles caldera, New Mexico, USA

Science.gov (United States)

Chipera, Steve J.; Goff, Fraser; Goff, Cathy J.; Fittipaldo, Melissa

2008-12-01

Quantitative X-ray diffraction analysis of about 80 rhyolite and associated lacustrine rocks has characterized previously unrecognized zeolitic alteration throughout the Valles caldera resurgent dome. The alteration assemblage consists primarily of smectite-clinoptilolite-mordenite-silica, which replaces groundmass and fills voids, especially in the tuffs and lacustrine rocks. Original rock textures are routinely preserved. Mineralization typically extends to depths of only a few tens of meters and resembles shallow "caldera-type zeolitization" as defined by Utada et al. [Utada, M., Shimizu, M., Ito, T., Inoue, A., 1999. Alteration of caldera-forming rocks related to the Sanzugawa volcanotectonic depression, northeast Honshu, Japan — with special reference to "caldera-type zeolitization." Resource Geol. Spec. Issue No. 20, 129-140]. Geology and 40Ar/ 39Ar dates limit the period of extensive zeolite growth to roughly the first 30 kyr after the current caldera formed (ca. 1.25 to 1.22 Ma). Zeolitic alteration was promoted by saturation of shallow rocks with alkaline lake water (a mixture of meteoric waters and degassed hydrothermal fluids) and by high thermal gradients caused by cooling of the underlying magma body and earliest post-caldera rhyolite eruptions. Zeolitic alteration of this type is not found in the later volcanic and lacustrine rocks of the caldera moat (≤ 0.8 Ma) suggesting that later lake waters were cooler and less alkaline. The shallow zeolitic alteration does not have characteristics resembling classic, alkaline lake zeolite deposits (no analcime, erionite, or chabazite) nor does it contain zeolites common in high-temperature hydrothermal systems (laumontite or wairakite). Although aerially extensive, the early zeolitic alteration does not form laterally continuous beds and are consequently, not of economic significance.

History of the magmatic feeding system of the Campi Flegrei caldera (Italy)

Science.gov (United States)

Civetta, L.; Arienzo, I.; D'Antonio, M.; di Renzo, V.; di Vito, M. A.; Orsi, G.

2007-05-01

The definition of the magmatic feeding system of active volcanoes in terms of architecture, composition, crystallization time-scale, relationships between composition of the erupted magmas and structural position of the vents, and magma processes, is of paramount importance for volcanic hazards evaluation. Investigations aimed at defining the Campi Flegeri magmatic system, include detailed mineralogical, geochemical and isotopic analyses (Sr, Nd, Pb, Th,U). The magmatic feeding system of the Campi Flegrei caldera is characterized by deep and shallow magma reservoirs. In the deep reservoirs (20-10 km depth) mantle- derived magmas differentiated and were contaminated by continental crust. In the shallow reservoirs isotopically distinct magmas, further differentiated, contaminated, and mixed and mingled before eruptions. These processes generated isotopically distinct components, variably interacting with the different structural elements of the Campi Flegrei caldera through time. The relationships between the structural position of the eruption vents, during the last 15 ka of activity, and the isotopic composition of the magmas erupted at the Campi Flegrei caldera allow us to reconstruct the architecture of the magmatic feeding system and to infer the chemical and isotopic composition of the magma feeding a future eruption, according to vent position.

Hollow volcanic tumulus caves of Kilauea Caldera, Hawaii County, Hawaii

Directory of Open Access Journals (Sweden)

William R. Halliday

1998-01-01

Full Text Available In addition to lava tube caves with commonly noted features, sizable subcrustal spaces of several types exist on the floor of Kilauea Caldera. Most of these are formed by drainage of partially stabilized volcanic structures enlarged or formed by injection of very fluid lava beneath a plastic crust. Most conspicuous are hollow tumuli, possibly first described by Walker in 1991. Walker mapped and described the outer chamber of Tumulus E-I Cave. Further exploration has revealed that it has a hyperthermic inner room beneath an adjoining tumulus with no connection evident on the surface. Two lengthy, sinuous hollow tumuli also are present in this part of the caldera. These findings support Walkers conclusions that hollow tumuli provide valuable insights into tumulus-forming mechanisms, and provide information about the processes of emplacement of pahoehoe sheet flows.

Reticulite‐producing fountains from ring fractures in Kīlauea Caldera ca. 1500 CE: Chapter 16

Science.gov (United States)

May, Michael; Carey, Rebecca J.; Swanson, Don; Houghton, Bruce F.; Carey, Rebecca; Cayol, Valérie; Poland, Michael P.; Weis, Dominique

2015-01-01

A widely dispersed reticulite bed occurs close to the base of the Keanakākoʻi Tephra at Kīlauea Volcano. It can be divided into six subunits in the northern sector of the volcano; the reticulite also occurs in the southern sector, but outcrops are sparse owing to penecontemporaneous erosion and burial. Multilobate isopachs for each subunit and the total deposit suggest that multiple fountaining vents were distributed in the northern half of the caldera, possibly along ring fractures for the newly formed caldera. Isopach maps also show a sharp decline in thickness along the dispersal axis of each lobe, which could be explained by remobilization of tephra and/or inclined fountains. Despite such isopach characteristics, thinning rates calculated from the isopach data indicate that the fountains were among the most intense and powerful of all studied Kīlauea fountains. Density analyses of the pyroclasts suggest that fountaining was high (>600m) yet complex, possibly due to lava ponding and reentrainment. The calculated volume of the reticulite deposited around the caldera rim is approximately 0.2km3, more voluminous than the deposits of the 1959 Kīlauea Iki eruption; this volume is a minimum, however, as the low-density tephra is easily remobilized, and 600m high caldera walls probably trapped tephra within the caldera, which is deeply buried today and not accounted for in the volume calculations. The duration of this eruption was most likely at least a few days to weeks, based on the calculated volume and estimated discharge rates as seen during the Kīlauea Iki 1959 eruption.

Electrical structure of Plaine des Sables caldera, Piton de la Fournaise volcano (Reunion Island

Directory of Open Access Journals (Sweden)

P. A. Schnegg

1997-06-01

Full Text Available An Audio Magnetotelluric (AMT profile has been carried out across the Plaine des Sables, a former caldera of the active Piton de la Fournaise volcano, Reunion Island. Located in the Western Indian Ocean, between the Mascarene and Madagascar basins, this basaltic shield volcano originates from the activity of a hot spot. Our aim was to determine the internal structure of the volcano, in particular the shallow electrical properties of an area extending between the old and the new caldera rims. Although several teams had already conducted AMT work in this region a few years ago, there was a need for more a detailed, in depth survey. Our final model displays a noticeable slope of the Plaine des Sables basement oriented toward the present Fournaise summit. This slope is interpreted as resulting from successive landslides toward the ocean. We conclude that this dipping, electrically good conducting layer, probably belongs to the flat layering of an older caldera.

Implications of a Caldera Origin of the Lunar Crater Copernicus

Science.gov (United States)

Green, J.

2007-12-01

The forthcoming renaissance in lunar exploration will focus on many objectives such as Copernicus. Copernicus appears to be a caldera for at least 8 reasons. If a caldera we see (1) transient activity (2) no overturned impact flap at the crater margins (3) internal sinuous leveed lava flow channels (4) a lava covered floor (5) terraces of different ages (6) multiple central volcanoes, one showing a directed volcanic blast (7) olivine-rich komatiitic lavas on central volcanoes and (8) magmatic inflation/deflation on caldera flanks localizing craterlets and extinct fumaroles in "loop" patterns. Regarding (6), directed volcanic blasts can remove a segment of the volcano wall as evidenced in terrestrial analogs at Mt. St. Helens and Bezymianny. Impact mechanisms to produce this feature in Copernicus are contrived. For (7) Clementine spectral data show a high olivine content of the central mountains on Copernicus which I interpret as forsteritic spinifex mineralization in komatiitic lavas and not as impact rebound of olivine-rich deep seated rocks. (8) MacDonald (1956) documented loop patterns on the flank of Halemaumau in Hawaii defining arcuate fractures localizing fumaroles and craterlets. Inflation/deflation of subjacent magma bodies are interpreted as the cause for these loops. Inflation/deflation mechanisms on caldera flanks are common around terrestrial calderas. "Loop" patterns on the flank of Copernicus localizing "gouge" craterlets have been interpreted as ballistic features resulting from the meteorite impact of this crater. Questioned is the logic of a linear N26E trending array of fragments within Copernicus to serve as a source of ballistic projectiles to form the loops localizing conjugate craterlets. The fused craterlet axes on the lunar loops do not point back to a presumed impact center in Copernicus. The axes are oriented parallel to a regional northwest (N35-60W) fracture zone. Implications for an endogenic origin of Copernicus would involve

Sill intrusion in volcanic calderas: implications for vent opening probability

Science.gov (United States)

Giudicepietro, Flora; Macedonio, Giovanni; Martini, Marcello; D'Auria, Luca

2017-04-01

Calderas show peculiar behaviors with remarkable dynamic processes, which do not often culminate in eruptions. Observations and studies conducted in recent decades have shown that the most common cause of unrest in the calderas is due to magma intrusion; in particular, the intrusion of sills at shallow depths. Monogenic cones, with large areal dispersion, are quite common in the calderas, suggesting that the susceptibility analysis based on geological features, is not strictly suitable for estimating the vent opening probability in calderas. In general, the opening of a new eruptive vent can be regarded as a rock failure process. The stress field in the rocks that surrounds and tops the magmatic reservoirs plays an important role in causing the rock failure and creating the path that magma can follow towards the surface. In this conceptual framework, we approach the problem of getting clues about the probability of vent opening in volcanic calderas through the study of the stress field produced by the intrusion of magma, in particular, by the intrusion of a sill. We simulate the intrusion of a sill free to expand radially, with shape and dimensions which vary with time. The intrusion process is controlled by the elastic response of the rock plate above the sill, which bends because of the intrusion, and by gravity, that drives the magma towards the zones where the thickness of the sill is smaller. We calculated the stress field in the plate rock above the sill. We found that at the bottom of the rock plate above the sill the maximum intensity of tensile stress is concentrated at the front of the sill and spreads radially with it, over time. For this reason, we think that the front of the spreading sill is prone to open for eruptive vents. Even in the central area of the sill the intensity of stress is relatively high, but at the base of the rock plate stress is compressive. Under isothermal conditions, the stress soon reaches its maximum value (time interval

The Chacana caldera complex in Ecuador

Energy Technology Data Exchange (ETDEWEB)

Hall, Minard L; Mothes, Patricia A [Instituto Geofisico, Escuela Politecnica Nacional, Quito (Ecuador)], E-mail: volcan_pete@yahoo.com

2008-10-01

The Chacana caldera, located immediately east of Quito, capital of Ecuador, forms the most-northern edifice of Ecuadoros rhyolite province. It is a 50X30 km Pleistocene structure that has remained active into historic times. Vitrophyres, welded tuffs, and ignimbrites of rhyolitic and dacitic composition constitute the outer flanks, meantime syngenetic breccias and tuffs, capped later by extensive dacite lava flows and basin sediments, filled the calderaos depression. A notable resurgence occurred that lifted quiet-water sediments to over 4000 m in elevation. The area has numerous hot springs, and little seismic activity.

The Chacana caldera complex in Ecuador

International Nuclear Information System (INIS)

Hall, Minard L; Mothes, Patricia A

2008-01-01

The Chacana caldera, located immediately east of Quito, capital of Ecuador, forms the most-northern edifice of Ecuadoros rhyolite province. It is a 50X30 km Pleistocene structure that has remained active into historic times. Vitrophyres, welded tuffs, and ignimbrites of rhyolitic and dacitic composition constitute the outer flanks, meantime syngenetic breccias and tuffs, capped later by extensive dacite lava flows and basin sediments, filled the calderaos depression. A notable resurgence occurred that lifted quiet-water sediments to over 4000 m in elevation. The area has numerous hot springs, and little seismic activity.

Advancing the business creed? The framing of decisions about public sector managed care.

Science.gov (United States)

Waitzkin, Howard; Yager, Joel; Santos, Richard

2012-01-01

Relatively little research has clarified how executives of for-profit healthcare organisations frame their own motivations and behaviour, or how government officials frame their interactions with executives. Because managed care has provided an organisational structure for health services in many countries, we focused our study on executives and government officials who were administering public sector managed care services. Emphasising theoretically the economic versus non-economic motivations that guide economic behaviour, we extended a long-term research project on public sector Medicaid managed care (MMC) in the United States. Our method involved in-depth, structured interviews with chief executive officers of managed care organisations, as well as high-ranking officials of state government. Data analysis involved iterative interpretation of interview data. We found that the rate of profit, which proved relatively low in the MMC programme, occupied a limited place in executives' self-described motivations and in state officials' descriptions of corporation-government interactions. Non-economic motivations included a strong orientation toward corporate social responsibility and a creed in which market processes advanced human wellbeing. Such patterns contradict some of the given wisdom about how corporate executives and government officials construct their reality. © 2011 The Authors. Sociology of Health & Illness © 2011 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd.

Structural controls on the emission of magmatic carbon dioxide gas, Long Valley Caldera, USA

Science.gov (United States)

Lucic, Gregor; Stix, John; Wing, Boswell

2015-04-01

We present a degassing study of Long Valley Caldera that explores the structural controls upon emissions of magmatic carbon dioxide gas. A total of 223 soil gas samples were collected and analyzed for stable carbon isotopes using a field-portable cavity ring-down spectrometer. This novel technique is flexible, accurate, and provides sampling feedback on a daily basis. Sampling sites included major and minor volcanic centers, regional throughgoing faults, caldera-related structures, zones of elevated seismicity, and zones of past and present hydrothermal activity. The classification of soil gases based on their δ13C and CO2 values reveals a mixing relationship among three end-members: atmospheric, biogenic, and magmatic. Signatures dominated by biogenic contributions (~4 vol %, -24‰) are found on the caldera floor, the interior of the resurgent dome, and areas associated with the Hilton Creek and Hartley Springs fault systems. With the introduction of the magmatic component (~100 vol %, -4.5‰), samples acquire mixing and hydrothermal signatures and are spatially associated with the central caldera and Mammoth Mountain. In particular, they are concentrated along the southern margin of the resurgent dome where the interplay between resurgence-related reverse faulting and a bend in the regional fault system has created a highly permeable fracture network, suitable for the formation of shallow hydrothermal systems. This contrasts with the south moat, where despite elevated seismicity, a thick sedimentary cover has formed an impermeable cap, inhibiting the ascent of fluids and gases to the surface.

Fault structure and kinematics of the Long Valley Caldera region, California, revealed by high-accuracy earthquake hypocenters and focal mechanism stress inversions

Science.gov (United States)

Prejean, Stephanie; Ellsworth, William L.; Zoback, Mark; Waldhauser, Felix

2002-01-01

We have determined high-resolution hypocenters for 45,000+ earthquakes that occurred between 1980 and 2000 in the Long Valley caldera area using a double-difference earthquake location algorithm and routinely determined arrival times. The locations reveal numerous discrete fault planes in the southern caldera and adjacent Sierra Nevada block (SNB). Intracaldera faults include a series of east/west-striking right-lateral strike-slip faults beneath the caldera's south moat and a series of more northerly striking strike-slip/normal faults beneath the caldera's resurgent dome. Seismicity in the SNB south of the caldera is confined to a crustal block bounded on the west by an east-dipping oblique normal fault and on the east by the Hilton Creek fault. Two NE-striking left-lateral strike-slip faults are responsible for most seismicity within this block. To understand better the stresses driving seismicity, we performed stress inversions using focal mechanisms with 50 or more first motions. This analysis reveals that the least principal stress direction systematically rotates across the studied region, from NE to SW in the caldera's south moat to WNW-ESE in Round Valley, 25 km to the SE. Because WNW-ESE extension is characteristic of the western boundary of the Basin and Range province, caldera area stresses appear to be locally perturbed. This stress perturbation does not seem to result from magma chamber inflation but may be related to the significant (???20 km) left step in the locus of extension along the Sierra Nevada/Basin and Range province boundary. This implies that regional-scale tectonic processes are driving seismic deformation in the Long Valley caldera.

Structure and evolution of an active resurgent dome evidenced by geophysical investigations: The Yenkahe dome-Yasur volcano system (Siwi caldera, Vanuatu)

Science.gov (United States)

Brothelande, E.; Lénat, J.-F.; Chaput, M.; Gailler, L.; Finizola, A.; Dumont, S.; Peltier, A.; Bachèlery, P.; Barde-Cabusson, S.; Byrdina, S.; Menny, P.; Colonge, J.; Douillet, G. A.; Letort, J.; Letourneur, L.; Merle, O.; Di Gangi, F.; Nakedau, D.; Garaebiti, E.

2016-08-01

In this contribution, we focus on one of the most active resurgences on Earth, that of the Yenkahe dome in the Siwi caldera (Tanna Island, Vanuatu), which is associated with the persistently active Yasur volcano. Gravity and magnetic surveys have been carried out over the past few years in the area, as well as electrical methods including electrical resistivity tomography (ERT), time domain electro-magnetics (TDEM) and self-potential (SP). These investigations were completed by thermometry, CO2 soil gas measurements, field observations and sampling. This multi-method approach allows geological structures within the caldera to be identified, as well as associated hydrothermal features. The global structure of the caldera is deduced from gravity data, which shows the caldera rim as a high density structure. Large lava fields, emplaced before and after the onset of resurgence, are evidenced by combined gravity, magnetic and resistivity signals. In the middle of the caldera, the Yenkahe dome apparently results from a combination of volcanic and tectonic events, showing that lava extrusion and resurgence have been operating simultaneously or alternately during the Siwi caldera post-collapse history. There is a clear distinction between the western and eastern parts of the dome. The western part is older and records the growth of an initial volcanic cone and the formation of a small caldera. This small caldera (paleo-Yasur caldera), partially filled with lava flows, is the present-day focus of volcanic activity and associated fluid circulation and alteration. The eastern part of the dome is presumably younger, and is characterized by intense, extensive hydrothermal alteration and activity. Its northern part is covered by lava flow piles and exhibits a shallow hydrothermal zone in ERT. The southern part has hydrothermal alteration and activity extending at least down to the base of the resurgent dome. This part of the dome is built up of low cohesion rock and is thus

A Physical Model of Sill Expansion to Explain the Dynamics of Unrest at Calderas with Application to Campi Flegrei

Directory of Open Access Journals (Sweden)

Flora Giudicepietro

2017-07-01

Full Text Available Many calderas show remarkable unrest, which often does not culminate in eruptions (non-eruptive unrest. In this context the interpretation of the geophysical data collected by the monitoring networks is difficult. When the unrest is eruptive, a vent opening process occurs, which leads to an eruption. In calderas, vent locations typically are scattered over a large area and monogenic cones form. The resulting pattern is characterized by a wide dispersion of eruptive vents, therefore, the location of the future vent is not easily predictable. We propose an interpretation of the deformation associated to unrest and vent pattern commonly observed at calderas, based on a physical model that simulates the intrusion and the expansion of a sill. The model can explain both the uplift and any subsequent subsidence through a single process. Considering that the stress mainly controls the vent opening process, we try to gain insight on the vent opening in calderas through the study of the stress field produced by the intrusion of an expanding sill. We find that the tensile stress in the rock above the sill is concentrated at the sill edge in a ring-shaped area with radius depending on the physical properties of magma and rock, the feeding rate and the magma cooling rate. This stress field is consistent with widely dispersed eruptive vents and monogenic cone formation, which are often observed in the calderas. However, considering the mechanical properties of the elastic plate and the rheology of magma, we show that remarkable deformations may be associated with low values of stress in the rock at the top of the intrusion, thereby resulting in non-eruptive unrest. Moreover, we have found that, under the assumption of isothermal conditions, the stress values decrease over time during the intrusion process. This result may explain why the long-term unrest, in general, do not culminate in an eruption. The proposed approach concerns a general process and is

California's restless giant: the Long Valley Caldera

Science.gov (United States)

Hill, David P.; Bailey, Roy A.; Hendley, James W.; Stauffer, Peter H.; Marcaida, Mae

2014-01-01

Scientists have monitored geologic unrest in the Long Valley, California, area since 1980. In that year, following a swarm of strong earthquakes, they discovered that the central part of the Long Valley Caldera had begun actively rising. Unrest in the area persists today. The U.S. Geological Survey (USGS) continues to provide the public and civil authorities with current information on the volcanic hazard at Long Valley and is prepared to give timely warnings of any impending eruption.

Colorado Water Institute

Science.gov (United States)

Colorado Water Institute Colorado State University header HomeMission StatementGRAD592NewslettersPublications/ReportsCSU Water ExpertsFunding OpportunitiesScholarshipsSubscribeEmploymentAdvisory BoardStaffContact UsCommentsLinks Water Center Logo Water Resources Archive Office of Engagement Ag Water

Vesuvius, the Tengger Mountains and the problem of calderas

NARCIS (Netherlands)

Escher, B.G.

1926-01-01

Until recently there was no good general map of the Tengger Mountains, so that in 1914 F. von Wolff (bibl. 1) in his work „Der Vulkanismus”, vol. I, p. 510—511, gives a reproduction of Pr. Junghuhn's map of 1844. For a volcanic district that has frequently been used as an example of a caldera and

The Role of Tectonic Stress in Triggering Large Silicic Caldera Eruptions

Science.gov (United States)

Cabaniss, Haley E.; Gregg, Patricia M.; Grosfils, Eric B.

2018-05-01

We utilize 3-D temperature-dependent viscoelastic finite element models to investigate the mechanical response of the host rock supporting large caldera-size magma reservoirs (volumes >102 km3) to local tectonic stresses. The mechanical stability of the host rock is used to determine the maximum predicted repose intervals and magma flux rates that systems may experience before successive eruption is triggered. Numerical results indicate that regional extension decreases the stability of the roof rock overlying a magma reservoir, thereby promoting early-onset caldera collapse. Alternatively, moderate amounts of compression (≤10 mm/year) on relatively short timescales (stresses on reservoir stability, our models indicate that the process of rejuvenation and mechanical failure is likely to take place over short time periods of hundreds to thousands of years. These findings support the short preeruption melt accumulation timescales indicated by U series disequilibrium studies.

2011 Kids Count in Colorado! The Impact of the Great Recession on Colorado's Children

Science.gov (United States)

Colorado Children's Campaign, 2011

2011-01-01

"Kids Count in Colorado!" is an annual publication of the Colorado Children's Campaign, which provides the best available state- and county-level data to measure and track the education, health and general well-being of the state's children. "Kids Count in Colorado!" informs policy debates and community discussions, serving as…

Geological Evidences for a Large Tsunami Generated by the 7.3 ka Kikai Caldera Eruption, Southern Japan

Science.gov (United States)

Yamada, M.; Fujino, S.; Satake, K.

2017-12-01

The 7.3 ka eruption of Kikai volcano, southern Kyushu, Japan, is one of the largest caldera-forming eruption in the world. Given that a huge caldera was formed in shallow sea area during the eruption, a tsunami must have been generated by a sea-level change associated. Pyroclastic flow and tsunami deposits by the eruption have been studied around the caldera, but they are not enough to evaluate the tsunami size. The goal of this study is to unravel sizes of tsunami and triggering caldera collapse by numerical simulations based on a widely-distributed tsunami deposit associated with the eruption. In this presentation, we will provide an initial data on distribution of the 7.3 ka tsunami deposit contained in sediment cores taken at three coastal lowlands in Wakayama, Tokushima, and Oita prefectures (560 km, 520 km, and 310 km north-east from the caldera, respectively). A volcanic ash from the eruption (Kikai Akahoya tephra: K-Ah) is evident in organic-rich muddy sedimentary sequence in all sediment cores. Up to 6-cm-thick sand layer, characterized by a grading structure and sharp bed boundary with lower mud, is observed immediately beneath the K-Ah tephra in all study sites. These sedimentary characteristics and broad distribution indicate that the sand layer was most likely deposited by a tsunami which can propagate to a wide area, but not by a local storm surge. Furthermore, the stratigraphic relationship implies that the study sites must have been inundated by the tsunami prior to the ash fall. A sand layer is also evident within the K-Ah tephra layer, suggesting that the sand layer was probably formed by a subsequent tsunami wave during the ash fall. These geological evidences for the 7.3 ka tsunami inundation will contribute to a better understanding of the caldera collapse and the resultant tsunami, but also of the tsunami generating system in the eruptive process.

78 FR 72700 - Notice of Inventory Completion: History Colorado, formerly Colorado Historical Society, Denver, CO

Science.gov (United States)

2013-12-03

... Mexico, were invited to consult but did not participate. History and Description of the Remains In the....R50000] Notice of Inventory Completion: History Colorado, formerly Colorado Historical Society, Denver, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: History Colorado has completed...

Jurassic ash-flow sheets, calderas, and related intrusions of the Cordilleran volcanic arc in southeastern Arizona: implications for regional tectonics and ore deposits

Science.gov (United States)

Lipman, P.W.; Hagstrum, J.T.

1992-01-01

Volcanologic, petrologic, and paleomagnetic studies of widespread Jurassic ash-flow sheets in the Huachuca-southern Dragoon Mountains area have led to identification of four large source calderas and associated comagnetic intracaldera intrusions. Stratigraphic, facies, and contact features of the caldera-related tuffs also provide constraints on the locations, lateral displacements, and very existence for some major northwest-trending faults and inferred regional thrusts in southeastern Arizona. Silicic alkalic compositions of the Jurassic caldera-related, ash-flow tuffs; bimodal associated mafic magmatism; and interstratified coarse sedimentary deposits provide evidence for synvolcanic extension and rifting within the Cordilleran magmatic arc. Gold-copper mineralization is associated with subvolcanic intrusions at several of the Jurassic calderas. -from Authors

78 FR 9629 - Irish Potatoes Grown in Colorado; Reestablishment of Membership on the Colorado Potato...

Science.gov (United States)

2013-02-11

... Service 7 CFR Part 948 [Doc. No. AMS-FV-12-0044; FV12-948-2 PR] Irish Potatoes Grown in Colorado; Reestablishment of Membership on the Colorado Potato Administrative Committee, Area No. 2 AGENCY: Agricultural... membership on the Colorado Potato Administrative Committee, Area No. 2 (Committee). The Committee locally...

Caldera formation and varied eruption styles on North Pacific seamounts: the clastic lithofacies record

Science.gov (United States)

Portner, Ryan A.; Clague, Dave A.; Paduan, Jennifer B.

2014-08-01

Detailed examination of volcaniclastic and sedimentary rocks collected from the Taney (30 Ma), President Jackson (4 Ma), Vance (3 Ma) and Alarcon (2 Ma) near-ridge seamount chains of the North Pacific reveals seven clastic lithofacies that record various modes of eruption, magma fragmentation, and particle dispersal. Lithofacies are distinguished by differences in lithology, bedding habit, compositional heterogeneity, and relationship to volcanic landforms. Breccia lithofacies were produced through mechanical fragmentation during caldera collapse (polymict) or effusive eruptions onto steep slopes (monomict). Rare globular lapilli mudstone lithofacies contain clasts with morphologies formed by magma-sediment mingling processes (peperite). Seamount summit pyroclastic deposits include proximal lapilli tuff with vesicular pyroclasts, and more distal limu o Pele tuff lithofacies. Much finer-grained hydrothermal mudstone/tuff lithofacies occurs around caldera rims and contains greenschist minerals, hydrothermal clays and basaltic ash that record subsurface phreatomagmatic fragmentation processes. Very fine-grained ash is transported to distal regions by oceanic currents and hydrothermal plumes, and is a component of the regional pelagic sediment budget. Pyroclastic lithofacies only occur on seamount summits suggesting formation during the latter stages of seamount evolution. As a seamount drifts away from an adjacent ridge axis and associated heat source, its magma supply is reduced allowing for magmatic gas buildup and mild explosive eruptions. During this stage, the diminished melt supply under the seamount is unable to fully compensate for extension along the ridge axis and vertical seamount growth. Lateral intrusion into spreading-related structures in this stage causes magma withdrawal and caldera formation. Formation of caldera ring faults also promotes seawater ingress into subseafloor hydrothermal cells, which interact with magma conduits causing phreatomagmatic

Decadal to monthly timescales of magma transfer and reservoir growth at a caldera volcano.

Science.gov (United States)

Druitt, T H; Costa, F; Deloule, E; Dungan, M; Scaillet, B

2012-02-01

Caldera-forming volcanic eruptions are low-frequency, high-impact events capable of discharging tens to thousands of cubic kilometres of magma explosively on timescales of hours to days, with devastating effects on local and global scales. Because no such eruption has been monitored during its long build-up phase, the precursor phenomena are not well understood. Geophysical signals obtained during recent episodes of unrest at calderas such as Yellowstone, USA, and Campi Flegrei, Italy, are difficult to interpret, and the conditions necessary for large eruptions are poorly constrained. Here we present a study of pre-eruptive magmatic processes and their timescales using chemically zoned crystals from the 'Minoan' caldera-forming eruption of Santorini volcano, Greece, which occurred in the late 1600s BC. The results provide insights into how rapidly large silicic systems may pass from a quiescent state to one on the edge of eruption. Despite the large volume of erupted magma (40-60 cubic kilometres), and the 18,000-year gestation period between the Minoan eruption and the previous major eruption, most crystals in the Minoan magma record processes that occurred less than about 100 years before the eruption. Recharge of the magma reservoir by large volumes of silicic magma (and some mafic magma) occurred during the century before eruption, and mixing between different silicic magma batches was still taking place during the final months. Final assembly of large silicic magma reservoirs may occur on timescales that are geologically very short by comparison with the preceding repose period, with major growth phases immediately before eruption. These observations have implications for the monitoring of long-dormant, but potentially active, caldera systems.

A three-dimensional QP imaging of the shallowest subsurface of Campi Flegrei offshore caldera, southern Italy

Science.gov (United States)

Serlenga, Vincenzo; de Lorenzo, Salvatore; Russo, Guido; Amoroso, Ortensia; Virieux, Jean; Garambois, Stephane; Zollo, Aldo

2017-04-01

We build a three-dimensional attenuation image of the shallowest subsurface of Campi Flegrei caldera, a resurgent caldera located 15 km west of Naples, southern Italy. Extracting tstar (t*) measurements from an active seismic dataset can be achieved by a spectral ratio method which has been intensively used for earthquakes. The applicability of such measurement has to be validated for active seismic datasets which have a narrower frequency band compared to frequency band of quakes. The validation, as well as the robustness, of such extraction for narrow Ricker source wavelet has been checked through many synthetic and realistic tests. These tests allow us to conclude that this measurement is valid as long as 1) short signal time window are chosen to perform the spectral analysis; 2) the effects caused by heterogeneities of the sampled medium on the seismic spectra have to be taken into account in the description of elastic Green's function. Through such a deconvolution strategy, contributions of the fine velocity structure on signal amplitudes have been significantly removed: in case of suspicious behavior of the spectrum ratio, the measurement is disregarded. This procedure, a kind of deconvolution of the phase propagation imprint, is expected to leave nearly untouched the attenuation signature of seismic traces we are interested in. Such refined measurement approach based on the spectral ratio method has been applied to the real active seismic SERAPIS database providing us a reasonable dataset of 11,873 differential t* measurements (dt*). These data are used for imaging anelastic properties of Campi Flegrei caldera through a linearized, iterative, damped attenuation tomography. Based on configuration of sources and receivers, an attenuating volume as large as 13 x 13 x 1.5 km3 has been imaged. The tomography, with a resolution of 1 km in the horizontal directions and 0.5 km in the vertical direction, allowed to image important features whose reliability has been

Renewed inflation of Long Valley Caldera, California (2011 to 2014)

Science.gov (United States)

Montgomery-Brown, Emily; Wicks, Chuck; Cervelli, Peter F.; Langbein, John O.; Svarc, Jerry L.; Shelly, David R.; Hill, David P.; Lisowski, Michael

2015-01-01

Slow inflation began at Long Valley Caldera in late 2011, coinciding with renewed swarm seismicity. Ongoing deformation is concentrated within the caldera. We analyze this deformation using a combination of GPS and InSAR (TerraSAR-X) data processed with a persistent scatterer technique. The extension rate of the dome-crossing baseline during this episode (CA99 to KRAC) is 1 cm/yr, similar to past inflation episodes (1990–1995 and 2002–2003), and about a tenth of the peak rate observed during the 1997 unrest. The current deformation is well modeled by the inflation of a prolate spheroidal magma reservoir ∼7 km beneath the resurgent dome, with a volume change of ∼6 × 106 m3/yr from 2011.7 through the end of 2014. The current data cannot resolve a second source, which was required to model the 1997 episode. This source appears to be in the same region as previous inflation episodes, suggesting a persistent reservoir.

Interpreting compositional zonation of the Zaragoza ignimbrite from Los Humeros caldera, Central Mexico

International Nuclear Information System (INIS)

Carrasco-Nunez, Gerardo; McCurry, Michael; Branney, Michael J

2008-01-01

Compositional zonation in ignimbrites is relatively common, and is often inferred to record gradual withdrawal by an eruption of a density-stratified magma chamber (with silicic magma towards the top and more dense, mafic magma at the bottom). We show that this model does not match observations at the ca. 0.1 Ma Zaragoza ignimbrite from Los Humeros caldera in central Mexico. Detailed petrologic studies reveal a more complex scenario: the ignimbrite exhibits a 'double' vertical zonation based on the compositions of pumice lapilli. We present evidence for mingling and limited mixing occurred during or immediately before the caldera-forming eruption. One possibility to explain the observations is that the ignimbrite eruption occurred in response to intrusion of a hybridized andesitic magma into a rhyodacitic magma chamber.

Surface heat flow density at the Phlegrean Fields caldera (southern Italy)

Energy Technology Data Exchange (ETDEWEB)

Corrado, Gennardo [Naples Univ., Dept. of Geophysics and Volcanology, Naples (Italy); De Lorenzo, Salvatore; Mongelli, Francesco; Tramacere, Antonio; Zito, Gianmaria [Bari Univ., Dept. of Geology and Geophysics, Bari (Italy)

1998-08-01

The Phlegrean Fields areas is a Holocene caldera located west of Naples, southern Italy. The recent post caldera activity is characterised by several eruptive centers inside the collapsed areas. In order to investigate the still active volcanic processes, surface heat flow measurement were carried out in 1995 in 30 sites of the Phlegrean Fields and a heat flow map compiled. Filtering of the map reveals some well-defined anomalies superimposed on a general southward-increasing trend. Local anomalies are related to small magma bodies, whereas the observed general trend has been attributed to the effect of ground-water flow. This effect was calculated and removed. The undisturbed mean value of the surface heat flow density in the eastern sector is 149mW/m{sup 2}, which is above the regional value of 85mW/m{sup 2} assigned to the eastern part of the Tyrrhenian Sea, and which is probably influenced by a very large, deep magmatic body. (Author)

Geotrail development to connect the dots in Muara Caldera Toba, Indonesia

Science.gov (United States)

Ginting, Nurlisa; Siregar, Narosu

2018-03-01

The growth of awareness in sustainable tourism has led to the development of geotourism all around the world, in which geotourism promotes conservation of geoheritage, appreciation of geosites, and interpretation of geoscience. The Toba Caldera in Indonesia is a genuine evidence of geological phenomena, and at present, the remaining geosites in its surrounding are potential as the tourism attraction. Previous works on geotourism have shown several perspectives in geology, however, research for geotourism planning in destinations is limited. Using the principle of tourism attraction, this paper introduces geotrail concept by connecting the values of each geosite in the Toba Caldera, particularly in Muara. Through qualitative approach, the prospect of initiating a geotrail in Muara is explored using panels, viewpoints, timeline, and stops. Collected data from observations and interviews were analysed with triangular method. The result indicates that natural element is dominant, built element can complement the nature, and it is suggested to strengthen cultural and social elements to optimize the geotrail development.

Distributed-Temperature-Sensing Using Optical Methods: A First Application in the Offshore Area of Campi Flegrei Caldera (Southern Italy for Volcano Monitoring

Directory of Open Access Journals (Sweden)

Stefano Carlino

2016-08-01

Full Text Available A temperature profile 2400 m along the off-shore active caldera of Campi Flegrei (Gulf of Pozzuoli was obtained by the installation of a permanent fiber-optic monitoring system within the framework of the Innovative Monitoring for Coastal and Marine Environment (MON.I.C.A project. The system consists of a submerged, reinforced, multi-fiber cable containing six single-mode telecom grade optical fibers that, exploiting the stimulated Brillouin scattering, provide distributed temperature sensing (DTS with 1 m of spatial resolution. The obtained data show that the offshore caldera, at least along the monitored profile, has many points of heat discharge associated with fluid emission. A loose association between the temperature profile and the main structural features of the offshore caldera was also evidenced by comparing DTS data with a high-resolution reflection seismic survey. This represents an important advancement in the monitoring of this high-risk volcanic area, since temperature variations are among the precursors of magma migration towards the surface and are also crucial data in the study of caldera dynamics. The adopted system can also be applied to many other calderas which are often partially or largely submerged and hence difficult to monitor.

Public views and attitudes concerning fire and fuels reduction strategies in the Valles Caldera National Preserve (VCNP) New Mexico

Science.gov (United States)

Kurt Anschuetz; Carol Raish

2010-01-01

The Valles Caldera National Preserve (VCNP), located in the heart of the Jemez Mountains in northcentral New Mexico, is a special place for many residents of the region. The large volcanic caldera, formerly the privately owned Baca Ranch, is an 89,000-acre property known for its scenic meadows and abundant wildlife, including herds of elk. The U.S. purchased the...

7 CFR 948.51 - Colorado Potato Committee.

Science.gov (United States)

2010-01-01

... 7 Agriculture 8 2010-01-01 2010-01-01 false Colorado Potato Committee. 948.51 Section 948.51... Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE IRISH POTATOES GROWN IN COLORADO Order Regulating Handling Committees § 948.51 Colorado Potato Committee. The Colorado Potato Committee...

The origin of a coarse lithic breccia in the 34 ka caldera-forming Sounkyo eruption, Taisetsu volcano group, central Hokkaido, Japan

Science.gov (United States)

Yasuda, Y.; Suzuki-Kamata, K.

2018-05-01

The 34 ka Sounkyo eruption produced 7.6 km3 of tephra ( 5 km3 DRE) as fallout, ignimbrite, and lithic breccia units, forming a small, 2-km-diameter summit caldera in the Taisetsu volcano group, Japan. The Sounkyo eruption products are made up of five eruptive units (SK-A to -E) in proximal regions, corresponding to the distal deposits, a 1- to 2-m-thick pumice fallout and the Px-type ignimbrite up to 220 m thick. The eruption began with a fallout phase, producing unstable low eruption columns during the earlier phase to form a 27-m-thick, unstratified and ungraded, coarse lithic breccia (SK-C). The failure in turn choked the conduit, and then the eruption stopped. After a short eruptive hiatus, the eruption resumed with a short-lived fall phase, establishing an eruption column up to 16 km high and producing a <6-m-thick scoria fallout (SK-D). Finally, the eruption ended with the generation of PDCs by eruption column collapse to form a 5- to 15-m-thick ignimbrite in the proximal area (SK-E). Volume relationships between the caldera, ejected magma, and ejected lithic fragments suggest that the caldera was not essentially formed by caldera collapse but, instead, by vent widening as a consequence of explosive erosion and failure of the shallow conduit. The dominance of shallow-origin volcanic rocks in the lithic fraction throughout the Sounkyo eruption products implies the development of a flaring funnel-shaped vent. Hence, the occurrence of lithic breccias within small caldera-forming eruption products does not necessarily reflect either the existence or the timing of caldera collapse, as commonly assumed in literature. Lithic breccias commonly overlie climactic ignimbrite/fallout deposits in small caldera-forming eruptions, and an alternative explanation is that this reflects the collapse of the shallow conduit after an eruption climax, whose walls had been highly fractured and had become unstable owing to progressive erosion.

Ballistic blocks around Kīlauea Caldera: Their vent locations and number of eruptions in the late 18th century

Science.gov (United States)

Swanson, Donald A.; Zolkos, Scott P.; Haravitch, Ben

2012-01-01

Thousands of ballistic blocks occur around Kīlauea Caldera and record part of the latest major period of explosive activity on the volcano, in late 1790 or within a few years thereafter. The sizes of the blocks – the largest of which is more than 2 m in nominal diameter – and differences in rock types allow the definition of at least 6 dispersal lobes of mostly undetermined relative age. The orientations of the lobes help approximate the locations of vents or explosion sources on the floor of the caldera, now deeply buried by younger lava flows. The vents may have been distributed northward for about 2 km from near the site of the modern Halema'uma'u Crater and were apparently confined to the western half of the caldera. The blocks are entirely lithic except for those in one dispersal lobe, which contains cored bombs and blocks as well as juvenile lapilli. Eruption parameters calculated from EJECT! suggest that the phreatic and phreatomagmatic explosions could have been generated at the water table, about 600 m below the high point on the caldera rim.

High-resolution aeromagnetic survey of the Mono Basin-Long Valley Caldera region, California

Science.gov (United States)

Ponce, D. A.; Mangan, M.; McPhee, D.

2013-12-01

A new high-resolution aeromagnetic survey of the Mono Basin-Long Valley Caldera region greatly enhances previous magnetic interpretations that were based on older, low-resolution, and regional aeromagnetic data sets and provides new insights into volcano-tectonic processes. The surveyed area covers a 8,750 km2 NNW-trending swath situated between the Sierra Nevada to the west and the Basin and Range Province to the east. The surveyed area includes the volcanic centers of Mono Lake, Mono-Inyo Craters, Mammoth Mountain, Devils Postpile, and Long Valley Caldera. The NW-trending eastern Sierra frontal fault zone crosses through the study area, including the active Mono Lake, Silver Lake, Hartley Springs, Laurel Creek, and Hilton Creek faults. Over 6,000 line-kilometers of aeromagnetic data were collected at a constant terrain clearance of 150 m, a flight-line spacing of 400 m, and a tie-line spacing of 4 km. Data were collected via helicopter with an attached stinger housing a magnetic sensor using a Scintrex CS-3 cesium magnetometer. In the northern part of the survey area, data improve the magnetic resolution of the individual domes and coulees along Mono Craters and a circular shaped magnetic anomaly that coincides with a poorly defined ring fracture mapped by Kistler (1966). Here, aeromagnetic data combined with other geophysical data suggests that Mono Craters may have preferentially followed a pre-existing plutonic basement feature that may have controlled the sickle shape of the volcanic chain. In the northeastern part of the survey, aeromagnetic data reveal a linear magnetic anomaly that correlates with and extends a mapped fault. In the southern part of the survey, in the Sierra Nevada block just south of Long Valley Caldera, aeromagnetic anomalies correlate with NNW-trending Sierran frontal faults rather than to linear NNE-trends observed in recent seismicity over the last 30 years. These data provide an important framework for the further analysis of the

Is there a geochemical link between volcanic and plutonic rocks in the Organ Mountains caldera?

Science.gov (United States)

Memeti, V.; Davidson, J.

2013-12-01

Results from separate volcanic and plutonic studies have led to inconsistent conclusions regarding the origins and thus links between volcanic and plutonic systems in continental arcs and the magmatic processes and time scales responsible for their compositional variations. Some have suggested that there is a geochemical and geochronological disconnect between volcanic and plutonic rocks and hence have questioned the existence of magma mush columns beneath active volcanoes. Investigating contemporary volcanic and plutonic rocks that are spatially connected is thus critical in exploring these issues. The ca. 36 Ma Organ Mountains caldera in New Mexico, USA, represents such a system exposing contemporaneous volcanic and plutonic rocks juxtaposed at the surface due to tilting during extensional tectonics along the Rio Grande Rift. Detailed geologic and structural mapping [1] and 40Ar/39Ar ages of both volcanics and plutons [2] demonstrate the spatial and temporal connection of both rock types with active magmatism over >2.5 myr. Three caldera-forming ignimbrites erupted within 600 kyr [2] from this system with a total erupted volume of 500-1,000 km3 as well as less voluminous pre- and post-caldera trachyte and andesite lavas. The ignimbrite sequence ranges from a crystal-poor, high-SiO2 rhyolite at the base to a more crystal-rich, low-SiO2 rhyolite at the top. Compositional zoning with quartz-monzonite at the base grading to syenite and alaskite at the top is also found in the Organ Needle pluton, the main intrusion, which is interpreted to be the source for the ignimbrites [1]. Other contemporaneous and slightly younger plutons have dioritic to leucogranitic compositions. We examined both volcanic and plutonic rocks with petrography and their textural variations with color cathodoluminescence, and used whole rock element and Sr, Nd and Pb isotope geochemistry to constrain magma compositions and origins. Electron microprobe analyses on feldspars have been completed to

Magnetotelluric Investigations of the Yellowstone Caldera: Understanding the Emplacement of Crustal Magma Bodies

Science.gov (United States)

Gurrola, R. M.; Neal, B. A.; Bennington, N. L.; Cronin, R.; Fry, B.; Hart, L.; Imamura, N.; Kelbert, A.; Bowles-martinez, E.; Miller, D. J.; Scholz, K. J.; Schultz, A.

2017-12-01

Wideband magnetotellurics (MT) presents an ideal method for imaging conductive shallow magma bodies associated with contemporary Yellowstone-Snake River Plain (YSRP) magmatism. Particularly, how do these magma bodies accumulate in the mid to upper crust underlying the Yellowstone Caldera, and furthermore, what role do hydrothermal fluids play in their ascent? During the summer 2017 field season, two field teams from Oregon State University and the University of Wisconsin-Madison installed forty-four wideband MT stations within and around the caldera, and using data slated for joint 3-D inversion with existing seismic data, two 2-D vertical conductivity sections of the crust and upper mantle were constructed. These models, in turn, provide preliminary insight into the emplacement of crustal magma bodies and hydrothermal processes in the YSRP region.

Interpreting compositional zonation of the Zaragoza ignimbrite from Los Humeros caldera, Central Mexico

Energy Technology Data Exchange (ETDEWEB)

Carrasco-Nunez, Gerardo [Centro de Geociencias, UNAM, Campus Juriquilla, Queretaro, Qro. (Mexico); McCurry, Michael [Department of Geology, Idaho State University, Pocatello, ID (United States); Branney, Michael J [Department of Geology, University of Leicester, Leicester (United Kingdom)

2008-10-01

Compositional zonation in ignimbrites is relatively common, and is often inferred to record gradual withdrawal by an eruption of a density-stratified magma chamber (with silicic magma towards the top and more dense, mafic magma at the bottom). We show that this model does not match observations at the ca. 0.1 Ma Zaragoza ignimbrite from Los Humeros caldera in central Mexico. Detailed petrologic studies reveal a more complex scenario: the ignimbrite exhibits a 'double' vertical zonation based on the compositions of pumice lapilli. We present evidence for mingling and limited mixing occurred during or immediately before the caldera-forming eruption. One possibility to explain the observations is that the ignimbrite eruption occurred in response to intrusion of a hybridized andesitic magma into a rhyodacitic magma chamber.

The Riscos Bayos Ignimbrites of the Caviahue-Copahue volcanic caldera complex, southern Andes, Argentina

Science.gov (United States)

Colvin, A.; Merrill, M.; Demoor, M.; Goss, A.; Varekamp, J. C.

2004-05-01

The Caviahue-Copahue volcanic complex (38 S, 70 W) is located on the eastern margin of the active arc in the southern Andes, Argentina. Volcán Copahue, an active stratovolcano which hosts an active hydrothermal system, sits on the southwestern rim of the elliptical Caviahue megacaldera (17 x 15 km). The caldera wall sequences are up to 0.6 km thick and consist of lavas with 51 -69 percent SiO2 and 0.2 - 5 percent MgO as well as breccias, dikes, sills, domes and minor ignimbrites. Andesitic lava flows also occur within the caldera, and are overlain by a chaotic complex of silicic lava and intracaldera pyroclastic flow deposits. The eastern wall sequence is capped by several extracaldera ignimbrites (Riscos Bayos formation) of about 50 m maximum thickness which extend 30 km east-southeast of the caldera. Young back-arc alkali basalt scoria cones occur east of the Caviahue-Copahue volcanic complex. The eruption of the Riscos Bayos formation at about 1.1 Ma (12 km cubed) may be related to the Caviahue caldera formation, though the Riscos Bayos account for only about 7 percent of the caldera volume. The Riscos Bayos consists of three lithic-bearing flow units: a grey basal flow, a tan middle flow and a bright-white, highly indurated uppermost flow. The basal unit consists of white and grey pumice fragments, black scoria clasts, black obsidian clasts (which give it the grey color), and accidental volcanic lithics set in a matrix of ash and crystals. The middle unit is composed of large mauve pumice fragments and accidental lithics set in a fine tan ash groundmass. The uppermost unit is composed of small pink and white pumice fragments set in a matrix of fine white ash. These pumices carry quartz and biotite crystals, whereas the lower two units are orthopyroxene-bearing trachy-dacites. The Caviahue-Copahue magmas all bear arc signatures, but possibly some magma mixing between the andesitic arc magmas and basaltic back-arc magmas may have occurred. The evolved top layer

The Laramide Mesa formation and the Ojo de Agua caldera, southeast of the Cananea copper mining district, Sonora, Mexico

Science.gov (United States)

Cox, Dennis P.; Miller, Robert J.; Woodbourne, Keith L.

2006-01-01

The Mesa Formation extends from Cananea, Mexico, southeast to the Sonora River and is the main host rock of Laramide porphyry copper deposits in the Cananea District and at the Alacran porphyry prospect to the east. The Mesa consists of two members-a lower andesite and an upper dacite. The lowest part of the dacite member is a crystal tuff about 100 m thick. This tuff is the outfall of a caldera centered near the village of Ojo de Agua, dated by 40Ar/39Ar at 65.8 Ma ?0.4. The Ojo de Agua Caldera is about 9 km in diameter and is filled by a light gray biotite dacite tuff with abundant flattened pumice fragments. The volume of the caldera is estimated to be 24 km3.

Anomalous shear wave delays and surface wave velocities at Yellowstone Caldera, Wyoming

International Nuclear Information System (INIS)

Daniel, R.G.; Boore, D.M.

1982-01-01

To investigate the effects of a geothermal area on the propagation of intermediate-period (1--30 s) teleseismic body waves and surface waves, a specially designed portable seismograph system was operated in Yellowstone Caldera, Wyoming. Travel time residuals, relative to a station outside the caldera, of up to 2 s for compressional phases are in agreement with short-period residuals for P phases measured by other investigators. Travel time delays for shear arrivals in the intermediate-period band range from 2 to 9 s and decrease with increasing dT/dΔ. Measured Rayleigh wave phase velocities are extremely low, ranging from 3.2 km/s at 27-s period to 2.0 km/s at 7-s period; the estimated uncertainty associated with these values is 15%. We propose a model for compressional and shear velocities and Poisson's ratio beneath the Yellowstone caldera which fits the teleseismic body and surface wave data: it consists of a highly anomalous crust with an average shear velocity of 3.0 km/s overlying an upper mantle with average velocity of 4.1 km/s. The high average value of Poisson's ratio in the crust (0.34) suggests the presence of fluids there; Poisson's ratio in the mantle between 40 and approximately 200 km is more nearly normal (0.29) than in the crust. A discrepancy between normal values of Poisson's ratio in the crust calculated from short-period data and high values calculated from teleseismic data can be resolved by postulating a viscoelastic crustal model with frequency-dependent shear velocity and attenuation

A fluid-driven earthquake swarm on the margin of the Yellowstone caldera

Science.gov (United States)

Shelly, David R.; Hill, David P.; Massin, Frederick; Farrell, Jamie; Smith, Robert B.; Taira, Taka'aki

2013-01-01

Over the past several decades, the Yellowstone caldera has experienced frequent earthquake swarms and repeated cycles of uplift and subsidence, reflecting dynamic volcanic and tectonic processes. Here, we examine the detailed spatial-temporal evolution of the 2010 Madison Plateau swarm, which occurred near the northwest boundary of the Yellowstone caldera. To fully explore the evolution of the swarm, we integrated procedures for seismic waveform-based earthquake detection with precise double-difference relative relocation. Using cross-correlation of continuous seismic data and waveform templates constructed from cataloged events, we detected and precisely located 8710 earthquakes during the three-week swarm, nearly four times the number of events included in the standard catalog. This high-resolution analysis reveals distinct migration of earthquake activity over the course of the swarm. The swarm initiated abruptly on January 17, 2010 at about 10 km depth and expanded dramatically outward (both shallower and deeper) over time, primarily along a NNW-striking, ~55º ENE-dipping structure. To explain these characteristics, we hypothesize that the swarm was triggered by the rupture of a zone of confined high-pressure aqueous fluids into a pre-existing crustal fault system, prompting release of accumulated stress. The high-pressure fluid injection may have been accommodated by hybrid shear and dilatational failure, as is commonly observed in exhumed hydrothermally affected fault zones. This process has likely occurred repeatedly in Yellowstone as aqueous fluids exsolved from magma migrate into the brittle crust, and it may be a key element in the observed cycles of caldera uplift and subsidence.

A complex magma reservoir system for a large volume intra- to extra-caldera ignimbrite: Mineralogical and chemical architecture of the VEI8, Permian Ora ignimbrite (Italy)

Science.gov (United States)

Willcock, M. A. W.; Bargossi, G. M.; Weinberg, R. F.; Gasparotto, G.; Cas, R. A. F.; Giordano, G.; Marocchi, M.

2015-11-01

Intra-caldera settings record a wealth of information on caldera-forming processes, yet field study is rarely possible due to lack of access and exposure. The Permian Ora Formation, Italy, preserves > 1000 m of vertical section through its intra-caldera succession. This provides an excellent opportunity to detail its mineralogical and geochemical architecture and gain understanding of the eruption evolution and insight into the pre-eruptive magma system. Detailed juvenile clast phenocryst and matrix crystal fragment point count and image analysis data, coupled with bulk-rock chemistry and single mineral compositional data, show that the Ora ignimbrite succession is rhyolitic (72.5-77.7% SiO2), crystal-rich (~ 25-57%; average 43%) and has a constant main mineral population (volcanic quartz + sanidine + plagioclase + biotite). Although a seemingly homogeneous ignimbrite succession, important subtle but detectable lateral and vertical variations in modal mineralogy and bulk-rock major and trace elements are identified here. The Ora Formation is comprised of multiple lithofacies, dominated by four densely welded ignimbrite lithofacies. They are crystal-rich, typically lithic-poor (pene-contemporaneous caldera depressions. Moreover, this data illustrates heterogeneity and local zonation from base-to-top of the main intra-caldera and extra-caldera successions. These variations together with crystal fragment size variations between ignimbrite lithofacies support the hypothesis of a multi-vent eruption process, incremental caldera in-filling by subtly compositionally different pyroclastic flow pulses, and a lower intensity eruption style (Willcock et al., 2013, 2014).

Applying hydrology to land management on the Valles Caldera National Preserve

Science.gov (United States)

Robert R. Parmenter

2009-01-01

Since 2004, the Valles Caldera National Preserve (VCNP) in the Jemez Mountains of northern New Mexico has hosted extensive field hydrology research by scientists from the Center for Sustainability of semi- Arid Hydrology and Riparian Areas (SAHRA) at the University of Arizona. With the development of a detailed hydrologic understanding of VCNP's climate, geology,...

Gradual caldera collapse at Bárdarbunga volcano, Iceland, regulated by lateral magma outflow.

Science.gov (United States)

Gudmundsson, Magnús T; Jónsdóttir, Kristín; Hooper, Andrew; Holohan, Eoghan P; Halldórsson, Sæmundur A; Ófeigsson, Benedikt G; Cesca, Simone; Vogfjörd, Kristín S; Sigmundsson, Freysteinn; Högnadóttir, Thórdís; Einarsson, Páll; Sigmarsson, Olgeir; Jarosch, Alexander H; Jónasson, Kristján; Magnússon, Eyjólfur; Hreinsdóttir, Sigrún; Bagnardi, Marco; Parks, Michelle M; Hjörleifsdóttir, Vala; Pálsson, Finnur; Walter, Thomas R; Schöpfer, Martin P J; Heimann, Sebastian; Reynolds, Hannah I; Dumont, Stéphanie; Bali, Eniko; Gudfinnsson, Gudmundur H; Dahm, Torsten; Roberts, Matthew J; Hensch, Martin; Belart, Joaquín M C; Spaans, Karsten; Jakobsson, Sigurdur; Gudmundsson, Gunnar B; Fridriksdóttir, Hildur M; Drouin, Vincent; Dürig, Tobias; Aðalgeirsdóttir, Guðfinna; Riishuus, Morten S; Pedersen, Gro B M; van Boeckel, Tayo; Oddsson, Björn; Pfeffer, Melissa A; Barsotti, Sara; Bergsson, Baldur; Donovan, Amy; Burton, Mike R; Aiuppa, Alessandro

2016-07-15

Large volcanic eruptions on Earth commonly occur with a collapse of the roof of a crustal magma reservoir, forming a caldera. Only a few such collapses occur per century, and the lack of detailed observations has obscured insight into the mechanical interplay between collapse and eruption. We use multiparameter geophysical and geochemical data to show that the 110-square-kilometer and 65-meter-deep collapse of Bárdarbunga caldera in 2014-2015 was initiated through withdrawal of magma, and lateral migration through a 48-kilometers-long dike, from a 12-kilometers deep reservoir. Interaction between the pressure exerted by the subsiding reservoir roof and the physical properties of the subsurface flow path explain the gradual, near-exponential decline of both collapse rate and the intensity of the 180-day-long eruption. Copyright © 2016, American Association for the Advancement of Science.

Title: Long Valley Caldera 2003 through 2012: Overview of low level unrest in the last decade Authors: Stuart Wilkinson, David Hill, Michael Lisowski, Deborah Bergfeld, Margaret Mangan

Science.gov (United States)

Wilkinson, S. K.; Hill, D. P.; Lisowski, M.; Bergfeld, D.; Mangan, M.

2012-12-01

Long Valley Caldera is located in central California along the eastern escarpment of the Sierra Nevada and at the western edge of the Basin and Range. The caldera formed 0.76 Ma ago during the eruption of 600 cubic kilometers the Bishop Tuff that resulted in the collapse of the partially evacuated magma chamber. Since at least late 1978, Long Valley Caldera has experienced recurring earthquake swarms and ground uplift, suggesting future eruptions are possible. Unrest in Long Valley Caldera during the 1980s to early 2000s is well documented in the literature. Episodes of inflation centered on the resurgent dome in the western part of the caldera occurred in 1979-1980, 1983, 1989-1990, 1997-1998, and 2002-2003, accumulating ~ 80 cm of uplift. Earthquakes of M ≥ 3.0 were numerous in the caldera and in the Sierra Nevada block to the south of the caldera from 1980 through 1983 (800 events including four M~ 6 earthquakes in 1980); in the caldera from 1997 through mid-1998 (150 events); and in the Sierra Nevada block from mid-1998 through 1999 (~160 events) and more modestly from 2002 through 2003 (7 events). In this presentation, we summarize the low-levels of caldera unrest during the last decade. The number of earthquakes in Sierra Nevada block and the caldera has gradually diminished over the last decade. Fifty Sierra Nevada earthquakes had magnitudes 3.0≤M≤4.6. In the caldera, only six earthquakes had magnitudes 3.0≤M≤3.8. A three-month swarm of minor earthquakes (235 events with 0.5≤M≤3.8; most below 2.0) occurred in the caldera in mid-2010. Analysis of continuous GPS data over the last year shows an inflationary pattern within the caldera centered on the resurgent dome, with a maximum uplift rate of ~ 2-3 cm/yr. The rate of deformation is comparable to that of 2002-2003, and well below ~ 70 cm/yr rates observed during the peak of inflation in the late 1990s. Steaming ground and diffuse CO2 discharge has long been a feature of Long Valley Caldera

Evidence for cross rift structural controls on deformation and seismicity at a continental rift caldera

Science.gov (United States)

Lloyd, Ryan; Biggs, Juliet; Wilks, Matthew; Nowacki, Andy; Kendall, J.-Michael; Ayele, Atalay; Lewi, Elias; Eysteinsson, Hjálmar

2018-04-01

In continental rifts structural heterogeneities, such as pre-existing faults and foliations, are thought to influence shallow crustal processes, particularly the formation of rift faults, magma reservoirs and surface volcanism. We focus on the Corbetti caldera, in the southern central Main Ethiopian Rift. We measure the surface deformation between 22nd June 2007 and 25th March 2009 using ALOS and ENVISAT SAR interferograms and observe a semi-circular pattern of deformation bounded by a sharp linear feature cross-cutting the caldera, coincident with the caldera long axis. The signal reverses in sign but is not seasonal: from June to December 2007 the region south of this structure moves upwards 3 cm relative to the north, while from December 2007 until November 2008 it subsides by 2 cm. Comparison of data taken from two different satellite look directions show that the displacement is primarily vertical. We discuss potential mechanisms and conclude that this deformation is associated with pressure changes within a shallow (statistically consistent with this fault structure, indicating that the fault has also controlled the migration of magma from a reservoir to the surface over tens of thousands of years. Spatial patterns of seismicity are consistent with a cross-rift structure that extents outside the caldera and to a depth of ∼30 km, and patterns of seismic anisotropy suggests stress partitioning occurs across the structure. We discuss the possible nature of this structure, and conclude that it is most likely associated with the Goba-Bonga lineament, which cross-cuts and pre-dates the current rift. Our observations show that pre-rift structures play an important role in magma transport and shallow hydrothermal processes, and therefore they should not be neglected when discussing these processes.

Three-Dimensional P-wave Velocity Structure Beneath Long Valley Caldera, California, Using Local-Regional Double-Difference Tomography

Science.gov (United States)

Menendez, H. M.; Thurber, C. H.

2011-12-01

Eastern California's Long Valley Caldera (LVC) and the Mono-Inyo Crater volcanic systems have been active for the past ~3.6 million years. Long Valley is known to produce very large silicic eruptions, the last of which resulted in the formation of a 17 km by 32 km wide, east-west trending caldera. Relatively recent unrest began between 1978-1980 with five ML ≥ 5.7 non-double-couple (NDC) earthquakes and associated aftershock swarms. Similar shallow seismic swarms have continued south of the resurgent dome and beneath Mammoth Mountain, surrounding sites of increased CO2 gas emissions. Nearly two decades of increased volcanic activity led to the 1997 installation of a temporary three-component array of 69 seismometers. This network, deployed by the Durham University, the USGS, and Duke University, recorded over 4,000 high-frequency events from May to September. A local tomographic inversion of 283 events surrounding Mammoth Mountain yielded a velocity structure with low Vp and Vp/Vs anomalies at 2-3 km bsl beneath the resurgent dome and Casa Diablo hot springs. These anomalies were interpreted to be CO2 reservoirs (Foulger et al., 2003). Several teleseismic and regional tomography studies have also imaged low Vp anomalies beneath the caldera at ~5-15 km depth, interpreted to be the underlying magma reservoir (Dawson et al., 1990; Weiland et al., 1995; Thurber et al., 2009). This study aims to improve the resolution of the LVC regional velocity model by performing tomographic inversions using the local events from 1997 in conjunction with regional events recorded by the Northern California Seismic Network (NCSN) between 1980 and 2010 and available refraction data. Initial tomographic inversions reveal a low velocity zone at ~2 to 6 km depth beneath the caldera. This structure may simply represent the caldera fill. Further iterations and the incorporation of teleseismic data may better resolve the overall shape and size of the underlying magma reservoir.

Pucarilla-Cerro Tipillas volcanic complex: the oldest recognized caldera in the southeastern portion of central volcanic zone of Central Andes?

Energy Technology Data Exchange (ETDEWEB)

Guzman, Silvina; Petrinovic, Ivan [CONICET -IBIGEO. Museo de Cs. Naturales, Universidad de Salta, Mendoza 2 (4400), Salta (Argentina)], E-mail: guzmansilvina@gmail.com

2008-10-01

We recognize the most eastern and oldest collapse caldera structure in the southern portion of the Central Volcanic Zone of the Andes. A description of Middle-Upper Miocene successions related to explosive- effusive events is presented. The location of this centre close to Cerro Galn Caldera attests a recurrence in the volcanism between 12 and 2 Ma in this portion of the Altiplano - Puna Plateau.

Evidence from cosmic ray exposure (CRE) dating for the existence of a pre-Minoan caldera on Santorini, Greece

Science.gov (United States)

Athanassas, C. D.; Bourlès, D. L.; Braucher, R.; Druitt, T. H.; Nomikou, P.; Léanni, L.

2016-05-01

Cosmic ray exposure (CRE) dating was performed on the caldera cliffs of Santorini with the aim of detecting cliff segments predating the Minoan eruption (17th century BCE). The methodology involved the determination of in situ-produced cosmogenic 36Cl concentration in basaltic-to-rhyodacitic whole rocks cropping out in the cliffs. After the samples were processed following the chemical protocol of 36Cl preparation for silicate rocks, 36Cl concentrations were measured by accelerator mass spectrometry (AMS). Important challenges during the implementation procedure were related to large amounts of radiogenic 36Cl, complex modeling of inherited 36Cl, and dominance of the thermal and epithermal (low-energy) neutron capture production pathway. Nevertheless, quantitative assessments on the basis of the contribution of the low-energy neutron capture pathway percent to the total production rate validated the calculated CRE dates. Current CRE ages demonstrate that an ancient caldera existed on pre-Minoan Santorini, occupying at least the northern half of the modern-day caldera.

Summary of recent research in Long Valley Caldera, California

Science.gov (United States)

Sorey, M.L.; McConnell, V.S.; Roeloffs, E.

2003-01-01

Since 1978, volcanic unrest in the form of earthquakes and ground deformation has persisted in the Long Valley caldera and adjacent parts of the Sierra Nevada. The papers in this special volume focus on periods of accelerated seismicity and deformation in 1980, 1983, 1989-1990, and 1997-1998 to delineate relations between geologic, tectonic, and hydrologic processes. The results distinguish between earthquake sequences that result from relaxation of existing stress accumulation through brittle failure and those in which brittle failure is driven by active intrusion. They also indicate that in addition to a relatively shallow (7-10-km) source beneath the resurgent dome, there exists a deeper (???15-km) source beneath the south moat. Analysis of microgravimety and deformation data indicates that the composition of the shallower source may involve a combination of silicic magma and hydrothermal fluid. Pressure and temperature fluctuations in wells have accompanied periods of crustal unrest, and additional pressure and temperature changes accompanying ongoing geothermal power production have resulted in land subsidence. The completion in 1998 of a 3000-m-deep drill hole on the resurgent dome has provided useful information on present and past periods of circulation of water at temperatures of 100-200??C within the crystalline basement rocks that underlie the post-caldera volcanics. The well is now being converted to a permanent geophysical monitoring station. ?? 2003 Elsevier B.V. All rights reserved.

Perspectives on managing multi-cultural landscapes: Use, access, and fire/fuels management attitudes and preferences of user groups concerning the Valles Caldera National Preserve (VCNP) and adjacent areas

Science.gov (United States)

Kurt F. Anschuetz

2014-01-01

The Valles Caldera National Preserve (VCNP), which consists of a large, 1.2- to 1.6-million-year-old volcanic caldera, forms the heart of the Jemez Mountains in north-central New Mexico (Figure 1). Known as the Valles Caldera, this bowl-shaped hollow is an especially treasured place within this beloved mountainous landscape for many residents of the region. Its valles...

Rhyolitic calderas and centers clustered within the active andesitic belt of Ecuador's Eastern Cordillera

Energy Technology Data Exchange (ETDEWEB)

Mothes, Patricia A; Hall, Minard L [Instituto Geofisico, Escuela Politecnica Nacional, Quito (Ecuador)], E-mail: pmothes@igepn.edu.ec

2008-10-01

In the Ecuadorian volcanic arc a cluster of scattered rhyolitic and dacitic centers within the mainly andesitic Eastern Cordillera includes large caldera structures (Chalupas, Chacana, Cosanga) as well as smaller edifices, built upon the Paleozoic-Mesozoic metamorphic basement. At the Chacana caldera magmatism dates from 2.7 Ma to historic times. These centers erupted enormous ash flows and thick pumice lapilli falls that covered the InterAndean Valley near Quito. The role of the 50-70 km-thick crust with a notable negative gravity anomaly appears to be related to the generation of this highly silicic magmatism occurring along the crest of the Andes in the NVZ.

Colorado State Capitol Geothermal project

Energy Technology Data Exchange (ETDEWEB)

Shepherd, Lance [Colorado Department of Personnel and Adminstration, Denver, CO (United States)

2016-04-29

Colorado State Capitol Geothermal Project - Final report is redacted due to space constraints. This project was an innovative large-scale ground-source heat pump (GSHP) project at the Colorado State Capitol in Denver, Colorado. The project employed two large wells on the property. One for pulling water from the aquifer, and another for returning the water to the aquifer, after performing the heat exchange. The two wells can work in either direction. Heat extracted/added to the water via a heat exchanger is used to perform space conditioning in the building.

Effects of host rock stratigraphy on the formation of ring-faults and the initiation of collapse calderas

International Nuclear Information System (INIS)

Kinvig, H S; Geyer, A; Gottsmann, J

2008-01-01

Most collapse calderas can be attributed to subsidence of the magma chamber roof along bounding sub-vertical normal faults (ring-faults) after a decompression of the magma chamber, following eruption. Here, we present new numerical models that use a Finite Element Method to investigate the effects of variable crustal stratigraphy (lithology/thickness/order of strata) above a magma chamber, on local stress field distribution and how these in turn compare with existing criteria for ring-fault initiation. Results indicate that the occurrence and relative distribution of mechanically different lithologies may be influential in generating or inhibiting caldera collapse.

Effects of host rock stratigraphy on the formation of ring-faults and the initiation of collapse calderas

Energy Technology Data Exchange (ETDEWEB)

Kinvig, H S; Geyer, A; Gottsmann, J [Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queen' s Road, BS8 1RJ, Bristol (United Kingdom)

2008-10-01

Most collapse calderas can be attributed to subsidence of the magma chamber roof along bounding sub-vertical normal faults (ring-faults) after a decompression of the magma chamber, following eruption. Here, we present new numerical models that use a Finite Element Method to investigate the effects of variable crustal stratigraphy (lithology/thickness/order of strata) above a magma chamber, on local stress field distribution and how these in turn compare with existing criteria for ring-fault initiation. Results indicate that the occurrence and relative distribution of mechanically different lithologies may be influential in generating or inhibiting caldera collapse.

El Morro caldera (33° 10‧ S, 66° 24‧ W), San Luis, Argentina: An exceptional case of fossil pre-collapse updoming

Science.gov (United States)

Sruoga, P.; Ibañes, O. D.; Japas, M. S.; Urbina, N. E.

2017-05-01

Volcanism at Sierra del Morro represents the final stages of the flat-slab related magmatism in the easternmost San Luis Neogene Volcanic Belt. This 80 km-long NW-WNW-trending belt tracks the episodic inland migration of both magmatism and tectonic deformation since 18 Ma. The Sierra del Morro stands out in the Eastern Sierras Pampeanas as a metamorphic block uplifted during the Late Miocene-Pleistocene by a combination of magma injection and tectonic deformation. Although sequences that preserve stages of basement updoming are not often preserved, exposures in Sierra del Morro are exception in providing key evidence and insight into the involved processes. Based on the comprehensive study of volcanic stratigraphy and structures, the reconstruction of the volcanic architecture has been carried out. We infer a three stage evolution of the El Morro caldera as follows: 1) pre-collapse updoming and volcanism, 2) collapse caldera formation and 3) post-caldera volcanism. The ascent of magma is recorded in small tumescence sites, strongly controlled by oblique transtensional WNW-NW and ENE-striking brittle-ductile megashear zones. Even though the area affected by tumescence was large, magma injection progressed only locally. At Cerros Guanaco and Pampa, metamorphic rocks were updomed and strongly brecciated, whereas at Sierra del Morro magma was emplaced as pre-collapse domes with associated block-and-ash flows, ignimbrite caldera-forming eruptions and post-caldera lava domes and dykes. The caldera is located in the intersection of two major oblique transtensional WNW-NW and ENE-trending brittle-ductile megashear zones, where the highest positive dilatation occurred.

Economic impact study of the Uranium Mill Tailings Remedial Action project in Colorado: Colorado state fiscal year 1995

International Nuclear Information System (INIS)

1995-12-01

This Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year (FY) 1995 (1 July 1994 through 30 June 1995). To capture employment information, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Gunnison, Maybell, Naturita, Rifle, and Slick Rock, Colorado. Economic data were requested from the Remedial Action Contractor (RAC), the Technical Assistance Contractor (TAC) and the US Department of Energy (DOE). The most significant benefits associated with the UMTRA Project in Colorado are summarized

Tilted lake shorelines record the onset of motion along the Hilton Creek fault adjacent to Long Valley caldera, CA, USA

Science.gov (United States)

Perkins, J. P.; Finnegan, N. J.; Cervelli, P. F.; Langbein, J. O.

2010-12-01

Prominent normal faults occur within and around Long Valley caldera, in the eastern Sierra Nevada of California. However, their relationship to both the magmatic and tectonic evolution of the caldera since the 760 ka eruption of the Bishop Tuff remains poorly understood. In particular, in the Mono-Inyo Craters north of Long Valley, extensional faulting appears to be replaced by dike intrusion where magma is available in the crust. However, it is unclear whether extensional faults in Long Valley caldera have been active since the eruption of the Bishop Tuff (when the current topography was established) or are a relatively young phenomenon owing to the cooling and crystallization of the Long Valley magma reservoir. Here we use GPS geodesy and geomorphology to investigate the evolution of the Hilton Creek fault, the primary range-front fault bounding Long Valley caldera to the southwest. Our primary goals are to determine how long the Hilton Creek fault has been active and whether slip rates have been constant over that time interval. To characterize the modern deformation field, we capitalize on recently (July, 2010) reoccupied GPS benchmarks first established in 1999-2000. These fixed-array GPS data show no discernible evidence for recent slip on the Hilton Creek fault, which further highlights the need for longer-term constraints on fault motion. To establish a fault slip history, we rely on a suite of five prominent shorelines from Pleistocene Long Valley Lake whose ages are well constrained based on field relationships to dated lavas, and that are tilted southward toward the Hilton Creek fault. A preliminary analysis of shoreline orientations using GPS surveys and a 5-m-resolution Topographic Synthetic Aperture Radar (TOPSAR) digital elevation model shows that lake shorelines tilt towards the Hilton Creek fault at roughly parallel gradients (~ 0.6%). The measured shorelines range in inferred age from 100 ka to 500 ka, which constrain recent slip on the Hilton

Layered hydrothermal barite-sulfide mound field, East Diamante Caldera, Mariana volcanic arc

Science.gov (United States)

Hein, James R.; de Ronde, Cornel E. J.; Koski, Randolph A.; Ditchburn, Robert G.; Mizell, Kira; Tamura, Yoshihiko; Stern, Robert J.; Conrad, Tracey; Ishizuka, Osamu; Leybourne, Matthew I.

2014-01-01

East Diamante is a submarine volcano in the southern Mariana arc that is host to a complex caldera ~5 × 10 km (elongated ENE-WSW) that is breached along its northern and southwestern sectors. A large field of barite-sulfide mounds was discovered in June 2009 and revisited in July 2010 with the R/V Natsushima, using the ROV Hyper-Dolphin. The mound field occurs on the northeast flank of a cluster of resurgent dacite domes in the central caldera, near an active black smoker vent field. A 40Ar/39Ar age of 20,000 ± 4000 years was obtained from a dacite sample. The mound field is aligned along a series of fractures and extends for more than 180 m east-west and >120 m north-south. Individual mounds are typically 1 to 3 m tall and 0.5 to 2 m wide, with lengths from about 3 to 8 m. The mounds are dominated by barite + sphalerite layers with the margins of each layer composed of barite with disseminated sulfides. Rare, inactive spires and chimneys sit atop some mounds and also occur as clusters away from the mounds. Iron and Mn oxides are currently forming small (caldera, mineralization resulted from focused flow along small segments of linear fractures rather than from a point source, typical of hydrothermal chimney fields. Based on the mineral assemblage, the maximum fluid temperatures were ~260°C, near the boiling point for the water depths of the mound field (367–406 m). Lateral fluid flow within the mounds precipitated interstitial sphalerite, silica, and Pb minerals within a network of barite with disseminated sulfides; silica was the final phase to precipitate. The current low-temperature precipitation of Fe and Mn oxides and silica may represent rejuvenation of the system.

40 CFR 81.406 - Colorado.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 17 2010-07-01 2010-07-01 false Colorado. 81.406 Section 81.406 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) DESIGNATION OF... Visibility Is an Important Value § 81.406 Colorado. Area name Acreage Public Law establishing Federal land...

Thermomechanical controls on magma supply and volcanic deformation: application to Aira caldera, Japan

Science.gov (United States)

Hickey, James; Gottsmann, Joachim; Nakamichi, Haruhisa; Iguchi, Masato

2016-01-01

Ground deformation often precedes volcanic eruptions, and results from complex interactions between source processes and the thermomechanical behaviour of surrounding rocks. Previous models aiming to constrain source processes were unable to include realistic mechanical and thermal rock properties, and the role of thermomechanical heterogeneity in magma accumulation was unclear. Here we show how spatio-temporal deformation and magma reservoir evolution are fundamentally controlled by three-dimensional thermomechanical heterogeneity. Using the example of continued inflation at Aira caldera, Japan, we demonstrate that magma is accumulating faster than it can be erupted, and the current uplift is approaching the level inferred prior to the violent 1914 Plinian eruption. Magma storage conditions coincide with estimates for the caldera-forming reservoir ~29,000 years ago, and the inferred magma supply rate indicates a ~130-year timeframe to amass enough magma to feed a future 1914-sized eruption. These new inferences are important for eruption forecasting and risk mitigation, and have significant implications for the interpretations of volcanic deformation worldwide. PMID:27619897

Thermomechanical controls on magma supply and volcanic deformation: application to Aira caldera, Japan.

Science.gov (United States)

Hickey, James; Gottsmann, Joachim; Nakamichi, Haruhisa; Iguchi, Masato

2016-09-13

Ground deformation often precedes volcanic eruptions, and results from complex interactions between source processes and the thermomechanical behaviour of surrounding rocks. Previous models aiming to constrain source processes were unable to include realistic mechanical and thermal rock properties, and the role of thermomechanical heterogeneity in magma accumulation was unclear. Here we show how spatio-temporal deformation and magma reservoir evolution are fundamentally controlled by three-dimensional thermomechanical heterogeneity. Using the example of continued inflation at Aira caldera, Japan, we demonstrate that magma is accumulating faster than it can be erupted, and the current uplift is approaching the level inferred prior to the violent 1914 Plinian eruption. Magma storage conditions coincide with estimates for the caldera-forming reservoir ~29,000 years ago, and the inferred magma supply rate indicates a ~130-year timeframe to amass enough magma to feed a future 1914-sized eruption. These new inferences are important for eruption forecasting and risk mitigation, and have significant implications for the interpretations of volcanic deformation worldwide.

The Late Cretaceous Middle Fork caldera, its resurgent intrusion, and enduring landscape stability in east-central Alaska

Science.gov (United States)

Bacon, Charles R.; Dusel-Bacon, Cynthia; Aleinikoff, John N.; Slack, John F.

2014-01-01

Dissected caldera structures expose thick intracaldera tuff and, uncommonly, cogenetic shallow plutons, while remnants of correlative outflow tuffs deposited on the pre-eruption ground surface record elements of ancient landscapes. The Middle Fork caldera encompasses a 10 km × 20 km area of rhyolite welded tuff and granite porphyry in east-central Alaska, ∼100 km west of the Yukon border. Intracaldera tuff is at least 850 m thick. The K-feldspar megacrystic granite porphyry is exposed over much of a 7 km × 12 km area having 650 m of relief within the western part of the caldera fill. Sensitive high-resolution ion microprobe with reverse geometry (SHRIMP-RG) analyses of zircon from intracaldera tuff, granite porphyry, and outflow tuff yield U-Pb ages of 70.0 ± 1.2, 69.7 ± 1.2, and 71.1 ± 0.5 Ma (95% confidence), respectively. An aeromagnetic survey indicates that the tuff is reversely magnetized, and, therefore, that the caldera-forming eruption occurred in the C31r geomagnetic polarity chron. The tuff and porphyry have arc geochemical signatures and a limited range in SiO2 of 69 to 72 wt%. Although their phenocrysts differ in size and abundance, similar quartz + K-feldspar + plagioclase + biotite mineralogy, whole-rock geochemistry, and analytically indistinguishable ages indicate that the tuff and porphyry were comagmatic. Resorption of phenocrysts in tuff and porphyry suggests that these magmas formed by thermal rejuvenation of near-solidus or solidified crystal mush. A rare magmatic enclave (54% SiO2, arc geochemical signature) in the porphyry may be similar to parental magma and provides evidence of mafic magma and thermal input.

Colorado Academic Library Master Plan, Spring 1982.

Science.gov (United States)

Breivik, Patricia Senn; And Others

Based on a need to assess current library strengths and weaknesses and to project potential library roles in supporting higher education, this master plan makes a series of recommendations to Colorado's academic libraries. It is noted that the plan was endorsed by both the Colorado Commission on Higher Education and the Colorado State Department…

Ignimbrite Analyses of Batur Caldera, Bali, based on 14C Dating

Directory of Open Access Journals (Sweden)

Igan S. Sutawidjaja

2014-06-01

Full Text Available http://dx.doi.org/10.17014/ijog.vol4no3.20094The Batur Caldera, in the northeastern part of Bali Island, is an elliptical collapse structure 13.8 by 10 km in size and another circular composite collapse structure with a diameter of 7.5 km in its centre. Two stages of the collapse were interrupted by silicic andesite lavas and domes. The first collapse was initiated by the eruption of about 84 km3 of the dacitic "Ubud Ignimbrite", about 29,300 years B.P., which caused a steep-walled depression about 1 km deep. The second ignimbrite was erupted from a large crater about the present lake, and it  produced about 19 km3 of a similar voluminous dacitic ignimbrite, called the "Gunungkawi Ignimbrite" about 20,150 years B.P. This second eruption trig- gered a second collapse, which created the central circular caldera, and formed a basin structure. Both the Ubud and Gunungkawi Ignimbrites consist of a similar dacitic composition, white to red (the most abundant nearly 90 % and dark grey to black dacitic pumice clasts. The large clasts, up to 20 cm in diameter, are in the non-welded ignimbrite, particularly in the upper part of the Gunungkawi Ignimbrite. The intracaldera ignimbrite, called the "Batur Ignimbrite" about 5 km3  in volume is a densely welded ignimbrite and generally shows typical welded features. The ignimbrite comprises at least five different flow units, separated by thin (15 - 40 cm welded pumiceous airfall deposits, with flattened pumice clasts. Another large eruption occurred about 5,500 years B.P., producing around 0.09 km3  andesitic ignimbrite. This was initiated by phreatomagmatic eruptions, indicated by thick phreatomagmatic and surge deposits, underlying the ignimbrite. The caldera and its vicinity are partly filled, and variably mantled by later eruptive products of dacitic and andesitic phreatomagmatic and airfall deposits.  

Geochemical constraints on the link between volcanism and plutonism at the Yunshan caldera complex, SE China

Science.gov (United States)

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

2018-01-01

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

Economic impact study of the Uranium Mill Tailings Remedial Action Project in Colorado: Colorado state fiscal year 1993

International Nuclear Information System (INIS)

1993-12-01

The Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year 1993 (July 1, 1992, through June 30, 1993). To capture employment benefits, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Rifle, and Gunnison, Colorado. An estimated 52 percent of the employees working on the UMTRA Project responded to this information request. Economic data were requested from each site prime subcontractor, as well as from the Remedial Action Contractor. The most significant benefits associated with the UMTRA Project in Colorado are summarized

Navigation Study, Colorado Locks, Colorado River, Matagorda, Texas

National Research Council Canada - National Science Library

McCollum, Randy

2000-01-01

A 1:70 physical navigation model was built to replicate the Matagorda Locks, approximately one mile of the GIWW east of the locks, approximately one-half mile of the Colorado River north of the GIWW...

Galileo's Last Fly-Bys of Io: NIMS Observations of Loki, Tupan, and Emakong Calderas

Science.gov (United States)

Lopes, Rosaly M. C.; Kamp, L. W.; Davies, A. G.; Smythe, W. D.; Carlson, R. W.; Doute, S.; McEwen, A.; Turtle, E. P.; Leader, F.; Mehlman, R.

2002-01-01

NIMS results from the 2001 Galileo fly-bys of Io will be presented, focusing on three calderas that may contain lava lakes. Preliminary results from the January 2002 Io fly-by will be presented. Additional information is contained in the original extended abstract.

Sistema de detección de fallos basado en PC en calderas pirotubulares

OpenAIRE

Rivas Pérez, R.; Feliu Batlle, V.; Sotomayor Moriano, J.

2005-01-01

Se ofrece un sistema basado en PC para la detección de fallos en calderas pirotubulares. Se presentan los algoritmos que posibilitan la detección rápida de fallos abruptos en esta clase de plantas, los cuales se basan en la detección de cambios en los

Colorado School Finance Partnership: Report and Recommendations. Financing Colorado's Future: Assessing Our School Finance System

Science.gov (United States)

Colorado Children's Campaign, 2012

2012-01-01

Over the last decade, Colorado has emerged as a national leader in crafting innovative solutions for challenges facing its public school system. From implementing the Colorado Student Assessment Program (CSAP) and No Child Left Behind (NCLB) reforms to more recent legislation including standards and assessments for a preschool-through-college…

Bibliography of literature pertaining to Long Valley Caldera and associated volcanic fields

Science.gov (United States)

Ewert, John W.; Harpel, Christopher J.; Brooks, Suzanna K.; Marcaida, Mae

2011-01-01

On May 25-27, 1980, Long Valley caldera was rocked by four M=6 earthquakes that heralded the onset of a wave of seismic activity within the caldera which has continued through the present. Unrest has taken the form of seismic swarms, uplift of the resurgent dome, and areas of vegetation killed by increased CO2 emissions, all interpreted as resulting from magma injection into different levels beneath the caldera, as well as beneath Mammoth Mountain along the southwest rim of the caldera. Continuing economic development in the Mammoth Lakes area has swelled the local population, increasing the risk to people and property if an eruption were to occur. The U.S. Geological Survey (USGS) has been monitoring geophysical activity in the Long Valley area since the mid-1970s and continues to track the unrest in real time with a sophisticated network of geophysical sensors. Hazards information obtained by this monitoring is provided to local, State, and Federal officials and to the public through the Long Valley Observatory. The Long Valley area also was scientifically important before the onset of current unrest. Lying at the eastern foot of the Sierra Nevada, the deposits from this active volcanic system have provided fertile ground for research into Neogene tectonics, Quaternary geology and geomorphology, regional stratigraphy, and volcanology. In the early 1970s, intensive studies of the area began through the USGS Geothermal Investigations Program, owing to the presence of a large young silicic volcanic system. The paroxysmal eruption of Long Valley caldera about 760,000 years ago produced the Bishop Tuff and associated Bishop ash. The Bishop Tuff is a well-preserved ignimbrite deposit that has continued to provide new and developing insights into the dynamics of ignimbrite-forming eruptions. Another extremely important aspect of the Bishop Tuff is that it is the oldest known normally magnetized unit of the Brunhes Chron. Thus, the age of the Bishop Tuff is used to

Modelling ground movements at Campi Flegrei caldera (Italy): the role of the shallow geothermal system

Science.gov (United States)

Troiano, Antonio; Giulia di Giuseppe, Maria; Petrillo, Zaccaria; Troise, Claudia; de Natale, Giuseppe

2010-05-01

Campi Flegrei caldera is characterized by large ground movements, well known since Roman times. Superimposed to a general secular subsidence occurring at a rate of 1.5-2.0 cm/year, an episode of sharp uplift is in progress since 1969, with peak rates up to 1 m/year (in 1982-1984), similar to another episode which culminated with the 1538 eruption. Peak uplift episodes are often followed by some amount of subsidence, which prevent a simple interpretation in terms of purely magmatic inflation phenomena. Such up and down episodes of ground deformations are rather common at large calderas, like in Yellowstone (USA), Long Valley (USA), etc. Here we propose an interpretation based on a mixed mechanical-fluid-dynamical model, in which part of the uplift is generated by increase of water pressure in the shallow geothermal system, as a response to rapid inflow of magmatic fluids exsolved from a deeper magma chamber. We use the program THOUGH2 to model the changes of temperature and pressure in the geothermal system due to the magmatic fluids inflow. Changes in pressure in the caldera volume are then used to compute ground deformations. This way, a theoretical time evolution of ground deformation has been obtained, which compares well with the observed one, if appropriate values of permeability are used. We discuss the implication of such a model for eruption forecast purposes, and the extent at which the required values of permeability can be really representative of the real medium.

The Effects of Vent Location, Event Scale, and Time Forecasts on Pyroclastic Density Current Hazard Maps at Campi Flegrei Caldera (Italy

Directory of Open Access Journals (Sweden)

Andrea Bevilacqua

2017-09-01

Full Text Available This study presents a new method for producing long-term hazard maps for pyroclastic density currents (PDC originating at Campi Flegrei caldera. Such method is based on a doubly stochastic approach and is able to combine the uncertainty assessments on the spatial location of the volcanic vent, the size of the flow and the expected time of such an event. The results are obtained by using a Monte Carlo approach and adopting a simplified invasion model based on the box model integral approximation. Temporal assessments are modeled through a Cox-type process including self-excitement effects, based on the eruptive record of the last 15 kyr. Mean and percentile maps of PDC invasion probability are produced, exploring their sensitivity to some sources of uncertainty and to the effects of the dependence between PDC scales and the caldera sector where they originated. Conditional maps representative of PDC originating inside limited zones of the caldera, or of PDC with a limited range of scales are also produced. Finally, the effect of assuming different time windows for the hazard estimates is explored, also including the potential occurrence of a sequence of multiple events. Assuming that the last eruption of Monte Nuovo (A.D. 1538 marked the beginning of a new epoch of activity similar to the previous ones, results of the statistical analysis indicate a mean probability of PDC invasion above 5% in the next 50 years on almost the entire caldera (with a probability peak of ~25% in the central part of the caldera. In contrast, probability values reduce by a factor of about 3 if the entire eruptive record is considered over the last 15 kyr, i.e., including both eruptive epochs and quiescent periods.

Water quality and water rights in Colorado

International Nuclear Information System (INIS)

MacDonnell, L.J.

1989-07-01

The report begins with a review of early Colorado water quality law. The present state statutory system of water quality protection is summarized. Special attention is given to those provisions of Colorado's water quality law aimed at protecting water rights. The report then addresses several specific issues which involve the relationship between water quality and water use. Finally, recommendations are made for improving Colorado's approach to integrating quality and quantity concerns

The effect of pressurized magma chamber growth on melt migration and pre-caldera vent locations through time at Mount Mazama, Crater Lake, Oregon

Science.gov (United States)

Karlstrom, Leif; Wright, Heather M.; Bacon, Charles R.

2015-01-01

The pattern of eruptions at long-lived volcanic centers provides a window into the co-evolution of crustal magma transport, tectonic stresses, and unsteady magma generation at depth. Mount Mazama in the Oregon Cascades has seen variable activity over the last 400 ky, including the 50 km3 climactic eruption at ca. 7.7 ka that produced Crater Lake caldera. The physical mechanisms responsible for the assembly of silicic magma reservoirs that are the precursors to caldera-forming eruptions are poorly understood. Here we argue that the spatial and temporal distribution of geographically clustered volcanic vents near Mazama reflects the development of a centralized magma chamber that fed the climactic eruption. Time-averaged eruption rates at Mount Mazama imply an order of magnitude increase in deep magma influx prior to the caldera-forming event, suggesting that unsteady mantle melting triggered a chamber growth episode that culminated in caldera formation. We model magma chamber–dike interactions over ∼50 ky preceding the climactic eruption to fit the observed distribution of surface eruptive vents in space and time, as well as petrologically estimated deep influx rates. Best fitting models predict an expanding zone of dike capture caused by a growing, oblate spheroidal magma chamber with 10–30 MPa of overpressure. This growing zone of chamber influence causes closest approaching regional mafic vent locations as well as more compositionally evolved Mazama eruptions to migrate away from the climactic eruptive center, returning as observed to the center after the chamber drains during the caldera-forming eruption.

Developing tourism facilities based on geotourism in Silalahi Village, Geopark Toba Caldera

Science.gov (United States)

Ginting, Nurlisa; Sasmita, Anggun

2018-03-01

Toba Caldera is one of the biggest lakes in Indonesia with supervolcano geology phenomenon, and its result amazing natural resources. It makes Toba Lake become the number one tourism in North Sumatera. However, tourism in Toba Lake is still needed development. Geotourism is one of the concept that suitable for this case. It is because geotourism is a new development tourism concept that focuses on the natural and geological phenomenon. Silalahi Village is one of the areas in Toba Caldera that still needs development, especially in tourism facilities sector. This research aims to investigation the facilities concept based on geotourism in Silalahi Village that would be analyzed by three element of tourism facilities namely, accommodation, support facilities and tourism auxiliary facilities. The method used for this research is mixed methods by distributing 100 questionnaires, observations directly to the area and interviews with three informants related parties interested in tourism, such as local people, government, and academics. The data would be processed and analyzed with techniques of exploration. The result shows that the three elements of tourism facilities are still lacking and needs to improve to increase the economy and tourism in the area.

Multi-stage volcanic island flank collapses with coeval explosive caldera-forming eruptions.

Science.gov (United States)

Hunt, James E; Cassidy, Michael; Talling, Peter J

2018-01-18

Volcanic flank collapses and explosive eruptions are among the largest and most destructive processes on Earth. Events at Mount St. Helens in May 1980 demonstrated how a relatively small (300 km 3 ), but can also occur in complex multiple stages. Here, we show that multistage retrogressive landslides on Tenerife triggered explosive caldera-forming eruptions, including the Diego Hernandez, Guajara and Ucanca caldera eruptions. Geochemical analyses were performed on volcanic glasses recovered from marine sedimentary deposits, called turbidites, associated with each individual stage of each multistage landslide. These analyses indicate only the lattermost stages of subaerial flank failure contain materials originating from respective coeval explosive eruption, suggesting that initial more voluminous submarine stages of multi-stage flank collapse induce these aforementioned explosive eruption. Furthermore, there are extended time lags identified between the individual stages of multi-stage collapse, and thus an extended time lag between the initial submarine stages of failure and the onset of subsequent explosive eruption. This time lag succeeding landslide-generated static decompression has implications for the response of magmatic systems to un-roofing and poses a significant implication for ocean island volcanism and civil emergency planning.

77 FR 23498 - Notice of Intent To Repatriate Cultural Items: The Colorado College, Colorado Springs, CO

Science.gov (United States)

2012-04-19

... Taylor Museum and the Colorado Springs Fine Arts Center) and the Denver Museum of Nature & Science... Davis, Chief of Staff, President's Office, Colorado College, Armstrong Hall, Room 201, 14 E. Cache La... objects, as well as other cultural items were removed from Canyon de Chelly, Apache County, AZ, under the...

Cooling history of the Valles Caldera, New Mexico using ESR dating method

International Nuclear Information System (INIS)

Ogoh, K.; Toyoda, S.; Ikeda, S.; Ikeya, M.; Goff, F.

1993-01-01

ESR dating was made at the Valles caldera by using the Al center and Ti center in quartz grains separated from the layers of the Valles Rhyolite. Obtained ESR ages were much younger than those by other methods (fission track and 39 Ar- 40 Ar). A reported thermal event of about 10-40 ka ago might explain the difference between the above ages. (author)

Real-time monitoring of seismicity and deformation during the Bárdarbunga rifting event and associated caldera subsidence

Science.gov (United States)

Jónsdóttir, Kristín; Ófeigsson, Benedikt; Vogfjörd, Kristín; Roberts, Matthew; Barsotti, Sara; Gudmundsson, Gunnar; Hensch, Martin; Bergsson, Bergur; Kjartansson, vilhjálmur; Erlendsson, Pálmi; Friðriksdóttir, Hildur; Hreinsdóttir, Sigrún; Guðmundsson, Magnús; Sigmundsson, Freysteinn; Árnadóttir, Thóra; Heimisson, Elías; Hjorleifsdóttir, Vala; Soring, Jón; Björnsson, Bogi; Oddsson, Björn

2015-04-01

We present a monitoring overview of a rifting event and associated caldera subsidence in a glaciated environment during the Bárðarbunga volcanic crisis. Following a slight increase in seismicity and a weak deformation signal, noticed a few months before the unrest by the SIL monitoring team, an intense seismic swarm began in the subglacial Bárðarbunga caldera on August 16 2014. During the following two weeks, a dyke intruded into the crust beneath the Vatnajökull ice cap, propagating 48 km from the caldera to the east-north-east and north of the glacier where an effusive eruption started in Holuhraun. The eruption is still ongoing at the time of writing and has become the largest eruption in over 200 years in Iceland. The dyke propagation was episodic with a variable rate and on several occasions low frequency seismic tremor was observed. Four ice cauldrons, manifestations of small subglacial eruptions, were detected. Soon after the swarm began the 7x11 km wide caldera started to subside and is still subsiding (although at slower rates) and has in total subsided over 60 meters. Unrest in subglacial volcanoes always calls for interdisciplinary efforts and teamwork plays a key role for efficient monitoring. Iceland has experienced six subglacial volcanic crises since modern digital monitoring started in the early 90s. With every crisis the monitoring capabilities, data interpretations, communication and information dissemination procedures have improved. The Civil Protection calls for a board of experts and scientists (Civil Protection Science Board, CPSB) to share their knowledge and provide up-to-date information on the current status of the volcano, the relevant hazards and most likely scenarios. The evolution of the rifting was monitored in real-time by the joint interpretation of seismic and cGPS data. The dyke propagation could be tracked and new, updated models of the dyke volume were presented at the CPSB meetings, often daily. In addition, deformation

Electrical Resistivity Structure of the Valles Caldera, New Mexico, USA: Results From 3D Inversion of Modern and Legacy Magnetotelluric Data Collected by Industry and the Summer of Applied Geophysical Experience (SAGE).

Science.gov (United States)

Feucht, D. W.; Bedrosian, P.; Jiracek, G. R.; Pellerin, L.; Nettleton, C. E.

2017-12-01

The Valles caldera, in north-central New Mexico, USA, is a 20-km wide topographic depression in the Jemez Mountains volcanic complex that formed during two massive ignimbrite eruptions 1.65 and 1.26 Ma. Post-collapse volcanic activity in the caldera includes the rise of a 1 km high resurgent dome, periodic eruptions of the Valles rhyolite along ring fractures, and the presence of a geothermal reservoir beneath the western caldera with temperatures in excess of 300°C at a mere 2 km depth. We present an electrical resistivity model of the upper crust from three-dimensional (3D) inversion of broadband (100 Hz to 600 s) magnetotelluric (MT) data collected in and around the Valles caldera. The Summer of Applied Geophysical Experience (SAGE) has been acquiring geophysical data in the northern Rio Grande rift for more than three decades (1983-2017). Included in that vast dataset are over 60 broadband magnetotelluric soundings that have recently been cataloged, geo-located, and digitized for use in modern geophysical processing and modeling. The resistivity models presented here were produced by inverting a subset of SAGE MT data along with 30 broadband MT soundings acquired by the Unocal Corporation in 1983 for geothermal exploration of the caldera. We use the 3D inversion algorithm ModEM (Egbert and Kelbert, 2012) to invert full impedance tensors and tipper functions from >30 MT stations for the electrical resistivity structure beneath the caldera. Our preferred model reveals the geometry and electrical properties of (1) the conductive caldera fill, (2) the resistive crystalline basement, and (3) an enigmatic mid-crustal conductor related to magmatic activity that post-dates caldera formation.

Barriers to Enrollment in Health Coverage in Colorado.

Science.gov (United States)

Martin, Laurie T; Bharmal, Nazleen; Blanchard, Janice C; Harvey, Melody; Williams, Malcolm

2015-03-20

As part of the implementation of the Affordable Care Act, Colorado has expanded Medicaid and also now operates its own health insurance exchange for individuals (called Connect for Health Colorado). As of early 2014, more than 300,000 Coloradans have newly enrolled in Medicaid or health insurance through Connect for Health Colorado, but there also continues to be a diverse mix of individuals in Colorado who remain eligible for but not enrolled in either private insurance or Medicaid. The Colorado Health Foundation commissioned the RAND Corporation to conduct a study to better understand why these individuals are not enrolled in health insurance coverage and to develop recommendations for how Colorado can strengthen its outreach and enrollment efforts during the next open enrollment period, which starts in November 2014. RAND conducted focus groups with uninsured and newly insured individuals across the state and interviews with local stakeholders responsible for enrollment efforts in their regions. The authors identified 11 commonly cited barriers, as well as several that were specific to certain regions or populations (such as young adults and seasonal workers). Collectively, these barriers point to a set of four priority recommendations that stakeholders in Colorado may wish to consider: (1) Support and expand localized outreach and tailored messaging; (2) Strengthen marketing and messaging to be clear, focused on health benefits of insurance (rather than politics and mandates), and actionable; (3) Improve the clarity and transparency of insurance and health care costs and enrollment procedures; and (4) Revisit the two-stage enrollment process and improve Connect for Health Colorado website navigation and technical support.

Months between rejuvenation and volcanic eruption at Yellowstone caldera, Wyoming

Science.gov (United States)

Till, Christy B.; Vazquez, Jorge A.; Boyce, Jeremy W

2015-01-01

Rejuvenation of previously intruded silicic magma is an important process leading to effusive rhyolite, which is the most common product of volcanism at calderas with protracted histories of eruption and unrest such as Yellowstone, Long Valley, and Valles, USA. Although orders of magnitude smaller in volume than rare caldera-forming super-eruptions, these relatively frequent effusions of rhyolite are comparable to the largest eruptions of the 20th century and pose a considerable volcanic hazard. However, the physical pathway from rejuvenation to eruption of silicic magma is unclear particularly because the time between reheating of a subvolcanic intrusion and eruption is poorly quantified. This study uses geospeedometry of trace element profiles with nanometer resolution in sanidine crystals to reveal that Yellowstone’s most recent volcanic cycle began when remobilization of a near- or sub-solidus silicic magma occurred less than 10 months prior to eruption, following a 220,000 year period of volcanic repose. Our results reveal a geologically rapid timescale for rejuvenation and effusion of ~3 km3 of high-silica rhyolite lava even after protracted cooling of the subvolcanic system, which is consistent with recent physical modeling that predict a timescale of several years or less. Future renewal of rhyolitic volcanism at Yellowstone is likely to require an energetic intrusion of mafic or silicic magma into the shallow subvolcanic reservoir and could rapidly generate an eruptible rhyolite on timescales similar to those documented here.

4D imaging of the source of ground deformation at Campi Flegrei caldera (Italy) during recent unrest episodes

Science.gov (United States)

D'Auria, L.; Giudicepietro, F.; Martini, M.; Lanari, R.

2011-12-01

Campi Flegrei caldera, has been affected in recent decades by three episodes of significant ground uplift. After the last crisis (1982-84), which was accompanied by strong seismicity, the ground has shown a general descending trend, occasionally interrupted by minor uplift episodes, together with low-magnitude volcano-tectonic and long-period seismicity. We assume that the source of minor ground deformations consists in a diffuse volumetric source, related to both thermoelastic and poroelastic strain. This is a reasonable assumption considering that Campi Flegrei are known to host a geothermal reservoir. We have inverted a DInSAR dataset spanning the interval 1995-2008. Results show that the geometry of the source is much more complex than previously recognized and, most important, it shows significant temporal variations, within few months. The deformation source, of the analyzed uplift episodes, starts with a volumetric expansion centered at a depth of about 5 km. The position of this volume is close to the caldera rims. Later the expansion migrates upward, reaching the surface along preferred paths, leading to the Solfatara area, located almost at the center of the caldera. This area is well known for its powerful geothermal emissions. During the upward migration, seismic long-period sources are activated. Their location is consistent with the path identified by the inversion of the DInSAR dataset. We infer, that this dynamics is linked to the injection of hot fluid batches, along the caldera rims and their upward migration, following preferential high permeability paths. Furthermore we have identified an injection episode which has not been previously recognized. The deformation source remains at depth slowly waning in few years. We show how this conceptual framework fits well with the observed geodetic, seismic and geochemical data.

Monitoring unrest in a large silicic caldera, the long Valley-inyo craters volcanic complex in east-central California

Science.gov (United States)

Hill, D. P.

1984-06-01

Recent patterns of geologic unrest in long Valley caldera in east-central California emphasize that this large, silicic volcanic system and the adjacent, geologically youthful Inyo-Mono Craters volcanic chain are still active and capable of producing locally hazardous volcanic eruptions. A series of four magnitude -6 earthquakes in May 1980 called attention to this current episode of unrest, and subsequent activity has included numerous earthquake swarms in the south moat of the caldera accompanied by inflation of the resurgent dome by more than 50 cm over the last five years. The seismicity associated with this unrest is currently monitored by a network of 31 telemetered seismic stations with an automatic processing system that yelds hypocentral locations and earthquake magnitudes in near-real time. Deformation of the ground is monitored by a) a series of overlapping trilateration networks that provide coverage ranging from annual measurements of regional deformation to daily measurements of deformation local to the active, southern section of the caldera, b) a regional network of level lines surveyed annually, c) a regional network of precise gravity stations occupied annually, d) local, L-shaped level figures surveyed every few months, and e) a network of fourteen borehole tiltmeter clusters (two instruments in each cluster) and a borehole dilatometer, the telemetered signals from which provide continuous data on deformation rates. Additional telemetered data provide continuous information on fluctuations in the local magnetic field, hydrogen gas emission rates at three sites, and water level and temperatures in three wells. Continuous data on disharge rates and temperatures from hot springs and fumaroles are collected by several on-site recorders within the caldera, and samples for liquid and gas chemistry are collected several times per year from selected hot springs and fumaroles.

The Campi Flegrei Deep Drilling Project: using borehole measurements to discriminate magmatic and geothermal effects in caldera unrest

Science.gov (United States)

De Natale, Giuseppe; Troise, Claudia; Carlino, Stefano; Troiano, Antonio; Giulia Di Giuseppe, Maria; Piochi, Monica; Somma, Renato; Tramelli, Anna; Kilburn, Christopher

2015-04-01

Large calderas are potentially the most risky volcanic areas in the world since they are capable of producing huge eruptions whose major effects can involve human life and activities from regional to global scale. Calderas worldwide are characterized by frequent episodes of unrest which, only in few cases, culminate with eruptions. This ambiguous behavior is generally explained in terms of magma intrusion or disturbance of geothermal fluids in the shallow crust, which are both source of ground deformations and seismicity. A major goal is to determine the relative contribution of each process, because the potential for eruptions significantly enhanced if magma movements emerge as the primary component. A very important case study is the active Campi Flegrei caldera, hosting part of the large city of Naples (Southern Italy). In the framework of the Campi Flegrei Deep Drilling Project new filed data from pilot borehole have been recorded (permeability and in situ stress) by using a novel procedure of Leak Off Test. These new data, particularly the actual permeability, are fundamental to calibrate the caldera unrest models at Campi Flegrei and, , to put constrains to forecast the maximum future eruptive scenario. We show here that these new data, integrated by fluid-dynamical modeling, allow to assess that only about a third of the maximum uplift recorded in 1982-1984 may be due to shallow aquifer perturbation, so that the remaining part should be due to magma inflow, corresponding to about 0.05 Km3 of new magma if we assume a sill-like reservoir located at 4 km of depth. Considering an almost equivalent magma inflow for the 1969-1972 unrest, which showed a similar uplift, we got a total magma inflow of 0.1 Km3. It is then very important to assess the times for cooling of such accumulated magma, in order to assess the eruption hazard.

Multidisciplinary study (CO2 flux, ERT, self-potential, permeability and structural surveys) in Fondi di Baia, Astroni and Agnano volcanoes: insights for the structural architecture of the Campi Flegrei caldera (southern Italy)

Science.gov (United States)

Isaia, Roberto; Carapezza, Maria Luisa; Conti, Eric; Giulia Di Giuseppe, Maria; Lucchetti, Carlo; Prinzi, Ernesto; Ranaldi, Massimo; Tarchini, Luca; Tramparulo, Francesco; Troiano, Antonio; Vitale, Stefano; Cascella, Enrico; Castello, Nicola; Cicatiello, Alessandro; Maiolino, Marco; Puzio, Domenico; Tazza, Lucia; Villani, Roberto

2017-04-01

Recent volcanism at Campi Flegrei caldera produced more than 70 eruptions in the last 15 ka formed different volcanic edifices. The vent distribution was related to the main volcano-tectonic structure active in the caldera along which also concentrated part of the present hydrothermal and fumarolic activity, such as in the Solfatara area. In order to define the role of major faults in the Campi Flegrei Caldera, we analyzed some volcanic craters (Fondi di Baia and Astroni) and the Agnano caldera, by means of different geochemical and geophysical technics including CO2 flux, electrical resistivity (ERT), self-potential and permeability surveys. We provided some ERT profiles and different maps of geochemical and geophysical features. Major fault planes were identified comparing ERT imaging with alignments of anomalies in maps. The results can improve the knowledge on the present state of these volcanoes actually not fully monitored though included in the area with high probability of future vent opening within the Campi Flegrei caldera.

Overview for geologic field-trip guides to Mount Mazama, Crater Lake Caldera, and Newberry Volcano, Oregon

Science.gov (United States)

Bacon, Charles R.; Donnelly-Nolan, Julie M.; Jensen, Robert A.; Wright, Heather M.

2017-08-16

These field-trip guides were written for the occasion of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) quadrennial scientific assembly in Portland, Oregon, in August 2017. The guide to Mount Mazama and Crater Lake caldera is an updated and expanded version of the guide (Bacon, 1989) for part of an earlier IAVCEI trip to the southern Cascade Range. The guide to Newberry Volcano describes the stops included in the 2017 field trip. Crater Lake and Newberry are the two best-preserved and most recent calderas in the Cascades Volcanic Arc. Although located in different settings in the arc, with Crater Lake on the arc axis and Newberry in the rear-arc, both volcanoes are located at the intersection of the arc and the northwest corner region of the extensional Basin and Range Province.

Chapter 9. The Valles Caldera National Preserve as a multi-layered ethnographic landscape

Science.gov (United States)

Kurt F. Anschuetz

2007-01-01

The land use history of the Valles Caldera National Preserve (VCNP), as represented in the documentary record maintained in various archives and libraries, focuses primarily on the Hispanic and Anglo-American occupation of the locale subsequent to 1860. In an act of June 21, 1860, the U.S. Congress authorized the Baca Land Grant heirs to choose as many as five square...

Keanakākoʻi Tephra produced by 300 years of explosive eruptions following collapse of Kīlauea's caldera in about 1500 CE

Science.gov (United States)

Swanson, Donald A.; Rose, Timothy R.; Fiske, Richard S.; McGeehin, John P.

2012-01-01

The Keanakākoʻi Tephra at Kīlauea Volcano has previously been interpreted by some as the product of a caldera-forming eruption in 1790 CE. Our study, however, finds stratigraphic and 14C evidence that the tephra instead results from numerous eruptions throughout a 300-year period between about 1500 and 1800. The stratigraphic evidence includes: (1) as many as six pure lithic ash beds interleaved in sand dunes made of earlier Keanakākoʻi vitric ash, (2) three lava flows from Kīlauea and Mauna Loa interbedded with the tephra, (3) buried syneruptive cultural structures, (4) numerous intraformational water-cut gullies, and (5) abundant organic layers rich in charcoal within the tephra section. Interpretation of 97 new accelerator mass spectrometry (AMS) 14C ages and 4 previous conventional ages suggests that explosive eruptions began in 1470–1510 CE, and that explosive activity continued episodically until the early 1800s, probably with two periods of quiescence lasting several decades. Kīlauea's caldera, rather than forming in 1790, predates the first eruption of the Keanakākoʻi and collapsed in 1470–1510, immediately following, and perhaps causing, the end of the 60-year-long, 4–6 km3 ʻAilāʻau eruption from the east side of Kīlauea's summit area. The caldera was several hundred meters deep when the Keanakākoʻi began erupting, consistent with oral tradition, and probably had a volume of 4–6 km3. The caldera formed by collapse, but no eruption of lava coincided with its formation. A large volume of magma may have quickly drained from the summit reservoir and intruded into the east rift zone, perhaps in response to a major south-flank slip event, leading to summit collapse. Alternatively, magma may have slowly drained from the reservoir during the prolonged ʻAilāʻau eruption, causing episodic collapses before the final, largest downdrop took place. Two prolonged periods of episodic explosive eruptions are known at Kīlauea, the Keanak

Keanakākoʻi Tephra produced by 300 years of explosive eruptions following collapse of Kīlauea's caldera in about 1500 CE

Science.gov (United States)

Swanson, Donald A.; Rose, Timothy R.; Fiske, Richard S.; McGeehin, John P.

2012-01-01

The Keanakākoʻi Tephra at Kīlauea Volcano has previously been interpreted by some as the product of a caldera-forming eruption in 1790 CE. Our study, however, finds stratigraphic and 14C evidence that the tephra instead results from numerous eruptions throughout a 300-year period between about 1500 and 1800. The stratigraphic evidence includes: (1) as many as six pure lithic ash beds interleaved in sand dunes made of earlier Keanakākoʻi vitric ash, (2) three lava flows from Kīlauea and Mauna Loa interbedded with the tephra, (3) buried syneruptive cultural structures, (4) numerous intraformational water-cut gullies, and (5) abundant organic layers rich in charcoal within the tephra section. Interpretation of 97 new accelerator mass spectrometry (AMS) 14C ages and 4 previous conventional ages suggests that explosive eruptions began in 1470–1510 CE, and that explosive activity continued episodically until the early 1800s, probably with two periods of quiescence lasting several decades. Kīlauea's caldera, rather than forming in 1790, predates the first eruption of the Keanakākoʻi and collapsed in 1470–1510, immediately following, and perhaps causing, the end of the 60-year-long, 4–6 km3 ʻAilāʻau eruption from the east side of Kīlauea's summit area. The caldera was several hundred meters deep when the Keanakākoʻi began erupting, consistent with oral tradition, and probably had a volume of 4–6 km3. The caldera formed by collapse, but no eruption of lava coincided with its formation. A large volume of magma may have quickly drained from the summit reservoir and intruded into the east rift zone, perhaps in response to a major south-flank slip event, leading to summit collapse. Alternatively, magma may have slowly drained from the reservoir during the prolonged ʻAilāʻau eruption, causing episodic collapses before the final, largest downdrop took place. Two prolonged periods of episodic explosive eruptions are known at Kīlauea, the Keanak

A geologic and anthropogenic journey from the Precambrian to the new energy economy through the San Juan volcanic field

Science.gov (United States)

Yager, Douglas B.; Burchell,; Johnson, Raymond H.

2010-01-01

The San Juan volcanic field comprises 25,000 km2 of intermediate composition mid-Tertiary volcanic rocks and dacitic to rhyolitic calderas including the San Juan–Uncompahgre and La Garita caldera-forming super-volcanoes. The region is famous for the geological, ecological, hydrological, archeological, and climatological diversity. These characteristics supported ancestral Puebloan populations. The area is also important for its mineral wealth that once fueled local economic vitality. Today, mitigating and/or investigating the impacts of mining and establishing the region as a climate base station are the focuses of ongoing research. Studies include advanced water treatment, the acid neutralizing capacity (ANC) of propylitic bedrock for use in mine-lands cleanup, and the use of soil amendments including biochar from beetle-kill pines. Biochar aids soil productivity and revegetation by incorporation into soils to improve moisture retention, reduce erosion, and support the natural terrestrial carbon sequestration (NTS) potential of volcanic soils to help offset atmospheric CO2 emissions. This field trip will examine the volcano-tectonic and cultural history of the San Juan volcanic field as well as its geologic structures, economic mineral deposits and impacts, recent mitigation measures, and associated climate research. Field trip stops will include a visit to (1) the Summitville Superfund site to explore quartz alunite-Au mineralization, and associated alteration and new water-quality mitigation strategies; (2) the historic Creede epithermal-polymetallic–vein district with remarkably preserved resurgent calderas, keystone-graben, and moat sediments; (3) the historic mining town of Silverton located in the nested San Juan–Silverton caldera complex that exhibits base-metal Au-Ag mineralization; and (4) the site of ANC and NTS studies. En route back to Denver, we will traverse Grand Mesa, a high NTS area with Neogene basalt-derived soils and will enjoy a soak

Estudio vulcanológico y qeoquímico del maar de la Caldera del Rey. Tenerife (Canarias

Directory of Open Access Journals (Sweden)

Paradas Herrero, A.

1984-12-01

Full Text Available In this study a cartographic, morphological, geochemical and petrographic study is made of the ''Caldera del Rey". The "Caldera del Rey" is a volcanic structure formed by two overlapping maars, The second one (maar that was formed is of greaten dimensions and destroyed part of the first one, Both maars erupted throught a possible fracture N 35 E, which is one of the directions with regional importance in the Archipelago. The eruption, which was very explosive, has been thought to be due in part to the great importance of the gaseous phase of the salic magma and also to the steam produced during the interaction of the magma with underground water. This explosivity can be clearly seen in the cleaf resalte cul out in the "Serie Basáltica Antigua" to some extent penetrated and fragmented by the eruption, The phreatomagmatic character of the eruption is evident because of the existence of accretionary lapilli. The materials emitted are exc1usively of aerial projection: agglomerates, tuffs cinerites. There was no flow of lava. ' Some of the fragments of tuffs as cinerites and pumice are comagmatic. These correspond to salic trachytic phonolitic rocks, which represent one of the last stages of differentiation of the alkaline oceanic magmas. The geochemical character of the materials of the "Caldera del Rey" is characteristic and can be easily distinguished from other nearly salic deposits formed in different cycles.

En este trabajo se hace el estudio cartográfico, morfológico, petrográfico y geoquímico de la Caldera del Rey. La Caldera del Reyes un edificio volcánico formado por dos maars imbricados. El que se formó en segundo lugar es de mayores dimensiones y destruyó en parte el primero. Ambos aprovecharon para hacer erupción una posible fractura de dirección N 35'"E, de importancia regional en el Archipiélago. La erupción fue de una gran explosividad, que se supone debida, en parte, a la gran importancia de la fase gaseosa del

Economic impact study of the Uranium Mill Tailings Remedial Action Project in Colorado: Colorado State fiscal year 1994. Revision 1

International Nuclear Information System (INIS)

1994-12-01

The Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year 1994 (1 July 1993 through 30 June 1994). To capture employment information, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Naturita, Gunnison, and Rifle, Colorado. Economic data were requested from each site prime subcontractor, as well as from the Remedial Action Contractor. Information on wages, taxes, and subcontract expenditures in combination with estimates and economic multipliers is used to estimate the dollar economic benefits to Colorado during the state fiscal year. Finally, the fiscal year 1994 estimates are compared to fiscal year 1993 employment and economic information

Chemical data and variation diagrams of igneous rocks from the Timber Mountain-Oasis Valley Caldera Complex, southern Nevada

Science.gov (United States)

Quinlivan, W.D.; Byers, F.M.

1977-01-01

Silica variation diagrams presented here are based on 162 chemical analyses of tuffs, lavas, and intrusives, representative of volcanic centers of the Timber Mountain-Oasis Valley caldera complex and cogenetic rocks of the Silent Canyon ca1dera. Most of the volcanic units sampled are shown on the U.S. Geological Survey geologic map of the Timber Mountain caldera area (I-891) and are described in U.S. Geological Survey Professional Paper 919. Early effusives of the complex, although slightly altered, are probably chemically, and petrographically, more like the calc-alkalic Fraction Tuff (Miocene) of the northern Nellis Air Force Base Bombing and Gunnery Range to the north, whereas effusives of later Miocene age, such as the Paintbrush and Timber Mountain Tuffs, are alkali-calcic.

Magnetotelluric imaging of the resurgent caldera on the island of Ischia (southern Italy): inferences for its structure and activity

Science.gov (United States)

Di Giuseppe, M. G.; Troiano, A.; Carlino, S.

2017-12-01

The island of Ischia (located in the Bay of Naples, Italy) represents a peculiar case of a well-exposed caldera that has experienced a large (>800 m) and rapid resurgence, accompanied by volcanic activity. What drives the resurgence of calderas is a crucial issue to investigate, because this process is associated with potential eruptions and high risk to people living within and around such large active volcanic systems. To improve the knowledge of volcano-tectonic processes affecting the caldera of Ischia, electromagnetic imaging of the structures associated with its resurgence was performed and integrated with available geological information. A magnetotelluric (MT) survey of the island was carried out along two main profiles through the central-western sector, providing an electrical resistivity map to a depth of 3 km. These resistivity cross sections allowed us to identify the presence of a very shallow magmatic intrusion, possibly a laccolith, at a depth of about 1 km, which was responsible for both the resurgence and the volcanic activity. Furthermore, the tectonic structures bordering the resurgent area and the occurrence of a large thermal anomaly in the western sector of the caldera also provided a signature in the resistivity cross sections, with the magma intrusion producing advection of hot fluids with high geothermal gradients (>150 °C km-1) in the southern and western sectors. All of these data are fundamental for the assessment of the island's volcano-tectonic dynamics and their associated hazards. The structure and activity of the island have been controlled by the process of resurgence associated with the arrival of new magma and the progressive intrusion of a laccolith at a shallow depth. The reactivation of such a shallow system may imply imminent eruption which would pose a major volcanic hazard.

New geologic evidence for additional 16.5-15.5 Ma silicic calderas in northwest Nevada related to initial impingement of the Yellowstone hot spot

International Nuclear Information System (INIS)

Coble, Matthew A; Mahood, Gail A

2008-01-01

Three silicic calderas have been newly identified in northwest Nevada west of McDermitt caldera. This volcanism is interpreted to have formed during a short interval at 16.5-15.5 Ma, during the waning stage of Steens flood basalt volcanism after the initial impingement of the Yellowstone hot spot. New mapping demonstrates that the area affected by this mid-Miocene silicic volcanism is significantly larger than previously appreciated in the western U.S.

New geologic evidence for additional 16.5-15.5 Ma silicic calderas in northwest Nevada related to initial impingement of the Yellowstone hot spot

Energy Technology Data Exchange (ETDEWEB)

Coble, Matthew A; Mahood, Gail A [Department Geological and Environmental Sciences, 450 Serra Mall, Bldg 320, Stanford University, Stanford, CA 94305-3115 (United States)

2008-10-01

Three silicic calderas have been newly identified in northwest Nevada west of McDermitt caldera. This volcanism is interpreted to have formed during a short interval at 16.5-15.5 Ma, during the waning stage of Steens flood basalt volcanism after the initial impingement of the Yellowstone hot spot. New mapping demonstrates that the area affected by this mid-Miocene silicic volcanism is significantly larger than previously appreciated in the western U.S.

Evidence for water influx from a caldera lake during the explosive hydromagmatic eruption of 1790, Kilauea volcano, Hawaii

Science.gov (United States)

Mastin, L.G.

1997-01-01

In 1790 a major hydromagmatic eruption at the summit of Kilauea volcano, Hawaii, deposited up to 10 m of pyroclastic fall and surge deposits and killed several dozen Hawaiian natives who were crossing the island. Previous studies have hypothesized that the explosivity of this eruption was due to the influx of groundwater into the conduit and mixing of the groundwater with ascending magma. This study proposes that surface water, not groundwater, was the agent responsible for the explosiveness of the eruption. That is, a lake or pond may have existed in the caldera in 1790 and explosions may have taken place when magma ascended into the lake from below. That assertion is based on two lines of evidence: (1) high vesicularity (averaging 73% of more than 3000 lapilli) and high vesicle number density (105-107 cm-3 melt) of pumice clasts suggest that some phases of the eruption involved vigorous, sustained magma ascent; and (2) numerical calculations suggest that under most circumstances, hydrostatic pressure would not be sufficient to drive water into the eruptive conduit during vigorous magma ascent unless the water table were above the ground surface. These results are supported by historical data on the rate of infilling of the caldera floor during the early 1800s. When extrapolated back to 1790, they suggest that the caldera floor was below the water table.

Assessing Vulnerability under Uncertainty in the Colorado River Basin: The Colorado River Basin Water Supply and Demand Study

Science.gov (United States)

Jerla, C.; Adams, P.; Butler, A.; Nowak, K.; Prairie, J. R.

2013-12-01

Spanning parts of the seven states, of Arizona, California, Colorado, New Mexico, Nevada, Utah, and Wyoming, the Colorado River is one of the most critical sources of water in the western United States. Colorado River allocations exceed the long-term supply and since the 1950s, there have been a number of years when the annual water use in the Colorado River Basin exceeded the yield. The Basin is entering its second decade of drought conditions which brings challenges that will only be compounded if projections of climate change are realized. It was against this backdrop that the Colorado River Basin Water Supply and Demand Study was conducted. The Study's objectives are to define current and future imbalances in the Basin over the next 50 years and to develop and analyze adaptation and mitigation strategies to resolve those imbalances. Long-term planning in the Basin involves the integration of uncertainty with respect to a changing climate and other uncertainties such as future demand and how policies may be modified to adapt to changing reliability. The Study adopted a scenario planning approach to address this uncertainty in which thousands of scenarios were developed to encompass a wide range of plausible future water supply and demand conditions. Using Reclamation's long-term planning model, the Colorado River Simulation System, the reliability of the system to meet Basin resource needs under these future conditions was projected both with and without additional future adaptation strategies in place. System reliability metrics were developed in order to define system vulnerabilities, the conditions that lead to those vulnerabilities, and sign posts to indicate if the system is approaching a vulnerable state. Options and strategies that reduce these vulnerabilities and improve system reliability were explored through the development of portfolios. Four portfolios, each with different management strategies, were analyzed to assess their effectiveness at

Geologic field-trip guide to Long Valley Caldera, California

Science.gov (United States)

Hildreth, Wes; Fierstein, Judy

2017-07-26

This guide to the geology of Long Valley Caldera is presented in four parts: (1) An overview of the volcanic geology; (2) a chronological summary of the principal geologic events; (3) a road log with directions and descriptions for 38 field-trip stops; and (4) a summary of the geophysical unrest since 1978 and discussion of its causes. The sequence of stops is arranged as a four-day excursion for the quadrennial General Assembly of the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI), centered in Portland, Oregon, in August 2017. Most stops, however, are written freestanding, with directions that allow each one to be visited independently, in any order selected.

E/V Nautilus Detection of Isolated Features in the Eastern Pacific Ocean: Newly Discovered Calderas and Methane Seeps

Science.gov (United States)

Raineault, N.; Irish, O.; Lubetkin, M.

2016-02-01

The E/V Nautilus mapped over 80,000 km2 of the seafloor in the Gulf of Mexico and Eastern Pacific Ocean during its 2015 expedition. The Nautilus used its Kongsberg EM302 multibeam system to map the seafloor prior to remotely operated vehicle (ROV) dives, both for scientific purposes (site selection) and navigational safety. The Nautilus also routinely maps during transits to identify previously un-mapped or unresolved seafloor features. During its transit from the Galapagos Islands to the California Borderland, the Nautilus mapped 44,695 km2 of seafloor. Isolated features on the seafloor and in the water-column, such as calderas and methane seeps, were detected during this data collection effort. Operating at a frequency of 30 kHz in waters ranging from 1000-5500 m, we discovered caldera features off the coast of Central America. Since seamounts are known hotspots of biodiversity, locating new ones may enrich our understanding of seamounts as "stepping stones" for species distribution and ocean current pathways. Satellite altimetry datasets prior to this data either did not discern these calderas or recognized the presence of a bathymetric high without great detail. This new multibeam bathymetry data, gridded at 50 m, gives a precise look at these seamounts that range in elevation from 350 to 1400 m from abyssal depth. The largest of the calderas is circular in shape and is 10,000 m in length and 5,000 m in width, with a distinct circular depression at the center of its highest point, 1,400 m above the surrounding abyssal depth. In the California Borderland region, located between San Diego and Los Angeles, four new seeps were discovered in water depths from 400-1,020 m. ROV exploration of these seeps revealed vent communities. Altogether, these discoveries reinforce how little we know about the global ocean, indicate the presence of isolated deep-sea ecosystems that support biologically diverse communities, and will impact our understanding of seafloor habitat.

Alternative Fuels Data Center: Colorado Airport Relies on Natural Gas

Science.gov (United States)

Fueling Stations Colorado Airport Relies on Natural Gas Fueling Stations to someone by E-mail Share Alternative Fuels Data Center: Colorado Airport Relies on Natural Gas Fueling Stations on Facebook Tweet about Alternative Fuels Data Center: Colorado Airport Relies on Natural Gas Fueling Stations on

Economic impact study of the Uranium Mill Tailings Remedial Action Project in Colorado: Colorado state fiscal year 1994

International Nuclear Information System (INIS)

1994-11-01

The Colorado economic impact study summarizes employment and economic benefits to the state from activities associated with the Uranium Mill Tailings Remedial Action (UMTRA) Project during Colorado state fiscal year 1994. To capture employment information, a questionnaire was distributed to subcontractor employees at the active UMTRA Project sites of Grand Junction, Naturita, Gunnison, and Rifle, Colorado. Economic data were requested from each site prime subcontractor, as well as from the Remedial Action Contractor. The most significant benefits associated with the UMTRA Project in Colorado are summarized. This study assesses benefits associated with the Grand Junction, Gunnison, Naturita, and Rifle UMTRA Projects sites for the 1-year period under study. Work at the Naturita site was initiated in April 1994 and involved demolition of buildings at the processing site. Actual start-up of remediation of Naturita is planned to begin in the spring of 1995. Work at the Slick Rock and Maybell sites is expected to begin in 1995. The only current economic benefits associated with these sites are related to UMTRA Project support work

Colorado's hydrothermal resource base: an assessment

Energy Technology Data Exchange (ETDEWEB)

Pearl, R.H.

1981-01-01

As part of its effort to more accurately describe the nations geothrmal resource potential, the US Department of Energy/Division of Geothermal Energy contracted with the Colorado Geological survey to appraise the hydrothermal (hot water) geothermal resources of Colorado. Part of this effort required that the amount of energy that could possibly be contained in the various hydrothermal systems in Colorado be estimated. The findings of that assessment are presented. To make these estimates the geothermometer reservoir temperatures estimated by Barrett and Pearl (1978) were used. In addition, the possible reservoir size and extent were estimated and used. This assessment shows that the total energy content of the thermal systems in Colorado could range from 4.872 x 10{sup 15} BTU's to 13.2386 x 10{sup 15} BTU's.

Rapid differentiation in a sill-like magma reservoir: a case study from the campi flegrei caldera.

Science.gov (United States)

Pappalardo, Lucia; Mastrolorenzo, Giuseppe

2012-01-01

In recent decades, geophysical investigations have detected wide magma reservoirs beneath quiescent calderas. However, the discovery of partially melted horizons inside the crust is not sufficient to put constraints on capability of reservoirs to supply cataclysmic eruptions, which strictly depends on the chemical-physical properties of magmas (composition, viscosity, gas content etc.), and thus on their differentiation histories. In this study, by using geochemical, isotopic and textural records of rocks erupted from the high-risk Campi Flegrei caldera, we show that the alkaline magmas have evolved toward a critical state of explosive behaviour over a time span shorter than the repose time of most volcanic systems and that these magmas have risen rapidly toward the surface. Moreover, similar results on the depth and timescale of magma storage were previously obtained for the neighbouring Somma-Vesuvius volcano. This consistency suggests that there might be a unique long-lived magma pool beneath the whole Neapolitan area.

Survey and assessment of post volcanic activities of a young caldera lake, Lake Cuicocha, Ecuador

Directory of Open Access Journals (Sweden)

G. Gunkel

2009-05-01

Full Text Available Cuicocha is a young volcano adjacent to the inactive Pleistocene Cotacachi volcano complex, located in the western cordilleras of the Ecuadorian Andes. A series of eruptions with intensive ash emission and collapse of the caldera occurred around 4500–3000 y BP. A crater 3.2 km in diameter and a maximum depth of 450 m was formed. Further eruptions of the volcano occurred 1300 y BP and formed four smaller domes within the caldera. Over the last few hundred years, a caldera lake has developed, with a maximum depth of 148 m. The lake water is characterized by sodium carbonate with elevated concentrations of manganese, calcium and chloride. Nowadays, an emission of gases, mainly CO₂, and an input of warm spring water occur in Lake Cuicocha. The zone of high activity is in the western basin of the lake at a depth of 78 m, and continuous gas emissions with sediment resuspension were observed using sonar. In the hypolimnion of the lake, CO₂ accumulation occurs up to 0.2% saturation, but the risk of a limnic eruption can be excluded at present. The lake possesses monomictic stratification behaviour, and during overturn an intensive gas exchange with the atmosphere occurs. Investigations concerning the sedimentation processes of the lake suggest only a thin sediment layer of up to 10–20 cm in the deeper lake basin; in the western bay, in the area of gas emissions, the lake bottom is partly depleted of sediment in the form of holes, and no lake colmation exists. Decreases in the lake water level of about 30 cm y⁻¹ indicate a percolation of water into fractures and fissures of the volcano, triggered by a nearby earthquake in 1987.

Manejo de Mercancías Químicas peligrosas en puerto Caldera, Puntarenas, Costa Rica.

Directory of Open Access Journals (Sweden)

José Carlos Mora

2016-03-01

Full Text Available Puerto Caldera, located in Puntarenas, Costa Rica, is one of the most important Harbors of Central America, which is a key point to transport about 1.5 millions of metric tons of different categories of products every year, including dangerous chemical merchandise. The chemical has have originated emergencies, which has given rise to the necessity to asses load and unload process, and storage. In attention to the matter the most important aspects related to the fulfillment of the national and international norms during the merchandise dangerous transportation in Harbors were evaluated. According to the evaluation of the different handling, storage and transportation processes, Puerto Caldera, face among others the following problems: Personal training necessities addressed to the employees involved in the process of handling dangerous merchandise. Insufficient equipment and materials to guarantee a safe environment. The permanence of merchandise for long periods in warehouse. Unsuitable conditions of warehouse for the proper storage of chemical merchandise. Absence of classification and location criteria of dangerous chemical merchandise in the unloading and loading areas as well as in warehouse. Based up the previous evaluations, the following aspects were developed: An improvement plan for adequate handling of chemical merchandise. Recommendation of specific guidelines to create a Contingencies Plan. The purposes of the two aspects are to promote actions to diminish the risk of accidents associated to the handling of a dangerous merchandise. In the same way, it was proposed a Plan of Improvement and basic lineaments to elaborate a Plan of Contingencies that includes actions to diminish the risk of accidents associated to the handling of dangerous merchandise and to diminish the consequences, in case of accident, as far as the loss of lives, damages to the people, the property and the environment. All this will make Puerto Caldera a safe place

Stress evolution during caldera collapse

Science.gov (United States)

Holohan, E. P.; Schöpfer, M. P. J.; Walsh, J. J.

2015-07-01

The mechanics of caldera collapse are subject of long-running debate. Particular uncertainties concern how stresses around a magma reservoir relate to fracturing as the reservoir roof collapses, and how roof collapse in turn impacts upon the reservoir. We used two-dimensional Distinct Element Method models to characterise the evolution of stress around a depleting sub-surface magma body during gravity-driven collapse of its roof. These models illustrate how principal stress orientations rotate during progressive deformation so that roof fracturing transitions from initial reverse faulting to later normal faulting. They also reveal four end-member stress paths to fracture, each corresponding to a particular location within the roof. Analysis of these paths indicates that fractures associated with ultimate roof failure initiate in compression (i.e. as shear fractures). We also report on how mechanical and geometric conditions in the roof affect pre-failure unloading and post-failure reloading of the reservoir. In particular, the models show how residual friction within a failed roof could, without friction reduction mechanisms or fluid-derived counter-effects, inhibit a return to a lithostatically equilibrated pressure in the magma reservoir. Many of these findings should be transferable to other gravity-driven collapse processes, such as sinkhole formation, mine collapse and subsidence above hydrocarbon reservoirs.

Pyroclastic eruptions from Axial caldera, Juan de Fuca Ridge, NE Pacific Ocean

Energy Technology Data Exchange (ETDEWEB)

Helo, Christoph; Stix, John [Department of Earth and Planetary Sciences, McGill University, 3450 University Street, Montreal, Quebec H3A 2A7 (Canada); Clague, Dave A [Monterey Bay Aquarium Research Institute 7700 Sandholdt Road, Moss Landing, CA 95039-9644 (United States)

2008-10-01

Unconsolidated volcaniclastic glass deposits on the flanks of Axial Seamount, a caldera system situated on the Juan de Fuca Ridge in the NE Pacific Ocean, demonstrate the occurrence of explosive events, in addition to effusive activity. The variety of produced glass fragments ranges from various angular forms to thin deep-sea limu o Pele, with dominantly moderately fractionated to occasionally primitive MOR basalt composition. A model involving the collapse of a magmatic foam layer may account for the observed spectrum of glass fragments.

2013 Kids Count in Colorado! Community Matters

Science.gov (United States)

Colorado Children's Campaign, 2013

2013-01-01

"Kids Count in Colorado!" is an annual publication of the Children's Campaign, providing state and county level data on child well-being factors including child health, education, and economic status. Since its first release 20 years ago, "Kids Count in Colorado!" has become the most trusted source for data and information on…

The earliest low and high δ18O caldera-forming eruptions of the Yellowstone plume: Implications for the 30–40 Ma Oregon calderas and speculations on plume-triggered delaminations

Directory of Open Access Journals (Sweden)

Angela Nicole Seligman

2014-11-01

Full Text Available We present new isotopic and trace element data for four eruptive centers in Oregon: Wildcat Mountain (40 Ma, Crooked River (32–28 Ma, Tower Mountain (32 Ma, and Mohawk River (32 Ma. The first three calderas are located too far east to be sourced through renewed subduction of the Farallon slab following accretion of the Yellowstone-produced Siletzia terrane at ~50 Ma. Basalts of the three eastern eruptive centers yield high Nb/Yb and Th/Yb ratios, indicating an enriched sublithospheric mantle source, while Mohawk River yields trace element and isotopic (δ18O and εHf values that correlate with its location above a subduction zone. The voluminous rhyolitic tuffs and lavas of Crooked River (41 x 27 km have δ18Ozircon values that include seven low δ18Ozircon units (1.8–4.5 ‰, one high δ18Ozircon unit (7.4–8.8 ‰, and two units with heterogeneous zircons (2.0–9.0 ‰, similar to younger Yellowstone-Snake River Plain rhyolites. In order to produce these low δ18O values, a large heat source, widespread hydrothermal circulation, and repeated remelting are all required. In contrast, Wildcat Mountain and Tower Mountain rocks yield high δ18Ozircon values (6.4–7.9 ‰ and normal to low εHfi values (5.2–12.6, indicating crustal melting of high-δ18O supracrustal rocks. We propose that these calderas were produced by the first appearance of the Yellowstone plume east of the Cascadia subduction zone, which is supported by plate reconstructions that put the Yellowstone plume under Crooked River at 32–28 Ma. Given the eastern location of these calderas along the suture of the accreted Siletzia terrane and North America, we suggest that the Yellowstone hotspot is directly responsible for magmatism at Crooked River, and for plume-assisted delamination of portions of the edge of the Blue Mountains that produced the Tower Mountain magmas, while the older Wildcat Mountain magmas are related to suture zone instabilities that were created

Market Assessment of Residential Grid-Tied PV Systems in Colorado

Energy Technology Data Exchange (ETDEWEB)

Farhar, B.; Coburn, T.

2000-09-29

This report presents research done in response to a decision by the Colorado Governor's Office of Energy Conservation and Management (OEC) and Colorado utility companies to consider making residential grid-tied photovoltaic (PV) systems available in Colorado. The idea was to locate homeowners willing to pay the costs of grid-tied PV (GPV) systems without batteries-$8,000 or $12,000 for a 2- or 3-kilowatt (kW) system, respectively, in 1996. These costs represented two-thirds of the actual installed cost of $6 per watt at that time and assumed the remainder would be subsidized. The National Renewable Energy Laboratory (NREL) and OEC partnered to conduct a market assessment for GPV technology in Colorado. The study encompassed both qualitative and quantitative phases. The market assessment concluded that a market for residential GPV systems exists in Colorado today. That market is substantial enough for companies to successfully market PV systems to Colorado homeowners. These homeo wners appear ready to learn more, inform themselves, and actively purchase GPV systems. The present situation is highly advantageous to Colorado's institutions-primarily its state government and its utility companies, and also its homebuilders-if they are ready to move forward on GPV technology.

The timing and origin of pre- and post-caldera volcanism associated with the Mesa Falls Tuff, Yellowstone Plateau volcanic field

Science.gov (United States)

Stelten, Mark E.; Champion, Duane E.; Kuntz, Mel A.

2018-01-01

We present new sanidine 40Ar/39Ar ages and paleomagnetic data for pre- and post-caldera rhyolites from the second volcanic cycle of the Yellowstone Plateau volcanic field, which culminated in the caldera-forming eruption of the Mesa Falls Tuff at ca. 1.3 Ma. These data allow for a detailed reconstruction of the eruptive history of the second volcanic cycle and provide new insights into the petrogenesis of rhyolite domes and flows erupted during this time period. 40Ar/39Ar age data for the biotite-bearing Bishop Mountain flow demonstrate that it erupted approximately 150 kyr prior to the Mesa Falls Tuff. Integrating 40Ar/39Ar ages and paleomagnetic data for the post-caldera Island Park rhyolite domes suggests that these five crystal-rich rhyolites erupted over a centuries-long time interval at 1.2905 ± 0.0020 Ma (2σ). The biotite-bearing Moonshine Mountain rhyolite dome was originally thought to be the downfaulted vent dome for the pre-caldera Bishop Mountain flow due to their similar petrographic and oxygen isotope characteristics, but new 40Ar/39Ar dating suggest that it erupted near contemporaneously with the Island Park rhyolite domes at 1.2931 ± 0.0018 Ma (2σ) and is a post-caldera eruption. Despite their similar eruption ages, the Island Park rhyolite domes and the Moonshine Mountain dome are chemically and petrographically distinct and are not derived from the same source. Integrating these new data with field relations and existing geochemical data, we present a petrogenetic model for the formation of the post-Mesa Falls Tuff rhyolites. Renewed influx of basaltic and/or silicic recharge magma into the crust at 1.2905 ± 0.0020 Ma led to [1] the formation of the Island Park rhyolite domes from the source region that earlier produced the Mesa Falls Tuff and [2] the formation of Moonshine Mountain dome from the source region that earlier produced the biotite-bearing Bishop Mountain flow. These magmas were stored in the crust for less than a few thousand

FEM-based linear inverse modeling using a 3D source array to image magma chambers with free geometry. Application to InSAR data from Rabaul Caldera (PNG).

Science.gov (United States)

Ronchin, Erika; Masterlark, Timothy; Dawson, John; Saunders, Steve; Martí Molist, Joan

2015-04-01

In this study, we present a method to fully integrate a family of finite element models (FEMs) into the regularized linear inversion of InSAR data collected at Rabaul caldera (PNG) between February 2007 and December 2010. During this period the caldera experienced a long-term steady subsidence that characterized surface movement both inside the caldera and outside, on its western side. The inversion is based on an array of FEM sources in the sense that the Green's function matrix is a library of forward numerical displacement solutions generated by the sources of an array common to all FEMs. Each entry of the library is the LOS surface displacement generated by injecting a unity mass of fluid, of known density and bulk modulus, into a different source cavity of the array for each FEM. By using FEMs, we are taking advantage of their capability of including topography and heterogeneous distribution of elastic material properties. All FEMs of the family share the same mesh in which only one source is activated at the time by removing the corresponding elements and applying the unity fluid flux. The domain therefore only needs to be discretized once. This precludes remeshing for each activated source, thus reducing computational requirements, often a downside of FEM-based inversions. Without imposing an a-priori source, the method allows us to identify, from a least-squares standpoint, a complex distribution of fluid flux (or change in pressure) with a 3D free geometry within the source array, as dictated by the data. The results of applying the proposed inversion to Rabaul InSAR data show a shallow magmatic system under the caldera made of two interconnected lobes located at the two opposite sides of the caldera. These lobes could be consistent with feeding reservoirs of the ongoing Tavuvur volcano eruption of andesitic products, on the eastern side, and of the past Vulcan volcano eruptions of more evolved materials, on the western side. The interconnection and

Post-glacial inflation-deflation cycles, tilting, and faulting in the Yellowstone Caldera based on Yellowstone Lake shorelines

Science.gov (United States)

Pierce, Kenneth L.; Cannon, Kenneth P.; Meyer, Grant A.; Trebesch, Matthew J.; Watts, Raymond D.

2002-01-01

The Yellowstone caldera, like many other later Quaternary calderas of the world, exhibits dramatic unrest. Between 1923 and 1985, the center of the Yellowstone caldera rose nearly one meter along an axis between its two resurgent domes (Pelton and Smith, 1979, Dzurisin and Yamashita, 1987). From 1985 until 1995-6, it subsided at about two cm/yr (Dzurisin and others, 1990). More recent radar interferometry studies show renewed inflation of the northeastern resurgent dome between 1995 and 1996; this inflation migrated to the southwestern resurgent dome from 1996 to 1997 (Wicks and others, 1998). We extend this record back in time using dated geomorphic evidence of postglacial Yellowstone Lake shorelines around the northern shore, and Yellowstone River levels in the outlet area. We date these shorelines using carbon isotopic and archeological methods. Following Meyer and Locke (1986) and Locke and Meyer (1994), we identify the modern shoreline as S1 (1.9 ? 0.3 m above the lake gage datum), map paleoshoreline terraces S2 to S6, and infer that the prominent shorelines were cut during intracaldera uplift episodes that produced rising water levels. Doming along the caldera axis reduces the gradient of the Yellowstone River from Le Hardys Rapids to the Yellowstone Lake outlet and ultimately causes an increase in lake level. The 1923-1985 doming is part of a longer uplift episode that has reduced the Yellowstone River gradient to a ?pool? with a drop of only 0.25 m over most of this 5 km reach. We also present new evidence that doming has caused submergence of some Holocene lake and river levels. Shoreline S5 is about 14 m above datum and estimated to be ~12.6 ka, because it post-dates a large hydrothermal explosion deposit from the Mary Bay area (MB-II) that occurred ~13 ka. S4 formed about 8 m above datum ~10.7 ka as dated by archeology and 14C, and was accompanied by offset on the Fishing Bridge fault. About 9.7 ka, the Yellowstone River eroded the ?S-meander?, followed

Groundwater quality in the Colorado River basins, California

Science.gov (United States)

Dawson, Barbara J. Milby; Belitz, Kenneth

2012-01-01

Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California created the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public access to groundwater-quality information. Four groundwater basins along the Colorado River make up one of the study areas being evaluated. The Colorado River study area is approximately 884 square miles (2,290 square kilometers) and includes the Needles, Palo Verde Mesa, Palo Verde Valley, and Yuma groundwater basins (California Department of Water Resources, 2003). The Colorado River study area has an arid climate and is part of the Sonoran Desert. Average annual rainfall is about 3 inches (8 centimeters). Land use in the study area is approximately 47 percent (%) natural (mostly shrubland), 47% agricultural, and 6% urban. The primary crops are pasture and hay. The largest urban area is the city of Blythe (2010 population of 21,000). Groundwater in these basins is used for public and domestic water supply and for irrigation. The main water-bearing units are gravel, sand, silt, and clay deposited by the Colorado River or derived from surrounding mountains. The primary aquifers in the Colorado River study area are defined as those parts of the aquifers corresponding to the perforated intervals of wells listed in the California Department of Public Health database. Public-supply wells in the Colorado River basins are completed to depths between 230 and 460 feet (70 to 140 meters), consist of solid casing from the land surface to a depth of 130 of 390 feet (39 to 119 meters), and are screened or perforated below the solid casing. The main source of recharge to the groundwater systems in the Needles, Palo Verde Mesa, and Palo Verde Valley basins is the Colorado River; in the Yuma basin, the main source of recharge is from

Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado

Science.gov (United States)

Cole, James C.; Trexler, James H.; Cashman, Patricia H.; Miller, Ian M.; Shroba, Ralph R.; Cosca, Michael A.; Workman, Jeremiah B.

2010-01-01

This field trip highlights recent research into the Laramide uplift, erosion, and sedimentation on the western side of the northern Colorado Front Range. The Laramide history of the North Park?Middle Park basin (designated the Colorado Headwaters Basin in this paper) is distinctly different from that of the Denver basin on the eastern flank of the range. The Denver basin stratigraphy records the transition from Late Cretaceous marine shale to recessional shoreline sandstones to continental, fluvial, marsh, and coal mires environments, followed by orogenic sediments that span the K-T boundary. Upper Cretaceous and Paleogene strata in the Denver basin consist of two mega-fan complexes that are separated by a 9 million-year interval of erosion/non-deposition between about 63 and 54 Ma. In contrast, the marine shale unit on the western flank of the Front Range was deeply eroded over most of the area of the Colorado Headwaters Basin (approximately one km removed) prior to any orogenic sediment accumulation. New 40Ar-39Ar ages indicate the oldest sediments on the western flank of the Front Range were as young as about 61 Ma. They comprise the Windy Gap Volcanic Member of the Middle Park Formation, which consists of coarse, immature volcanic conglomerates derived from nearby alkalic-mafic volcanic edifices that were forming at about 65?61 Ma. Clasts of Proterozoic granite, pegmatite, and gneiss (eroded from the uplifted core of the Front Range) seem to arrive in the Colorado Headwaters Basin at different times in different places, but they become dominant in arkosic sandstones and conglomerates about one km above the base of the Colorado Headwaters Basin section. Paleocurrent trends suggest the southern end of the Colorado Headwaters Basin was structurally closed because all fluvial deposits show a northward component of transport. Lacustrine depositional environments are indicated by various sedimentological features in several sections within the >3 km of sediment

77 FR 42510 - Notice of Inventory Completion: History Colorado, Denver, CO

Science.gov (United States)

2012-07-19

... associated funerary objects may contact History Colorado. Disposition of the human remains and associated... human remains and associated funerary objects under the control of History Colorado, Denver, CO. One set... detailed assessment of the human remains and associated funerary objects was made by History Colorado...

Petrogenesis of Rinjani Post-1257-Caldera-Forming-Eruption Lava Flows

Directory of Open Access Journals (Sweden)

Heryadi Rachmat

2016-06-01

Full Text Available DOI:10.17014/ijog.3.2.107-126After the catastrophic 1257 caldera-forming eruption, a new chapter of Old Rinjani volcanic activity beganwith the appearance of Rombongan and Barujari Volcanoes within the caldera. However, no published petrogeneticstudy focuses mainly on these products. The Rombongan eruption in 1944 and Barujari eruptions in pre-1944, 1966,1994, 2004, and 2009 produced basaltic andesite pyroclastic materials and lava flows. A total of thirty-one sampleswere analyzed, including six samples for each period of eruption except from 2004 (only one sample. The sampleswere used for petrography, whole-rock geochemistry, and trace and rare earth element analyses. The Rombonganand Barujari lavas are composed of calc-alkaline and high K calc-alkaline porphyritic basaltic andesite. The magmashows narrow variation of SiO2 content that implies small changes during its generation. The magma that formedRombongan and Barujari lavas is island-arc alkaline basalt. Generally, data show that the rocks are enriched in LargeIon Lithophile Elements (LILE: K, Rb, Ba, Sr, and Ba and depleted in High Field Strength Elements (HFSE: Y, Ti,and Nb which are typically a suite from a subduction zone. The pattern shows a medium enrichment in Light REEand relatively depleted in Heavy REE. The processes are dominantly controlled by fractional crystallization andmagma mixing. All of the Barujari and Rombongan lavas would have been produced by the same source of magmawith little variation in composition caused by host rock filter process. New flux of magma would likely have occurredfrom pre-1944 until 2009 period that indicates slightly decrease and increase of SiO2 content. The Rombongan andBarujari lava generations show an arc magma differentiation trend.

Evolution of silicic magmas in the Kos-Nisyros volcanic center, Greece: a petrological cycle associated with caldera collapse

Science.gov (United States)

Bachmann, Olivier; Deering, Chad D.; Ruprecht, Janina S.; Huber, Christian; Skopelitis, Alexandra; Schnyder, Cedric

2012-01-01

Multiple eruptions of silicic magma (dacite and rhyolites) occurred over the last ~3 My in the Kos-Nisyros volcanic center (eastern Aegean sea). During this period, magmas have changed from hornblende-biotite-rich units with low eruption temperatures (≤750-800°C; Kefalos and Kos dacites and rhyolites) to hotter, pyroxene-bearing units (>800-850°C; Nisyros rhyodacites) and are transitioning back to cooler magmas (Yali rhyolites). New whole-rock compositions, mineral chemistry, and zircon Hf isotopes show that these three types of silicic magmas followed the same differentiation trend: they all evolved by crystal fractionation and minor crustal assimilation (AFC) from parents with intermediate compositions characterized by high Sr/Y and low Nb content, following a wet, high oxygen fugacity liquid line of descent typical of subduction zones. As the transition between the Kos-Kefalos and Nisyros-type magmas occurred immediately and abruptly after the major caldera collapse in the area (the 161 ka Kos Plateau Tuff; KPT), we suggest that the efficient emptying of the magma chamber during the KPT drew out most of the eruptible, volatile-charged magma and partly solidified the unerupted mush zone in the upper crust due to rapid unloading, decompression, and coincident crystallization. Subsequently, the system reestablished a shallow silicic production zone from more mafic parents, recharged from the mid to lower crust. The first silicic eruptions evolving from these parents after the caldera collapse (Nisyros units) were hotter (up to >100°C) than the caldera-forming event and erupted from reservoirs characterized by different mineral proportions (more plagioclase and less amphibole). We interpret such a change as a reflection of slightly drier conditions in the magmatic column after the caldera collapse due to the decompression event. With time, the upper crustal intermediate mush progressively transitioned into the cold-wet state that prevailed during the Kefalos

Salinity Trends in the Upper Colorado River Basin Upstream From the Grand Valley Salinity Control Unit, Colorado, 1986-2003

Science.gov (United States)

Leib, Kenneth J.; Bauch, Nancy J.

2008-01-01

In 1974, the Colorado River Basin Salinity Control Act was passed into law. This law was enacted to address concerns regarding the salinity content of the Colorado River. The law authorized various construction projects in selected areas or 'units' of the Colorado River Basin intended to reduce the salinity load in the Colorado River. One such area was the Grand Valley Salinity Control Unit in western Colorado. The U. S. Geological Survey has done extensive studies and research in the Grand Valley Salinity Control Unit that provide information to aid the U.S. Bureau of Reclamation and the Natural Resources Conservation Service in determining where salinity-control work may provide the best results, and to what extent salinity-control work was effective in reducing salinity concentrations and loads in the Colorado River. Previous studies have indicated that salinity concentrations and loads have been decreasing downstream from the Grand Valley Salinity Control Unit, and that the decreases are likely the result of salinity control work in these areas. Several of these reports; however, also document decreasing salinity loads upstream from the Grand Valley Salinity Control Unit. This finding was important because only a small amount of salinity-control work was being done in areas upstream from the Grand Valley Salinity Control Unit at the time the findings were reported (late 1990?s). As a result of those previous findings, the U.S. Bureau of Reclamation entered into a cooperative agreement with the U.S. Geological Survey to investigate salinity trends in selected areas bracketing the Grand Valley Salinity Control Unit and regions upstream from the Grand Valley Salinity Control Unit. The results of the study indicate that salinity loads were decreasing upstream from the Grand Valley Salinity Control Unit from 1986 through 2003, but the rates of decrease have slowed during the last 10 years. The average rate of decrease in salinity load upstream from the Grand Valley

Caldera unrest driven by CO2-induced drying of the deep hydrothermal system.

Science.gov (United States)

Moretti, R; Troise, C; Sarno, F; De Natale, G

2018-05-29

Interpreting volcanic unrest is a highly challenging and non-unique problem at calderas, since large hydrothermal systems may either hide or amplify the dynamics of buried magma(s). Here we use the exceptional ground displacement and geochemical datasets from the actively degassing Campi Flegrei caldera (Southern Italy) to show that ambiguities disappear when the thermal evolution of the deep hydrothermal system is accurately tracked. By using temperatures from the CO 2 -CH 4 exchange of 13 C and thermodynamic analysis of gas ascending in the crust, we demonstrate that after the last 1982-84 crisis the deep hydrothermal system evolved through supercritical conditions under the continuous isenthalpic inflow of hot CO 2 -rich gases released from the deep (~8 km) magma reservoir of regional size. This resulted in the drying of the base of the hot hydrothermal system, no more buffered along the liquid-vapour equilibrium, and excludes any shallow arrival of new magma, whose abundant steam degassing due to decompression would have restored liquid-vapour equilibrium. The consequent CO 2 -infiltration and progressive heating of the surrounding deforming rock volume cause the build-up of pore pressure in aquifers, and generate the striking temporal symmetry that characterizes the ongoing uplift and the post-1984 subsidence, both originated by the same but reversed deformation mechanism.

Colorado River cutthroat trout: a technical conservation assessment

Science.gov (United States)

Michael K. Young

2008-01-01

The Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus) was once distributed throughout the colder waters of the Colorado River basin above the Grand Canyon. About 8 percent of its historical range is occupied by unhybridized or ecologically significant populations. It has been petitioned for listing under the Endangered Species Act...

Material toughness, internal structure, and caldera-collapse frequencies in basaltic and composite edifices

Energy Technology Data Exchange (ETDEWEB)

Gudmundsson, Agust [Department of Earth Sciences, Queen' s Building, Royal Holloway University of London, Egham TW20 OEX (United Kingdom)], E-mail: a.gudmundsson@es.rhul.ac.uk

2008-10-01

Formation of, and slip on existing, collapse calderas is much more common in basaltic edifices than in composite edifices. I suggest that this difference is partly due to the composite edifices being tougher and more resistant to ring-fault formation than a basaltic edifices. The high matieral toughness of composite edifices is related to their being composed of rock layers with widely different elastic properties, the elastic mismatch promoting deflection and/or arrest of potential ring faults at layer contacts.

Environmental Setting and Implications on Water Quality, Upper Colorado River Basin, Colorado and Utah

Science.gov (United States)

Apodaca, Lori E.; Driver, Nancy E.; Stephens, Verlin C.; Spahr, Norman E.

1995-01-01

The Upper Colorado River Basin in Colorado and Utah is 1 of 60 study units selected for water-quality assessment as part of the U.S. Geological Survey's National Water-Quality Assessment program, which began full implementation in 1991. Understanding the environmental setting of the Upper Colorado River Basin study unit is important in evaluating water-quality issues in the basin. Natural and human factors that affect water quality in the basin are presented, including an overview of the physiography, climatic conditions, general geology and soils, ecoregions, population, land use, water management and use, hydrologic characteristics, and to the extent possible aquatic biology. These factors have substantial implications on water-quality conditions in the basin. For example, high concentrations of dissolved solids and selenium are present in the natural background water conditions of surface and ground water in parts ofthe basin. In addition, mining, urban, and agricultural land and water uses result in the presence of certain constituents in the surface and ground water of the basin that can detrimentally affect water quality. The environmental setting of the study unit provides a framework of the basin characteristics, which is important in the design of integrated studies of surface water, ground water, and biology.

Tracking Water-Use in Colorado's Energy Exploration and Development

Science.gov (United States)

Halamka, T. A.; Ge, S.

2017-12-01

By the year 2050 Colorado's population is projected to nearly double, posing many important questions about the stresses that Colorado's water resources will experience. Growing in tandem with Colorado's population is the state's energy exploration and development industry. As water demands increase across the state, the energy exploration and development industry must adapt to and prepare for future difficulties surrounding the legal acquisition of water. The goal of this study is to map out the potential sources of water within the state of Colorado that are being purchased, or will be eligible for purchase, for unconventional subsurface energy extraction. The background of this study includes an overview of the intertwined relationship between water, the energy industry, and the Colorado economy. The project also aims to determine the original purpose of legally appropriated water that is used in Colorado's energy exploration and development. Is the water primarily being purchased or leased from the agricultural sector? Is the water mostly surface water or groundwater? In order to answer these questions, we accessed data from numerous water reporting agencies and examined legal methods of acquisition of water for use in the energy industry. Using these data, we assess the future water quantity available to the energy industry. Knowledge and foresight on the origins of the water used by the energy industry will allow for better and strategic planning of water resources and how the industry will respond to statewide water-related stresses.

1992 Colorado Economic Impact Study for the US Department of Energy and Colorado Department of Health Uranium Mill Tailings Remedial Action (UMTRA) Project

International Nuclear Information System (INIS)

1991-01-01

The findings of the 1992 Colorado Economic Impact Study (CEIS) for the Uranium Mill Tailings Remedial Action (UMTRA) Project are outlined below. All dollar amounts used in the study are in year-of-expenditure dollars. The total funding requirement for the State of Colorado for the UMTRA Project is estimated to be $66.8 million, or 10 percent of the remedial action costs for the UMTRA Project in Colorado. The UMTRA Project will generate $487.5 million in gross labor income in Colorado between 1983 and 1996. This includes $54.4 million in state and local tax revenues and $41.2 million in federal individual income tax revenues. The net economic benefit of the UMTRA Project to Colorado is $355.1 million. For every dollar the State of Colorado invests in the UMTRA Project, it will realize $5.32 in gross labor income. The employment impact to the Western Slope region is significant. The UMTRA Project will create a total employment impact of 13,749 fulltime equivalents (FTES) spread over. a period of 13 years in seven site areas. Nearly 100 percent of the labor will be drawn from the local communities. The State of Colorado's Western Slope is anticipated to be minimally impacted by the phaseout of the UMTRA Project. Unlike industries that shut down operations without warning, the UMTRA Project workers, local government, and businesses know the schedule for completion and can consider and prepare for the impact of UMTRA Project conclusion. Further, because the majority of the work force is local, there has not been a significant investment in each community's infrastructure. Any small increases in the infrastructure will not be abandoned at the end of the UMTRA Project due to a marked increase in migration out of the local community

Dynamics of uranium ore formation in the basement and frame of the Streltsovskaya Caldera

International Nuclear Information System (INIS)

Petrov, V.; Schukin, S.

2014-01-01

The analysis of geological-geophysical, paleo-geodynamics, mineralogical, geochemical, isotope, geochronological, and thermo-baro-geochemical data allow us to offer a model of uranium ore formation dynamics in the basement and frame of the Streltsovskaya Caldera connected to activity of the fluid-conducting fault zones network with the aim to identify prospective areas The most ancient fluid-conducting structures are inter-block NE-SW, NNE-submeridional, NW-SE and, probably, WNW-sub-latitudinal faults. The oldest NE-SW faults and schistosity zones were formed during Proterozoic tectonic cycle (TC) with reactivation in T3-J2 time due to global reorganization of stress field and reactivation of tectonic movements. The NNE-submeridional and NW-SE faults were extended with increased fluid permeability during Caledonian and Variscan TCs. They also were reactivated in the process of Late Mesozoic tectonic and magmatic activation (TMA). Thus already at early stages of geotectonic evolution within the intersection of NE-SW (N-Urulyunguyevskiy fault) and NNE-submeridional (Chindachinskaya zone) faults the areas of increased fluid and magmatic activity were formed. The dynamics of fault formation in the basement and frame of the Streltsovskaya caldera and its volcano-sedimentary cover differs. In the basement and granite framework NE-SW, NNEsubmeridional and NW-SE faults are interblock structures of the I rank. Their intersection formed areas of long-term circulation of hydrothermal solutions and telescopic appearance of multi-age metasomatites that created conditions for localizing of vein-stockwork mineralization. In volcanosedimentary cover the NE-SW and NNE-submeridional faults should be considered as interblock structures of the I rank where intersections provided inflow of ore-bearing solutions and their redistribution within the cover. Here the main ore distributing role belongs to NW-SE shears. They are intrablock II rank structures which were formed due to dextral

Guia del Proceso del IFSP de Colorado: Conexiones para la Ninez Temprana, Iniciativa Infantil de Colorado Parte C del Acta de Educacion para Individuos con Desabilidades (Colorado Guidelines for the IFSP Process: Early Childhood Connections, Colorado's Infant/Toddler Initiative for Part C of the Individuals with Disabilities Education Act).

Science.gov (United States)

Miller, Jerri; Petersen, Sandy

This booklet for Spanish-speaking parents of young children with disabilities describes Colorado's Individualized Family Service Plan (IFSP) process. It explains guidelines, shares family stories and reflections for families and care providers, and the describes the values that drive the IFSP process in Colorado. Information is provided on…

Understanding uncertainties in future Colorado River streamflow

Science.gov (United States)

Julie A. Vano,; Bradley Udall,; Cayan, Daniel; Jonathan T Overpeck,; Brekke, Levi D.; Das, Tapash; Hartmann, Holly C.; Hidalgo, Hugo G.; Hoerling, Martin P; McCabe, Gregory J.; Morino, Kiyomi; Webb, Robert S.; Werner, Kevin; Lettenmaier, Dennis P.

2014-01-01

The Colorado River is the primary water source for more than 30 million people in the United States and Mexico. Recent studies that project streamf low changes in the Colorado River all project annual declines, but the magnitude of the projected decreases range from less than 10% to 45% by the mid-twenty-first century. To understand these differences, we address the questions the management community has raised: Why is there such a wide range of projections of impacts of future climate change on Colorado River streamflow, and how should this uncertainty be interpreted? We identify four major sources of disparities among studies that arise from both methodological and model differences. In order of importance, these are differences in 1) the global climate models (GCMs) and emission scenarios used; 2) the ability of land surface and atmospheric models to simulate properly the high-elevation runoff source areas; 3) the sensitivities of land surface hydrology models to precipitation and temperature changes; and 4) the methods used to statistically downscale GCM scenarios. In accounting for these differences, there is substantial evidence across studies that future Colorado River streamflow will be reduced under the current trajectories of anthropogenic greenhouse gas emissions because of a combination of strong temperature-induced runoff curtailment and reduced annual precipitation. Reconstructions of preinstrumental streamflows provide additional insights; the greatest risk to Colorado River streamf lows is a multidecadal drought, like that observed in paleoreconstructions, exacerbated by a steady reduction in flows due to climate change. This could result in decades of sustained streamflows much lower than have been observed in the ~100 years of instrumental record.

Extensive Green Roof Research Program at Colorado State University

Science.gov (United States)

In the high elevation, semi-arid climate of Colorado, green roofs have not been scientifically tested. This research examined alternative plant species, media blends, and plant interactions on an existing modular extensive green roof in Denver, Colorado. Six plant species were ev...

A 2-D FEM thermal model to simulate water flow in a porous media: Campi Flegrei caldera case study

Directory of Open Access Journals (Sweden)

V. Romano

2012-05-01

Full Text Available Volcanic and geothermal aspects both exist in many geologically young areas. In these areas the heat transfer process is of fundamental importance, so that the thermal and fluid-dynamic processes characterizing a viscous fluid in a porous medium are very important to understand the complex dynamics of the these areas. The Campi Flegrei caldera, located west of the city of Naples, within the central-southern sector of the large graben of Campanian plain, is a region where both volcanic and geothermal phenomena are present. The upper part of the geothermal system can be considered roughly as a succession of volcanic porous material (tuff saturated by a mixture formed mainly by water and carbon dioxide. We have implemented a finite elements approach in transient conditions to simulate water flow in a 2-D porous medium to model the changes of temperature in the geothermal system due to magmatic fluid inflow, accounting for a transient phase, not considered in the analytical solutions and fluid compressibility. The thermal model is described by means of conductive/convective equations, in which we propose a thermal source represented by a parabolic shape function to better simulate an increase of temperature in the central part (magma chamber of a box, simulating the Campi Flegrei caldera and using more recent evaluations, from literature, for the medium's parameters (specific heat capacity, density, thermal conductivity, permeability. A best-fit velocity for the permeant is evaluated by comparing the simulated temperatures with those measured in wells drilled by Agip (Italian Oil Agency in the 1980s in the framework of geothermal exploration. A few tens of days are enough to reach the thermal steady state, showing the quick response of the system to heat injection. The increase in the pressure due to the heat transport is then used to compute ground deformation, in particular the vertical displacements characteristics of the Campi Flegrei caldera

Stratigraphy and AMS radiocarbon dates of cored sediments (IrBH-2) from the Irosin caldera, the Philippines

International Nuclear Information System (INIS)

Mirabueno, Ma. Hannah T.; Laguerta, Eduardo P.; Delos Reyes, Perla J.; Bariso, Ericson B.; Torii, Masayuki; Fujiki, Toshiyuki; Okuno, Mitsuru; Nakamura, Toshio; Danhara, Tohru; Saito-Kokubu, Yoko; Kobayashi, Tetsuo

2014-01-01

Core drilling at Site IrBH-2 within the Irosin caldera in Sorsogon Province, southern Luzon reached a depth of 50 m. Systematic logging and documentation were carried out to describe and interpret the sediments. The accelerator mass spectrometer (AMS) radiocarbon dates obtained from plant fragments at 7.02-10.40-m depth were 1000 to 1800 BP. Lahars and fluvial deposits were the predominant deposits in the core sequence. The upper 12 m consisted mostly of andesitic fluvial and minor lahar deposits. These deposits may be correlated with the reworking of eruptive products from resurgent andesitic volcanism. One pyroclastic flow and 12 fallout deposits, including five possible fallout deposits, were intercalated with reworked sediments at depths of 12-50 m. The refractive index of representative samples indicated that post-caldera eruptions involved mainly andesite to dacite, with minor rhyolite magmas. The rhyolite fallout in the core had similar petrographic characteristics to the 41 cal kBP Irosin ignimbrite, suggesting that the fallout and the ignimbrite were sourced from the same magma. (author)

Centauri High School Teacher Honored as Colorado Outstanding Biology

Science.gov (United States)

Teacher Centauri High School Teacher Honored as Colorado Outstanding Biology Teacher For more information contact: e:mail: Public Affairs Golden, Colo., May 2, 1997 -- Tracy Swedlund, biology teacher at Centauri High School in LaJara, was selected as Colorado's 1997 Outstanding Biology Teacher and will be

Colorado Fathers' Resource Guide = Guia de Recursos para los Padres en Colorado.

Science.gov (United States)

Colorado Foundation for Families and Children, Denver.

Developed through the Colorado Fatherhood Connection, this guide, in English- and Spanish-language versions, provides suggestions and resources for fathers as well as tips on discipline, communication, and activities fathers can do with their children. Topics addressed in the guide include characteristics of responsible fatherhood, characteristics…

Mega-rings Surrounding Timber Mountain Nested Calderas, Geophysical Anomalies: Rethinking Structure and Volcanism Near Yucca Mountain (YM), Nevada

Science.gov (United States)

Tynan, M. C.; Smith, K. D.; Savino, J. M.; Vogt, T. J.

2004-12-01

Observed regional mega-rings define a zone ˜80-100 km in diameter centered on Timber Mountain (TM). The mega-rings encompass known smaller rhyolitic nested Miocene calderas ( ˜11-15 my, structural relationships. Mega-rings consist of arcuate faulted blocks with deformation (some remain active structures) patterns showing a genetic relationship to the TM volcanic system; they appear to be spatially associated and temporally correlated with Miocene volcanism and two geophysically identified crustal/upper mantle features. A 50+ km diameter pipe-like high velocity anomaly extends from crustal depth to over 200 km beneath TM (evidence for 400km depth to NE). The pipe is located between two ˜100 km sub-parallel N/S linear trends of small-magnitude earthquake activity, one extending through the central NV Test Site, and a second located near Beatty, NV. Neither the kinematics nor relational mechanism of 100km seismically active N/S linear zones, pipe, and mega-rings are understood. Interpreted mega-rings are: 1) Similar in size to larger terrestrial volcanic complexes (e.g., Yellowstone, Indonesia's Toba system); 2) Located in the region of structural transition from the Mohave block to the south, N/S Basin and Range features to the north, Walker Lane to the NW, and the Las Vegas Valley shear zone to the SE; 3) Associated with the two seismically active zones (similar to other caldera fault-bounded sags), the mantle high velocity feature, and possibly a regional bouguer gravity anomaly; 4) Nearly coincident with area hydrologic basins and sub-basins; 5) Similar to features described from terrestrial and planetary caldera-collapse studies, and as modeled in laboratory scaled investigations (ice melt, balloon/sand). Post Mid-Miocene basalts commonly occur within or adjacent to the older rhyolitic caldera moats; other basaltic material occurs marginal to both the outer rings of the interpreted mega-ring system and high velocity pipe. The YM repository may be situated in

The link between volcanism and plutonism in epizonal magma systems; high-precision U–Pb zircon geochronology from the Organ Mountains caldera and batholith, New Mexico

Science.gov (United States)

Rioux, Matthew; Farmer, Lang; Bowring, Samuel; Wooton, Kathleen M.; Amato, Jeffrey M.; Coleman, Drew S.; Verplanck, Philip L.

2016-01-01

The Organ Mountains caldera and batholith expose the volcanic and epizonal plutonic record of an Eocene caldera complex. The caldera and batholith are well exposed, and extensive previous mapping and geochemical analyses have suggested a clear link between the volcanic and plutonic sections, making this an ideal location to study magmatic processes associated with caldera volcanism. Here we present high-precision thermal ionization mass spectrometry U–Pb zircon dates from throughout the caldera and batholith, and use these dates to test and improve existing petrogenetic models. The new dates indicate that Eocene volcanic and plutonic rocks in the Organ Mountains formed from ~44 to 34 Ma. The three largest caldera-related tuff units yielded weighted mean 206Pb/238U dates of 36.441 ± 0.020 Ma (Cueva Tuff), 36.259 ± 0.016 Ma (Achenback Park tuff), and 36.215 ± 0.016 Ma (Squaw Mountain tuff). An alkali feldspar granite, which is chemically similar to the erupted tuffs, yielded a synchronous weighted mean 206Pb/238U date of 36.259 ± 0.021 Ma. Weighted mean 206Pb/238U dates from the larger volume syenitic phase of the underlying Organ Needle pluton range from 36.130 ± 0.031 to 36.071 ± 0.012 Ma, and the youngest sample is 144 ± 20 to 188 ± 20 ka younger than the Squaw Mountain and Achenback Park tuffs, respectively. Younger plutonism in the batholith continued through at least 34.051 ± 0.029 Ma. We propose that the Achenback Park tuff, Squaw Mountain tuff, alkali feldspar granite and Organ Needle pluton formed from a single, long-lived magma chamber/mush zone. Early silicic magmas generated by partial melting of the lower crust rose to form an epizonal magma chamber. Underplating of the resulting mush zone led to partial melting and generation of a high-silica alkali feldspar granite cap, which erupted to form the tuffs. The deeper parts of the chamber underwent continued recharge and crystallization for 144 ± 20 ka after the

Colorado Disciplinary Practices, 2008-2010: Disciplinary Actions, Student Behaviors, Race, and Gender

Science.gov (United States)

Pfleger, Ryan; Wiley, Kathryn

2012-01-01

The Colorado legislature has recently taken school discipline policies under review, pursuant to SB 11-133. To inform the discussion in Colorado as well as a national discussion about discipline, this report presents an analysis of the most complete set of Colorado discipline data. It adds to and reinforces existing studies, documenting some…

Assessment of surface-water quantity and quality, Eagle River watershed, Colorado, 1947-2007

Science.gov (United States)

Williams, Cory A.; Moore, Jennifer L.; Richards, Rodney J.

2011-01-01

From the early mining days to the current tourism-based economy, the Eagle River watershed (ERW) in central Colorado has undergone a sequence of land-use changes that has affected the hydrology, habitat, and water quality of the area. In 2000, the USGS, in cooperation with the Colorado River Water Conservation District, Eagle County, Eagle River Water and Sanitation District, Upper Eagle Regional Water Authority, Colorado Department of Transportation, City of Aurora, Town of Eagle, Town of Gypsum, Town of Minturn, Town of Vail, Vail Resorts, City of Colorado Springs, Colorado Springs Utilities, and Denver Water, initiated a retrospective analysis of surface-water quantity and quality in the ERW.

Western Slope Colorado

International Nuclear Information System (INIS)

Epis, R.C.; Callender, J.F.

1981-01-01

A conference on the geology and geologic resources of the Western Slope of western Colorado and eastern Utah is presented. Fourteen papers from the conference have been abstracted and indexed for the Department of Energy's Energy Data Base. These papers covered such topics as uranium resources, oil shale deposits, coal resources, oil and gas resources, and geothermal resources of the area

BLM Colorado Federal Mineral Estate

Data.gov (United States)

Department of the Interior — Shapefile Format –This Federal Mineral Estate (Subsurface) dataset is a result of combining data sets that were collected at each BLM Colorado Field Office and using...

Colorado's Prospects for Interstate Commerce in Renewable Power

Energy Technology Data Exchange (ETDEWEB)

Hurlbut, D. J.

2009-12-01

Colorado has more renewable energy potential than it is ever likely to need for its own in-state electricity consumption. Such abundance may suggest an opportunity for the state to sell renewable power elsewhere, but Colorado faces considerable competition from other western states that may have better resources and easier access to key markets on the West Coast. This report examines factors that will be important to the development of interstate commerce for electricity generated from renewable resources. It examines market fundamentals in a regional context, and then looks at the implications for Colorado.

Latinos in Colorado: A Profile of Culture, Changes, and Challenges. Volume V.

Science.gov (United States)

Pappas, Georgia, Ed.; Guajardo, Maria, Ed.

It is projected that the population of Colorado will increase by 25% between 1990 and 2000. The Latino community will experience a slight increase in the proportion of Colorado's population, and will remain the largest ethnic group over the next 30 years. The chapters in this profile describe the Latino population of Colorado. The following essays…

Colorado Children's Budget 2013

Science.gov (United States)

Buck, Beverly; Baker, Robin

2013-01-01

The "Colorado Children's Budget" presents and analyzes investments and spending trends during the past five state fiscal years on services that benefit children. The "Children's Budget" focuses mainly on state investment and spending, with some analysis of federal investments and spending to provide broader context of state…

The Colorado Plateau II: biophysical, socioeconomic, and cultural research

Science.gov (United States)

Mattson, David J.; van Riper, Charles

2005-01-01

The publication of The Colorado Plateau: Cultural, Biological, and Physical Research in 2004 marked a timely summation of current research in the Four Corners states. This new volume, derived from the seventh Biennial Conference on the Colorado Plateau in 2003, complements the previous book by focusing on the integration of science into resource management issues. The 32 chapters range in content from measuring human impacts on cultural resources, through grazing and the wildland-urban interface issues, to parameters of climate change on the Plateau. The book also introduces economic perspectives by considering shifting patterns and regional disparities in the Colorado Plateau economy. A series of chapters on mountain lions explores the human-wildland interface. These chapters deal with the entire spectrum of challenges associated with managing this large mammal species in Arizona and on the Colorado Plateau, conveying a wealth of timely information of interest to wildlife managers and enthusiasts. Another provocative set of chapters on biophysical resources explores the management of forest restoration, from the micro scale all the way up to large-scale GIS analyses of ponderosa pine ecosystems on the Colorado Plateau. Given recent concerns for forest health in the wake of fires, severe drought, and bark-beetle infestation, these chapters will prove enlightening for forest service, park service, and land management professionals at both the federal and state level, as well as general readers interested in how forest management practices will ultimately affect their recreation activities. With broad coverage that touches on topics as diverse as movement patterns of rattlesnakes, calculating watersheds, and rescuing looted rockshelters, this volume stands as a compendium of cutting-edge research on the Colorado Plateau that offers a wealth of insights for many scholars.

Transpiration characteristics of forests and shrubland under land cover change within the large caldera of Mt. Aso, Japan

Science.gov (United States)

Miyazawa, Y.; Inoue, A.; Maruyama, A.

2013-12-01

Grassland within a caldera of Mt. Aso has been maintained for fertilizer production from grasses and cattle feeding. Due to the changes in the agricultural and social structure since 1950's, a large part of the grassland was converted to plantations or abandoned to shrublands. Because vegetations of different plant functional types differ in evapotranspiration; ET, a research project was launched to examine the effects of the ongoing land use change on the ET within the caldera, and consequently affect the surface and groundwater discharge of the region. As the part of the project, transpiration rate; E of the major 3 forest types were investigated using sap flow measurements. Based on the measured data, stomatal conductance; Gs was inversely calculated and its response to the environmental factors was modeled using Jarvis-type equation in order to estimate ET of a given part of the caldera based on the plant functional type and the weather data. The selected forests were conifer plantation, deciduous broadleaved plantation and shrubland, which were installed with sap flow sensors to calculate stand-level transpiration rate. Sap flux; Js did not show clear differences among sites despite the large differences in sapwood area. In early summer solar radiation was limited to low levels due to frequent rainfall events and therefore, Js was the function of solar radiation rather than other environmental factors, such as vapor pressure deficit and soil water content. Gs was well regressed with the vapor pressure deficit and solar radiation. The estimated E based on Gs model and the weather data was 0.3-1.2 mm day-1 for each site and was comparable to the E of grassland in other study sites. Results suggested that transpiration rate in growing was not different between vegetations but its annual value are thought to differ due to the different phenology.

Colorado State Briefing Book for low-level radioactive-waste management

International Nuclear Information System (INIS)

1981-10-01

The Colorado State Briefing Book is one of a series of state briefing books on low-level radioactive waste management practices. It has been prepared to assist state and federal agency officials in planning for safe low-level radioactive waste disposal. The report contains a profile of low-level radioactive waste generators in Colorado. The profile is the result of a survey of NRC licensees in Colorado. The briefing book also contains a comprehensive assessment of low-level radioactive waste management issues and concerns as defined by all major interested parties including industry, government, the media, and interest groups. The assessment was developed through personal communications with representatives of interested parties, and through a review of media sources. Lastly, the briefing book provides demographic and socioeconomic data and a discussion of relevant government agencies and activities, all of which may impact waste management practices in Colorado

BLM Colorado Oil Shale Leases

Data.gov (United States)

Department of the Interior — KMZ file Format –This data set contains the Oil Shale Leases for the State of Colorado, derived from Legal Land Descriptions (LLD) contained in the US Bureau of Land...

30 CFR 906.25 - Approval of Colorado abandoned mine land reclamation plan amendments.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Approval of Colorado abandoned mine land reclamation plan amendments. 906.25 Section 906.25 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND... STATE COLORADO § 906.25 Approval of Colorado abandoned mine land reclamation plan amendments. The...

Into the void: Regulating pesticide use in Colorado's commercial cannabis markets.

Science.gov (United States)

Subritzky, Todd; Pettigrew, Simone; Lenton, Simon

2017-04-01

In 2014, Colorado implemented the world's first seed-to-sale recreational cannabis market under a commercial model. This paper aims to provide a thick descriptive account that gives insight into the issues and complexities of Colorado's pioneering and evolving attempt to regulate the use of pesticides on commercial cannabis plantations. The paper examines multiple data sets including: (i) Colorado State Government documents; (ii) recreational cannabis regulations; (iii) mass and niche media publications (n=175); (iv) face-to-face interviews with key stakeholders, including seniors, regulators and industry executives (n=8); and (v) field notes from relevant conferences and cultivation facility tours in Denver in October, 2016. Two key issues are identified. First, a public safety threat has arisen relating to application of pesticides on cannabis with intensified toxicity in concentrated products of particular concern. Second, as a pioneering jurisdiction, Colorado faces a considerable knowledge gap. To expand collective learning on this issue, for which no regulatory template and little research exists, state regulators tapped industry and other stakeholder expertise while attempting to ensure public safety goals were achieved and regulatory capture by industry was limited. Four years since the recreational cannabis market in Colorado was legalised, the State continues to grapple with the pesticide issue as testing regulations and cultivation standards are yet to be finalised. While more work is needed, Colorado has made significant progress in developing regulations relating to this complex matter. As governments of countries such as Canada and US states, including California, contemplate changes to recreational cannabis laws, Colorado's experience can assist regulators in other jurisdictions considering policy change. Copyright © 2017 Elsevier B.V. All rights reserved.

Colorado Children's Budget 2010

Science.gov (United States)

Colorado Children's Campaign, 2010

2010-01-01

The "Children's Budget 2010" is intended to be a resource guide for policymakers and advocates who are interested in better understanding how Colorado funds children's programs and services. It attempts to clarify often confusing budget information and describe where the state's investment trends are and where those trends will lead the…

30 CFR 906.15 - Approval of Colorado regulatory program amendments.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Approval of Colorado regulatory program amendments. 906.15 Section 906.15 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE COLORADO...

Assessing future vent opening locations at the Somma-Vesuvio volcanic complex: 2. Probability maps of the caldera for a future Plinian/sub-Plinian event with uncertainty quantification

Science.gov (United States)

Tadini, A.; Bevilacqua, A.; Neri, A.; Cioni, R.; Aspinall, W. P.; Bisson, M.; Isaia, R.; Mazzarini, F.; Valentine, G. A.; Vitale, S.; Baxter, P. J.; Bertagnini, A.; Cerminara, M.; de Michieli Vitturi, M.; Di Roberto, A.; Engwell, S.; Esposti Ongaro, T.; Flandoli, F.; Pistolesi, M.

2017-06-01

In this study, we combine reconstructions of volcanological data sets and inputs from a structured expert judgment to produce a first long-term probability map for vent opening location for the next Plinian or sub-Plinian eruption of Somma-Vesuvio. In the past, the volcano has exhibited significant spatial variability in vent location; this can exert a significant control on where hazards materialize (particularly of pyroclastic density currents). The new vent opening probability mapping has been performed through (i) development of spatial probability density maps with Gaussian kernel functions for different data sets and (ii) weighted linear combination of these spatial density maps. The epistemic uncertainties affecting these data sets were quantified explicitly with expert judgments and implemented following a doubly stochastic approach. Various elicitation pooling metrics and subgroupings of experts and target questions were tested to evaluate the robustness of outcomes. Our findings indicate that (a) Somma-Vesuvio vent opening probabilities are distributed inside the whole caldera, with a peak corresponding to the area of the present crater, but with more than 50% probability that the next vent could open elsewhere within the caldera; (b) there is a mean probability of about 30% that the next vent will open west of the present edifice; (c) there is a mean probability of about 9.5% that the next medium-large eruption will enlarge the present Somma-Vesuvio caldera, and (d) there is a nonnegligible probability (mean value of 6-10%) that the next Plinian or sub-Plinian eruption will have its initial vent opening outside the present Somma-Vesuvio caldera.

A Market Assessment of Residential Grid-Tied PV Systems in Colorado: Executive Summary

Energy Technology Data Exchange (ETDEWEB)

Farhar, B.; Coburn, T.

2000-09-13

This is the Executive Summary of a report that presents research done in response to a decision by the Colorado Governor's Office of Energy Conservation and Management (OEC) and Colorado utility companies to consider making residential grid-tied photovoltaic (PV) systems available in Colorado. The idea was to locate homeowners willing to pay the costs of grid-tied PV (GPV) systems without batteries--$8,000 or $12,000 for a 2- or 3-kilowatt (kW) system, respectively, in 1996. These costs represented two-thirds of the actual installed cost of $6 per watt at that time and assumed the remainder would be subsidized. The National Renewable Energy Laboratory (NREL) and OEC partnered to conduct a market assessment for GPV technology in Colorado. The study encompassed both qualitative and quantitative phases. The market assessment concluded that a market for residential GPV systems exists in Colorado today. That market is substantial enough for companies to successfully market PV systems to Colorado homeowners. These homeowners appear ready to learn more, inform themselves, and actively purchase GPV systems. The present situation is highly advantageous to Colorado's institutions--primarily its state government and its utility companies, and also its homebuilders--if they are ready to move forward on GPV technology.

Residential Energy Efficiency Potential: Colorado

Energy Technology Data Exchange (ETDEWEB)

Wilson, Eric J [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-11-16

Energy used by Colorado single-family homes that can be saved through cost-effective improvements. Prepared by Eric Wilson and Noel Merket, NREL, and Erin Boyd, U.S. Department of Energy Office of Energy Policy and Systems Analysis.

Monitoreo de un sistema de secado de bagazo acoplado a una caldera en un ingenio de México Monitoring of a bagasse drying system attached to a boiler in a sugar mill in Mexico

Directory of Open Access Journals (Sweden)

Federico J. Franck Colombres

Full Text Available Se evaluó el desempeño de un secador de bagazo diseñado por la Estación Experimental Agroindustrial Obispo Colombres, acoplado a una caldera bagacera convencional en un ingenio de México (caldera Nº 5. Para ello, se realizaron ensayos de mediciones y balances de materia y energía, para la caldera operando con el secador y sin él en funcionamiento. La caldera Nº 5, de una producción nominal de 60 t/h de vapor y una presión máxima de trabajo de 29 bar, cuando fue alimentada únicamente con bagazo húmedo pudo generar como máximo 33 t/h de vapor a 19 bar y 269ºC, con un rendimiento energético de 60,4% y un índice de generación de 1,6 kg de vapor/ kg de bagazo. Con la adición del secador, se logró secar 28,6 toneladas de bagazo de 50,2% a 30,4% de humedad. Aproximadamente un 72% de este bagazo presecado se mezcló con bagazo húmedo y se utilizó para alimentar la caldera, produciéndose así 58,4 t/h de vapor; es decir, 77% más de vapor que sin secador. El rendimiento energético del sistema caldera-secador fue de 73,6%, un 21,8% superior al de la caldera sin secador, mientras que el índice de generación fue de 2,0 kg de vapor/ kg de bagazo, 25% mayor que el de la caldera original. Este aumento en la producción de vapor permitió sacar de servicio a la caldera Nº 6, que producía aproximadamente 20 t/h de vapor, con un rendimiento similar al de la caldera Nº 5 sin secador. Estas mejoras dieron como resultado, un ahorro de energía de 45,4 MJ/h, aproximadamente un 18% respecto a la energía consumida por ambas calderas (Nº 5 y Nº 6 cuando no funcionaba el secador. Este ahorro equivale a 1103 l/h de "fuel oil", es decir, alrededor de 1,5 millones de dólares por zafra.A bagasse dryer designed by Estación Experimental Agroindustrial Obispo Colombres was attached to a conventional bagasse boiler (Boiler No. 5 in a sugar mill in Mexico for evaluation. Measurement tests and material and energy balances for the boiler operating

77 FR 51792 - Colorado Interstate Gas Company, L.L.C.; Notice of Application

Science.gov (United States)

2012-08-27

... Interstate Gas Company, L.L.C.; Notice of Application Take notice that on August 7, 2012, Colorado Interstate Gas Company, L.L.C. (CIG), Post Office Box 1087, Colorado Springs, Colorado 80944, filed in the above captioned docket an application pursuant to section 7(c) of the Natural Gas Act (NGA) for a certificate of...

Analysis of vector magnetic anomalies over the Bayonnaise Knoll caldera obtained from a deep-sea magnetic exploration by AUV

Science.gov (United States)

Sayanagi, K.; Isezaki, N.; Matsuo, J.; Harada, M.; Kasaya, T.

2011-12-01

Bayonnaise Knoll is a submarine caldera with an outer rim of 2.5-3 km and a floor of 840-920 m, which is located in the Izu-Ogasawara arc. A large hydrothermal deposit, Hakurei deposit, lies in the southeast part of the caldera. In the R/V Bosei-maru cruise, we observed three components of magnetic anomalies at depths of 400-570 m along SE-NW and WE tracks across the caldera. In the R/V Yokosuka YK10-17 cruise, we observed three components and total intensity of magnetic anomalies at altitudes of 60-100 m around the Hakurei deposit and at depth of 500 m above the caldera. The analysis of these data is now energetically pushed forward. A 3D gridded data set of the vector magnetic anomaly in the latter cruise was made by solving the Laplace's equation in the areas where observation data were not available, which is the unique procedure for analysis of the vector anomalies. Several magnetization solutions have been so far obtained by successive approximation and inversion methods. We will here present the measurement of the geomagnetic field and analysis of magnetization structure in Bayonnaise Knoll caldera. Note that this study has been supported by the Ministry of Education, Culture, Sports, Science & Technology (MEXT).

77 FR 21803 - Notice of Competitive Coal Lease Sale, Colorado

Science.gov (United States)

2012-04-11

..., COC-70615] Notice of Competitive Coal Lease Sale, Colorado AGENCY: Bureau of Land Management, Interior... described below in Gunnison County, Colorado, will be offered for competitive lease by sealed bid in accordance with the provisions of the Mineral Leasing Act of 1920, as amended. DATES: The lease sale will be...

77 FR 40630 - Notice of Competitive Coal Lease Sale, Colorado

Science.gov (United States)

2012-07-10

..., COC-74219] Notice of Competitive Coal Lease Sale, Colorado AGENCY: Bureau of Land Management, Interior... in the Wadge Seam described below in Routt County, Colorado, will be offered for competitive lease by sealed bid in accordance with the provisions of the Mineral Leasing Act of 1920, as amended. DATES: The...

Mineralogy, structural control and age of the Incachule Sb epithermal veins, the Cerro Aguas Calientes collapse caldera, Central Puna

Science.gov (United States)

Salado Paz, Natalia; Petrinovic, Iván; Do Campo, Margarita; Brod, José Affonso; Nieto, Fernando; da Silva Souza, Valmir; Wemmer, Klauss; Payrola, Patricio; Ventura, Roberto

2018-03-01

The Incachule Sb epithermal veins is located near to the N-E rim of the Cerro Aguas Calientes collapse caldera (17.5-10.8 Ma), in the geologic province of Puna, Salta- Argentina. It is hosted in Miocene felsic volcanic rocks with continental arc signature. The district includes twelve vein systems with mineralization of Sb occurring in hydrothermal breccias and stockwork. The veins are composed of quartz-sulfide with pyrite, stibnite and arsenopyrite. All around the veins, wall rocks are variably altered to clay minerals and sulfates in an area of around 2.5 km wide by more than 7 km long. The hydrothermal alterations recognized are: silicic, phyllic and argillic. The veins are characterized by high contents of Sb, As, and Tl and intermediate contents of Pb-Zn-Cu, and traces of Ag and Au. Homogenization and ice-melting temperatures of fluid inclusions vary from 125 °C to 189 °C and -2.4 °C to -0.8 °C. The isotopic data indicated a range of δ34S -3.04‰ to +0.72‰ consistent with a magmatic source for sulfur. We present the firsts K-Ar ages for hydrothermal illite/smectite mixed layers (I/SR1, 60% illite layers) and illite that constrain the age of the ore deposit (8.5-6.7 ± 0.2 Ma). The data shown here, let characterized the Incachule district as a shallow low sulfidation epithermal system hosted in a collapse caldera. Our data also indicate that mineralization is structurally controlled by a fault system related to the 10.3 Ma collapse of Aguas Calientes caldera. The interpreted local stress field is consistent with the regional one.

75 FR 58426 - Notice of Inventory Completion: The Colorado College, Colorado Springs, CO; Correction

Science.gov (United States)

2010-09-24

... Counsel, The Colorado College c/o Jan Bernstein, President, Bernstein & Associates - NAGPRA Consultants... responsible for notifying the Hopi Tribe of Arizona; Navajo Nation, Arizona, New Mexico & Utah; Ohkay Owingeh, New Mexico; Pueblo of Acoma, New Mexico; Pueblo of Cochiti, New Mexico; Pueblo of Isleta, New Mexico...

The 1996-2009 borehole dilatometer installations, operation, and maintenance at sites in Long Valley Caldera, CA

Science.gov (United States)

Myren, Glenn; Johnston, Malcolm; Mueller, Robert

2011-01-01

High seismicity levels with accelerating uplift (under the resurgent dome) in Long Valley caldera in the eastern Sierra Nevada from 1989 to 1997, triggered upgrades to dilational strainmeters and other instrumentation installed in the early 1980's following a series of magnitude 6 earthquakes. This included two additional high-resolution borehole strainmeters and replacement of the failed strainmeter at Devil's Postpile. The purpose of the borehole-monitoring network is to monitor crustal deformation and other geophysical parameters associated with volcanic intrusions and earthquakes in the Long Valley Caldera. Additional instrumentation was added at these sites to improve the capability of providing continuous monitoring of the magma source under the resurgent dome. Sites were selected in regions of hard crystalline rock, where the expected signals from magmatic activity were calculated to be a maximum and the probability of an earthquake of magnitude 4 or greater is large. For the most part, the dilatometers were installed near existing arrays of surface tiltmeters, seismometers, level line, and GPS arrays. At each site, attempts are made to separate tectonic and volcanic signals from known noise sources in each instrument type. Each of these sites was planned to be a multi-parameter monitoring site, which included measurements of 3-component seismic velocity and acceleration, borehole strain, tilt, pore pressure and magnetic field. Using seismicity, geophysical knowledge, geologic and topographic maps, and geologists recommendations, lists of preliminary sites were chosen. Additional requirements were access, and telemetry constraints. When the final site choice was made, a permit was obtained from the U.S. Forest Service. Following this selection process, two new borehole sites were installed on the north and south side of the Long Valley Caldera in June of 1999. One site was located near Big Spring Campground to the east of Crestview. The second site was

The thermal regime in the resurgent dome of Long Valley Caldera, California: Inferences from precision temperature logs in deep wells

Science.gov (United States)

Hurwitz, S.; Farrar, C.D.; Williams, C.F.

2010-01-01

Long Valley Caldera in eastern California formed 0.76Ma ago in a cataclysmic eruption that resulted in the deposition of 600km3 of Bishop Tuff. The total current heat flow from the caldera floor is estimated to be ~290MW, and a geothermal power plant in Casa Diablo on the flanks of the resurgent dome (RD) generates ~40MWe. The RD in the center of the caldera was uplifted by ~80cm between 1980 and 1999 and was explained by most models as a response to magma intrusion into the shallow crust. This unrest has led to extensive research on geothermal resources and volcanic hazards in the caldera. Here we present results from precise, high-resolution, temperature-depth profiles in five deep boreholes (327-1,158m) on the RD to assess its thermal state, and more specifically 1) to provide bounds on the advective heat transport as a guide for future geothermal exploration, 2) to provide constraints on the occurrence of magma at shallow crustal depths, and 3) to provide a baseline for future transient thermal phenomena in response to large earthquakes, volcanic activity, or geothermal production. The temperature profiles display substantial non-linearity within each profile and variability between the different profiles. All profiles display significant temperature reversals with depth and temperature gradients <50??C/km at their bottom. The maximum temperature in the individual boreholes ranges between 124.7??C and 129.5??C and bottom hole temperatures range between 99.4??C and 129.5??C. The high-temperature units in the three Fumarole Valley boreholes are at the approximate same elevation as the high-temperature unit in borehole M-1 in Casa Diablo indicating lateral or sub-lateral hydrothermal flow through the resurgent dome. Small differences in temperature between measurements in consecutive years in three of the wells suggest slow cooling of the shallow hydrothermal flow system. By matching theoretical curves to segments of the measured temperature profiles, we calculate

Imaging the complex geometry of a magma reservoir using FEM-based linear inverse modeling of InSAR data: application to Rabaul Caldera, Papua New Guinea

Science.gov (United States)

Ronchin, Erika; Masterlark, Timothy; Dawson, John; Saunders, Steve; Martì Molist, Joan

2017-06-01

We test an innovative inversion scheme using Green's functions from an array of pressure sources embedded in finite-element method (FEM) models to image, without assuming an a-priori geometry, the composite and complex shape of a volcano deformation source. We invert interferometric synthetic aperture radar (InSAR) data to estimate the pressurization and shape of the magma reservoir of Rabaul caldera, Papua New Guinea. The results image the extended shallow magmatic system responsible for a broad and long-term subsidence of the caldera between 2007 February and 2010 December. Elastic FEM solutions are integrated into the regularized linear inversion of InSAR data of volcano surface displacements in order to obtain a 3-D image of the source of deformation. The Green's function matrix is constructed from a library of forward line-of-sight displacement solutions for a grid of cubic elementary deformation sources. Each source is sequentially generated by removing the corresponding cubic elements from a common meshed domain and simulating the injection of a fluid mass flux into the cavity, which results in a pressurization and volumetric change of the fluid-filled cavity. The use of a single mesh for the generation of all FEM models avoids the computationally expensive process of non-linear inversion and remeshing a variable geometry domain. Without assuming an a-priori source geometry other than the configuration of the 3-D grid that generates the library of Green's functions, the geodetic data dictate the geometry of the magma reservoir as a 3-D distribution of pressure (or flux of magma) within the source array. The inversion of InSAR data of Rabaul caldera shows a distribution of interconnected sources forming an amorphous, shallow magmatic system elongated under two opposite sides of the caldera. The marginal areas at the sides of the imaged magmatic system are the possible feeding reservoirs of the ongoing Tavurvur volcano eruption of andesitic products on the

Seismic and gravity signature of the Ischia Island Caldera (Italy)

Science.gov (United States)

Capuano, P.; de Matteis, R.; Russo, G.

2009-04-01

The Campania (Italy) coasts are characterized by the presence of several volcanoes. The island of Ischia, located at the northwestern end of the Gulf of Naples, belongs to the Neapolitan Volcanic District together with Phlegrean Fields and Vesuvius, having all these Pleistocene volcanoes erupted in historical times, and it is characterized by diffuse hydrothermal phenomena The island represents the emergent part of a more extensive volcanic area developed mainly westward of the island, with underwater volcanoes aligned along regional fault patterns. The activity of Ischia volcano is testified by the occurrence of eruptions in historical times, the presence of intense hydrothermal phenomena, and by seismic activity (e.g. the 1883 Casamicciola earthquake). Ischia is populated by about 50,000 inhabitants increasing, mainly in the summer, due to thriving tourism business, partially due to its active volcanic state. Hazard assessment at active, densely populated volcanoes is critically based on knowledge of the volcanoes past behavior and the definition of its present state. As a contribution to the definition of the present state of the Ischia island volcano, we obtain a model of the shallow crust using geophysical observables through seismic tomography and 3D gravity inversion. In particular we use travel times collected during the Serapis experiment on the island and its surroundings and free air anomaly. A new 3D gravity inversion procedure has been developed to take better into account the shape and the effects of topography approximating it by a triangular mesh. Below each triangle, a sequence of triangular prisms is built, the uppermost prism having the upper face coincident with the triangle following the topography. The inversion is performed searching for a regularized solution using the minimum norm stabilizer. The main results inferable from the 3D seismic and gravity images are the definition of the caldera rims hypothesize by many authors along the

Gunnison, Colorado, subpile study report

International Nuclear Information System (INIS)

1994-03-01

To protect human health and the environment, the UMTRA project will remediate the uranium mill tailings site at Gunnison, Colorado. There are explicit requirements (i.e., 40 Part CFR Part 192) for the surface remediation of radiologically contaminated soils on UMTRA sites. The removal of subpile sediment to the depth required by 40 CFR Part 192 will leave in place deeper foundation sediment that is contaminated with hazardous constituents other than radium-226 and thorium-230. The Department of Energy and the Colorado Department of Health have questioned whether this contaminated soil could potentially act as a continuing source of ground water contamination even after surface remediation based on 40 CFR Part 192 is complete. To evaluate the subpile sediments as a potential source of ground water contamination, the Gunnison subpile study was initiated. This report summarizes the results and findings of this study

The marine digital terrain model of the Panarea caldera (Aeolian Islands, Southern Italy

Directory of Open Access Journals (Sweden)

M. Anzidei

1998-06-01

Full Text Available A Marine Digital Elevation Model (MDEM of the still active volcanic area of Panarea caldera is presented in this paper. A fast and accurate survey was performed by means of the Differential Global Positioning System (DGPS geodetic technique coupled with an echo-sounding gear and a real time navigation software. The instrumentation was installed on board of a low draught boat in order to collect data starting from the bathymeter of one meter. Planar positions and depths were obtained with average accuracies of 30 cm and 10 cm respectively providing a 3D map of the seafloor useful for geomorphological, geophysical and volcanic hazard applications.

Magnetotelluric survey of Ischia resurgent caldera (Southern Italy): inference for volcano-tectonics and dynamic

Science.gov (United States)

Carlino, S.; Di Giuseppe, M. G.; Troiano, A.

2017-12-01

The island of Ischia (located in the Bay of Naples) represents a peculiar case of well-exposed caldera that has experienced a large (>800m) and rapid resurgence, until recent time. It gives us the possibility for a better understanding of caldera resurgence process, by integrating the available geological information with new geophysical data of the deeper structures associated to the resurgence. To this aim, a magnetotelluric survey of the island, has been performed along two main profiles of the central-western sector, obtaining the first electrical resistivity map down to a depth of 3km. The resurgence is tough to be associated to a shallow magma intrusion, which also produced a vigorous hot fluids circulation with high geothermal gradients (>150°Ckm-1) in the southern and western sector. The interpretation of resistivity variations allow us to recognize the main volcano-tectonic features of central-western part of the island, along the two profiles, such as the presence of a possible very shallow magmatic intrusion to a depth of about 1km, the tectonic structures bordering the resurgent area and the occurrence of large thermal anomaly of the western sector. All these data are fundamental for the assessment of volcano-dynamic of the island and associated hazard. Furthermore, this study show a not common example of a large resurgence that is likely generated by a laccolith intrusion. This process is generally associated to the arrival of fresh magma into the system that, in turn, may imply imminent eruption and high volcanic hazard.

Mechanical and geometric controls on the structural evolution of pit crater and caldera subsidence

Science.gov (United States)

Holohan, E. P.; SchöPfer, M. P. J.; Walsh, J. J.

2011-07-01

Pit craters and calderas are volcanic depressions produced by subsidence of a magma reservoir roof. To identify how geometric and mechanical factors may influence the structural evolution of this subsidence, we used two-dimensional distinct element method numerical models. The reservoir host rock was represented as an assemblage of bonded circular particles that interact according to elastic-frictional laws. Varying particle and bond properties produced a range of bulk material properties characteristic of natural rock masses. Fracturing results when bonds break, once their shear or tensile strength is exceeded. The magma reservoir was represented as a region of nonbonded low-friction particles. Withdrawal of magma was simulated by incrementally reducing the area of the reservoir particles. Resultant gravity-driven failure and subsidence of the reservoir roof were explicitly replicated. Interaction of the roof's strength, Young's modulus, thickness/diameter ratio (T/D), and the reservoir's shape yields a variety of model structures and subsidence styles. In conceptual terms, four end-member subsidence styles developed: (1) "central sagging" favored by low strength and low T/D; (2) "central snapping" favored by high strength, low T/D, and a sill-like reservoir shape; (3) "single central block" favored by low to intermediate strength, high Young's modulus, and intermediate T/D; and (4) "multiple central blocks" favored by high strength, low Young's modulus, and high T/D. Most model realizations incorporated some combination of each style, however. The models provide a geomechanical framework for understanding natural pit crater or caldera structures, as at Nindiri (Nicaragua), Fernandina (Galapagos), Dolomieu (La Reunion), and Miyakejima (Japan).

78 FR 44186 - Colorado Disaster # CO-00058 Declaration of Economic Injury

Science.gov (United States)

2013-07-23

... SMALL BUSINESS ADMINISTRATION [Disaster Declaration 13662] Colorado Disaster CO-00058 Declaration... notice of an Economic Injury Disaster Loan (EIDL) declaration for the State of Colorado, dated 07/15/2013... areas have been determined to be adversely affected by the disaster: Primary Counties: Hinsdale, Mineral...

The Colorado Plateau III: integrating research and resources management for effective conservation

Science.gov (United States)

Sogge, Mark K.; van Riper, Charles

2008-01-01

Roughly centered on the Four Corners region of the southwestern United States, the Colorado Plateau covers an area of 130,000 square miles. The relatively high semi-arid province boasts nine national parks, sixteen national monuments, many state parks, and dozens of wilderness areas. With the highest concentration of parklands in North America and unique geological and ecological features, the area is of particular interest to researchers. Derived from the Eighth Biennial Conference of Research on the Colorado Plateau, this third volume in a series of research on the Colorado Plateau expands upon the previous two books. This volume focuses on the integration of science into resource management issues, summarizes what criteria make a successful collaborative effort, outlines land management concerns about drought, provides summaries of current biological, sociological, and archaeological research, and highlights current environmental issues in the Four Corner States of Arizona, New Mexico, Colorado, and Utah. With broad coverage that touches on topics as diverse as historical aspects of pronghorn antelope movement patterns through calculating watershed prescriptions to the role of wind-blown sand in preserving archaeological sites on the Colorado River, this volume stands as a compendium of cuttingedge management-oriented research on the Colorado Plateau. The book also introduces, for the first time, tools that can be used to assist with collaboration efforts among landowners and managers who wish to work together toward preserving resources on the Colorado Plateau and offers a wealth of insights into land management questions for many readers, especially people interested in the natural history, biology, anthropology, wildlife, and cultural management issues of the region.

A probability tomography approach to the analysis of potential field data in the Campi Flegrei caldera (Italy)

Energy Technology Data Exchange (ETDEWEB)

Iuliano, T.; Patella, D. [Naples Univ. Federico 2., Naples (Italy). Dipartimento di Scienze Fisiche; Mauriello, P. [Consiglio Nazionale delle Ricerche, Istituto per le Tecnologie Applicate ai Beni Culturali, Rome (Italy)

2001-04-01

The results of the application of the 3a probability tomography imaging approach to the study of the Ca mpi Fagarol (Cf) caldera are presented and discussed. The tomography approach has been applied to gravity, magnetic and ground deformation data already available in literature. The analysis of the 3a tomographic images is preceded by a brief qualitative interpretation of the original survey maps and by an outline of the probability tomography approach for each geophysical prospecting method. The results derived from the 3a tomographic images are the high occurrence probabilities of both gravity and ground deformation source centers in the Cf caldera under the town of Palazzo. A Bagger negative anomaly source centre is highlighted in the depth range 1.6-2 km b.s.l., whereas a positive ground deformation point source, responsible for the bradyseismic crisis of 1982-1984, is estimated at a mean depth of 3-4 km b.s.l. These inferences, combined with the results of a previous analysis of magnetotelluric, dipolar geolectrical and self-potential data, corroborate the hypothesis that the bradyseismic events in the CF area may be explained by hot fluids vertical advection and subsequent lateral diffusion within a trapped reservoir overlying a magma chamber.

A probability tomography approach to the analysis of potential field data in the Campi Flegrei caldera (Italy

Directory of Open Access Journals (Sweden)

D. Patella

2001-06-01

Full Text Available The results of the application of the 3D probability tomography imaging approach to the study of the Campi Flegrei (CF caldera are presented and discussed. The tomography approach has been applied to gravity, magnetic and ground deformation data already available in literature. The analysis of the 3D tomographic images is preceded by a brief qualitative interpretation of the original survey maps and by an outline of the probability tomography approach for each geophysical prospecting method. The results derived from the 3D tomographic images are the high occurrence probabilities of both gravity and ground deformation source centres in the CF caldera under the town of Pozzuoli. A Bouguer negative anomaly source centre is highlighted in the depth range 1.6-2 km b.s.l., whereas a positive ground deformation point source, responsible for the bradyseismic crisis of 1982-1984, is estimated at a mean depth of 3-4 km b.s.l. These inferences, combined with the results of a previous analysis of magnetotelluric, dipolar geoelectrical and self-potential data, corroborate the hypothesis that the bradyseismic events in the CF area may be explained by hot fluids vertical advection and subsequent lateral diffusion within a trapped reservoir overlying a magma chamber.

Volcanic calderas delineate biogeographic provinces among Yellowstone thermophiles.

Science.gov (United States)

Takacs-Vesbach, Cristina; Mitchell, Kendra; Jackson-Weaver, Olan; Reysenbach, Anna-Louise

2008-07-01

It has been suggested that the distribution of microorganisms should be cosmopolitan because of their enormous capacity for dispersal. However, recent studies have revealed that geographically isolated microbial populations do exist. Geographic distance as a barrier to dispersal is most often invoked to explain these distributions. Here we show that unique and diverse sequences of the bacterial genus Sulfurihydrogenibium exist in Yellowstone thermal springs, indicating that these sites are geographically isolated. Although there was no correlation with geographic distance or the associated geochemistry of the springs, there was a strong historical signal. We found that the Yellowstone calderas, remnants of prehistoric volcanic eruptions, delineate biogeographical provinces for the Sulfurihydrogenibium within Yellowstone (chi(2): 9.7, P = 0.002). The pattern of distribution that we have detected suggests that major geological events in the past 2 million years explain more of the variation in sequence diversity in this system than do contemporary factors such as habitat or geographic distance. These findings highlight the importance of historical legacies in determining contemporary microbial distributions and suggest that the same factors that determine the biogeography of macroorganisms are also evident among bacteria.

Stress field control during large caldera-forming eruptions

Directory of Open Access Journals (Sweden)

Antonio Costa

2016-10-01

Full Text Available Crustal stress field can have a significant influence on the way magma is channelled through the crust and erupted explosively at the surface. Large Caldera Forming Eruptions (LCFEs can erupt hundreds to thousands of cubic kilometres of magma in a relatively short time along fissures under the control of a far-field extensional stress. The associated eruption intensities are estimated in the range 109 - 1011 kg/s. We analyse syn-eruptive dynamics of LCFEs, by simulating numerically explosive flow of magma through a shallow dyke conduit connected to a magma chamber that in turn is fed by a deeper magma reservoir, both under the action of an extensional far-field stress. Results indicate that huge amounts of high viscosity silicic magma can be erupted over timescales of a few to several hours. Our study provides answers to outstanding questions relating to the intensity and duration of catastrophic volcanic eruptions in the past. In addition, it presents far-reaching implications for the understanding of dynamics and intensity of large-magnitude volcanic eruptions on Earth and to highlight the necessity of a future research to advance our knowledge of these rare catastrophic events.

Explosive eruptive history of Pantelleria, Italy: Repeated caldera collapse and ignimbrite emplacement at a peralkaline volcano

Science.gov (United States)

Jordan, Nina J.; Rotolo, Silvio G.; Williams, Rebecca; Speranza, Fabio; McIntosh, William C.; Branney, Michael J.; Scaillet, Stéphane

2018-01-01

A new, pre-Green Tuff (46 ka) volcanic stratigraphy is presented for the peralkaline Pantelleria Volcano, Italy. New 40Ar/39Ar and paleomagnetic data are combined with detailed field studies to develop a comprehensive stratigraphic reconstruction of the island. We find that the pre-46 ka succession is characterised by eight silica-rich peralkaline (trachyte to pantellerite) ignimbrites, many of which blanketed the entire island. The ignimbrites are typically welded to rheomorphic, and are commonly associated with lithic breccias and/or pumice deposits. They record sustained radial pyroclastic density currents fed by low pyroclastic fountains. The onset of ignimbrite emplacement is typically preceded (more rarely followed) by pumice fallout with limited dispersal, and some eruptions lack any associated pumice fall deposit, suggesting the absence of tall eruption columns. Particular attention is given to the correlation of well-developed lithic breccias in the ignimbrites, interpreted as probable tracers of caldera collapses. They record as many as five caldera collapse events, in contrast to the two events reported to date. Inter-ignimbrite periods are characterised by explosive and effusive eruptions with limited dispersal, such as small pumice cones, as well as pedogenesis. These periods have similar characteristics as the current post-Green Tuff activity on the island, and, while not imminent, it is reasonable to postulate the occurrence of another ignimbrite-forming eruption sometime in the future.

Modificaciones en las calderas igneotubulares cubanas // Modifications in the Cuban boilers of fire tube

Directory of Open Access Journals (Sweden)

I. Pérez Mallea

1998-01-01

Full Text Available El objetivo de este trabajo es optimizar y diseñar las calderas igneotubulares nacionales, incluyendo las de inversión de llama yagua caliente. Con este fin se creo un software como soporte científico técnico que permite realizar los diferentes cálculosverificativos a través de los cuales se optimiza._________________________________________________________________________Abstract .The objective of this work is the optimizing and designing of the Cuban boilers of fire tube, including those of inverting offlame and hot water. A software have been developed as technical scientific supper for different calculations and optimizingprocess.

75 FR 3333 - Irish Potatoes Grown in Colorado; Modification of the Handling Regulation for Area No. 2

Science.gov (United States)

2010-01-21

... FR] Irish Potatoes Grown in Colorado; Modification of the Handling Regulation for Area No. 2 AGENCY... requirement under the Colorado potato marketing order, Area No. 2. The marketing order regulates the handling of Irish potatoes grown in Colorado, and is administered locally by the Colorado Potato...

77 FR 13629 - Notice of Inventory Completion: History Colorado, Denver, CO

Science.gov (United States)

2012-03-07

... Fort Hall Reservation of Idaho; and the Zuni Tribe of the Zuni Reservation, New Mexico. History and...: History Colorado, Denver, CO AGENCY: National Park Service, Interior. ACTION: Notice. SUMMARY: History... human remains may contact History Colorado. Disposition of the human remains to the Indian tribes stated...

Business Metrics for High-Performance Homes: A Colorado Springs Case Study

Energy Technology Data Exchange (ETDEWEB)

Beach, R. [IBACOS, Inc, Pittsburgh, PA (United States); Jones, A. [IBACOS, Inc, Pittsburgh, PA (United States)

2016-04-26

This report explores the correlation between energy efficiency and the business success of home builders by examining a data set of builders and homes in the Colorado Springs, Colorado, market between 2006 and 2014. During this time, the Great Recession of 2007 to 2009 occurred, and new-home sales plummeted both nationally and in Colorado Springs. What is evident from an analysis of builders and homes in Colorado Springs is that builders who had Home Energy Rating System (HERS) ratings performed on some or all of their homes during the Recession remained in business during this challenging economic period. Many builders who did not have HERS ratings performed on their homes at that time went out of business or left the area. From the analysis presented in this report, it is evident that a correlation exists between energy efficiency and the business success of home builders, although the reasons for this correlation remain largely anecdotal and not yet clearly understood.

Graben structure in the Las Cañadas edifice (Tenerife, Canary Islands): implications for active degassing and insights on the caldera formation

Science.gov (United States)

Galindo, Inés; Soriano, Carles; Martí, Joan; Pérez, Nemesio

2005-06-01

A graben structure has been identified at the western area of the Las Cañadas caldera wall, here referred as the Los Azulejos Graben. This graben is 1 km wide and is bounded by two major normal faults trending NE-SW, the Los Azulejos Fault and the Ucanca Fault. The graben was active for at least 0.5 Ma, from the end of the Ucanca Fm to the end of the Guajara Fm, and before the collapse of the Las Cañadas edifice that formed the western caldera. A right-lateral transtension regime operated in the graben as suggested by small fault orientations and kinematics. The prolongation of the NE rift zone of Tenerife to the Cañadas edifice is the most likely volcano-tectonic scenario for the graben. In this context, inflation of phonolitic shallow magma chambers may have produced reverse faults and reactivation of normal faults. An intense and widespread hydrothermal alteration, here called Azulejos-type, occurred mainly before the graben formation, while a fault-related hydrothermal alteration occurred during and after the graben. Diffuse carbon dioxide and hydrogen degassing in and around the Las Cañadas caldera show relatively enriched values along a NE-SW trend suggesting that faults in the Los Azulejos Graben act as a pathway for deep-seated gases to the surface. Diffuse degassing and hydrothermalism indicate that the graben area has been a zone of intense fluid circulation during the evolution of the Las Cañadas edifice.

78 FR 52984 - Stone Age Interiors, Inc.; d/b/a Colorado Springs Marble and Granite Including On-Site Leased...

Science.gov (United States)

2013-08-27

....; d/b/a Colorado Springs Marble and Granite Including On-Site Leased Workers From Express Employment... Colorado Springs Marble and Granite, Colorado Springs, Colorado (hereafter collectively referred to as..., Inc., d/b/a Colorado Springs Marble and Granite, including on-site leased workers from Express...

Heat flow in the north-central Colorado Plateau

International Nuclear Information System (INIS)

Bodell, J.M.; Chapman, D.S.

1982-01-01

We report new heat flow measurements at 25 evenly distributed sites in the north-central Colorado Plateau. Heat flow values computed for these new sites and one previously published site range from 43 to 116 mW m -2 but fall into the following district subsets related to physiographic and tectonic elements within the Plateau: (1) heat flow of 51 mW m -2 (12 sites; s.d. 6) in the San Rafael Swell and Green River Desert which constitute the core of the Colorado Plateau at this latitude, (2) heat flows of 69 mW m -2 (5 sites; s.d. 10) in successive parallel north-south bands approaching the Wasatch Plateau to the west but still 80 km east of the Basin and Range physiographic boundary, (3) heat flow of 64 mW m -2 (5 sites; s.d. 2) along the Salt Anticline trend which strikes northwest in the region of Moab, Utah. Heat flow results for the entire Colorado Plateau have been reexamined in view of our new results, and the overall pattern supports the concept of a low heat flow 'thermal interior' for the plateau surrounded by a periphery some 100 km wide having substantially higher heat flow. Average heat flow in the thermal interior is about 60 mW m -2 compared to 80--90 mW m -2 in the periphery. This regional heat flow pattern supports a model of tertiary lithospheric thinning under the Colorado Plateau whereby the plateau is still in transient thermal response and a 15--20 m.y. lag between uplift and corresponding surface heat flow anomaly is to be expected. The position of the heat flow transition between our interior and peripheral regions in the northwest plateau is roughly consistent with lateral warming and weakening of the Colorado Plateau lithosphere initiated at the Basin and Range boundary some 20 m.y. ago

Mineral exploration with ERTS imagery. [Colorado

Science.gov (United States)

Nicolais, S. M.

1974-01-01

Ten potential target areas for metallic mineral exploration were selected on the basis of a photo-lineament interpretation of the ERTS image 1172-17141 in central Colorado. An evaluation of bias indicated that prior geologic knowledge of the region had little, if any, effect on target selection. In addition, a contoured plot of the frequency of photo-lineament intersections was made to determine what relationships exist between the photo-lineaments and mineral districts. Comparison of this plot with a plot of the mineral districts indicates that areas with a high frequency of intersections commonly coincide with known mineral districts. The results of this experiment suggest that photo-lineaments are fractures or fracture-controlled features, and their distribution may be a guide to metallic mineral deposits in Colorado, and probably other areas as well.

Environmental assessment, expanded Ponnequin wind energy project, Weld County, Colorado

International Nuclear Information System (INIS)

1999-02-01

The US Department of Energy (DOE) has considered a proposal from the State of Colorado, Office of Energy Conservation (OEC), for funding construction of the Expanded Ponnequin Wind Project in Weld County, Colorado. OEC plans to enter into a contracting arrangement with Public Service Company of Colorado (PSCo) for the completion of these activities. PSCo, along with its subcontractors and business partners, are jointly developing the Expanded Ponnequin Wind Project. The purpose of this Final Environmental Assessment (EA) is to provide DOE and the public with information on potential environmental impacts associated with the Expanded Ponnequin Wind Energy Project. This EA, and public comments received on it, were used in DOE's deliberations on whether to release funding for the expanded project under the Commercialization Ventures Program

Environmental assessment, expanded Ponnequin wind energy project, Weld County, Colorado

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-02-01

The US Department of Energy (DOE) has considered a proposal from the State of Colorado, Office of Energy Conservation (OEC), for funding construction of the Expanded Ponnequin Wind Project in Weld County, Colorado. OEC plans to enter into a contracting arrangement with Public Service Company of Colorado (PSCo) for the completion of these activities. PSCo, along with its subcontractors and business partners, are jointly developing the Expanded Ponnequin Wind Project. The purpose of this Final Environmental Assessment (EA) is to provide DOE and the public with information on potential environmental impacts associated with the Expanded Ponnequin Wind Energy Project. This EA, and public comments received on it, were used in DOE`s deliberations on whether to release funding for the expanded project under the Commercialization Ventures Program.

Land and federal mineral ownership coverage for northwestern Colorado

Science.gov (United States)

Biewick, L.H.; Mercier, T.J.; Levitt, Pam; Deikman, Doug; Vlahos, Bob

1999-01-01

This Arc/Info coverage contains land status and Federal mineral ownership for approximately 26,800 square miles in northwestern Colorado. The polygon coverage (which is also provided here as a shapefile) contains two attributes of ownership information for each polygon. One attribute indicates where the surface is State owned, privately owned, or, if Federally owned, which Federal agency manages the land surface. The other attribute indicates which minerals, if any, are owned by the Federal govenment. This coverage is based on land status and Federal mineral ownership data compiled by the U.S. Geological Survey (USGS) and three Colorado State Bureau of Land Management (BLM) former district offices at a scale of 1:24,000. This coverage was compiled primarily to serve the USGS National Oil and Gas Resource Assessment Project in the Uinta-Piceance Basin Province and the USGS National Coal Resource Assessment Project in the Colorado Plateau.

Tourism Development Based on Geopark in Bakkara Caldera Toba, Indonesia

Science.gov (United States)

Ginting, N.; Vinky Rahman, N.; Sembiring, G.

2017-03-01

Bakkara Caldera Toba is an outstanding product of natural phenomena of Toba Supervolcano which has fascinating nature and culture. Bakkara has a great potential to develop world tourism further. It requires a model of sustainable planning Geopark to develop Bakkara. This sustainable concept helps to improve the local community and tourist’s quality of life and also still maintain the quality of the environment. through field observation and depth interview. The Collected data with a triangulation method. Development tourism destination such as attractions and environment; facilities and services; accessibility; image; and price to consume. It associated based on Geopark aspects there are; geological heritage; geo-conservation activities; sustainable tourism activities; educational; activities; community involvement products; strong management structure; and secure basis, infrastructure, and activities. The results of this study indicate that the Bakkara has the potential to become a tourist destination by applying the concept of Geotourism which accentuate its natural side, by optimizing the management of its destination attractions, its facilities and services, and its accessibilities.

Carbon Sequestration in Colorado's Lands: A Spatial and Policy Analysis

Science.gov (United States)

Brandt, N.; Brazeau, A.; Browning, K.; Meier, R.

2017-12-01

Managing landscapes to enhance terrestrial carbon sequestration has significant potential to mitigate climate change. While a previous carbon baseline assessment in Colorado has been published (Conant et al, 2007), our study pulls from the existing literature to conduct an updated baseline assessment of carbon stocks and a unique review of carbon policies in Colorado. Through a multi-level spatial analysis based in GIS and informed by a literature review, we established a carbon stock baseline and ran four land use and carbon stock projection scenarios using Monte Carlo simulations. We identified 11 key policy recommendations for improving Colorado's carbon stocks, and evaluated each using Bardach's policy matrix approach (Bardach, 2012). We utilized a series of case studies to support our policy recommendations. We found that Colorado's lands have a carbon stock of 3,334 MMT CO2eq, with Forests and Woodlands holding the largest stocks, at 1,490 and 774 MMT CO2eq respectively. Avoided conversion of all Grasslands, Forests, and Wetlands in Colorado projected over 40 years would increase carbon stocks by 32 MMT CO2eq, 1,053 MMT CO2eq, and 36 MMT CO2eq, respectively. Over the 40-year study period, Forests and Woodlands areas are projected to shrink while Shrublands and Developed areas are projected to grow. Those projections suggest sizable increases in area of future wildfires and development in Colorado. We found that numerous policy opportunities to sequester carbon exist at different jurisdictional levels and across land cover types. The largest opportunities were found in state-level policies and policies impacting Forests, Grasslands, and Wetlands. The passage of statewide emission reduction legislation has the highest potential to impact carbon sequestration, although political and administrative feasibility of this option are relatively low. This study contributes to the broader field of carbon sequestration literature by examining the nexus of carbon stocks

The Colorado Front Range Ecosystem Management Research Project: Accomplishments to date

Science.gov (United States)

Brian Kent; Wayne D. Shepperd; Deborah J. Shields

2000-01-01

This article briefly describes the goals and objectives for the Colorado Front Range Ecosystem Management Project (FREM). Research under this project has addressed both biophysical and human dimensions problems relating to ecosystem management in the Colorado Front Range. Results of completed work are described, and the status of the ongoing demonstration project at...

Colorado family physicians' attitudes toward medical marijuana.

Science.gov (United States)

Kondrad, Elin; Reid, Alfred

2013-01-01

Over the last decade, the use of medical marijuana has expanded dramatically; it is now permitted in 16 states and the District of Columbia. Our study of family physicians in Colorado is the first to gather information about physician attitudes toward this evolving practice. We distributed an anonymous web-based electronic survey to the 1727 members of the Colorado Academy of Family Physicians' listserv. Items included individual and practice characteristics as well as experience with and attitudes toward medical marijuana. Five hundred twenty family physicians responded (30% response rate). Of these, 46% did not support physicians recommending medical marijuana; only 19% thought that physicians should recommend it. A minority thought that marijuana conferred significant benefits to physical (27%) and mental (15%) health. Most agreed that marijuana poses serious mental (64%) and physical (61%) health risks. Eighty-one percent agreed that physicians should have formal training before recommending medical marijuana, and 92% agreed that continuing medical education about medical marijuana should be available to family physicians. Despite a high prevalence of use in Colorado, most family physicians are not convinced of marijuana's health benefits and believe its use carries risks. Nearly all agreed on the need for further medical education about medical marijuana.

Deformation regime and long-term precursors to eruption at large calderas: Rabaul, Papua New Guinea

Science.gov (United States)

Robertson, Robert M.; Kilburn, Christopher R. J.

2016-03-01

Eruptions at large calderas are normally preceded by variable rates of unrest that continue for decades or more. A classic example is the 1994 eruption of Rabaul caldera, in Papua New Guinea, which began after 23 years of surface uplift and volcano-tectonic (VT) seismicity at rates that changed unevenly with time by an order of magnitude. Although the VT event rate and uplift rate peaked in 1983-1985, eruptions only began a decade later and followed just 27 hours of anomalous changes in precursory signal. Here we argue that the entire 23 years of unrest belongs to a single sequence of damage accumulation in the crust and that, in 1991-1992, the crust's response to applied stress changed from quasi-elastic (elastic deformation with minor fault movement) to inelastic (deformation predominantly by fault movement alone). The change in behaviour yields limiting trends in the variation of VT event rate with deformation and can be quantified with a mean-field model for an elastic crust that contains a dispersed population of small faults. The results show that identifying the deformation regime for elastic-brittle crust provides new criteria for using precursory time series to evaluate the potential for eruption. They suggest that, in the quasi-elastic regime, short-term increases in rates of deformation and VT events are unreliable indicators of an imminent eruption, but that, in the inelastic regime, the precursory rates may follow hyperbolic increases with time and offer the promise of developing forecasts of eruption as much as months beforehand.

Viscoelastic crustal deformation by magmatic intrusion: A case study in the Kutcharo caldera, eastern Hokkaido, Japan

Science.gov (United States)

Yamasaki, Tadashi; Kobayashi, Tomokazu; Wright, Tim J.; Fukahata, Yukitoshi

2018-01-01

Geodetic signals observed at volcanoes, particularly their temporal patterns, have required us to make the correlation between the surface displacement and magmatic process at depth in terms of viscoelastic crustal rheology. Here we use a parallelized 3-D finite element model to examine the response of the linear Maxwell viscoelastic crust and mantle to the inflation of a sill in order to show the characteristics of a long-term volcano deformation. In the model, an oblate-spheroidal sill is instantaneously or gradually inflated in a two-layered medium that consists of an elastic layer underlain by a viscoelastic layer. Our numerical experiments show that syn-inflation surface uplift is followed by post-inflation surface subsidence as the viscoelastic substrate relaxes. For gradual inflation events, the magnitude of inflation-induced uplift is reduced by the relaxation, through which the volume of a magma inferred by matching the prediction of an elastic model with observed surface uplift could be underestimated. For a given crustal viscosity, sill depth is the principal factor controlling subsidence caused by viscoelastic relaxation. The subsidence rate is highest when the inflation occurs at the boundary between the elastic and the viscoelastic layers. The mantle viscosity has an insignificant impact unless the depth of the inflation is greater than a half the crustal thickness. We apply the viscoelastic model to the interferometric synthetic aperture radar (InSAR) data in the Kutcharo caldera, eastern Hokkaido, Japan, where the surface has slowly subsided over a period of approximately three years following about a two-year period of inflation. The emplacement of a magmatic sill is constrained to occur at a depth of 4.5 km, which is significantly shallower than the geophysically imaged large-scale magma chamber. The geodetically detected deformation in the caldera reflects the small-scale emplacement of a magma that ascended from the deeper chamber, but not the

Native gold and gold-rich sulfide deposits in a submarine basaltic caldera, Higashi-Aogashima hydrothermal field, Izu-Ogasawara frontal arc, Japan

Science.gov (United States)

Iizasa, Kokichi; Asada, Akira; Mizuno, Katsunori; Katase, Fuyuki; Lee, Sangkyun; Kojima, Mitsuhiro; Ogawa, Nobuhiro

2018-04-01

Sulfide deposits with extremely high Au concentrations (up to 275 ppm; avg. 102 ppm, n = 15), high Au/Ag ratios (0.24, n = 15), and low Cu/(Cu + Zn) ratios (0.03, n = 15) were discovered in 2015 in active hydrothermal fields at a water depth of 760 m in a basalt-dominated submarine caldera in the Izu-Ogasawara frontal arc, Japan. Native gold grains occur in massive sulfide fragments, concretions, and metalliferous sediments from a sulfide mound (40 m across and 20 m high) with up to 30-m-high black smoker chimneys. Tiny native gold grains up to 14 μm in diameter are mainly present in sulfide fallouts from chimney orifices and plumes. Larger native gold grains up to 150 μm long occur mostly as discrete particles and/or with amorphous silica and sulfides. The larger gold grains are interpreted to represent direct precipitation from Au-bearing hydrothermal fluids circulating in and/or beneath the unconsolidated sulfide mound deposits. Sulfur isotope compositions from a limited number of sulfide separates (n = 4) range from 4.3 to 5.8‰ δ34S, similar to the quaternary volcanic rocks of the arc. Barite separates have values of 22.2 and 23.1‰, close to modern seawater values, and indicate probable seawater sulfate origin. The Cu, Zn, and Pb concentrations in bulk samples of sulfide-rich rocks are similar to those of volcanogenic massive sulfides formed in continental crustal environments. The gold is interpreted to have formed by low-temperature hydrothermal activity, perhaps genetically different from systems with documented magmatic contributions or from seafloor hydrothermal systems in other island arc settings. Its presence suggests that basalt-dominated submarine calderas situated on relatively thick continental crust in an intraoceanic arc setting such as the Higashi-Aogashima knoll caldera may be perspective for gold mineralization.

Measuring the Health of an Invisible Population: Lessons from the Colorado Transgender Health Survey.

Science.gov (United States)

Christian, Robin; Mellies, Amy Anderson; Bui, Alison Grace; Lee, Rita; Kattari, Leo; Gray, Courtney

2018-05-15

Transgender people, those whose gender identity does not match their sex assigned at birth, face barriers to receiving health care. These include discrimination, prohibitive cost, and difficulty finding transgender-inclusive providers. As transgender identities are not typically recognized in public health research, the ability to compare the health of the transgender population to the overall population is limited. The Colorado Transgender Health Survey sought to explore current disparities and their effects on the health of transgender people in Colorado. The Colorado Transgender Health Survey, based on the Behavioral Risk Factor Surveillance System (BRFSS), was developed by the Colorado Department of Public Health and Environment, transgender advocates, and transgender community members. Outreach was targeted to transgender-inclusive events and organizations. Responses to the 2014 Colorado Transgender Health Survey were compared side by side to Colorado 2014 BRFSS data. Results from 406 transgender or gender-nonconforming adults who live in Colorado were included in the analysis. Forty percent of respondents report delaying medical care due to cost, inadequate insurance, and/or fear of discrimination. Respondents report significant mental health concerns, with 43% reporting depression, 36% reporting suicidal thoughts, and 10% attempting suicide in the past year. Respondents with a transgender-inclusive provider were more likely to receive wellness exams (76 versus 48%), less likely to delay care due to discrimination (24 versus 42%), less depressed (38 versus 54%), and less likely to attempt suicide (7 versus 15%) than those without. The transgender community in Colorado faces significant disparities, especially around mental health. However, a transgender-inclusive provider is associated with improved mental and physical health and health behaviors. Further population-level research and provider education on transgender health should to be incorporated into

Cost-Effectiveness Analysis of the Residential Provisions of the 2015 IECC for Colorado

Energy Technology Data Exchange (ETDEWEB)

Mendon, Vrushali V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhao, Mingjie [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Taylor, Zachary T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Poehlman, Eric A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-02-15

The 2015 IECC provides cost-effective savings for residential buildings in Colorado. Moving to the 2015 IECC from the 2009 IECC base code is cost-effective for residential buildings in all climate zones in Colorado.

78 FR 50088 - Notice of Availability of the Northwest Colorado Greater Sage-Grouse Draft Resource Management...

Science.gov (United States)

2013-08-16

... Availability of the Northwest Colorado Greater Sage- Grouse Draft Resource Management Plan Amendment and Draft... Land Management (BLM) has prepared a Northwest Colorado Greater Sage-Grouse Draft Resource Management.../or mailings. ADDRESSES: You may submit comments related to the Northwest Colorado Greater Sage-Grouse...

77 FR 21760 - Atmos Energy Colorado/Kansas Division; Notice of Baseline Filing

Science.gov (United States)

2012-04-11

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PR12-19-000] Atmos Energy Colorado/Kansas Division; Notice of Baseline Filing Take notice that on March 30, 2012, Atmos Energy Colorado/Kansas Division (Atmos) submitted a baseline filing of their Statement of Operating Conditions for...

Colorado Plateau magmatism and uplift by warming of heterogeneous lithosphere.

Science.gov (United States)

Roy, Mousumi; Jordan, Thomas H; Pederson, Joel

2009-06-18

The forces that drove rock uplift of the low-relief, high-elevation, tectonically stable Colorado Plateau are the subject of long-standing debate. While the adjacent Basin and Range province and Rio Grande rift province underwent Cenozoic shortening followed by extension, the plateau experienced approximately 2 km of rock uplift without significant internal deformation. Here we propose that warming of the thicker, more iron-depleted Colorado Plateau lithosphere over 35-40 Myr following mid-Cenozoic removal of the Farallon plate from beneath North America is the primary mechanism driving rock uplift. In our model, conductive re-equilibration not only explains the rock uplift of the plateau, but also provides a robust geodynamic interpretation of observed contrasts between the Colorado Plateau margins and the plateau interior. In particular, the model matches the encroachment of Cenozoic magmatism from the margins towards the plateau interior at rates of 3-6 km Myr(-1) and is consistent with lower seismic velocities and more negative Bouguer gravity at the margins than in the plateau interior. We suggest that warming of heterogeneous lithosphere is a powerful mechanism for driving epeirogenic rock uplift of the Colorado Plateau and may be of general importance in plate-interior settings.

Agricultural water conservation programs in the lower Colorado River Authority

International Nuclear Information System (INIS)

Kabir, J.

1993-01-01

Rice irrigation is the largest user of water within the area served by the Lower Colorado River Authority (LCRA), accounting for approximately 75 percent of total annual surface and ground water demands. In an average year, about 30 percent of surface water supplied to rice irrigation is satisfied with water released from the storage in the Highland Lakes located at the upstream reaches of the Lower Colorado River and its tributaries. During a severe drought, the demand for stored water could be as much as 70 percent of annual rice irrigation demand. LCRA owns and operates two irrigation canal systems which together supply water to irrigate 60,000 acres of rice each year. These irrigation systems are the Lakeside and Gulf Coast Irrigation Divisions. The Lakeside system is located in Colorado and Wharton Counties and the Gulf Coast system is located in Wharton and Matagorda Counties. In the 1987 and 1989, the Lower Colorado River Authority Board of Directors authorized implementation and funding for Canal Rehabilitation Project and Irrigation Water Measurement Project respectively. These two projects are key initiatives to agricultural water conservation goals established in the LCRA Water Management Plan and Water Conservation Policy. In addition LCRA participated actively in agricultural water conservation research projects and technology transfer activities

Living with wildfire in Colorado

Science.gov (United States)

Patricia A. Champ; Nicholas Flores; Hannah Brenkert-Smith

2010-01-01

In this presentation, we describe results of a survey to homeowners living in wildfire-prone areas of two counties along the Front Range of the Rocky Mountains in Colorado. The survey was designed to elicit information on homeowners' experience with wildfire, perceptions of wildfire risk on their property and neighboring properties, mitigation efforts undertaken...

Colorado's prospectus on uranium milling

International Nuclear Information System (INIS)

Hazle, A.J.; Franz, G.A.; Gamewell, R.

1982-01-01

The first part of this paper will discuss Colorado's control of uranium mill tailings under Titles I and II of the Uranium Mill Tailings Radiation Control Act of 1978. Colorado has a legacy of nine inactive mill sites requiring reclamation under Title I, and two presently active plus a number of new mill proposals which must be regulated in accordance with Title II. Past failures in siting and control on the part of federal jurisdictions have left the state with a heavy legacy requiring extensive effort to address impacts to the state's environment and population. The second part of this paper will discuss the remedial action programme authorized under Public Law 92-314 for Mesa Country, where lack of federal control led to the dispersal of several hundred thousand tons of uranium mill tailings on thousands of properties, including hundreds of homes, schools and other structures. Successful completion of the State efforts under both programmes will depend on a high level of funding and on the maintenance of adequate regulatory standards. (author)

Energy Smart Colorado, Final Report

Energy Technology Data Exchange (ETDEWEB)

Gitchell, John M. [Program Administrator; Palmer, Adam L. [Program Manager

2014-03-31

Energy Smart Colorado is an energy efficiency program established in 2011 in the central mountain region of Colorado. The program was funded through a grant of $4.9 million, awarded in August 2010 by the U.S. Department of Energy’s Better Buildings Program. As primary grant recipient, Eagle County coordinated program activities, managed the budget, and reported results. Eagle County staff worked closely with local community education and outreach partner Eagle Valley Alliance for Sustainability (now Walking Mountains Science Center) to engage residents in the program. Sub-recipients Pitkin County and Gunnison County assigned local implementation of the program in their regions to their respective community efficiency organizations, Community Office for Resource Efficiency (CORE) in Pitkin County, and Office for Resource Efficiency (ORE) in Gunnison County. Utility partners contributed $166,600 to support Home Energy Assessments for their customers. Program staff opened Energy Resource Centers, engaged a network of qualified contractors, developed a work-flow, an enrollment website, a loan program, and a data management system to track results.

Biodiversity of Thermophilic Prokaryotes with Hydrolytic Activities in Hot Springs of Uzon Caldera, Kamchatka (Russia)▿ †

OpenAIRE

Kublanov, Ilya V.; Perevalova, Anna A.; Slobodkina, Galina B.; Lebedinsky, Aleksander V.; Bidzhieva, Salima K.; Kolganova, Tatyana V.; Kaliberda, Elena N.; Rumsh, Lev D.; Haertlé, Thomas; Bonch-Osmolovskaya, Elizaveta A.

2008-01-01

Samples of water from the hot springs of Uzon Caldera with temperatures from 68 to 87°C and pHs of 4.1 to 7.0, supplemented with proteinaceous (albumin, casein, or α- or β-keratin) or carbohydrate (cellulose, carboxymethyl cellulose, chitin, or agarose) biological polymers, were filled with thermal water and incubated at the same sites, with the contents of the tubes freely accessible to the hydrothermal fluid. As a result, several enrichment cultures growing in situ on different polymeric su...

30 CFR 906.20 - Approval of Colorado abandoned mine land reclamation plan.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 3 2010-07-01 2010-07-01 false Approval of Colorado abandoned mine land reclamation plan. 906.20 Section 906.20 Mineral Resources OFFICE OF SURFACE MINING RECLAMATION AND ENFORCEMENT, DEPARTMENT OF THE INTERIOR PROGRAMS FOR THE CONDUCT OF SURFACE MINING OPERATIONS WITHIN EACH STATE COLORADO...

Small Wind Turbine Applications: Current Practice in Colorado

International Nuclear Information System (INIS)

Green, Jim

1999-01-01

Numerous small wind turbines are being used by homeowners in Colorado. Some of these installations are quite recent while others date back to the federal tax-credit era of the early 1980s. Through visits with small wind turbine owners in Colorado, I have developed case studies of six small wind energy applications focusing on the wind turbine technology, wind turbine siting, the power systems and electric loads, regulatory issues, and motivations about wind energy. These case studies offer a glimpse into the current state-of-the-art of small-scale wind energy and provide some insight into issues affecting development of a wider market

Relationships between mineralization and silicic volcanism in the central Andes

Energy Technology Data Exchange (ETDEWEB)

Francis, P.W.; Halls, C.; Baker, M.C.W.

1983-10-01

Studies of late Tertiary silicic volcanic centers in the Western and Eastern Cordilleras of the Central Andes show that three volcanic environments are appropriate sites for mineralization: (1) ring-fracture extrusions post-dating large calderas; (2) similar extrusions within ignimbrite shields; and (3) isolated, small silicic volcanoes. Subvolcanic tin mineralization in the Eastern Cordillera is located in silicic stocks and associated breccias of Miocene age. The Cerro Rico stock, Potosi, Bolivia, contains tin and silver mineralization and has an intrusion age apparently millions of years younger than that of the associated Kari Kari caldera. Similar age relationships between mineralization and caldera formation have been described from the San Juan province, Colorado. The vein deposits of Chocaya, southern Bolivia, were emplaced in the lower part of an ignimbrite shield, a type of volcanic edifice as yet unrecognized in comparable areas of silicic volcanism. The El Salvador porphyry copper deposit, Chile, is related to silicic stocks which may have been intruded along a caldera ring fracture. Existing models for the genesis of porphyry copper deposits suggest that they formed in granodioritic stocks located in the infrastructure of andesitic stratovolcanoes. The dome of La Soufriere, Guadeloupe is proposed as a modern analog for the surface expression of subvolcanic mineralization processes, the phreatic eruptions there suggesting the formation of hydrothermal breccia bodies in depth.

Business Metrics for High-Performance Homes: A Colorado Springs Case Study

Energy Technology Data Exchange (ETDEWEB)

Beach, R. [IBACOS, Inc., Pittsburgh, PA (United States); Jones, A. [IBACOS, Inc., Pittsburgh, PA (United States)

2016-04-26

The building industry needs to understand how energy ratings can impact homebuilders. Of interest is how energy efficiency may or may not have a positive impact on homebuilders’ business success. Focusing on Colorado Springs, Colorado, as a case study, the U.S. Department of Energy’s Building America research team IBACOS suggests a win–win between a builder’s investment in energy efficiency and that builder’s ability to sell homes. Although this research did not ultimately determine why a correlation may exist, a builder’s investment in voluntary energy-efficiency programs correlated with that builder’s ability to survive the Great Recession of 2007 to 2009. This report explores the relationship between energy-efficiency ratings and the market performance of several builders in Colorado Springs.

Los 'Colorados': Etnohistoria y Toponimia

NARCIS (Netherlands)

Gómez-Rendón, J.

2015-01-01

Los "colorados" comprendían varios grupos étnicos emparentados etnolingüísticamente que ocupaban el piedemonte andino occidental desde El Carchi hasta Bolívar así como las tierras bajas del Pacífico en los sistemas hidrográficos de los ríos Esmeraldas y Guayas. Aunque la ocupación "colorada" de

Decay of aspen in Colorado

Science.gov (United States)

Ross W. Davidson; Thomas E. Hinds; Frank G. Hawksworth

1959-01-01

Quaking aspen (Populus tremuloides Michx.) stands are extensive in the central Rocky Mountains. The species reaches its maximum development in the mountains and high mesas west of the Continental Divide in Colorado (Baker, 1925). On the better sites aspen yields a greater volume of wood in a shorter period than most of the conifers growing at comparable elevations. The...

Reducing Energy Burden with Solar: Colorado's Strategy and Roadmap for States

Energy Technology Data Exchange (ETDEWEB)

Cook, Jeffrey J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Shah, Monisha [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2018-03-03

The Colorado Energy Office (CEO) recently implemented a multi-pronged strategy to reduce energy burden for low-income (LI) Colorado residents through the deployment of solar electricity generation. Due to these efforts, approximately 20 MW of photovoltaic (PV) solar may be deployed in Colorado by the end of 2019 specifically for low-income households. Relying on interviews with ten subject-matter experts and other research, this report outlines the details of the CEO strategy including why the agency pursued this strategy, how it was carried out, and lessons learned from implementation. Though CEO's strategy is unique and tailored to the needs of Colorado, it is possible that other states might learn from CEO's experiences when designing their own LI strategies. As a result, the report concludes by outlining six primary steps for designing a comprehensive low-income solar strategy.

Ground deformation at collapse calderas: influence of host rock lithology and reservoir multiplicity

Energy Technology Data Exchange (ETDEWEB)

Geyer, A; Gottsmann, J [Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queen' s Road, BS8 1RJ, Bristol (United Kingdom)], E-mail: A.GeverTraver@bristol.ac.uk

2008-10-01

A variety of source mechanisms have been proposed to account for observed caldera deformation. Here we present a systematic set of new results from numerical forward modelling using a Finite Element Method. which provides a link between measured ground deformation and the inaccessible deformation source. We simulate surface displacements due to pressure changes in a shallow oblate reservoir overlain by host rock with variable mechanical properties. We find that the amplitude and wavelength of resultant ground deformation is dependent on the distribution of mechanically stiff and soft lithologies and their relative distribution above a reservoir. In addition, we note an influence of layering on the critical ratio of horizontal over vertical displacements, a criterion employed to discriminate between different finite source geometries.

76 FR 76109 - Colorado Regulatory Program

Science.gov (United States)

2011-12-06

... its program to improve operational efficiency. This document gives the times and locations that the... the amendment during regular business hours at the following locations: Kenneth Walker, Chief, Denver... available for you to read at the locations listed above under ADDRESSES. Specifically, Colorado proposes...

Economic impact study of the Uranium Mill Tailings Remedial Action project in Colorado: Colorado state fiscal year 1995. Revision 1

International Nuclear Information System (INIS)

1995-12-01

As required by the Romer-Twining Agreement of 1990, the US Department of Energy (DOE) has prepared this annual economic impact study for the state of Colorado. This report assesses the economic impacts related to the DOE Uranium Mill Tailings Remedial Action (UMTRA) Project in Colorado during the state fiscal year (FY) between 1 July 1994 and 30 June 1995. To estimate net economic benefit, employment, salaries and wages, and other related economic benefits are discussed, quantified, and then compared to the state's 10 percent share of the remedial action costs. Actual data obtained from sites currently undergoing remedial action were used as the basis for analyses. If data were not available, estimates were used to derive economic indicators. This study describes the types of employment associated with the UMTRA Project and estimates of the numbers of people employed by UMTRA Project subcontractors in Colorado during state FY 1995. Employment totals are reported in estimated average annual jobs; however, the actual number of workers at the site fluctuates depending on weather and on the status of remedial action activities. In addition, the actual number of people employed on the Project during the year may be higher than the average annual employment reported due to the temporary nature of some of the jobs

The Colorado River and its deposits downstream from Grand Canyon in Arizona, California, and Nevada

Science.gov (United States)

Crow, Ryan S.; Block, Debra L.; Felger, Tracey J.; House, P. Kyle; Pearthree, Philip A.; Gootee, Brian F.; Youberg, Ann M.; Howard, Keith A.; Beard, L. Sue

2018-02-05

Understanding the evolution of the Colorado River system has direct implications for (1) the processes and timing of continental-scale river system integration, (2) the formation of iconic landscapes like those in and around Grand Canyon, and (3) the availability of groundwater resources. Spatial patterns in the position and type of Colorado River deposits, only discernible through geologic mapping, can be used to test models related to Colorado River evolution. This is particularly true downstream from Grand Canyon where ancestral Colorado River deposits are well-exposed. We are principally interested in (1) regional patterns in the minimum and maximum elevation of each depositional unit, which are affected by depositional mechanism and postdepositional deformation; and (2) the volume of each unit, which reflects regional changes in erosion, transport efficiency, and accommodation space. The volume of Colorado River deposits below Grand Canyon has implications for groundwater resources, as the primary regional aquifer there is composed of those deposits. To this end, we are presently mapping Colorado River deposits and compiling and updating older mapping. This preliminary data release shows the current status of our mapping and compilation efforts. We plan to update it at regular intervals in conjunction with ongoing mapping.

BLM Colorado Oil & Gas Geophysical Permits (Dissolved)

Data.gov (United States)

Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

BLM Colorado Oil and Gas Leases (Dissolved)

Data.gov (United States)

Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

BLM Colorado Oil and Gas Units (Dissolve)

Data.gov (United States)

Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

Die vraag na die noodsaaklikheid van 'n eietydse belydenis: Nuwe Testamenties en hermeneuties beoordeel

Directory of Open Access Journals (Sweden)

G. M.M. Pelser

1999-12-01

Full Text Available The question regarding the need for a contemporary creed: Argued from a New Testament and hermeneutieal perspective. As indicated in the title of this study, what is in essence at issue here is the quesion as to whether there is a need for a creed to be contemporaneous with the day and age the church finds itself in. It is argued that to produce a creed in accordance with current hermeneutieal insights is much more difficult than the way in which the existing creeds were created. It is therefore further argued that, for a creed to junction as it ought to, it should in the first place be the result of an interpretation of the Biblical text(s on the basis of current hermeneutieal theory and practice, and in the second place be a means for expressing one's faith in a meaningful way in every life situation or faith experience. To this end a creed should be contemporaneous with each and every situation encountered by the individual believer or community of faith.

Dynamics Days US 2013 Conference Held in Denver, Colorado on 3-6 January 2013. Abstracts

Science.gov (United States)

2013-12-17

down before population collapse using replicate laboratory populations of the budding yeast Saccharomyces cerevisiae. We mapped the bifurcation diagram...agreement with the theory. Furthermore, we connected yeast populations spatially to evaluate warning signals based on spatio-temporal fluctuations...Colorado School of Mines $125 ARO 54 Franson, Andrew U Colorado School of Mines $125 ARO 55 Slater, Michael U Colorado School of Mines $125 ARO 56 Brewer

Debris Flow Occurrence and Sediment Persistence, Upper Colorado River Valley, CO.

Science.gov (United States)

Grimsley, K J; Rathburn, S L; Friedman, J M; Mangano, J F

2016-07-01

Debris flow magnitudes and frequencies are compared across the Upper Colorado River valley to assess influences on debris flow occurrence and to evaluate valley geometry effects on sediment persistence. Dendrochronology, field mapping, and aerial photographic analysis are used to evaluate whether a 19th century earthen, water-conveyance ditch has altered the regime of debris flow occurrence in the Colorado River headwaters. Identifying any shifts in disturbance processes or changes in magnitudes and frequencies of occurrence is fundamental to establishing the historical range of variability (HRV) at the site. We found no substantial difference in frequency of debris flows cataloged at eleven sites of deposition between the east (8) and west (11) sides of the Colorado River valley over the last century, but four of the five largest debris flows originated on the west side of the valley in association with the earthen ditch, while the fifth is on a steep hillslope of hydrothermally altered rock on the east side. These results suggest that the ditch has altered the regime of debris flow activity in the Colorado River headwaters as compared to HRV by increasing the frequency of debris flows large enough to reach the Colorado River valley. Valley confinement is a dominant control on response to debris flows, influencing volumes of aggradation and persistence of debris flow deposits. Large, frequent debris flows, exceeding HRV, create persistent effects due to valley geometry and geomorphic setting conducive to sediment storage that are easily delineated by valley confinement ratios which are useful to land managers.

A Collaborative Approach to Diabetes Management: The Choice Made for Colorado Schools

Science.gov (United States)

Bobo, Nichole; Wyckoff, Leah; Patrick, Kathleen; White, Cathy; Glass, Sue; Carlson, Jessie Parker; Perreault, Christine

2011-01-01

Students with diabetes deserve a school nurse who can effectively manage the disease. Tensions between the school and families sometimes emerge when a child with diabetes goes to school. To resolve these tensions in Colorado, stakeholders collaborated to implement a statewide program to meet the needs of students with diabetes. Colorado school…

Literacy in a Bag: Colorado School for the Deaf Sends Reading Home

Science.gov (United States)

Branch, Deborah

2009-01-01

To assist parents with deaf or hard of hearing children who may need help supporting their child's learning, the Colorado School for the Deaf and the Blind developed Family Literacy Packs. These literacy packs, available to families within the state of Colorado, provide fun, interactive activities that help parents support their children's…

Uranium exploration of the Colorado Plateau: interim staff report

International Nuclear Information System (INIS)

1980-10-01

This report is an issue of the original draft copy of the Interim Staff Report on Uranium Exploration on the Colorado Plateau, dated June 1951. The original draft copy was only recently located and is being published at this time because of the interest in the contained historical content. The table of contents of this report lists: history of uranium mining; geology; proposed program for the geologic investigations section; general activities of industry and government; and future exploration of sedimentary uranium deposits and anticipated results. Under the proposed program section are: future of the copper-uranium deposits as a source of uranium; uraniferous asphaltite deposits; and commission exploration and future possibilities. The section on general activities of industry and government includes: exploratory and development drilling; field investigations and mapping; early geologic investigations and investigations by the US geological survey; and geophysical exploration. Tables are also presented on: uranium production by districts; US Geological survey drilling statistics; Colorado Exploration Branch drilling statistics; summary of drilling projects; and comparative yearly core-drill statistics on the Colorado Plateau

Denver Radium Boom and the Colorado School of Mines

International Nuclear Information System (INIS)

Hart, S.S.

1986-01-01

The November 7, 1985, Rocky Mountain News, proclaimed Radiation hot spot detected at Mines. This hot spot discovery was the result of investigative reports by a local television station, with follow-up radiation monitoring by the Colorado Department of Health. Not an isolated occurrence of alpha and gamma radiation contamination, the School of Mines discovery is only the latest in a five-year series of discoveries of radioactive waste disposal sites in the Denver metropolitan area. These discoveries have involved not only the Colorado Department of Health, but also the Environmental Protection Agency, at least five consulting firms, and numerous businessmen and homeowners. In 1982, the sites were combined into a single project called the Denver Radium Site and selected for clean-up under the Federal Superfund program. This paper reviews the historical aspects of these hot spots by describing the history of radium processing in Denver; early work of the Colorado School of Mines, National Radium Institute, the Golden Experiment Station, and other institutional research; and the commercial production of radium. 20 references

BLM Colorado Oil & Gas Geophysical Permits (Dissolved)

Data.gov (United States)

Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

BLM Colorado Oil and Gas Leases (Dissolved)

Data.gov (United States)

Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

BLM Colorado Oil and Gas Units (Dissolve)

Data.gov (United States)

Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

Estimated Colorado Golf Course Irrigation Water Use, 2005

Science.gov (United States)

Ivahnenko, Tamara

2009-01-01

Golf course irrigation water-use data were collected as part of the U.S. Geological Survey National Water Use Program's 2005 compilation to provide baseline information, as no golf course irrigation water-use data (separate from crop irrigation) have been reported in previous compilations. A Web-based survey, designed by the U.S. Geological Survey, in cooperation with the Rocky Mountain Golf Course Superintendents Association (RMGCSA), was electronically distributed by the association to the 237 members in Colorado. Forty-three percent of the members returned the survey, and additional source water information was collected by telephone for all but 20 of the 245 association member and non-member Colorado golf courses. For golf courses where no data were collected at all, an average 'per hole' coefficient, based on returned surveys from that same county, were applied. In counties where no data were collected at all, a State average 'per hole' value of 13.2 acre-feet was used as the coefficient. In 2005, Colorado had 243 turf golf courses (there are 2 sand courses in the State) that had an estimated 2.27 acre-feet per irrigated course acre, and 65 percent of the source water for these courses was surface water. Ground water, potable water (public supply), and reclaimed wastewater, either partially or wholly, were source waters for the remaining courses. Fifty-three of the 64 counties in Colorado have at least one golf course, with the greatest number of courses in Jefferson (23 courses), Arapahoe (22 courses), and El Paso Counties (20 courses). In 2005, an estimated 5,647.8 acre-feet in Jefferson County, 5,402 acre-feet in Arapahoe County, and 4,473.3 acre-feet in El Paso County were used to irrigate the turf grass.

Regional analysis of tertiary volcanic Calderas (western U.S.) using Landsat Thematic Mapper imagery

Science.gov (United States)

Spatz, David M.; Taranik, James V.

1989-01-01

The Landsat Thematic Mapper (TM) imagery of the Basin and Range province of southern Nevada was analyzed to identify and map volcanic rock assemblages at three Tertiary calderas. It was found that the longer-wavelength visible and the NIR TM Bands 3, 5, and 7 provide more effective lithologic discrimination than the shorter-wavelength bands, due partly to deeper penetration of the longer-wavelength bands, resulting in more lithologically driven radiances. Shorter-wavelength TM Bands 1 and 2 are affected more by surficial weathering products including desert varnish which may or may not provide an indirect link to lithologic identity. Guidelines for lithologic analysis of volcanic terrains using Landsat TM imagery are outlined.

Fluid geochemistry and soil gas fluxes (CO2-CH4-H2S) at a promissory Hot Dry Rock Geothermal System: The Acoculco caldera, Mexico

Science.gov (United States)

Peiffer, L.; Bernard-Romero, R.; Mazot, A.; Taran, Y. A.; Guevara, M.; Santoyo, E.

2014-09-01

The Acoculco caldera has been recognized by the Mexican Federal Electricity Company (CFE) as a Hot Dry Rock Geothermal System (HDR) and could be a potential candidate for developing an Enhanced Geothermal System (EGS). Apart from hydrothermally altered rocks, geothermal manifestations within the Acoculco caldera are scarce. Close to ambient temperature bubbling springs and soil degassing are reported inside the caldera while a few springs discharge warm water on the periphery of the caldera. In this study, we infer the origin of fluids and we characterize for the first time the soil degassing dynamic. Chemical and isotopic (δ18O-δD) analyses of spring waters indicate a meteoric origin and the dissolution of CO2 and H2S gases, while gas chemical and isotopic compositions (N2/He, 3He/4He, 13C, 15N) reveal a magmatic contribution with both MORB- and arc-type signatures which could be explained by an extension regime created by local and regional fault systems. Gas geothermometry results are in agreement with temperature measured during well drilling (260 °C-300 °C). Absence of well-developed water reservoir at depth impedes re-equilibration of gases upon surface. A multi-gas flux survey including CO2, CH4 and H2S measurements was performed within the caldera. Using the graphical statistical analysis (GSA) approach, CO2 flux measurements were classified in two populations. Population A, representing 95% of measured fluxes is characterized by low values (mean: 18 g m- 2 day- 1) while the remaining 5% fluxes belonging to Population B are much higher (mean: 5543 g m- 2 day- 1). This low degassing rate probably reflects the low permeability of the system, a consequence of the intense hydrothermal alteration observed in the upper 800 m of volcanic rocks. An attempt to interpret the origin and transport mechanism of these fluxes is proposed by means of flux ratios as well as by numerical modeling. Measurements with CO2/CH4 and CO2/H2S flux ratios similar to mass ratios

Validation studies on indexed sequential modeling for the Colorado River Basin

International Nuclear Information System (INIS)

Labadie, J.W.; Fontane, D.G.; Salas, J.D.; Ouarda, T.

1991-01-01

This paper reports on a method called indexed sequential modeling (ISM) that has been developed by the Western Area Power Administration to estimate reliable levels of project dependable power capacity (PDC) and applied to several federal hydro systems in the Western U.S. The validity of ISM in relation to more commonly accepted stochastic modeling approaches is analyzed by applying it to the Colorado River Basin using the Colorado River Simulation System (CRSS) developed by the U.S. Bureau of Reclamation. Performance of ISM is compared with results from input of stochastically generated data using the LAST Applied Stochastic Techniques Package. Results indicate that output generated from ISM synthetically generated sequences display an acceptable correspondence with results obtained from final convergent stochastically generated hydrology for the Colorado River Basin

Colorado Multicultural Resources for Arts Education: Dance, Music, Theatre, and Visual Art.

Science.gov (United States)

Cassio, Charles J., Ed.

This Colorado resource guide is based on the premise that the arts (dance, music, theatre, and visual art) provide a natural arena for teaching multiculturalism to students of all ages. The guide provides information to Colorado schools about printed, disc, video, and audio tape visual prints, as well as about individuals and organizations that…

PIEDRA WILDERNESS STUDY AREA, COLORADO.

Science.gov (United States)

Condon, Steven M.; Brown, S. Don

1984-01-01

The Pedra Wilderness Study Area, located approximately 30 mi northeast of Durango, Colorado, was evaluated for its mineral-resource potential. Geochemical and geophysical studies indicate little promise for the occurrence of mineral or energy resources in this area. This conclusion is supported by the findings of the earlier study and is suggested by the absence of significant mining activity in the area.

The historical distribution of Gunnison Sage-Grouse in Colorado

Science.gov (United States)

Braun, Clait E.; Oyler-McCance, Sara J.; Nehring, Jennifer A.; Commons, Michelle L.; Young, Jessica R.; Potter, Kim M.

2014-01-01

The historical distribution of Gunnison Sage-Grouse (Centrocercus minimus) in Colorado is described based on published literature, observations, museum specimens, and the known distribution of sagebrush (Artemisia spp.). Historically, Gunnison Sage-Grouse were widely but patchily distributed in up to 22 counties in south-central and southwestern Colorado. The historical distribution of this species was south of the Colorado-Eagle river drainages primarily west of the Continental Divide. Potential contact areas with Greater Sage-Grouse (C. urophasianus) were along the Colorado-Eagle river system in Mesa, Garfield, and Eagle counties, west of the Continental Divide. Gunnison Sage-Grouse historically occupied habitats that were naturally highly fragmented by forested mountains and plateaus/mesas, intermountain basins without robust species of sagebrush, and river systems. This species adapted to use areas with more deciduous shrubs (i.e., Quercus spp., Amelanchier spp., Prunus spp.) in conjunction with sagebrush. Most areas historically occupied were small, linear, and patchily distributed within the overall landscape matrix. The exception was the large intermountain basin in Gunnison, Hinsdale, and Saguache counties. The documented distribution east of the Continental Divide within the large expanse of the San Luis Valley (Alamosa, Conejos, Costilla, and Rio Grande counties) was minimal and mostly on the eastern, northern, and southern fringes. Many formerly occupied habitat patches were vacant by the mid 1940s with extirpations continuing to the late 1990s. Counties from which populations were recently extirpated include Archuleta and Pitkin (1960s), and Eagle, Garfield, Montezuma, and Ouray (1990s).

76 FR 70170 - Proposed Alternative Soils Standards for the Uravan, Colorado Uranium Mill

Science.gov (United States)

2011-11-10

..., Colorado Uranium Mill AGENCY: Nuclear Regulatory Commission. ACTION: Uranium milling alternative standards... Agreements to regulate uranium mill tailings (11e.(2) byproduct material). Six Agreement States have this... in Colorado are acceptable. Discussion The Uravan site began operations in 1912 as a radium mill and...

Rendimiento térmico de calderas bagaceras modernas en Tucumán, R. Argentina Thermal efficiency of modern bagasse boilers in Tucumán, Argentina

Directory of Open Access Journals (Sweden)

Federico J. Franck Colombres

2011-12-01

Full Text Available Se evaluaron tres calderas de vapor modernas instaladas en ingenios azucareros de Tucumán, R. Argentina, equipos que se encuadran dentro de las tecnologías de producción más limpia. Tomando como base la metodología de cálculo de la eficiencia térmica de generadores de vapor desarrollada en 2008 por la Sección Ingeniería y Proyectos Agroindustriales de la Estación Experimental Agroindustrial Obispo Colombres, y a partir de los datos recolectados por medio de mediciones y balances de materia y energía, se determinaron sus principales variables características de operación. Las eficiencias energéticas determinadas para cada una fueron del 73,5%; 75,2% y 77,3%. Se realizó además una comparación con las calderas de vapor convencionales y se determinó el ahorro de bagazo que puede obtenerse con las calderas modernas, el cual resultó ser de un 27,6%. Como una ventaja adicional, se hace mención a la posibilidad de mejora del rendimiento térmico del ciclo motriz de la planta, que viene acompañada con el aumento de la presión de trabajo de la caldera.Three modern steam boilers, installed in sugar mills in Tucumán, R. Argentina, to attain a cleaner production, were evaluated. Their major operating variables were determined using the methodology for calculating thermal efficiency of steam generators developed by Sección Ingeniería y Proyectos Agroindustriales of Estación Experimental Agroindustrial Obispo Colombres in 2008, and data obtained from measurements and material and energy balances. Energy efficiency values determined for each boiler were 73.5%, 75.2% and 77.3%, respectively. A comparison with conventional steam boilers was drawn and it was found that bagasse savings amounted to about 27.6% when modern boilers were used. The possibility of improving the thermal efficiency of the plant cycle by increasing boiler pressure is mentioned as an additional advantage.

Good Days on the Trail, 1938-1942: Film Footage of the Rocky Mountains, Colorado

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This film documents student hiking trips conducted by the University of Colorado at Boulder in the Rocky Mountains, Colorado, USA during the summers of 1938-1942....

Feeding stimulants for the colorado beetle

NARCIS (Netherlands)

Ritter, F.J.

1967-01-01

Potato leaf extract was fractionated and the fractions obtained were tested for their activity as feeding stimulants for Colorado beetle larvae. Also leaves and leaf extracts of different kinds of plants, as well as a number of known pure compounds and mixtures of them, were tested for this

78 FR 35743 - Irish Potatoes Grown in Colorado; Modification of the General Cull and Handling Regulation for...

Science.gov (United States)

2013-06-14

... IR] Irish Potatoes Grown in Colorado; Modification of the General Cull and Handling Regulation for.... SUMMARY: This interim rule modifies the size requirements for potatoes handled under the Colorado potato marketing order, Area No. 2 (order). The order regulates the handling of Irish potatoes grown in Colorado...

’n Oorsig oor die diakoniologiese rol van die Gereformeerde belydenisskrifte in kerkwees

Directory of Open Access Journals (Sweden)

B. Spoelstra

1991-06-01

Full Text Available While theology usually concentrates on the history and content of the Reformational creeds, less systematised information is available about the ministry and service which these creeds should fulfil in the life of the church as believers. This study points to a consistent continuity in the way confessions of faith were used by the early Christians, the Reformers and in the creeds of the Reformation. The content of the Heidelberg Catechism in particular bears a remarkable correspondence to the tradition in the early churches. Creeds can only be confessions of faith if they communicate the revelation from Scriptures. If creeds function thus, the current widespread indifference to the practical use of even the Heidelberg Catechism in the practical world of the church must be ascribed to the illegitimate distinction which Rationalism draws between practical (or subjective and doctrinal (or objective theology.

76 FR 5432 - United Western Bank Denver, Colorado; Notice of Appointment of Receiver

Science.gov (United States)

2011-01-31

... DEPARTMENT OF THE TREASURY Office of Thrift Supervision United Western Bank Denver, Colorado... section 5(d)(2) of the Home Owners' Loan Act, the Office of Thrift Supervision has duly appointed the Federal Deposit Insurance Corporation as sole Receiver for United Western Bank, Denver, Colorado, (OTS No...

77 FR 23244 - Atmos Energy Colorado/Kansas Division; Notice of Revised Baseline Filing

Science.gov (United States)

2012-04-18

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. PR12-22-000] Atmos Energy Colorado/Kansas Division; Notice of Revised Baseline Filing Take notice that on April 10, 2012, Atmos Energy Colorado/Kansas Division (Atmos) filed a revised baseline filing of their Statement of Operating...

75 FR 17034 - Irish Potatoes Grown in Colorado; Relaxation of the Handling Regulation for Area No. 3

Science.gov (United States)

2010-04-05

...; FV09-948-2 IFR] Irish Potatoes Grown in Colorado; Relaxation of the Handling Regulation for Area No. 3...: This rule relaxes the size requirement prescribed under the Colorado potato marketing order. The marketing order regulates the handling of Irish potatoes grown in Colorado, and is administered locally by...

78 FR 77397 - Flood Control Regulations, Marshall Ford Dam (Mansfield Dam and Lake Travis), Colorado River, Texas

Science.gov (United States)

2013-12-23

... Regulations, Marshall Ford Dam (Mansfield Dam and Lake Travis), Colorado River, Texas AGENCY: U.S. Army Corps... Marshall Ford Dam (Mansfield Dam and Lake Travis), Colorado River, Texas. In 1997, the Lower Colorado River... regulations to reflect changes in ownership and responsibilities of flood control management of Marshall Ford...

Surface Chloride Levels in Colorado Structural Concrete

Science.gov (United States)

2018-01-01

This project focused on the chloride-induced corrosion of reinforcing steel in structural concrete. The primary goal of this project is to analyze the surface chloride concentration level of the concrete bridge decks throughout Colorado. The study in...

Measurement of flows for two irrigation districts in the lower Colorado River basin, Texas

Science.gov (United States)

Coplin, L.S.; Liscum, Fred; East, J.W.; Goldstein, L.B.

1996-01-01

The Lower Colorado River Authority sells and distributes water for irrigation of rice farms in two irrigation districts, the Lakeside district and the Gulf Coast district, in the lower Colorado River Basin of Texas. In 1993, the Lower Colorado River Authority implemented a water-measurement program to account for the water delivered to rice farms and to promote water conservation. During the rice-irrigation season (summer and fall) of 1995, the U.S. Geological Survey measured flows at 30 sites in the Lakeside district and 24 sites in the Gulf Coast district coincident with Lower Colorado River Authority measuring sites. In each district, the Survey made essentially simultaneous flow measurements with different types of meters twice a day once in the morning and once in the afternoon at each site on selected days for comparison with Lower Colorado River Authority measurements. One-hundred pairs of corresponding (same site, same date) Lower Colorado River Authority and U.S. Geological Survey measurements from the Lakeside district and 104 measurement pairs from the Gulf Coast district are compared statistically and graphically. For comparison, the measurement pairs are grouped by irrigation district and further subdivided by the time difference between corresponding measurements less than or equal to 1 hour or more than 1 hour. Wilcoxon signed-rank tests (to indicate whether two groups of paired observations are statistically different) on Lakeside district measurement pairs with 1 hour or less between measurements indicate that the Lower Colorado River Authority and U.S. Geological Survey measurements are not statistically different. The median absolute percent difference between the flow measurements is 5.9 percent; and 33 percent of the flow measurements differ by more than 10 percent. Similar statistical tests on Gulf Coast district measurement pairs with 1 hour or less between measurements indicate that the Lower Colorado River Authority and U.S. Geological

Crash Fatality Rates After Recreational Marijuana Legalization in Washington and Colorado.

Science.gov (United States)

Aydelotte, Jayson D; Brown, Lawrence H; Luftman, Kevin M; Mardock, Alexandra L; Teixeira, Pedro G R; Coopwood, Ben; Brown, Carlos V R

2017-08-01

To evaluate motor vehicle crash fatality rates in the first 2 states with recreational marijuana legalization and compare them with motor vehicle crash fatality rates in similar states without recreational marijuana legalization. We used the US Fatality Analysis Reporting System to determine the annual numbers of motor vehicle crash fatalities between 2009 and 2015 in Washington, Colorado, and 8 control states. We compared year-over-year changes in motor vehicle crash fatality rates (per billion vehicle miles traveled) before and after recreational marijuana legalization with a difference-in-differences approach that controlled for underlying time trends and state-specific population, economic, and traffic characteristics. Pre-recreational marijuana legalization annual changes in motor vehicle crash fatality rates for Washington and Colorado were similar to those for the control states. Post-recreational marijuana legalization changes in motor vehicle crash fatality rates for Washington and Colorado also did not significantly differ from those for the control states (adjusted difference-in-differences coefficient = +0.2 fatalities/billion vehicle miles traveled; 95% confidence interval = -0.4, +0.9). Three years after recreational marijuana legalization, changes in motor vehicle crash fatality rates for Washington and Colorado were not statistically different from those in similar states without recreational marijuana legalization. Future studies over a longer time remain warranted.

78 FR 3 - Irish Potatoes Grown in Colorado; Modification of the Handling Regulation for Area No. 2

Science.gov (United States)

2013-01-02

...; FV12-948-1 IR] Irish Potatoes Grown in Colorado; Modification of the Handling Regulation for Area No. 2...: This rule modifies the grade requirements for potatoes handled under the Colorado potato marketing order, Area No. 2 (order). The order regulates the handling of Irish potatoes grown in Colorado and is...

2014 Kids Count in Colorado! The Big Picture: Taking the Whole Child Approach to Child Well-Being

Science.gov (United States)

Colorado Children's Campaign, 2014

2014-01-01

"Kids Count in Colorado!" is an annual publication of the Colorado Children's Campaign, which provides the best available state- and county-level data to measure and track the education, health and general well-being of the state's children. "Kids Count in Colorado!" informs policy debates and community discussions, serving as…

Remedial action plan for the inactive uranium processing site at Naturita, Colorado. DOE responses to comments from U.S. Nuclear Regulatory Commission and Colorado Department of Public Health and Environment

International Nuclear Information System (INIS)

1998-01-01

This report contains responses by the US Department of Energy to comments from the US Nuclear Regulatory Commission and the Colorado Department of Public Health and Environment on the Naturita remedial action plan. This was done in an attempt to clarify information. The site is an inactive uranium processing site at Naturita, Colorado

Impact of energy development on water resources in the Upper Colorado River Basin. Completion report

International Nuclear Information System (INIS)

Flug, M.; Walker, W.R.; Skogerboe, G.V.; Smith, S.W.

1977-08-01

The Upper Colorado River Basin contains appreciable amounts of undeveloped coal, oil shale, and uranium resources, which are important in the national energy demand system. A mathematical model, which simulates the salt and water exchange phase of potential fuel conversions, has been developed, based on a subbasin analysis identifying available mineral and water resources. Potential energy developments are evaluated with respect to the resulting impacts upon both the quantity and salinity of the waters in the Colorado River. Model solutions are generated by use of a multilevel minimum cost linear programming algorithm, minimum cost referring to the cost of developing predetermined levels of energy output. Level one in the model analysis represents an aggregation of subbasins along state boundaries and thereby optimizes energy developments over the five states of the Upper Colorado River Basin. In each of the five second level problems, energy developments over a subbasin division within the respective states are optimized. Development policies which use high salinity waters of the Upper Colorado River enable a net salinity reduction to be realized in the Colorado River at Lee Ferry, Arizona

Zircon and whole-rock Zr/Hf ratios as markers of the evolution of granitic magmas: Examples from the Teplice caldera (Czech Republic/Germany)

Czech Academy of Sciences Publication Activity Database

Breiter, Karel; Škoda, R.

2017-01-01

Roč. 111, č. 4 (2017), s. 435-457 ISSN 0930-0708 R&D Projects: GA ČR GA14-13600S Institutional support: RVO:67985831 Keywords : Zr/Hf value * zircon * Teplice caldera * rhyolite * rare-metal granite * Cínovec deposit Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Mineralogy Impact factor: 1.236, year: 2016

Inferences on the hydrothermal system beneath the resurgent dome in Long Valley Caldera, east-central California, USA, from recent pumping tests and geochemical sampling

Science.gov (United States)

Farrar, Christopher D.; Sorey, Michael L.; Roeloffs, Evelyn; Galloway, Devin L.; Howle, James F.; Jacobson, Ronald

2003-10-01

Quaternary volcanic unrest has provided heat for episodic hydrothermal circulation in the Long Valley caldera, including the present-day hydrothermal system, which has been active over the past 40 kyr. The most recent period of crustal unrest in this region of east-central California began around 1980 and has included periods of intense seismicity and ground deformation. Uplift totaling more than 0.7 m has been centered on the caldera's resurgent dome, and is best modeled by a near-vertical ellipsoidal source centered at depths of 6-7 km. Modeling of both deformation and microgravity data now suggests that (1) there are two inflation sources beneath the caldera, a shallower source 7-10 km beneath the resurgent dome and a deeper source ˜15 km beneath the caldera's south moat and (2) the shallower source may contain components of magmatic brine and gas. The Long Valley Exploration Well (LVEW), completed in 1998 on the resurgent dome, penetrates to a depth of 3 km directly above this shallower source, but bottoms in a zone of 100°C fluid with zero vertical thermal gradient. Although these results preclude extrapolations of temperatures at depths below 3 km, other information obtained from flow tests and fluid sampling at this well indicates the presence of magmatic volatiles and fault-related permeability within the metamorphic basement rocks underlying the volcanic fill. In this paper, we present recently acquired data from LVEW and compare them with information from other drill holes and thermal springs in Long Valley to delineate the likely flow paths and fluid system properties under the resurgent dome. Additional information from mineralogical assemblages in core obtained from fracture zones in LVEW documents a previous period of more vigorous and energetic fluid circulation beneath the resurgent dome. Although this system apparently died off as a result of mineral deposition and cooling (and/or deepening) of magmatic heat sources, flow testing and tidal

Development of industrial minerals in Colorado

Science.gov (United States)

Arbogast, Belinda F.; Knepper, Daniel H.; Langer, William H.; Cappa, James A.; Keller, John W.; Widmann, Beth L.; Ellefsen, Karl J.; Klein, Terry L.; Lucius, Jeffrey E.; Dersch, John S.

2011-01-01

Technology and engineering have helped make mining safer and cleaner for both humans and the environment. Inevitably, mineral development entails costs as well as benefits. Developing a mine is an environmental, engineering, and planning challenge that must conform to many Federal, State, and local regulations. Community collaboration, creative design, and best management practices of sustainability and biodiversity can be positive indicators for the mining industry. A better understanding of aesthetics, culture, economics, geology, climate, vegetation and wildlife, topography, historical significance, and regional land planning is important in resolving land-use issues and managing mineral resources wisely. Ultimately, the consuming public makes choices about product use (including water, food, highways, housing, and thousands of other items) that influence operations of the mineral industry. Land planners, resource managers, earth scientists, designers, and public groups have a responsibility to consider sound scientific information, society's needs, and community appeals in making smart decisions concerning resource use and how complex landscapes should change. An effort to provide comprehensive geosciences data for land management agencies in central Colorado was undertaken in 2003 by scientists of the U.S. Geological Survey and the Colorado Geological Survey. This effort, the Central Colorado Assessment Project, addressed a variety of land-use issues: an understanding of the availability of industrial and metallic rocks and minerals, the geochemical and environmental effects of historic mining activity on surface water and groundwater, and the geologic controls on the availability and quality of groundwater. The USDA Forest Service and other land management agencies have the opportunity to contribute to the sustainable management of natural aggregate and other mineral resources through the identification and selective development of mineral resources and the

A Precise 6 Ma Start Date for Fluvial Incision of the Northeastern Colorado Plateau Canyonlands

Science.gov (United States)

Thomson, S. N.; Soreghan, G. S.; Reiners, P. W.; Peyton, S. L.; Murray, K. E.

2015-12-01

Outstanding questions regarding late Cenozoic Colorado Plateau landscape evolution include: (1) the relative roles of isostatic rebound as result Colorado River incision versus longer-term geodynamic processes in driving overall rock uplift of the plateau; and (2) whether incision was triggered by river integration or by a change in deep-seated mantle lithosphere dynamics. A key to answering these questions is to date more precisely the onset of incision to refine previous estimates of between 6 and 10 Ma. We present new low-temperature thermochronologic results from bedrock and deep borehole samples in the northeastern Colorado Plateau to show that rapid river incision began here at 6 Ma (5.93±0.66 Ma) with incision rates increasing from 15-50 m/Myr to 160-200 m/Myr. The onset time is constrained independently by both inverse time-temperature modeling and by the break-in-slope in fission track age-elevation relationships. This new time constraint has several important implications. First, the coincidence in time with 5.97-5.3 Ma integration of the lower Colorado River through the Grand Canyon to the Gulf of California strongly favors downstream river integration triggering carving of the canyonlands of the upper Colorado River system. Second, it implies integration of the entire Colorado River system in less than 2 million years. Third, rock uplift of the plateau driven by the flexural isostatic response to river incision is restricted to just the last 6 Ma, as is associated increased sediment budget. Fourth, incision starting at 6 Ma means that previous estimates of upper Colorado River incision rates based on 10-12 Ma basalt datum levels are too low. This also changes the dependency of measured time interval on incision rate from a non-steady-state negative power-law dependence (exponent of -0.24) to a near steady-state dependence (exponent of 0.07) meaning that long-term upper Colorado river incision rates can provide a reliable proxy for rock uplift rates.

Availability of Medical and Recreational Marijuana Stores and Neighborhood Characteristics in Colorado

OpenAIRE

Shi, Yuyan; Meseck, Kristin; Jankowska, Marta M.

2016-01-01

Objective. To examine the availability of marijuana stores in Colorado and associations with neighborhood characteristics. Methods. The addresses for 650 medical and recreational marijuana stores were geocoded and linked to the characteristics of 1249 census tracts in Colorado. Accounting for spatial autocorrelations, autologistic regressions were used to quantify the associations of census tract socioeconomic characteristics with the availability of marijuana stores. Results. Regardless of s...

Gunnison, Colorado subpile study report. Revision 1

International Nuclear Information System (INIS)

1994-08-01

To protect human health and the environment, the Uranium Mill Tailings Remedial Action (UMTRA) Project will remediate the uranium mill tailings site at Gunnison Colorado. There are explicit requirements (i.e., 40 CFR Part 192) for the surface remediation of radiologically contaminated soils on UMTRA sites. The removal of subpile sediment to the depth required by 40 CFR Part 192 will leave in place deeper foundation sediment that is contaminated with hazardous constituents other than radium-226 and thorium-230. The Department of Energy and the Colorado Department of Health have questioned whether this contaminated soil could potentially act as a continuing source of ground water contamination even after surface remediation based on 40 CFR Part 192 is complete. To evaluate the subpile sediments as a potential source of ground water contamination, the Gunnison Subpile study was initiated. This report summarizes the results and findings of this study

Documentation of input datasets for the soil-water balance groundwater recharge model of the Upper Colorado River Basin

Science.gov (United States)

Tillman, Fred D.

2015-01-01

The Colorado River and its tributaries supply water to more than 35 million people in the United States and 3 million people in Mexico, irrigating more than 4.5 million acres of farmland, and generating about 12 billion kilowatt hours of hydroelectric power annually. The Upper Colorado River Basin, encompassing more than 110,000 square miles (mi2), contains the headwaters of the Colorado River (also known as the River) and is an important source of snowmelt runoff to the River. Groundwater discharge also is an important source of water in the River and its tributaries, with estimates ranging from 21 to 58 percent of streamflow in the upper basin. Planning for the sustainable management of the Colorado River in future climates requires an understanding of the Upper Colorado River Basin groundwater system. This report documents input datasets for a Soil-Water Balance groundwater recharge model that was developed for the Upper Colorado River Basin.

Community-based restoration of desert wetlands: the case of the Colorado River delta

Science.gov (United States)

Osvel Hinojosa-Huerta; Mark Briggs; Yamilett Carrillo-Guerroro; Edward P. Glenn; Miriam Lara-Flores; Martha Roman-Rodriguez

2005-01-01

Wetland areas have been drastically reduced through the Pacific Flyway and the Sonoran Desert, with severe consequences for avian populations. In the Colorado River delta, wetlands have been reduced by 80 percent due to water management practices in the Colorado River basin. However, excess flows and agricultural drainage water has restored some areas, providing...

77 FR 21451 - Approval and Promulgation of Air Quality Implementation Plans; Colorado; Procedural Rules...

Science.gov (United States)

2012-04-10

... Promulgation of Air Quality Implementation Plans; Colorado; Procedural Rules; Conflicts of Interest AGENCY... potential conflicts of interest. We are also approving the remaining portion of Colorado's January 7, 2008... or more Indian tribes, on the relationship between the Federal Government and Indian tribes, or on...

Investigation of the enzyme system of detoxification of insecticides in the Colorado beetle

International Nuclear Information System (INIS)

Leonova, I.N.; Nedel'kina, S.V.; Salganik, R.I.

1986-01-01

The activity of three enzymes systems of xenobiotic metabolism - cytochrome P-450-dependent monooxygenases, nonspecific esterases, and glutathione S-transferases - was investigated at various stages of the development of the Colorado beetle Leptinotarsa decemlineata. Substantial sex and ontogenetic differences in the content of cytochrome P-450, the position of the maxima of the CO-differential spectra of its reduced form, and the substrate specificity of cytochrome P-450 were demonstrated. An increase in the activity of nonspecific esterases with increasing age of Colorado beetle larvae was observed. The insecticide 1-naphtholenol methylcarbamate, which is metabolized by the system of cytochrome P-450-dependent monooxygenases, is more toxic at the larval stage of development in comparison with the imaginal stage, which is in good agreement with the activity of this system at different stages of development. The inhibitor of microsomal monooxygenases piperonyl butoxide more than doubles the toxicity of the insecticide in the Colorado beetle imago. The data presented are evidence of a different contribution of the systems of detoxification to the sensitivity of the Colorado beetle to insecticides at different stages of metamorphosis

238U-230Th dating of chevkinite in high-silica rhyolites from La Primavera and Yellowstone calderas

Science.gov (United States)

Vazquez, Jorge A.; Velasco, Noel O.; Schmitt, Axel K.; Bleick, Heather A.; Stelten, Mark E.

2014-01-01

Application of 238U-230Th disequilibrium dating of accessory minerals with contrasting stabilities and compositions can provide a unique perspective on magmatic evolution by placing the thermochemical evolution of magma within the framework of absolute time. Chevkinite, a Th-rich accessory mineral that occurs in peralkaline and metaluminous rhyolites, may be particularly useful as a chronometer of crystallization and differentiation because its composition may reflect the chemical changes of its host melt. Ion microprobe 128U-230Th dating of single chevkinite microphenocrysts from pre- and post-caldera La Primavera, Mexico, rhyolites yields model crystallization ages that are within 10's of k.y. of their corresponding K-Ar ages of ca. 125 ka to 85 ka, while chevkinite microphenocrysts from a post-caldera Yellowstone, USA, rhyolite yield a range of ages from ca. 110 ka to 250 ka, which is indistinguishable from the age distribution of coexisting zircon. Internal chevkinite-zircon isochrons from La Primavera yield Pleistocene ages with ~5% precision due to the nearly two order difference in Th/U between both minerals. Coupling chevkinite 238U-230Th ages and compositional analyses reveals a secular trend of Th/U and rare earth elements recorded in Yellowstone rhyolite, likely reflecting progressive compositional evolution of host magma. The relatively short timescale between chevkinite-zircon crystallization and eruption suggests that crystal-poor rhyolites at La Primavera were erupted shortly after differentiation and/or reheating. These results indicate that 238U-230Th dating of chevkinite via ion microprobe analysis may be used to date crystallization and chemical evolution of silicic magmas.

Water quality and trend analysis of Colorado--Big Thompson system reservoirs and related conveyances, 1969 through 2000

Science.gov (United States)

Stevens, Michael R.

2003-01-01

The U.S. Geological Survey, in an ongoing cooperative monitoring program with the Northern Colorado Water Conservancy District, Bureau of Reclamation, and City of Fort Collins, has collected water-quality data in north-central Colorado since 1969 in reservoirs and conveyances, such as canals and tunnels, related to the Colorado?Big Thompson Project, a water-storage, collection, and distribution system. Ongoing changes in water use among agricultural and municipal users on the eastern slope of the Rocky Mountains in Colorado, changing land use in reservoir watersheds, and other water-quality issues among Northern Colorado Water Conservancy District customers necessitated a reexamination of water-quality trends in the Colorado?Big Thompson system reservoirs and related conveyances. The sampling sites are on reservoirs, canals, and tunnels in the headwaters of the Colorado River (on the western side of the transcontinental diversion operations) and the headwaters of the Big Thompson River (on the eastern side of the transcontinental diversion operations). Carter Lake Reservoir and Horsetooth Reservoir are off-channel water-storage facilities, located in the foothills of the northern Colorado Front Range, for water supplied from the Colorado?Big Thompson Project. The length of water-quality record ranges from approximately 3 to 30 years depending on the site and the type of measurement or constituent. Changes in sampling frequency, analytical methods, and minimum reporting limits have occurred repeatedly over the period of record. The objective of this report was to complete a retrospective water-quality and trend analysis of reservoir profiles, nutrients, major ions, selected trace elements, chlorophyll-a, and hypolimnetic oxygen data from 1969 through 2000 in Lake Granby, Shadow Mountain Lake, and the Granby Pump Canal in Grand County, Colorado, and Horsetooth Reservoir, Carter Lake, Lake Estes, Alva B. Adams Tunnel, and Olympus Tunnel in Larimer County, Colorado

BLM Colorado Oil and Gas Communitization Agreements (Dissolve)

Data.gov (United States)

Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

BLM Colorado Oil and Gas Storage Agreements (Dissolve)

Data.gov (United States)

Department of the Interior — Shapefile Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

Progress Report Phase I: Use, access, and fire/fuels management attitudes and preferences of user groups concerning the Valles Caldera National Preserve (VCNP) and adjacent areas

Science.gov (United States)

Kurt F. Anschuetz; Carol B. Raish

2010-01-01

This document represents a progress report of activities completed during Phase I of the study titled, Use, Access, and Fire/Fuels Management Attitudes and Preferences of User Groups Concerning the Valles Caldera National Preserve (VCNP) and Adjacent Areas, and the preliminary findings of this work.

Colorado Basin Structure and Rifting, Argentine passive margin

Science.gov (United States)

Autin, Julia; Scheck-Wenderoth, Magdalena; Loegering, Markus; Anka, Zahie; Vallejo, Eduardo; Rodriguez, Jorge; Marchal, Denis; Reichert, Christian; di Primio, Rolando

2010-05-01

The Argentine margin presents a strong segmentation with considerable strike-slip movements along the fracture zones. We focus on the volcanic segment (between the Salado and Colorado transfer zones), which is characterized by seaward dipping reflectors (SDR) all along the ocean-continent transition [e.g. Franke et al., 2006; Gladczenko et al., 1997; Hinz et al., 1999]. The segment is structured by E-W trending basins, which differs from the South African margin basins and cannot be explained by classical models of rifting. Thus the study of the relationship between the basins and the Argentine margin itself will allow the understanding of their contemporary development. Moreover the comparison of the conjugate margins suggests a particular evolution of rifting and break-up. We firstly focus on the Colorado Basin, which is thought to be the conjugate of the well studied Orange Basin [Hirsch et al., 2009] at the South African margin [e.g. Franke et al., 2006]. This work presents results of a combined approach using seismic interpretation and structural, isostatic and thermal modelling highlighting the structure of the crust. The seismic interpretation shows two rift-related discordances: one intra syn-rift and the break-up unconformity. The overlying sediments of the sag phase are less deformed (no sedimentary wedges) and accumulated before the generation of oceanic crust. The axis of the Colorado Basin trends E-W in the western part, where the deepest pre-rift series are preserved. In contrast, the basin axis turns to a NW-SE direction in its eastern part, where mainly post-rift sediments accumulated. The most distal part reaches the margin slope and opens into the oceanic basin. The general basin direction is almost orthogonal to the present-day margin trend. The most frequent hypothesis explaining this geometry is that the Colorado Basin is an aborted rift resulting from a previous RRR triple junction [e.g. Franke et al., 2002]. The structural interpretation

BLM Colorado Oil and Gas Communitization Agreements (Dissolve)

Data.gov (United States)

Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

BLM Colorado Oil and Gas Storage Agreements (Dissolve)

Data.gov (United States)

Department of the Interior — KMZ File Format –This data is one feature type that is a part of a set consisting of six shapefiles pertaining to energy development and production in Colorado. The...

Bibliography of theses and dissertations on Colorado, 1968-1980

International Nuclear Information System (INIS)

Anon.

1981-01-01

This thesis bibliography for Colorado is the sixth (of 14) state bibliographies to be published in The Mountain Geologist by the R.M.A.G. Titles Committee. In an effort to update existing thesis publications and publicize more current work in the western United States, this R.M.A.G. thesis study covers only the last decade's theses and dissertations, specifically the period from 1968-1980. A total of 440 (Colorado) masters theses and dissertations have been compiled in this R.M.A.G. study for this period. Of these, 104 cover general or regional topics. In these cases, the titles are designated in the listings with asterisks (*) and have not been plotted on the accompanying location maps

Application of 2-D Inversion, to Magnetotelluric data on the Newberry Caldera, Oregon, for Potential Geothermal Power

Science.gov (United States)

Martin, T. P.; Schultz, A.

2012-12-01

Newberry Volcano lies immediately to the east of the Cascades volcanic arc in Oregon. However, Newberry differs from the main Cascadia arc, both chemically and in its physical setting. Newberry was formed by a combination of a shallow mantle source hot spot and subduction melts. This conclusion is suggested by depleted 3He/4He ratios and enriched Ba, Sr and Pb, which together indicate an oceanic crust subduction melt. As a result Newberry cannot be only formed from a stationary deep mantle source, or any other fixed source. Newberry also lies at the westernmost extent of an E-W oriented volcanic belt that appears to terminate in the east with the hot spot trace of the Snake River Plain/Yellowstone. Newberry's complex structure is also attributed to its proximity to the northernmost end of the Brothers Fault Zone (BFZ), related to regional tectonic fabric attributable to the transition to the Basin and Range province. The most recent volcanism at the caldera is a large obsidian flow, which erupted approximately 1,300 years ago. The United States Geological Survey considers Newberry to be a very high threat and to be "Central Oregon's Sleeping Giant." The western outer flank of the caldera is the site of an Enhanced Geothermal System (EGS) demonstration project being carried out by AltaRock Energy, Inc. and Davenport Newberry Holdings, LLC. EGS injection well stimulation is planned to open up a fracture network in a hot but dry series of altered basaltic/andesitic formations 2000-3000 m below ground level. Under Department of Energy funding, a collaboration between Oregon State University, the Department of Energy's National Energy Technology Laboratory, and Zonge International, Inc., seeks to image changes in fluid infiltration and migration, changes in porosity and permeability, and ultimately changes in the geothermal reservoir's capacity to produce thermal energy for sustained periods in response to changes in reservoir pressurization and injection rates. To

Mecanismo de falla de los tubos del sobrecalentador de una caldera acuotubular

Directory of Open Access Journals (Sweden)

John Jairo Coronado Marín

2007-09-01

Full Text Available En este artículo se investigaron las causas de las fallas presentadas por fisuración longitudinal a partir de la superficie externa en los tubos del sobrecalentador de una caldera acuotubular. La superficie externa de los tubos presentó una capa de color blanco-rojizo que presentó cadenas parafínicas: C-H, grupos funcionales: C-O, N-H y compuestos de azufre, esta capa frágil impide la transferencia de calor, causando un aumento de temperatura del tubo. La falla se presentó por termofluencia debido al sobrecalentamiento de larga duración, la microestructura del tubo de acero en el lado externo presentó: crecimiento de grano, globulización de la cemen-tita y fisuras intergranulares que producen pérdidas de las propiedades mecánicas del acero. Las observaciones anteriores evidencian un deterioro de la microestructura facilitado por un material que no está en capacidad de operar usando exclusivamente bagazo como combustible.

Contrasting styles of post-caldera volcanism along the Main Ethiopian Rift: Implications for contemporary volcanic hazards

Science.gov (United States)

Fontijn, Karen; McNamara, Keri; Zafu Tadesse, Amdemichael; Pyle, David M.; Dessalegn, Firawalin; Hutchison, William; Mather, Tamsin A.; Yirgu, Gezahegn

2018-05-01

The Main Ethiopian Rift (MER, 7-9°N) is the type example of a magma-assisted continental rift. The rift axis is populated with regularly spaced silicic caldera complexes and central stratovolcanoes, interspersed with large fields of small mafic scoria cones. The recent (latest Pleistocene to Holocene) history of volcanism in the MER is poorly known, and no eruptions have occurred in the living memory of the local population. Assessment of contemporary volcanic hazards and associated risk is primarily based on the study of the most recent eruptive products, typically those emplaced within the last 10-20 ky. We integrate new and published field observations and geochemical data on tephra deposits from the main Late Quaternary volcanic centres in the central MER to assess contemporary volcanic hazards. Most central volcanoes in the MER host large mid-Pleistocene calderas, with typical diameters of 5-15 km, and associated ignimbrites of trachyte and peralkaline rhyolite composition. In contrast, post-caldera activity at most centres comprises eruptions of peralkaline rhyolitic magmas as obsidian flows, domes and pumice cones. The frequency and magnitude of events varies between individual volcanoes. Some volcanoes have predominantly erupted obsidian lava flows in their most recent post-caldera stage (Fentale), whereas other have had up to 3 moderate-scale (VEI 3-4) explosive eruptions per millennium (Aluto). At some volcanoes we find evidence for multiple large explosive eruptions (Corbetti, Bora-Baricha, Boset-Bericha) which have deposited several centimetres to metres of pumice and ash in currently densely populated regions. This new overview has important implications when assessing the present-day volcanic hazard in this rapidly developing region. Supplementary Table 2 Main Ethiopian Rift outcrop localities with brief description of geology. All coordinates in Latitude - Longitude, WGS84 datum. Sample names (as listed in Supplementary Table 3a) follow outcrop name

Environmental Impact Analysis Process. Draft Environmental Assessment. SAC Low-Altitude Flight Operations at the Airburst Range, Colorado

Science.gov (United States)

1990-01-01

Engineering and Housing Fort Carson, Colorado (719) 579-2022 Bill Giordano Department of Planning and Zoning Fremont County, Colorado (719) 275-7510 Anita...Originator. Melissa Mooney Person Contacted: Melvin Nail, Manager Alamosa/Monte Vista National Wildlife Refuge Subject- Request for species lists I called...I CONTACT REPORT Date of Contact- December 1, 1989 0 Originator. Melissa Mooney Person Contacted: Dave Kuntz Colorado Natural Areas Progiam

Aeromagnetic Study of the Nortern Acambay Graben and Amealco Caldera, Central Mexican Volcanic Belt

Science.gov (United States)

Gonzalez, T.

2011-12-01

The Mexican Volcanic Belt (MVB) is characterized by E-W striking faults which form a series of en echelon graben along its length. In the central region of the MVB is located the Acambay graben an intra-arc tectonic depression structure, of apparent Quaternary age, which gives rise to pronounced scarps over a distance of about 80 Km. and 15 to 35 Km wide. The general arrangement of the faults that constitute the Acambay graben shows E-W trend which defines the fronts of the graben exhibits a major fault discontinuity. The graben is limited of the north by the Acambay- Tixmadeje and Epitafio Huerta faults and in the south by the Pastores and Venta de Bravo faults.. In the northern wall in the graben is located the Amealco caldera. This volcanic center (approximately 10 km in diameter) was formed by several discrete volcanic events, which produced an ignimbrite which covers the area. It is partially cut by a regional fault and the southern portion of the Amealco Caldera was displaced by a normal faulting along a segment of the Epitafio Huerta system. Continued tectonic activity in the Acambay area is confirmed by recent seismic episodes The Amealco tuff is the most important volcanic unit because of its volume and distribution. Aeromagnetic data was obtained and analyzed the anomalies. The anomaly map was compared with the surface geology and larger anomalies were correlated with major volcanic features. Since our main interest was in mapping the subsurface intrusive and volcanic bodies, the total field magnetic anomalies were reduced to the pole by using the double integral Fourier method. The reduced to the pole anomaly map results in a simplified pattern of isolated positive and negative anomalies, which show an improved correlation with all major volcanic structures. For the analysis and interpretation of the anomalies, the reduced to the pole anomalies were continued upward at various reference levels. These operations result in smoothing of the anomaly field by

Temporal trends in marijuana attitudes, availability and use in Colorado compared to non-medical marijuana states: 2003-11.

Science.gov (United States)

Schuermeyer, Joseph; Salomonsen-Sautel, Stacy; Price, Rumi Kato; Balan, Sundari; Thurstone, Christian; Min, Sung-Joon; Sakai, Joseph T

2014-07-01

In 2009, policy changes were accompanied by a rapid increase in the number of medical marijuana cardholders in Colorado. Little published epidemiological work has tracked changes in the state around this time. Using the National Survey on Drug Use and Health, we tested for temporal changes in marijuana attitudes and marijuana-use-related outcomes in Colorado (2003-11) and differences within-year between Colorado and thirty-four non-medical-marijuana states (NMMS). Using regression analyses, we further tested whether patterns seen in Colorado prior to (2006-8) and during (2009-11) marijuana commercialization differed from patterns in NMMS while controlling for demographics. Within Colorado those reporting "great-risk" to using marijuana 1-2 times/week dropped significantly in all age groups studied between 2007-8 and 2010-11 (e.g. from 45% to 31% among those 26 years and older; p=0.0006). By 2010-11 past-year marijuana abuse/dependence had become more prevalent in Colorado for 12-17 year olds (5% in Colorado, 3% in NMMS; p=0.03) and 18-25 year olds (9% vs. 5%; p=0.02). Regressions demonstrated significantly greater reductions in perceived risk (12-17 year olds, p=0.005; those 26 years and older, p=0.01), and trend for difference in changes in availability among those 26 years and older and marijuana abuse/dependence among 12-17 year olds in Colorado compared to NMMS in more recent years (2009-11 vs. 2006-8). Our results show that commercialization of marijuana in Colorado has been associated with lower risk perception. Evidence is suggestive for marijuana abuse/dependence. Analyses including subsequent years 2012+ once available, will help determine whether such changes represent momentary vs. sustained effects. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

78 FR 37586 - Stone Age Interiors, Inc., D/B/A Colorado Springs Marble and Granite, Including On-Site Leased...

Science.gov (United States)

2013-06-21

... DEPARTMENT OF LABOR Employment and Training Administration [TA-W-82,440] Stone Age Interiors, Inc., D/B/A Colorado Springs Marble and Granite, Including On-Site Leased Workers From Express Employment... Marble and Granite, Colorado Springs, Colorado (subject firm). The negative determination was issued on...

Tobacco Use Among Arab Immigrants Living in Colorado: Prevalence and Cultural Predictors.

Science.gov (United States)

El Hajj, Dana G; Cook, Paul F; Magilvy, Kathy; Galbraith, Michael E; Gilbert, Lynn; Corwin, Marla

2017-03-01

The authors determined the prevalence of smoking among Arab immigrants living in Colorado. The authors also evaluated the relationship between acculturation and tobacco use, including both cigarettes and hookah among Arab immigrants. A cross-sectional survey of 100 adult Arab immigrants living in Colorado was carried out. The results revealed that 19% of the study participants were current cigarette smokers and 21% were current hookah smokers. Participants who were more integrated into Arab culture were more likely to use tobacco products ( p = .03) and to have family members ( p = .02) and friends who use tobacco products ( p = .007). Acculturation plays a major role in affecting the health habits of Arab immigrants living in Colorado, especially in the area of hookah smoking. Understanding some culturally relevant predictors of tobacco use might assist health care providers in designing successful smoking cessation programs.

Unintentional Pediatric Exposures to Marijuana in Colorado, 2009-2015.

Science.gov (United States)

Wang, George Sam; Le Lait, Marie-Claire; Deakyne, Sara J; Bronstein, Alvin C; Bajaj, Lalit; Roosevelt, Genie

2016-09-06

As of 2015, almost half of US states allow medical marijuana, and 4 states allow recreational marijuana. To our knowledge, the effect of recreational marijuana on the pediatric population has not been evaluated. To compare the incidence of pediatric marijuana exposures evaluated at a children's hospital and regional poison center (RPC) in Colorado before and after recreational marijuana legalization and to compare population rate trends of RPC cases for marijuana exposures with the rest of the United States. Retrospective cohort study of hospital admissions and RPC cases between January 1, 2009, and December 31, 2015, at Children's Hospital Colorado, Aurora, a tertiary care children's hospital. Participants included patients 0 to 9 years of age evaluated at the hospital's emergency department, urgent care centers, or inpatient unit and RPC cases from Colorado for single-substance marijuana exposures. Marijuana. Marijuana exposure visits and RPC cases, marijuana source and type, clinical effects, scenarios, disposition, and length of stay. Eighty-one patients were evaluated at the children's hospital, and Colorado's RPC received 163 marijuana exposure cases between January 1, 2009, and December 31, 2015, for children younger than 10 years of age. The median age of children's hospital visits was 2.4 years (IQR, 1.4-3.4); 25 were girls (40%) . The median age of RPC marijuana exposures was 2 years (IQR, 1.3-4.0), and 85 patients were girls (52%). The mean rate of marijuana-related visits to the children's hospital increased from 1.2 per 100 000 population 2 years prior to legalization to 2.3 per 100,000 population 2 years after legalization (P = .02). Known marijuana products involved in the exposure included 30 infused edibles (48%). Median length of stay was 11 hours (interquartile range [IQR], 6-19) and 26 hours (IQR, 19-38) for admitted patients. Annual RPC pediatric marijuana cases increased more than 5-fold from 2009 (9) to 2015 (47). Colorado had an

Cancer incidence study in Mesa County, Colorado

International Nuclear Information System (INIS)

Ouimette, D.R.; Ferguson, S.W.; Zoglo, D.; Murphy, S.; Alley, S.; Bahler, S.

1983-01-01

In November of 1982 the Colorado Department of Health completed an epidemiologic investigation of leukemia, multiple myeloma, and cancers of the lung, stomach, pancreas and colon in Mesa County, Colorado for the years 1970 to 1979. This investigation was performed in response to a concern that the presence of uranium mill tailings in some Mesa County homes presents a potential cancer hazard. The results of the investigation show that the incidence of multiple myeloma, colon, stomach and pancreatic cancer are not above expected rates. The incidence of leukemia is not above expected rates for the entire study period, 1970 to 1979. The incidence of lung cancer appears elevated when compared to the The Third National Cancer Survey data for Colorado but lower than expected when compared to Surveillance, Epidemiology and End Results data. To further examine the leukemia and lung cancer incidence findings, a case/control study was conducted. The controls consisted of colon, stomach and pancreatic cancer cases. The results of the leukemia case/control analysis show no association with the radiation exposure variables: occupational radiation exposure; uranium mining exposure; having ever lived in a type A home (uranium tailings home); and radiation therapy. The lung cancer case/control analysis shows a significant association with only the radiation exposure variable, uranium mining history, indicating cases were more likely to have been uranium miners than were controls. As with leukemia, the study found no association between lung cancer and living in a uranium mill tailings home. The relatively low radiation exposures typical of type A homes and the small number of persons exposed make it very difficult to establish, by epidemiologic methods, that a risk exists

Water clarity of the Colorado River—Implications for food webs and fish communities

Science.gov (United States)

Voichick, Nicholas; Kennedy, Theodore A.; Topping, David; Griffiths, Ronald; Fry, Kyrie

2016-11-01

The closure of Glen Canyon Dam in 1963 resulted in drastic changes to water clarity, temperature, and flow of the Colorado River in Glen, Marble, and Grand Canyons. The Colorado River is now much clearer, water temperature is less variable throughout the year, and the river is much colder in the summer months. The flow—regulated by the dam—is now less variable annually, but has larger daily fluctuations than during pre-dam times. All of these changes have resulted in a different fish community and different food resources for fish than existed before the dam was built. Recent monitoring of water clarity, by measuring turbidity, has helped scientists and river managers understand modern water-clarity patterns in the dam-regulated Colorado River. These data were then used to estimate pre-dam turbidity in the Colorado River in order to make comparisons of pre-dam and dam-regulated conditions, which are useful for assessing biological changes in the river over time. Prior to dam construction, the large sediment load resulted in low water clarity almost all of the time, a condition which was more favorable for the native fish community.

Implications of Zn/Fe ratios for the sources of Colorado Plateau basalts

Science.gov (United States)

Rudzitis, S.; Reid, M. R.

2011-12-01

Early Miocene to recent mafic magmatism migrated across the Arizona Transition Zone towards the center of the stable Colorado Plateau at a rate of ~ 3-6 km/Myr (Roy et al., 2009). Present-day volcanic centers are close to a stepwise change in the thickness of the lithosphere between the Colorado Plateau and Basin and Range. Accordingly, volcanic migration might track progressive thinning of the lithosphere towards the center of the Colorado Plateau. This project aims to determine the conditions of melt generation across the transition zone in order to investigate the temporal/spatial correlation between volcanism and thinning of the Colorado Plateau lithosphere. Pressure and temperature estimates for Colorado Plateau basalts can be obtained from the Mg and Si contents of melts (Lee et al, 2009) but require melting of a peridotitic source. Eclogite and pyroxenite xenoliths reported in Colorado Plateau basalts show that melt sources could be olivine-poor. Zn/Fe ratios in melts can help to distinguish contributions from olivine-poor sources because they are sensitive to differences in bulk chemistry and to mineralogy (Le Roux et al., 2010). Specifically, Zn/Fe is not fractionated between melt, olivine, and orthopyroxene, but is highly fractionated when clinopyroxene and garnet are present. Our work to date has focused on laser ablation-IC-PMS analysis of individual olivine grains from high-Mg basalts (>8.0 wt. %) from the San Francisco and Mormon Mountain volcanic fields. Preliminary values of Zn/Fe ratios that represent the averages of multiple analyses of several grains in individual samples range from 7.9 to 9.3 (x10000). Variations of up to 1.7 (x10000) in the ratios exist between individual grains within samples and could be the result of co-crystallization of clinopyroxene with olivine. The lowest values in each sample should approach the Zn/Fe ratios of parental melts, and are, in turn, similar to MORB values and predicted peridotite melts. The results suggest

Geologic map of the Frisco quadrangle, Summit County, Colorado

Science.gov (United States)

Kellogg, Karl S.; Bartos, Paul J.; Williams, Cindy L.

2002-01-01

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Frisco quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, K.S., 1999, Neogene basins of the northern Rio Grande rift?partitioning and asymmetry inherited from Laramide and older uplifts: Tectonophysics, v. 305, p. 141-152.), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts the northeastern corner of the quadrangle. The oldest rocks in the quadrangle underlie the Tenmile Range and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, Ogden, 1987, Rock units of the Precambrian- basement in Colorado: U.S. Geological Survey Professional Paper 1321-A, 54 p.). The oldest sedimentary unit is the Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. The sedimentary rocks are intruded by sills and dikes of dacite porphyry sills of Swan Mountain, dated at 44 Ma (Marvin, R.F., Mehnert, H.H., Naeser, C.W., and Zartman, R.E., 1989, U.S. Geological Survey radiometric ages, compilation ?C??Part five?Colorado, Montana, Utah, and Wyoming: Isochron/West, no. 53, p. 14-19. Simmons, E.C., and Hedge, C.E., 1978, Minor-element and Sr-isotope geochemistry of Tertiary stocks, Colorado mineral belt

Biopsychosocial law, health care reform, and the control of medical inflation in Colorado.

Science.gov (United States)

Bruns, Daniel; Mueller, Kathryn; Warren, Pamela A

2012-05-01

A noteworthy attempt at health care reform was the 1992 Colorado workers' compensation reform bill, which led to the creation of what has been called "biopsychosocial laws." These laws mandated the use of treatment guidelines for patients with injury or chronic pain, which advocated a biopsychosocial model of rehabilitation, and aspired to use a "best practice" approach to controlling costs. The purpose of this study was to examine the financial impact of this health care reform process, and to test the hypothesis that this approach can be an effective strategy to contain costs while providing good care. This study utilized a dataset collected prospectively from 1992 to 2007 in 45 U.S. states for regulatory purposes. These data summarized the medical treatment and disability costs of 520,314 injured workers in Colorado, and an estimated 28.6 million injured workers nationally. As no other state passed a comparable bill, the Colorado worker compensation reform bill created a natural experiment, where a treatment group was created by legally enforceable medical treatment guidelines. In the 15 years following the implementation of the reform, the inflation of medical costs in Colorado workers' compensation was only one third that of the national average, saving an estimated $859 million on patients injured in 2007 alone. Although there were confounding variables, and causality could not be determined, these data are consistent with the hypothesis that Colorado's 1992 legislative efforts to reform workers compensation law using the biopsychosocial model worked as intended to provide good care while controlling costs. PsycINFO Database Record (c) 2012 APA, all rights reserved.

Insects associated with ponderosa pine in Colorado

Science.gov (United States)

Robert E. Stevens; J. Wayne Brewer; David A. Leatherman

1980-01-01

Ponderosa pine serves as a host for a wide variety of insects. Many of these, including all the particularly destructive ones in Colorado, are discussed in this report. Included are a key to the major insect groups, an annotated list of the major groups, a glossary, and a list of references.

The Chapter 1 Challenge: Colorado's Contribution 1993.

Science.gov (United States)

Petro, Janice Rose; And Others

An overview is provided of Colorado's participation in Chapter 1, the largest federally funded program designed to provide services to elementary and secondary students. Chapter 1 provides financial assistance to state and local education agencies to meet the special needs of educationally deprived children who reside in areas with high…

Casa de la Esperanza: A Case Study of Service Coordination at Work in Colorado.

Science.gov (United States)

Franquiz, Maria E.; Hernandez, Carlota Loya

This chapter describes how a federally funded farmworker housing facility in northern Colorado--Casa de la Esperanza--has changed the lives of migrant students and their families. The history of migrant workers in Colorado is described, as well as the struggle to construct a permanent farmworker housing facility. Casa was built in Boulder County,…

VS of the uppermost crust structure of the Campi Flegrei caldera (southern Italy) from ambient noise Rayleigh wave analysis

Science.gov (United States)

Costanzo, M. R.; Nunziata, C.; Strollo, R.

2017-11-01

Shear wave velocities (VS) are defined in the uppermost 1-2 km of the Campi Flegrei caldera through the non-linear inversion of the group velocity dispersion curves of fundamental-mode Rayleigh waves extracted from ambient noise cross-correlations between two receivers. Noise recordings, three months long, at 12 seismic stations are cross-correlated between all couples of stations. The experiment provided successful results along 54 paths (inter-stations distance), of which 27 sampled a depth > 1 km. VS contour lines are drawn from 0.06 km b.s.l. to 1 km depth b.s.l. and show difference between the offshore (gulf of Pozzuoli and coastline) and the onshore areas. At 0.06 km b.s.l., the gulf of Pozzuoli and the coastline are characterized by VS of 0.3-0.5 km/s and of 0.5-0.7 km/s, respectively. Such velocities are typical of Neapolitan pyroclastic soils and fractured or altered tuffs. The inland shows VS in the range 0.7-0.9 km/s, typical of Neapolitan compact tuffs. Velocities increase with depth and, at 1 km depth b.s.l., velocities lower than 1.5 km/s are still present in the gulf and along the coastline while velocities higher than 1.9 km/s characterize the eastern sector (grossly coincident with the Neapolitan Yellow Tuff caldera rim), the S. Vito plain and the area between Solfatara and SW of Astroni. Such features are much more evident along two cross-sections drawn in the offshore and onshore sectors by integrating our VS models with literature data. Our models join previous noise cross-correlation studies at greater scale at depths of 0.7-0.8 km, hence the picture of the Campi Flegrei caldera is shown up to a depth of 15 km. VS of about 1.7 km/s, corresponding to compression velocities (VP) of about 3 km/s (computed by using the VP/VS ratio resulted in the inversion), are found at depths of 1.1 km, in the centre of the gulf of Pozzuoli, and at a depth of about 0.7 km b.s.l. onshore. An increment of VS velocity ( 1.9-2.0 km/s) is locally observed onshore

Isotopic and trace element characteristics of rhyolites from the Valles Caldera, New Mexico. Final technical report

Energy Technology Data Exchange (ETDEWEB)

Self, S.; Sykes, M.L. [Hawaii Univ., Honolulu, HI (United States). Dept. of Geology and Geophysics; Wolff, J.A. [Texas Univ., Arlington, TX (United States). Dept. of Geology; Skuba, C.E. [McMaster Univ., Hamilton, ON (Canada). Dept. of Geology

1991-09-01

This report is a summary of work supported by DOE grant No. DE-FGO5-87ER13795 that was completed or is still in progress. The stated purpose of this grant was to collect geochemical information (trace element, radiogenic isotope and stable oxygen and hydrogen isotope) on samples from core holes VC-I and VC-2a in the Valles caldera in order to establish a consistent detailed intracaldera stratigraphy and relate this to extracaldera volcanic rock units of the Jemez Mountains. Careful stratigraphic control of the intracaldera units is necessary to evaluate models of caldera formation, ignimbrite deposition, and resurgence. Combined stable and radiogenic isotope and trace element data will also provide major insights to petrogenesis of the Bandelier magma system. The composition of non-hydrothermally altered samples from outflow units of the Bandelier Tuff and related volcanics must be known to assess isotopic variations of intracaldera ignimbrite samples. On detailed examination of the VC-2a core samples, it became apparent that hydrothermal alteration is so extensive that no geochemical information useful for stratigraphic fingerprinting or petrogenesis could be obtained, and that correlation with other intracaldera units and extracaldera units must be made on the basis of stratigraphic position and gross lithologic characteristics. Accordingly, we emphasize geochemical data from the extracaldera Bandelier Tuffs and related units which will be useful for comparison with proposed drill hole VC-4 and for any future studies of the region. The stable isotope, radiogenic isotope and trace element data obtained from this project, combined with existing major and trace element data for volcanic rocks from this area, provide an extensive data base essential to future Continental Scientific Drilling Program projects in the Jemez Mountains of New Mexico.

Application of sediment characteristics and transport conditions to resource management in selected main-stem reaches of the Upper Colorado River, Colorado and Utah, 1965-2007

Science.gov (United States)

Williams, Cory A.; Schaffrath, Keelin R.; Elliott, John G.; Richards, Rodney J.

2013-01-01

The Colorado River Basin provides habitat for 14 native fish, including 4 endangered species protected under the Federal Endangered Species Act of 1973. These endangered fish species once thrived in the Colorado River system, but water-resource development, including the building of numerous diversion dams and several large reservoirs, and the introduction of non-native fish, resulted in large reductions in the numbers and range of the four species through loss of habitat and stream function. Understanding how stream conditions and habitat change in response to alterations in streamflow is important for water administrators and wildlife managers and can be determined from an understanding of sediment transport. Characterization of the processes that are controlling sediment transport is an important first step in identifying flow regimes needed for restored channel morphology and the sustained recovery of endangered fishes within these river systems. The U.S. Geological Survey, in cooperation with the Upper Colorado River Endangered Fish Recovery Program, Bureau of Reclamation, U.S. Fish and Wildlife Service, Argonne National Laboratory, Western Area Power Administration, and Wyoming State Engineer’s Office, began a study in 2004 to characterize sediment transport at selected locations on the Colorado, Gunnison, and Green Rivers to begin addressing gaps in existing datasets and conceptual models of the river systems. This report identifies and characterizes the relation between streamflow (magnitude and timing) and sediment transport and presents the findings through discussions of (1) suspended-sediment transport, (2) incipient motion of streambed material, and (3) a case study of sediment-transport conditions for a reach of the Green River identified as a razorback sucker spawning habitat (See report for full abstract).

Green pricing: A Colorado case study

Energy Technology Data Exchange (ETDEWEB)

Blank, E.; Udall, J.R.

1996-12-31

A model program for green pricing targeted primarily at large customers is proposed in this paper. The program would create a partnership between a local community group, a renewables advocacy group, and several Colorado utilities. The first part of the paper summarizes pertinent background issues, including utility experience with green pricing programs. The rest of the paper outlines the program proposal, focusing primarily on organizational structure.

76 FR 53693 - Notice of Invitation To Participate; Coal Exploration License Application COC-74911, Colorado

Science.gov (United States)

2011-08-29

...] Notice of Invitation To Participate; Coal Exploration License Application COC-74911, Colorado AGENCY: Bureau of Land Management, Interior. ACTION: Notice. SUMMARY: Pursuant to the Mineral Leasing Act of 1920... America in lands located in Delta County, Colorado. DATES: This notice of invitation was published in the...

A geochemical and geophysical reappraisal to the significance of the recent unrest at Campi Flegrei caldera (Southern Italy)

Science.gov (United States)

Moretti, Roberto; De Natale, Giuseppe; Troise, Claudia

2017-04-01

Volcanic unrest at calderas involve complex interaction between magma, hydrothermal fluids and crustal stress and strain. Campi Flegrei caldera (CFc), located in the Naples (Italy) area and characterised by the highest volcanic risk on Earth for the extreme urbanisation, undergoes unrest phenomena involving several meters of uplift and intense shallow micro-seismicity since several decades. Despite unrest episodes display in the last decade only moderate ground deformation and seismicity, current interpretations of geochemical data point to a highly pressurized hydrothermal system. We show that at CFc, the usual assumption of vapour-liquid coexistence in the fumarole plumes leads to largely overestimated hydrothermal pressures and, accordingly, interpretations of elevated unrest. By relaxing unconstrained geochemical assumptions, we infer an alternative model yielding better agreement between geophysical and geochemical observations. The model reconciles discrepancies between what observed 1) for two decades since the 1982-84 large unrest, when shallow magma was supplying heat and fluids to the hydrothermal system, and 2) in the last decade. Compared to the 1980's unrest, the post-2005 phenomena are characterized by much lower aquifers overpressure and magmatic involvement, as indicated by geophysical data and despite large changes in geochemical indicators. Our interpretation points out a model in which shallow sills, intruded during 1969-1984, have completely cooled, so that fumarole emissions are affected now by deeper, CO2-richer, magmatic gases producing a relatively modest heating and overpressure of the hydrothermal system. Our results do have important implications on the short-term eruption hazard assessment and on the best strategies for monitoring and interpreting geochemical data.

Annual report to the Advisory Council on Historic Preservation and the Colorado State Historic Preservation Officer on the US Department of Energy's cultural resource activities at Colorado UMTRA Project sites, January--December 1991

International Nuclear Information System (INIS)

1992-04-01

This report is a summary of the US Department of Energy's (DOE) cultural resource investigations for the Uranium Mill Tailings Remedial Action (UMTRA) Project sites in Colorado. This report is intended to fulfill the DOE's obligation for an annual report as stated in the Programmatic Memorandum of Agreement executed between the DOE, the Advisory Council on Historic Preservation, and the Colorado State Historic Preservation Officer in December 1984. Summaries of the cultural resource surveys and identified resources are provided for the UMTRA Project sites in the vicinities of Durango, Grand Junction, Gunnison, Maybell, Naturita, Rifle, and Slick Rock. This report covers all UMTRA Project cultural resource activities in Colorado from January through December 1991

Metadata, Cataloging, Digitization and Retrieval--Who's Doing What to Whom: The Colorado Digitization Project Experience.

Science.gov (United States)

Bishoff, Liz; Garrison, William A.

This paper describes the experiences of the Colorado Digitization Project (CDP) related to accessing a diverse set of primary resources held by many different cultural heritage institutions. The CDP is a collaborative initiative involving Colorado's archives, historical societies, libraries, and museums. The CDP's goal is to create a virtual…

Surface morphology of caldera-forming eruption deposits revealed by lidar mapping of Crater Lake National Park, Oregon- Implications for emplacement and surface modification

Science.gov (United States)

Robinson, Joel E.; Bacon, Charles R.; Major, Jon J.; Wright, Heather M.; Vallance, James W.

2017-01-01

Large explosive eruptions of silicic magma can produce widespread pumice fall, extensive ignimbrite sheets, and collapse calderas. The surfaces of voluminous ignimbrites are rarely preserved or documented because most terrestrial examples are heavily vegetated, or severely modified by post-depositional processes. Much research addresses the internal sedimentary characteristics, flow processes, and depositional mechanisms of ignimbrites, however, surface features of ignimbrites are less well documented and understood, except for comparatively small-volume deposits of historical eruptions. The ~7,700 calendar year B.P. climactic eruption of Mount Mazama, USA vented ~50 km3 of magma, deposited first as rhyodacite pumice fall and then as a zoned rhyodacite-to-andesite ignimbrite as Crater Lake caldera collapsed. Lidar collected during summer 2010 reveals the remarkably well-preserved surface of the Mazama ignimbrite and related deposits surrounding Crater Lake caldera in unprecedented detail despite forest cover. The ±1 m lateral and ±4 cm vertical resolution lidar allows surface morphologies to be classified. Surface morphologies are created by internal depositional processes and can point to the processes at work when pyroclastic flows come to rest. We describe nine surface features including furrow-ridge sets and wedge-shaped mounds in pumice fall eroded by high-energy pyroclastic surges, flow- parallel ridges that record the passage of multiple pyroclastic flows, perched benches of marginal deposits stranded by more-mobile pyroclastic-flow cores, hummocks of dense clasts interpreted as lag deposit, transverse ridges that mark the compression and imbrication of flows as they came to rest, scarps indicating ignimbrite remobilization, fields of pit craters caused by phreatic explosions, fractures and cracks caused by extensional processes resulting from ignimbrite volume loss, and stream channels eroded in the newly formed surface. The nine morphologies presented

Effect of food factor on microevolution of Colorado beetle

Directory of Open Access Journals (Sweden)

N. А. Ryabchenko

2005-12-01

Full Text Available Many-sided research of interaction of Colorado beetle and fodder plant (potato, nightshade sweetly-bitter defines the role of the plants as guiding factor of microevolutional processes in pest population.

Locations and attributes of wind turbines in Colorado, 2011

Science.gov (United States)

Carr, Natasha B.; Diffendorfer, James E.; Fancher, Tammy; Hawkins, Sarah J.; Latysh, Natalie; Leib, Kenneth J.; Matherne, Anne Marie

2013-01-01

This dataset represents an update to U.S. Geological Survey Data Series 597. Locations and attributes of wind turbines in Colorado, 2009 (available at http://pubs.usgs.gov/ds/597/). This updated Colorado wind turbine Data Series provides geospatial data for all 1,204 wind turbines established within the State of Colorado as of September 2011, an increase of 297 wind turbines from 2009. Attributes specific to each turbine include: turbine location, manufacturer and model, rotor diameter, hub height, rotor height, potential megawatt output, land ownership, county, and development status of the wind turbine. Wind energy facility data for each turbine include: facility name, facility power capacity, number of turbines associated with each facility to date, facility developer, facility ownership, and year the facility went online. The locations of turbines are derived from 1-meter true-color aerial photographs produced by the National Agriculture Imagery Program (NAIP); the photographs have a positional accuracy of about ±5 meters. Locations of turbines constructed during or prior to August 2009 are based on August 2009 NAIP imagery and turbine locations constructed after August 2009 were based on September 2011 NAIP imagery. The location of turbines under construction during September 2011 likely will be less accurate than the location of existing turbines. This data series contributes to an Online Interactive Energy Atlas developed by the U.S. Geological Survey (http://my.usgs.gov/eerma/). The Energy Atlas synthesizes data on existing and potential energy development in Colorado and New Mexico and includes additional natural resource data layers. This information may be used by decisionmakers to evaluate and compare the potential benefits and tradeoffs associated with different energy development strategies or scenarios. Interactive maps, downloadable data layers, comprehensive metadata, and decision-support tools also are included in the Energy Atlas. The format of

Comparability among four invertebrate sampling methods and two multimetric indexes, Fountain Creek Basin, Colorado, 2010–2012

Science.gov (United States)

Bruce, James F.; Roberts, James J.; Zuellig, Robert E.

2018-05-24

The U.S. Geological Survey (USGS), in cooperation with Colorado Springs City Engineering and Colorado Springs Utilities, analyzed previously collected invertebrate data to determine the comparability among four sampling methods and two versions (2010 and 2017) of the Colorado Benthic Macroinvertebrate Multimetric Index (MMI). For this study, annual macroinvertebrate samples were collected concurrently (in space and time) at 15 USGS surface-water gaging stations in the Fountain Creek Basin from 2010 to 2012 using four sampling methods. The USGS monitoring project in the basin uses two of the methods and the Colorado Department of Public Health and Environment recommends the other two. These methods belong to two distinct sample types, one that targets single habitats and one that targets multiple habitats. The study results indicate that there are significant differences in MMI values obtained from the single-habitat and multihabitat sample types but methods from each program within each sample type produced comparable values. This study also determined that MMI values calculated by different versions of the Colorado Benthic Macroinvertebrate MMI are indistinguishable. This indicates that the Colorado Department of Public Health and Environment methods are comparable with the USGS monitoring project methods for single-habitat and multihabitat sample types. This report discusses the direct application of the study results to inform the revision of the existing USGS monitoring project in the Fountain Creek Basin.

Radioactive mineral occurences of Colorado and bibliography

International Nuclear Information System (INIS)

Nelson-Moore, J.L.; Collins, D.B.; Hornbaker, A.L.

1978-01-01

This two-part report provides an essentially complete listing of radioactive occurrences in Colorado, with a comprehensive bibliography and bibliographic cross-indexes. Part 1 lists approximately 3000 known radioactive occurrences with their locations and brief accounts of the geology, mineralogy, radioactivity, host rock, production data, and source of data for each. The occurrences are classified by host rock and plotted on U.S. Geological Survey 1 0 x 2 0 topographic quadrangle maps with a special 1 : 100,000-scale base map for the Uravan mineral belt. Part 2 contains the bibliography of approximately 2500 citations on radioactive mineral occurrences in the state, with cross-indexes by county, host rock, and the special categories of ''Front Range,'' ''Colorado Plateau,'' and ''thorium.'' The term ''occurrence'' as used in this report is defined as any site where the concentration of uranium or thorium is at least 0.01% or where the range of radioactivity is greater than twice the background radioactivity. All citations and occurrence data are stored on computer diskettes for easy retrieval, correction, and updating

Elementary particle physics and high energy phenomena. [Dept. of Physics, Univ. of Colorado, Boulder, Colorado

Energy Technology Data Exchange (ETDEWEB)

Barker, A.R.; Cumalat, J.P.; De Alwis, S.P.; DeGrand, T.A.; Ford, W.T.; Mahanthappa, K.T.; Nauenberg, U.; Rankin, P.; Smith, J.G.

1992-06-01

Experimental and theoretical high-energy physics programs at the University of Colorado are reported. Areas of concentration include the following: study of the properties of the Z[sup 0] with the SLD detector; fixed-target K-decay experiments; the R D program for the muon system: the SDC detector; high-energy photoproduction of states containing heavy quarks; electron--positron physics with the CLEO II detector at CESR; lattice QCD; and spin models and dynamically triangulated random surfaces. 24 figs., 2 tabs., 117 refs.

Floods in Colorado

Science.gov (United States)

Follansbee, Robert; Sawyer, Leon R.

1948-01-01

The first records of floods in Colorado antedated the settlement of the State by about 30 years. These were records of floods on the Arkansas and Republican Rivers in 1826. Other floods noted by traders, hunters and emigrants, some of whom were on their way to the Far West, occurred in 1844 on the Arkansas River, and by inference on the South Platte River. Other early floods were those on the Purgatoire, the Lower Arkansas, and the San Juan Rivers about 1859. The most serious flood since settlement began was that on the Arkansas River during June 1921, which caused the loss of about 100 lives and an estimated property loss of $19,000,000. Many floods of lesser magnitude have occurred, and some of these have caused loss of life and very considerable property damage. Topography is the chief factor in determining the location of storms and resulting floods. These occur most frequently on the eastern slope of the Front Range. In the mountains farther west precipitation is insufficient to cause floods except during periods of melting snow, in June. In the southwestern part of the State, where precipitation during periods of melting snow is insufficient to cause floods, the severest floods yet experienced resulted from heavy rains in September 1909 and October 1911. In the eastern foothills region, usually below an altitude of about 7,500 feet and extending for a distance of about 50 miles east of the mountains, is a zone subject to rainfalls of great intensity known as cloudbursts. These cloudbursts are of short duration and are confined to very small areas. At times the intensity is so great as to make breathing difficult for those exposed to a storm. The areas of intense rainfall are so small that Weather Bureau precipitation stations have not been located in them. Local residents, being cloudburst conscious, frequently measure the rainfall in receptacles in their yards, and such records constitute the only source of information regarding the intensity. A flood

Magma mixing and the generation of isotopically juvenile silicic magma at Yellowstone caldera inferred from coupling 238U–230Th ages with trace elements and Hf and O isotopes in zircon and Pb isotopes in sanidine

Science.gov (United States)

Stelten, Mark E.; Cooper, Kari M.; Vazquez, Jorge A.; Reid, Mary R.; Barfod, Gry H.; Wimpenny, Josh; Yin, Qing-Zhu

2013-01-01

The nature of compositional heterogeneity within large silicic magma bodies has important implications for how silicic reservoirs are assembled and evolve through time. We examine compositional heterogeneity in the youngest (~170 to 70 ka) post-caldera volcanism at Yellowstone caldera, the Central Plateau Member (CPM) rhyolites, as a case study. We compare 238U–230Th age, trace-element, and Hf isotopic data from zircons, and major-element, Ba, and Pb isotopic data from sanidines hosted in two CPM rhyolites (Hayden Valley and Solfatara Plateau flows) and one extracaldera rhyolite (Gibbon River flow), all of which erupted near the caldera margin ca. 100 ka. The Hayden Valley flow hosts two zircon populations and one sanidine population that are consistent with residence in the CPM reservoir. The Gibbon River flow hosts one zircon population that is compositionally distinct from Hayden Valley flow zircons. The Solfatara Plateau flow contains multiple sanidine populations and all three zircon populations found in the Hayden Valley and Gibbon River flows, demonstrating that the Solfatara Plateau flow formed by mixing extracaldera magma with the margin of the CPM reservoir. This process highlights the dynamic nature of magmatic interactions at the margins of large silicic reservoirs. More generally, Hf isotopic data from the CPM zircons provide the first direct evidence for isotopically juvenile magmas contributing mass to the youngest post-caldera magmatic system and demonstrate that the sources contributing magma to the CPM reservoir were heterogeneous in 176Hf/177Hf at ca. 100 ka. Thus, the limited compositional variability of CPM glasses reflects homogenization occurring within the CPM reservoir, not a homogeneous source.

The Colorado river delta (Mexico: ecological importance and management = O delta do rio Colorado (Mexico: importância ecológica e gerenciamento

Directory of Open Access Journals (Sweden)

José Luis Fermán Almada

2008-10-01

Full Text Available The Colorado river delta is a unique coastal system in the world, as it combines two important systems: the Colorado river and the Gulf of California. Consequently, the delta is dominated by bilateral interests, and influenced by administrative, political and natural processes, which involve the countries of the United States and Mexico. Located in the northern part of the Gulf of California, under a condition of natural isolation, a series of environmental attributeshave been developed (biotic and abiotic that are only observed in is region. In this work, the development of the bilateral political relations and the most important ecological characteristicsare presented, as well as the management instruments that have been developed for over 80 years. From these issues, the possible scenario for the region is defined, and the development of methodologies for monitoring the effects of these possible tendencies on the natural components of the delta is proposed.O delta do rio Colorado é uma zona costeira única em todo o mundo, porassociar dois importantes sistemas: o próprio rio Colorado e o Golfo da Califórnia. Conseqüentemente, o delta é dominado por interesses bi-nacionais e influenciado por processos administrativos, políticos e naturais, envolvendo os Estados Unidos e o México. Localizado no norte do Golfo da Califórnia, sob uma condição de isolamento natural,desenvolveu-se uma série de atributos ambientais (bióticos e abióticos que só podem ser vistos nessa região. Neste trabalho, são apresentados o desenvolvimento das relações políticas bilaterais e as características ecológicas mais importantes, bem como osmecanismos de gerenciamento que vêm sido desenvolvidos por mais de 80 anos. A partir dessas questões, é definido um cenário tendencial possível para a região, e o desenvolvimento de metodologias para o acompanhamento dos efeitos dessas possíveis tendências sobre os componentes naturais do delta é proposto.

Evolution of silicic magmas in the Kos-Nisyros volcanic center: cycles associated with caldera collapse

Science.gov (United States)

Ruprecht, J. S.; Bachmann, O.; Deering, C. D.; Huber, C.; Skopelitis, A.; Schnyder, C.

2010-12-01

Multiple eruptions of silicic magma (dacite and rhyolites) occurred over the last ~ 3 My in the Kos-Nisyros volcanic center (eastern Aegean sea). Over the course of this period, magmas have changed from hornblende-biotite rich units with low eruption temperatures (≤750-800 °C; Kefalos and Kos units) to hotter (>800-850 °C), pyroxene-bearing units (Nisyros units) and are transitioning back to colder magmas (Yali units). Using bulk-rock compositions, mineral chemistry, and zircon Hf isotopes, we show that the two different types of silicic magmas followed the same differentiation trend; they all evolved by crystal fractionation (and minor assimilation) from parents with intermediate compositions characterized by high Sr/Y and low Nb content, following a wet, high oxygen fugacity liquid line of descent typical of subduction zones. As the transition between the Kos-Kefalos and Nisyros-type magmas occurred immediately and abruptly after the major caldera collapse in the area (the 161 ky Kos Plateau Tuff; KPT), we suggest that the efficient emptying of the magma chamber during the KPT drew most of the eruptible magma out and partly froze the silicic magma source zone in the upper crust due to rapid unloading, decompression and resulting crystallization. Therefore, the system had to reinstate a shallow silicic production zone from more mafic parents, recharged at temperatures typically around 850-900 °C from the mid to lower crust. The first silicic eruptions evolving from these parents after the caldera collapse (Nisyros units) were thus slightly hotter and less evolved than the Kefalos-Kos package. However, with time, the upper crustal intermediate mush grew and cooled, leading to interstitial melt compositions reaching again the highly-evolved, cold state that prevailed prior to the Kefalos-Kos. The recent (albeit not precisely dated) eruption of the high-SiO2 rhyolite of Yali suggests that another large, potentially explosive magma chamber is presently building

Evaluation of guardrail embedded lighting system in Trinidad, Colorado.

Science.gov (United States)

2014-02-01

This report provides information on the design considerations of the embedded highway lighting : design on Interstate-25 in Trinidad, Colorado, in terms of visibility. The information is based on : visibility characterizations of small targets using ...

Sidney-North Yuma 230-kV Transmission Line Project, Colorado and Nebraska

Energy Technology Data Exchange (ETDEWEB)

1991-06-01

This report describes the need for a 230-kV overhead transmission line to supply power from Sidney, Nebraska to eastern Colorado. The alternative scenario compared to construction of the line is No Action. Rejected alternatives include underground lines and different routing paths, with a possible extension to the Sterling area. Both scenarios are evaluated for environmental effects, cost, and consequences for the eastern Colorado region. The proposed route is determined to be the environmentally preferred choice. 120 refs., 6 figs., 13 tabs. (MHB)

Evaluación de la eficiencia de remoción de material particulado y dióxido de azufre (so2) en un lavador tipo venturi para una caldera que emplea carbón como combustible

OpenAIRE

Jiménez Riaño, Quelver Yesid

2012-01-01

El aporte de las emisiones industriales a la contaminación del aire de Bogotá es significativo y, dentro de las industrias, aquellas que usan carbón como fuente de combustible para la generación de vapor en calderas son las que mayor impacto negativo tiene en la calidad del aire de la ciudad. En este trabajo se llevó a cabo la evaluación de las variables de operación de un sistema de control de emisiones atmosféricas para una caldera industrial a carbón. Se diseño, construyó y puso en marcha ...

Bats of the Colorado oil shale region

Energy Technology Data Exchange (ETDEWEB)

Finley, R.B. Jr.; Caire, W.; Wilhelm, D.E.

1984-10-31

New records for Myotis californicus, M. evotis, M. leibii, M. lucifugus, M. thysanodes, M. volans, M. yumanensis, Lasionycteris noctivagans, Pipistrellus hesperus, Eptesicus fuscus, Lasiurus cinereus, Plecotus townsendii, and Antrozous pallidus and their habitat occurrence in northwestern Colorado are reported. Mortality of 27 bats of six species trapped in an oil sludge pit is described. 7 references.

Late Quaternary eruption of the Ranau Caldera and new geological slip rates of the Sumatran Fault Zone in Southern Sumatra, Indonesia

Science.gov (United States)

Natawidjaja, Danny Hilman; Bradley, Kyle; Daryono, Mudrik R.; Aribowo, Sonny; Herrin, Jason

2017-12-01

Over the last decade, studies of natural hazards in Sumatra have focused primarily on great earthquakes and associated tsunamis produced by rupture of the Sunda megathrust. However, the Sumatran Fault and the active volcanic arc present proximal hazards to populations on mainland Sumatra. At present, there is little reliable information on the maximum magnitudes and recurrence intervals of Sumatran Fault earthquakes, or the frequency of paroxysmal caldera-forming (VEI 7-8) eruptions. Here, we present new radiocarbon dates of paleosols buried under the voluminous Ranau Tuff that constrain the large caldera-forming eruption to around 33,830-33,450 calender year BP (95% probability). We use the lateral displacement of river channels incised into the Ranau Tuff to constrain the long-term slip rate of two segments of the Sumatran Fault. South of Ranau Lake, the Kumering segment preserves isochronous right-lateral channel offsets of approximately 350 ± 50 m, yielding a minimum slip rate of 10.4 ± 1.5 mm/year for the primary active fault trace. South of Suoh pull-apart depression, the West Semangko segment offsets the Semangko River by 230 ± 60 m, yielding an inferred slip rate of 6.8 ± 1.8 mm/year. Compared with previous studies, these results indicate more recent high-volume volcanism in South Sumatra and increased seismic potency of the southernmost segments of the Sumatran Fault Zone.

Colorado State University (CSU) accelerator and FEL facility

NARCIS (Netherlands)

Milton, S.; Biedron, S.; Harris, J.; Martinez, J.; D'Audney, A.; Edelen, J.; Einstein, J.; Hall, C.; Horovitz, K.; Morin, A.; Sipahi, N.; Sipahi, T.; Williams, J.; Carrico, C.; Van Der Slot, P. J M

2014-01-01

The Colorado State University (CSU) Accelerator Facility will include a 6-MeV L-Band (1.3 GHz) electron linear accelerator (linac) with a free-electron laser (FEL) system capable of producing Terahertz (THz) radiation, a laser laboratory, a microwave test laboratory, and a magnetic test laboratory.

Cloud condensation nuclei in Western Colorado: Observations and model predictions

Science.gov (United States)

Ward, Daniel Stewart

Variations in the warm cloud-active portion of atmospheric aerosols, or cloud condensation nuclei (CCN), have been shown to impact cloud droplet number concentration and subsequently cloud and precipitation processes. This issue carries special significance in western Colorado where a significant portion of the region's water resources is supplied by precipitation from winter season, orographic clouds, which are particularly sensitive to variations in CCN. Temporal and spatial variations in CCN in western Colorado were investigated using a combination of observations and a new method for modeling CCN. As part of the Inhibition of Snowfall by Pollution Aerosols (ISPA-III) field campaign, total particle and CCN number concentration were measured for a 24-day period in Mesa Verde National Park, climatologically upwind of the San Juan Mountains. These data were combined with CCN observations from Storm Peak Lab (SPL) in northwestern Colorado and from the King Air platform, flying north to south along the Western Slope. Altogether, the sampled aerosols were characteristic of a rural continental environment and the cloud-active portion varied slowly in time, and little in space. Estimates of the is hygroscopicity parameter indicated consistently low aerosol hygroscopicity typical of organic aerosol species. The modeling approach included the addition of prognostic CCN to the Regional Atmospheric Modeling System (RAMS). The RAMS droplet activation scheme was altered using parcel model simulations to include variations in aerosol hygroscopicity, represented by K. Analysis of the parcel model output and a supplemental sensitivity study showed that model CCN will be sensitive to changes in aerosol hygroscopicity, but only for conditions of low supersaturation or small particle sizes. Aerosol number, size distribution median radius, and hygroscopicity (represented by the K parameter) in RAMS were constrained by nudging to forecasts of these quantities from the Weather

The 2014 Greeley, Colorado Earthquakes: Science, Industry, Regulation, and Media

Science.gov (United States)

Yeck, W. L.; Sheehan, A. F.; Weingarten, M.; Nakai, J.; Ge, S.

2014-12-01

On June 1, 2014 (UTC) a magnitude 3.2 earthquake occurred east of the town of Greeley, Colorado. The earthquake was widely felt, with reports from Boulder and Golden, over 60 miles away from the epicenter. The location of the earthquake in a region long considered aseismic but now the locus of active oil and gas production prompted the question of whether this was a natural or induced earthquake. Several classic induced seismicity cases hail from Colorado, including the Rocky Mountain Arsenal earthquakes in the 1960s and the Paradox Valley earthquakes in western Colorado. In both cases the earthquakes were linked to wastewater injection. The Greeley earthquake epicenter was close to a Class II well that had been injecting waste fluid into the deepest sedimentary formation of the Denver Basin at rates as high as 350,000 barrels/month for less than a year. The closest seismometers to the June 1 event were more than 100 km away, necessitating deployment of a local seismic network for detailed study. IRIS provided six seismometers to the University of Colorado which were deployed starting within 3 days of the mainshock. Telemetry at one site allowed for real time monitoring of the ongoing seismic sequence. Local media interest was extremely high with speculation that the earthquake was linked to the oil and gas industry. The timetable of media demand for information provided some challenges given the time needed for data collection and analysis. We adopted a policy of open data and open communication with all interested parties, and made proactive attempts to provide information to industry and regulators. After 3 weeks of data collection and analysis, the proximity and timing of the mainshock and aftershocks to the C4A injection well, along with a sharp increase in seismicity culminating in an M 2.6 aftershock, led to a decision by the Colorado Oil and Gas Corporation Commission (COGCC) to recommend a temporary halt to injection at the C4A injection well. This was the

33 CFR 162.220 - Hoover Dam, Lake Mead, and Lake Mohave (Colorado River), Ariz.-Nev.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Hoover Dam, Lake Mead, and Lake... REGULATIONS § 162.220 Hoover Dam, Lake Mead, and Lake Mohave (Colorado River), Ariz.-Nev. (a) Lake Mead and... the axis of Hoover Dam and that portion of Lake Mohave (Colorado River) extending 4,500 feet...

Annual Copper Mountain Conferences on Multigrid and Iterative Methods, Copper Mountain, Colorado

International Nuclear Information System (INIS)

McCormick, Stephen F.

2016-01-01

This project supported the Copper Mountain Conference on Multigrid and Iterative Methods, held from 2007 to 2015, at Copper Mountain, Colorado. The subject of the Copper Mountain Conference Series alternated between Multigrid Methods in odd-numbered years and Iterative Methods in even-numbered years. Begun in 1983, the Series represents an important forum for the exchange of ideas in these two closely related fields. This report describes the Copper Mountain Conference on Multigrid and Iterative Methods, 2007-2015. Information on the conference series is available at http://grandmaster.colorado.edu/~copper/

Annual Copper Mountain Conferences on Multigrid and Iterative Methods, Copper Mountain, Colorado

Energy Technology Data Exchange (ETDEWEB)

McCormick, Stephen F. [Front Range Scientific, Inc., Lake City, CO (United States)

2016-03-25

This project supported the Copper Mountain Conference on Multigrid and Iterative Methods, held from 2007 to 2015, at Copper Mountain, Colorado. The subject of the Copper Mountain Conference Series alternated between Multigrid Methods in odd-numbered years and Iterative Methods in even-numbered years. Begun in 1983, the Series represents an important forum for the exchange of ideas in these two closely related fields. This report describes the Copper Mountain Conference on Multigrid and Iterative Methods, 2007-2015. Information on the conference series is available at http://grandmaster.colorado.edu/~copper/.

78 FR 39765 - Notice of Proposed Classification of Public Lands/Minerals for State Indemnity Selection, Colorado

Science.gov (United States)

2013-07-02

... Proposed Classification of Public Lands/Minerals for State Indemnity Selection, Colorado AGENCY: Bureau of Land Management, Interior. ACTION: Notice of Proposed Classification. SUMMARY: The Colorado State Board... public lands and mineral estate in lieu of lands to which the State was entitled but did not receive...

Regional earthquakes followed by delayed ground uplifts at Campi Flegrei Caldera, Italy: Arguments for a causal link

Science.gov (United States)

Lupi, Matteo; Frehner, Marcel; Weis, Philipp; Skelton, Alasdair; Saenger, Erik H.; Tisato, Nicola; Geiger, Sebastian; Chiodini, Giovanni; Driesner, Thomas

2017-09-01

Earthquake-triggered volcanic activity promoted by dynamic and static stresses are considered rare and difficult-to-capture geological processes. Calderas are ideal natural laboratories to investigate earthquake-volcano interactions due to their sensitivity to incoming seismic energy. The Campi Flegrei caldera, Italy, is one of the most monitored volcanic systems worldwide. We compare ground elevation time series at Campi Flegrei with earthquake catalogues showing that uplift events at Campi Flegrei are associated with large regional earthquakes. Such association is supported by (yet non-definitive) binomial tests. Over a 70-year time window we identify 14 uplift events, 12 of them were preceded by an earthquake, and for 8 of them the earthquake-to-uplift timespan ranges from immediate responses to 1.2 yr. Such variability in the response delay may be due to the preparedness of the system with faster responses probably occurring in periods during which the Campi Flegrei system was already in a critical state. To investigate the process that may be responsible for the proposed association we simulate the propagation of elastic waves and show that passing body waves impose high dynamic strains at the roof of the magmatic reservoir of the Campi Flegrei at about 7 km depth. This may promote a short-lived embrittlement of the magma reservoir's carapace otherwise marked by a ductile behaviour. Such failure allows magma and exsolved volatiles to be released from the magmatic reservoir. The fluids, namely exsolved volatiles and/or melts, ascend through a nominally plastic zone above the magmatic reservoir. This mechanism and the associated inherent uncertainties require further investigations but the new concept already implies that geological processes triggered by passing seismic waves may become apparent several months after passage of the seismic waves.

Geothermal resource assessment of western San Luis Valley, Colorado

Energy Technology Data Exchange (ETDEWEB)

Zacharakis, Ted G.; Pearl, Richard Howard; Ringrose, Charles D.

1983-01-01

The Colorado Geological Survey initiated and carried out a fully integrated assessment program of the geothermal resource potential of the western San Luis Valley during 1979 and 1980. The San Luis Valley is a large intermontane basin located in southcentral Colorado. While thermal springs and wells are found throughout the Valley, the only thermal waters found along the western part of the Valley are found at Shaw Warm Springs which is a relatively unused spring located approximately 6 miles (9.66 km) north of Del Norte, Colorado. The waters at Shaws Warm Spring have a temperature of 86 F (30 C), a discharge of 40 gallons per minute and contain approximately 408 mg/l of total dissolved solids. The assessment program carried out din the western San Luis Valley consisted of: soil mercury geochemical surveys; geothermal gradient drilling; and dipole-dipole electrical resistivity traverses, Schlumberger soundings, Audio-magnetotelluric surveys, telluric surveys, and time-domain electro-magnetic soundings and seismic surveys. Shaw Warm Springs appears to be the only source of thermal waters along the western side of the Valley. From the various investigations conducted the springs appear to be fault controlled and is very limited in extent. Based on best evidence presently available estimates are presented on the size and extent of Shaw Warm Springs thermal system. It is estimated that this could have an areal extent of 0.63 sq. miles (1.62 sq. km) and contain 0.0148 Q's of heat energy.

New insights on lithofacies architecture, sedimentological characteristics and volcanological evolution of pre-caldera (> 22 ka), multi-phase, scoria- and spatter-cones at Somma-Vesuvius

Science.gov (United States)

Sparice, Domenico; Scarpati, Claudio; Perrotta, Annamaria; Mazzeo, Fabio Carmine; Calvert, Andrew T.; Lanphere, Marvin A.

2017-11-01

Pre-caldera (> 22 ka) lateral activity at Somma-Vesuvius is related to scoria- and spatter-cone forming events of monogenetic or polygenetic nature. A new stratigraphic, sedimentological, textural and lithofacies investigation was performed on five parasitic cones (Pollena cones, Traianello cone, S. Maria a Castello cone and the recently found Terzigno cone) occurring below the Pomici di Base (22 ka) Plinian products emplaced during the first caldera collapse at Somma-Vesuvius. A new Ar/Ar age of 23.6 ± 0.3 ka obtained for the Traianello cone as well as the absence of a paleosol or reworked material between the S. Maria a Castello cone and the Pomici di Base deposits suggest that such cone-forming eruptions occurred near the upper limit of the pre-caldera period (22-39 ky). The stratigraphy of three of these eccentric cones (Pollena cones and Traianello cone) exhibits erosion surfaces, exotic tephras, volcaniclastic layers, paleosols, unconformity and paraconformity between superimposed eruptive units revealing their multi-phase, polygenetic evolution related to activation of separate vents and periods of quiescence. Such eccentric cones have been described as composed of scoria deposits and pure effusive lavas by previous authors. Lavas are here re-interpreted as welded horizons (lava-like) composed of coalesced spatter fragments whose pyroclastic nature is locally revealed by relicts of original fragments and remnants of clast outlines. These welded horizons show, locally, rheomorphic structures allowing to define them as emplaced as clastogenic lava flows. The lava-like facies is transitional, upward and downward, to less welded facies composed of agglutinated to unwelded spatter horizons in which clasts outlines are increasingly discernible. Such textural characteristics and facies variation are consistent with a continuous fall deposition of Hawaiian fire-fountains episodes alternated with Strombolian phases emplacing loose scoria deposits. High enrichment

DYNAMIC MIXING MODEL OF THE CHIGNAHUAPAN THERMAL SPRING IN THE GEOTHERMAL ZONE OF THE ACOCULCO CALDERA, PUEBLA, MEXICO

Science.gov (United States)

Gutierrez-Cirlos, A.; Torres-Rodriguez, V.

2009-12-01

The Acoculco Caldera, of Pliocenic age, is located within the limits of the Transmexican Volcanic Belt (CVT) and the Sierra Madre Oriental (SMOr). The Acoculco geothermal zone consists of a 790m thick igneous sequence, related to a volcanic complex formed by andesites and rhyolitic domes emplaced in an 18 Km diameter annular fracture. It unconformably overlies a 5000 m thick section of folded and faulted Jurassic-Cretaceous carbonate rocks. The Chignahuapan Spring, located in the extreme eastern part of the Geothermal Zone of the Acoculco Caldera, yields temperatures of 49°C and discharges an estimated of 98 lps from the karstified Lower Cretaceous limestone. Both major and trace element geochemical analysis were carried out, and results were interpreted using Piper and Stiff diagrams, as well as geothermometry. The results indicate that water belongs to the calcium-bicarbonate type and yield temperatures in a range of 70-80°C at depth, which suggest an extensive lateral flow from the main reservoir and mixing with shallow groundwaters. The spring suffers significant variations in its temperature throughout the year, especially during the rainy season, when water temperature decreases up to 10°C. Analyzing the hot spring water temperature data from of the last 10 years and comparing it with the precipitation and air temperature curves of the region, we expect to develop a dynamic mixing model which depicts the relation between these factors and the importance of each one in the water temperature variation. We also look forward to be able to forecast water temperature trends for the next several years and correlate it with climate change in the area.

Colorado Multicultural Resources for Arts Education: Dance, Music, Theatre, Visual Arts, and Folk Arts. Second Edition.

Science.gov (United States)

Kitzelman, Jacquie, Ed.

This resource guide recognizes that the arts provide a natural arena for teaching multicultural perspectives to students of all ages. The guide features the four most prevalent ethnic minorities in Colorado, African American, Asian American, Hispanic American, and Native American, plus a section prepared by Colorado's state folklorists. The…

Development of large-volume rhyolitic ignibrites (LRI'S): The Chalupas Caldera, an example from Ecuador

International Nuclear Information System (INIS)

Hammersley, L.; DePaolo, D.J; Beate, B

2001-01-01

The mechanisms responsible for the generation of large volumes of silicic magma and the eruption of large-volume rhyolitic ignimbrites (LRI's) remain poorly understood. Of particular interest are the relative roles of crustal assimilation, fractional crystallization and magma supply and the processes by which large volumes of magma accumulate in crustal chambers rather than erupt in smaller batches. Isotope geochemistry, combined with study of major and trace element variations of lavas, can be used to infer the relative contribution of crustal material and continued magmatic supply. Timescales for the accumulation of magma can be estimated using detailed geochronology. Magma supply rates can be estimated from eruption rates of nearby volcanoes. In this study we investigate the evolution of the Chalupas LRI, a caldera system in the Ecuadorian Andes where LRI's are rare in comparison to the Southern Volcanic Zone (SVZ) of South America (au)

The Colorado Plateau V: research, environmental planning, and management for collaborative conservation

Science.gov (United States)

Villarreal, Miguel L.; van Riper, Carena J.; Johnson, Matthew J.; van Riper, Charles

2012-01-01

Roughly centered on the Four Corners region of the southwestern United States, the Colorado Plateau covers some 130,000 square miles of sparsely vegetated plateaus, mesas, canyons, arches, and cliffs in Arizona, Utah, Colorado, and New Mexico. With elevations ranging from 3,000 to 14,000 feet, the natural systems found within the plateau are dramatically varied, from desert to alpine conditions. This volume, the fifth from the University of Arizona Press and the tenth overall, focuses on adaptation of resource management and conservation to climate change and water scarcity, protecting biodiversity through restructured energy policies, ensuring wildlife habitat connectivity across barriers, building effective conservation networks, and exploring new opportunities for education and leadership in conservation science. An informative read for people interested in the conservation and natural history of the region, the book will also serve as a valuable reference for those people engaged in the management of cultural and biological resources of the Colorado Plateau, as well as scientists interested in methods and tools for land and resource management throughout the West.

Electric Vehicles in Colorado: Anticipating Consumer Demand for Direct Current Fast Charging

Energy Technology Data Exchange (ETDEWEB)

Wood, Eric W. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rames, Clement L. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-07-01

To support the State of Colorado in planning for growth in direct current fast charging (DCFC) for electric vehicles, the National Renewable Energy Laboratory (NREL) has partnered with the Regional Air Quality Council (RAQC) and the Colorado Department of Transportation (CDOT) to analyze a number of DCFC investment scenarios. NREL analyzed existing electric vehicle registration data from IHS Markit (IHS) to highlight early trends in the electric vehicle market, which were compared with sales forecasts predicting large growth in the Colorado electric vehicle market. Electric vehicle forecasts were then used to develop future DCFC scenarios to be evaluated in a simulation environment to estimate consumer benefits of the hypothetical DCFC networks in terms of increased driving range and electric vehicle miles traveled (eVMT). Simulated utilization of the hypothetical DCFC networks was analyzed for geographic trends, particularly for correlations with vehicle electric range. Finally, a subset of simulations is presented for consumers with potentially inconsistent access to charging at their home location and presumably greater reliance on public DCFC infrastructure.

Epidemiologic characterization of Colorado backyard bird flocks.

Science.gov (United States)

Smith, Emily I; Reif, John S; Hill, Ashley E; Slota, Katharine E; Miller, Ryan S; Bjork, Kathe E; Pabilonia, Kristy L

2012-06-01

Backyard gallinaceous bird flocks may play an important role in the spread of infectious diseases within poultry populations as well as the transmission of zoonotic diseases to humans. An epidemiologic characterization was conducted of Colorado backyard flocks to gather information on general flock characteristics, human movement of birds, human-bird interaction, biosecurity practices, and flock health. Our results suggest that backyard poultry flocks in Colorado are small-sized flocks (68.6% of flocks had meat or egg) production for the family (86.44%) or as pet or hobby birds (42.27%). The backyard flock environment may promote bird-to-bird transmission as well as bird-to-human transmission of infectious disease. Birds are primarily housed with free access to the outside (96.85%), and many are moved from the home premises (46.06% within 1 yr). Human contact with backyard flocks is high, biosecurity practices are minimal, and bird health is negatively impacted by increased movement events. Increased knowledge of backyard bird characteristics and associated management practices can provide guidelines for the development of measures to decrease disease transmission between bird populations, decrease disease transmission from birds to humans, and increase the overall health of backyard birds.

Seasonal gravity change at Yellowstone caldera

Science.gov (United States)

Poland, M. P.; de Zeeuw-van Dalfsen, E.

2017-12-01

The driving forces behind Yellowstone's dynamic deformation, vigorous hydrothermal system, and abundant seismicity are usually ascribed to "magmatic fluids," which could refer to magma, water, volatiles, or some combination. Deformation data alone cannot distinguish the relative importance of these fluids. Gravity measurements, however, provide an indication of mass change over time and, when combined with surface displacements, can constrain the density of subsurface fluids. Unfortunately, several decades of gravity surveys at Yellowstone have yielded ambiguous results. We suspect that the difficulty in interpreting Yellowstone gravity data is due to seasonal variations in environmental conditions—especially surface and ground water. Yellowstone gravity surveys are usually carried out at the same time of year (generally late summer) to minimize the impact of seasonality. Nevertheless, surface and subsurface water levels are not likely to be constant from year to year, given annual differences in precipitation. To assess the overall magnitude of seasonal gravity changes, we conducted gravity surveys of benchmarks in and around Yellowstone caldera in May, July, August, and October 2017. Our goal was to characterize seasonal variations due to snow melt/accumulation, changes in river and lake levels, changes in groundwater levels, and changes in hydrothermal activity. We also hope to identify sites that show little variation in gravity over the course of the 2017 surveys, as these locations may be less prone to seasonal changes and more likely to detect small variations due to magmatic processes. Preliminary examination of data collected in May and July 2017 emphasizes the importance of site location relative to sources of water. For example, a site on the banks of the Yellowstone River showed a gravity increase of several hundred microgals associated with a 50 cm increase in the river level. A high-altitude site far from rivers and lakes, in contrast, showed a

Connecting Colorado's Renewable Resources to the Markets in a Cabon-Constrained Electricity Sector

Energy Technology Data Exchange (ETDEWEB)

None

2009-12-31

The benchmark goal that drives the report is to achieve a 20 percent reduction in carbon dioxide (CO{sub 2}) emissions in Colorado's electricity sector below 2005 levels by 2020. We refer to this as the '20 x 20 goal.' In discussing how to meet this goal, the report concentrates particularly on the role of utility-scale renewable energy and high-voltage transmission. An underlying recognition is that any proposed actions must not interfere with electric system reliability and should minimize financial impacts on customers and utilities. The report also describes the goals of Colorado's New Energy Economy5 - identified here, in summary, as the integration of energy, environment, and economic policies that leads to an increased quality of life in Colorado. We recognize that a wide array of options are under constant consideration by professionals in the electric industry, and the regulatory community. Many options are under discussion on this topic, and the costs and benefits of the options are inherently difficult to quantify. Accordingly, this report should not be viewed as a blueprint with specific recommendations for the timing, siting, and sizing of generating plants and high-voltage transmission lines. We convened the project with the goal of supplying information inputs for consideration by the state's electric utilities, legislators, regulators, and others as we work creatively to shape our electricity sector in a carbon-constrained world. The report addresses various issues that were raised in the Connecting Colorado's Renewable Resources to the Markets report, also known as the SB07-91 Report. That report was produced by the Senate Bill 2007-91 Renewable Resource Generation Development Areas Task Force and presented to the Colorado General Assembly in 2007. The SB07-91 Report provided the Governor, the General Assembly, and the people of Colorado with an assessment of the capability of Colorado's utility-scale renewable

A Colorado Response to the Information Society: The Changing Academic Library. Proceedings of a Conference (Denver, Colorado, October 6-7, 1983).

Science.gov (United States)

Breivik, Patricia Senn, Ed.

As suggested by a Colorado Academic Library Master Plan developed in 1982, a statewide conference that brought together academicians and librarians was held to explore the role of academic libraries in the information society. People came in teams of three from institutions and included library directors, academic vice presidents, and faculty…

Climate Projections and Drought: Verification for the Colorado River Basin

Science.gov (United States)

Santos, N. I.; Piechota, T. C.; Miller, W. P.; Ahmad, S.

2017-12-01

The Colorado River Basin has experienced the driest 17 year period (2000-2016) in over 100 years of historical record keeping. While the Colorado River reservoir system began the current drought at near 100% capacity, reservoir storage has fallen to just above 50% during the drought. Even though federal and state water agencies have worked together to mitigate the impact of the drought and have collaboratively sponsored conservation programs and drought contingency plans, the 17-years of observed data beg the question as to whether the most recent climate projections would have been able to project the current drought's severity. The objective of this study is to analyze observations and ensemble projections (e.g. temperature, precipitation, streamflow) from the CMIP3 and CMIP5 archive in the Colorado River Basin and compare metrics related to skill scores, the Palmer Drought Severity Index, and water supply sustainability index. Furthermore, a sub-ensemble of CMIP3/CMIP5 projections, developed using a teleconnection replication verification technique developed by the author, will also be compared to the observed record to assist in further validating the technique as a usable process to increase skill in climatological projections. In the end, this study will assist to better inform water resource managers about the ability of climate ensembles to project hydroclimatic variability and the appearance of decadal drought periods.

Knowledge, Norms and Preferences for Tamarisk Management in the Green and Colorado River Corridors of the Colorado Plateau

OpenAIRE

Allred, E. Clay

2012-01-01

Extensive research exists regarding invasive alien plant species including impacts to native ecosystems and efficacy of control methods on public lands and river corridors. Many studies have identified the need for more research regarding the social implications of invasive alien species management. More specifically, additional research is needed regarding the impacts of invasive alien plant management on the Colorado Plateau to river-based recreation experiences. It is important for public ...

Radon from coal ash in Colorado. Final report

International Nuclear Information System (INIS)

Morse, J.G.

1981-01-01

An attempt was made to develop a radiation profile of Colorado, based on available measured radon data. Data reported indicate that the release of radon to the atmosphere during uranium milling and mining is not a significant health hazard or air pollutant, when compared with radon in soils. 1 figure, 2 tables

77 FR 35669 - AltaGas Renewable Energy Colorado LLC; Supplemental Notice That Initial Market-Based Rate Filing...

Science.gov (United States)

2012-06-14

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER12-1875-000] AltaGas Renewable Energy Colorado LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request... of AltaGas Renewable Energy Colorado LLC application for market-based rate authority, with an...

78 FR 46552 - Approval and Promulgation of Air Quality Implementation Plans; State of Colorado; Second Ten-Year...

Science.gov (United States)

2013-08-01

... ENVIRONMENTAL PROTECTION AGENCY 40 CFR Part 52 [EPA-R08-OAR-2011-0659; FRL-9840-6] Approval and Promulgation of Air Quality Implementation Plans; State of Colorado; Second Ten-Year Carbon Monoxide Maintenance Plan for Colorado Springs AGENCY: Environmental Protection Agency (EPA). ACTION: Proposed rule...

Multicriteria GIS modeling of wind and solar farms in Colorado

Energy Technology Data Exchange (ETDEWEB)

Janke, Jason R. [Metropolitan State College of Denver, Department of Earth and Atmospheric Sciences, CB 22 P.O. Box 173362-22, Denver, CO 80217-3362 (United States)

2010-10-15

The majority of electricity and heat in Colorado comes from coal and natural gas; however, renewable energy sources will play an integral role in the state's energy future. Colorado is the 11th windiest state and has more than 250 sunny days per year. The objectives of this research are to: 1) determine which landcover classes are affiliated with high wind and solar potential; and 2) identify areas that are suitable for wind and solar farms using multicriteria GIS modelling techniques. Renewable potential (NREL wind speed measurements at 50 m above the ground and NREL annual insolation data), landcover, population density, federal lands, and distance to roads, transmission lines, and cities were reclassified according to their suitability. Each was assigned weights based on their relative importance to one another. Superb wind classes are located in high alpine areas. Unfortunately, these areas are not suitable for large-scale wind farm development due to their inaccessibility and location within a sensitive ecosystem. Federal lands have low wind potential. According to the GIS model, ideal areas for wind farm development are located in northeastern Colorado. About 41 850 km{sup 2} of the state has model scores that are in the 90-100% range. Although annual solar radiation varies slightly, inter-mountain areas receive the most insolation. As far as federal lands, Indian reservations have the greatest solar input. The GIS model indicates that ideal areas for solar development are located in northwestern Colorado and east of Denver. Only 191 km{sup 2} of the state had model scores that were in the 90-100% range. These results suggest that the variables used in this analysis have more of an effect at eliminating non-suitable areas for large-scale solar farms; a greater area exists for suitable wind farms. However, given the statewide high insolation values with minimal variance, solar projects may be better suited for small-scale residential or commercial

Geomicrobiological exploration and characterization of novel deep-sea hydrothermal activities accompanying with extremely acidic white smokers and elemental sulfur chimneys at the TOTO caldera in the Mariana Volcanic Arc

Science.gov (United States)

Takai, K.; Nakagawa, T.; Suzuki, Y.; Hirayama, H.; Kosaka, A.; Tsunogai, U.; Gamo, T.; Nealson, K. H.; Horikoshi, K.

2004-12-01

Novel hydrothermal activities accompanying effluent white smokers and elemental sulfur chimney structures at the northeast lava dome of the TOTO caldera depression in the Mariana Volcanic Arc were explored by the manned submersible Shinkai 6500 and characterized by geochemical and microbiological surveys. The white smoker hydrothermal fluids were observed in the potential hydrothermal activity center of the field and represented a maximal temperature of 172 degree C and a lowest pH of 1.59, that was the lowest pH of the hydrothermal fluid ever recorded. The chimney structures consisting all of elemental sulfur (sulfur chimney) were also peculiar to the TOTO caldera hydrothermal field in the world. The geochemical characterization strongly suggested that the TOTO caldera hydrothermal field was a novel system driven by subseafloor mixing between the oxygenated seawater and the superheated volcanic gasses. Microbial community structures in a sulfur chimney structure and its formation hydrothermal fluid with a high concentration of hydrogen sulfide (15 mM) were investigated by culture-dependent and _|independent analyses. Ribosomal rRNA gene clone analysis and fluorescence in situ hybridization (FISH) analysis revealed that epsilon-Proteobacteria, specifically classified into Group G and Group B, dominated the microbial communities in the sulfur chimney structure and formed a dense microbial mat covering the sulfur chimney surface. Archaeal phylotypes were consistently minor components in the communities and related to the genera Thermococcus, Pyrodictium, Aeropyrum, and the uncultivated archaeal group of Deep-sea Hydrothermal Vent Euryarchaeotal Group. Cultivation analysis suggested that the microbial components inhabiting in the sulfur chimney structure might be entrained by hydrothermal fluids from the potential subsurface habitats

Sr isotope evidence for a lacustrine origin for the upper Miocene to Pliocene Bouse Formation, lower Colorado River trough, and implications for timing of Colorado Plateau uplift

Science.gov (United States)

Spencer, J.E.; Patchett, P.J.

1997-01-01

The upper Miocene to Pliocene Bouse Formation in the lower Colorado River trough, which consists largely of siltstone with basal tufa and marl, has been interpreted as estuarine on the basis of paleontology. This interpretation requires abrupt marine inundation that has been linked to early rifting in the Gulf of California and Salton trough. New strontium isotope measurements reported here from carbonates and invertebrate shells in the Bouse Formation reveal no evidence of marine water, but are consistent with deposition in a lake or chain of lakes fed by the Colorado River. Furthermore, the absence of a southward decrease in 87Sr/86Sr within the Bouse Formation does not support the estuarine model in which low 87Sr/86Sr marine Sr would have dominated the mouth of the hypothetical Bouse estuary. Elevation of originally marine 87Sr/86Sr in the Bouse Formation to its present level, due to postdepositional interaction with ground water, is unlikely because Sr from secondary calcite above, below, and within the Bouse Formation is consistently less radiogenic, not more, than Bouse marl and shells. In contrast to Bouse Sr, strontium from mollusks in tidal-flat and delta-front paleoenvironments in the contemporaneous Imperial Formation in the Salton trough and from the subsurface south of Yuma was derived from sea water and confirms the dominance of marine strontium near or at the mouth of the late Miocene to early Pliocene Colorado River. Inferred post-early Pliocene uplift of the Bouse Formation from below sea level to modern elevations of up to 550 m has been used to support a late Cenozoic uplift age for the nearby Colorado Plateau. This constraint on uplift timing is eliminated if the Bouse Formation is lacustrine.

GPS Imaging suggests links between climate, magmatism, seismicity, and tectonics in the Sierra Nevada-Long Valley Caldera-Walker Lane system, western United States

Science.gov (United States)

Hammond, W. C.; Blewitt, G.; Kreemer, C.; Smith, K.

2017-12-01

The Walker Lane is a region of complex active crustal transtension in the western Great Basin of the western United States, accommodating about 20% of the 50 mm/yr relative motion between the Pacific and North American plates. The Long Valley caldera lies in the central Walker Lane in eastern California, adjacent to the eastern boundary of the Sierra Nevada/Great Valley microplate, and experiences intermittent inflation, uplift, and volcanic unrest from the magma chamber that resides at middle crustal depths. Normal and transform faults accommodating regional tectonic transtension pass by and through the caldera, complicating the interpretation of the GPS-measured strain rate field, estimates of fault slip rates, and seismic hazard. Several dozen continuously recording GPS stations measure strain and uplift in the area with mm precision. They observe that the most recent episode of uplift at Long Valley began in mid-2011, continuing until late 2016, raising the surface by 100 mm in 6 years. The timing of the initiation of uplift coincides with the beginning of severe drought in California. Furthermore, the timing of a recent pause in uplift coincides with the very wet 2016-2017 winter, which saw approximately double normal snow pack. In prior studies, we showed that the timing of changes in geodetically measured uplift rate of the Sierra Nevada coincides with the timing of drought conditions in California, suggesting a link between hydrological loading and Sierra Nevada elevation. Here we take the analysis three steps further to show that changes in Sierra Nevada uplift rate coincide in time with 1) enhanced inflation at the Long Valley caldera, 2) shifts in the patterns and rates of horizontal tensor strain rate, and 3) seismicity patterns in the central Walker Lane. We use GPS solutions from the Nevada Geodetic Laboratory and the new GPS Imaging technique to produce robust animations of the time variable strain and uplift fields. The goals of this work are to

University of Colorado Students Join Pros in Covering Columbine Incident.

Science.gov (United States)

Litherland, Chip

1999-01-01

Describes the experiences and feelings of a university photojournalist as he covered the shootings at Columbine High School in Littleton, Colorado. Notes the onslaught of the media presence and the overwhelming emotion he witnessed. (RS)

Sustainable water deliveries from the Colorado River in a changing climate.

Science.gov (United States)

Barnett, Tim P; Pierce, David W

2009-05-05

The Colorado River supplies water to 27 million users in 7 states and 2 countries and irrigates over 3 million acres of farmland. Global climate models almost unanimously project that human-induced climate change will reduce runoff in this region by 10-30%. This work explores whether currently scheduled future water deliveries from the Colorado River system are sustainable under different climate-change scenarios. If climate change reduces runoff by 10%, scheduled deliveries will be missed approximately 58% of the time by 2050. If runoff reduces 20%, they will be missed approximately 88% of the time. The mean shortfall when full deliveries cannot be met increases from approximately 0.5-0.7 billion cubic meters per year (bcm/yr) in 2025 to approximately 1.2-1.9 bcm/yr by 2050 out of a request of approximately 17.3 bcm/yr. Such values are small enough to be manageable. The chance of a year with deliveries climate-change or long-term mean flows, currently scheduled future water deliveries from the Colorado River are not sustainable. However, the ability of the system to mitigate droughts can be maintained if the various users of the river find a way to reduce average deliveries.

Advancing the "Colorado Graduates" Agenda: Understanding the Dropout Problem and Mobilizing to Meet the Graduation Challenge

Science.gov (United States)

Mac Iver, Martha Abele; Balfanz, Robert; Byrnes, Vaughan

2009-01-01

The ambitious goal set by Colorado's governor to address the state's dropout problem is a model for the nation. Helping thousands of young people to receive their high school diplomas instead of leaving school without them is a crucial step in improving the quality of life for all Colorado residents. Accomplishing this goal will require focused…

78 FR 5196 - Notice of Invitation To Participate; Exploration for Coal in Colorado License Application COC-75642

Science.gov (United States)

2013-01-24

...] Notice of Invitation To Participate; Exploration for Coal in Colorado License Application COC-75642... Mineral Leasing Act of 1920, as amended by the Federal Coal Leasing Amendments Act of 1976, and to Bureau..., Colorado. DATES: Any party electing to participate in this exploration program must send written notice to...

Magmatic storage conditions, decompression rate, and incipient caldera collapse of the 1902 eruption of Santa Maria Volcano, Guatemala

Science.gov (United States)

Andrews, Benjamin J.

2014-08-01

Phase equilibria experiments and analysis of natural pumice and phenocryst compositions indicate the 1902 Santa Maria dacite was stored at ~ 140-170 MPa and 840-850 °C prior to eruption. H2O-saturated, cold-seal experiments conducted in vessels with an intrinsic log fO2 of NNO + 1 ± 0.5 show that the natural phase assemblage (melt + plagioclase + amphibole + orthopyroxene + Fe-Ti oxides + apatite) is stable from approximately 115-140 MPa at temperatures below ~ 825 °C, to ~ 840-860 °C at 150 MPa, to > 850 and Ridolfi et al., 2010) applied to experimental samples suggest two populations of amphiboles, phenocrysts grown during the experiments and inherited xenocrysts, but the pressure-temperature conditions returned by the geothermobarometer are routinely > 50 MPa and > 50 °C greater than experimental run conditions; precise estimates of magmatic conditions based solely upon amphibole composition are likely inaccurate. The experimental results and analysis of natural crystals suggest that although the natural amphiboles likely record a broad range of magmatic conditions, only the lower bounds of that range reflect pre-eruptive storage conditions. Comparison of Santa Maria microlite abundances with decompression experiments examining other silicic systems from the literature suggests that the 1902 dacite decompressed at the rate of ~ 0.005 to 0.01 MPa/s during the eruption. Applying the decompression rate with the previously described eruption rate of approximately 2-3 × 108 kg/s (Williams and Self, 1983; Carey and Sparks, 1986) to the conduit model CONFLOW reveals that the eruption conduit was dike-like with an along-strike length > 1 km. Despite depositing ~ 20 km3 of dacite tephra (equivalent to ~ 8.5 km3 magma), the 1902 eruption did not form an obvious caldera. This work suggests that collapse of the dike-like conduit terminated the eruption, preventing full caldera collapse.

Being PREPaREd for Crisis in Northern Colorado

Science.gov (United States)

Hancock, Kathy; Malvey, Michelle; Rastatter, Dennis

2010-01-01

The Thompson School District recognized after the Columbine incident in the spring of 1999 that it was lacking an adequate plan for crisis response. Colorado legislation led to a mandate for having a crisis response plan so the district purchased a "canned" crisis response plan that served the needs of response in a very immediate but…

Radar imaging of glaciovolcanic stratigraphy, Mount Wrangell caldera, Alaska - Interpretation model and results

Science.gov (United States)

Clarke, Garry K. C.; Cross, Guy M.; Benson, Carl S.

1989-01-01

Glaciological measurements and an airborne radar sounding survey of the glacier lying in Mount Wrangell caldera raise many questions concerning the glacier thermal regime and volcanic history of Mount Wrangell. An interpretation model has been developed that allows the depth variation of temperature, heat flux, pressure, density, ice velocity, depositional age, and thermal and dielectric properties to be calculated. Some predictions of the interpretation model are that the basal ice melting rate is 0.64 m/yr and the volcanic heat flux is 7.0 W/sq m. By using the interpretation model to calculate two-way travel time and propagation losses, radar sounding traces can be transformed to give estimates of the variation of power reflection coefficient as a function of depth and depositional age. Prominent internal reflecting zones are located at depths of approximately 59-91m, 150m, 203m, and 230m. These internal reflectors are attributed to buried horizons of acidic ice, possibly intermixed with volcanic ash, that were deposited during past eruptions of Mount Wrangell.

78 FR 23829 - Irish Potatoes Grown in Colorado; Modification of the Handling Regulation for Area No. 2

Science.gov (United States)

2013-04-23

... FIR] Irish Potatoes Grown in Colorado; Modification of the Handling Regulation for Area No. 2 AGENCY... the grade requirements for potatoes handled under the Colorado potato marketing order, Area No. 2. The..., red- skinned potatoes handled under the marketing order from U.S. No. 1 to U.S. Commercial. This...

78 FR 70191 - Irish Potatoes Grown in Colorado; Modification of the General Cull and Handling Regulation for...

Science.gov (United States)

2013-11-25

...-FV-13-0001; FV13-948-1 FIR] Irish Potatoes Grown in Colorado; Modification of the General Cull and..., without change, an interim rule that modified the size requirements for potatoes handled under the Colorado potato marketing order, Area No. 2 (order). The order regulates the handling of Irish potatoes...

78 FR 71493 - Special Local Regulation; Lake Havasu City Christmas Boat Parade of Lights; Colorado River; Lake...

Science.gov (United States)

2013-11-29

...-AA00 Special Local Regulation; Lake Havasu City Christmas Boat Parade of Lights; Colorado River; Lake... temporarily modifying the dates for the special local regulation in support of the Lake Havasu City Christmas Boat Parade of Lights on the Colorado River. This modification is necessary to reflect the actual dates...

76 FR 55701 - Notice of Invitation to Participate; Exploration for Coal in Colorado License Application COC-74895

Science.gov (United States)

2011-09-08

...] Notice of Invitation to Participate; Exploration for Coal in Colorado License Application COC-74895... Mineral Leasing Act of 1920, as amended by the Federal Coal Leasing Amendments Act of 1976, and to Bureau... coal deposits owned by the United States of America in lands located in Routt County, Colorado. DATES...

33 CFR 208.19 - Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Marshall Ford Dam and Reservoir... Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Tex. The Secretary of the Interior, through his agent, the Lower Colorado River Authority (LCRA) shall operate the Marshall Ford Dam...

Amphibious Magnetotelluric Investigation of the Aleutian Arc: Mantle Melt Generation and Migration beneath Okmok Caldera

Science.gov (United States)

Zelenak, G.; Key, K.; Bennington, N. L.; Bedrosian, P.

2015-12-01

Understanding the factors controlling the release of volatiles from the downgoing slab, the subsequent generation of melt in the overlying mantle wedge, the migration of melt to the crust, and its evolution and emplacement within the crust are important for advancing our understanding of arc magmatism and crustal genesis. Because melt and aqueous fluids are a few orders of magnitude more electrically conductive than unmelted peridotite, the conductivity-mapping magnetotelluric (MT) method is well-suited to imaging fluids and melt beneath arc volcanoes. Here we present conductivity results from an amphibious MT profile crossing Okmok volcano in the central Aleutian arc. The Aleutian arc is one of the most volcanically active regions in North America, making it an ideal location for studying arc magnetism. Okmok volcano, located on the northeastern portion of Umnak Island, is among the most active volcanoes in the Aleutian chain. In addition to two caldera-forming events in the Holocene, numerous eruptions in the past century indicate a robust magmatic supply. Previous coarse resolution seismic studies have inferred a crustal magma reservoir. In order to investigate the role fluids play in melting the mantle wedge, how melts ascend through the corner flow regime of the mantle wedge, how melt migrates and is stored within the upper mantle and crust, and how this impacts explosive caldera forming eruptions, we carried out an amphibious geophysical survey across the arc in June-July 2015. Twenty-nine onshore MT stations and 10 offshore stations were collected in a 3D array covering Okmok, and 43 additional offshore MT stations completed a 300 km amphibious profile starting at the trench, crossing the forearc, arc and backarc. Thirteen onshore passive seismic stations were also installed and will remain in place for one year to supplement the twelve permanent stations on the island. Data collected by this project will be used to map seismic velocity and electrical

Lessons learned after three years of legalized, recreational marijuana: The Colorado experience.

Science.gov (United States)

Ghosh, Tista S; Vigil, Daniel I; Maffey, Ali; Tolliver, Rickey; Van Dyke, Mike; Kattari, Leonardo; Krug, Heather; Reed, Jack K; Wolk, Larry

2017-11-01

In November 2012 Colorado voters approved legalized recreational marijuana. On January 1, 2014 Colorado became the first state to allow legal sales of non-medical marijuana for adults over the age of 21. Since that time, the state has been monitoring potential impacts on population health. In this paper we present lessons learned in the first three years following legal sales of recreational marijuana. These lessons pertain to health behaviors and health outcomes, as well as to health policy issues. Our intent is to share these lessons with other states as they face the prospect of recreational marijuana legalization. Copyright © 2017 Elsevier Inc. All rights reserved.

Annual report on the U.S. Department of Energy's cultural resource activities at Colorado UMTRA Project sites for October 1995--September 1996

International Nuclear Information System (INIS)

1996-09-01

This report summarizes the results of cultural resource activities conducted by the U.S. Department of Energy (DOE) at Uranium Mill Tailings Remedial Action (UMTRA) Project sites in Colorado for the period of October 1, 1995 through September 30, 1996. The inactive uranium mill tailings sites in Colorado are at Durango, Grand Junction, Gunnison, Maybell, Naturita, Rifle, and Slick Rock. On December 6, 1984, the DOE, the Advisory Council on Historic Preservation, and the Colorado State Historic Preservation Officer (SHPO) entered into a programmatic memorandum of understanding (PMOU). This PMOU requires the DOE to fulfillment of its obligations under various state and federal regulations for the protection and preservation of cultural resources. This report provides the state of Colorado with an annual report on the cultural resource activities performed for all UMTRA Project sites in Colorado. Due to the completion of surface activities at the UMTRA Project sites, this will be the last annual report to the state of Colorado. Cultural resources activities subsequent to this report will be reported to the state through site-specific correspondence

Landslides in Colorado, USA--Impacts and loss estimation for 2010

Science.gov (United States)

Highland, Lynn M.

2012-01-01

The focus of this study is to investigate landslides and consequent losses which affected Colorado in the year 2010. By obtaining landslide reports from a variety of sources, this report will demonstrate the feasibility of creating a profile of landslides and their effects on communities. A short overview of the current status of landslide-loss studies for the United States is introduced, followed by a compilation of landslide occurrence and associated losses and impacts which affected Colorado for the year 2010. Direct costs are summarized in descriptive and tabular form, and where possible, indirect costs are also noted or estimated. Total direct costs of landslides in Colorado for the year 2010 were approximately $9,149,335.00 (2010 U.S. dollars). (Since not all data for damages and costs were obtained, this figure realistically could be considerably higher.) Indirect costs were noted where available but are not totaled due to the fact that most indirect costs were not obtainable for various reasons outlined later in this report. Casualty data are considered as being within the scope of loss evaluation, and are reported in Appendix 1, but are not assigned dollar losses. More details on the source material for loss data not found in the reference section are reported in Appendix 2, and Appendix 3 summarizes notes on landslide-loss investigations in general and lessons learned during the process of loss-data collection.

Mount Zirkel Wilderness and vicinity, Colorado

International Nuclear Information System (INIS)

Snyder, G.L.; Patten, L.L.

1984-01-01

Several areas of metallic and nonmetallic mineralization have been identified from surface occurrences within the Mount Zirkel Wilderness and vicinity, Colorado. Three areas of probable copper-lead-zinc-silver-gold resource potential, two areas of probable chrome-platinum resource potential, four areas of probable uranium-thorium resource potential, two areas of probable molybdenum resource potential, and one area of probable fluorspar potential were identified by studies in 1965-1973 by the USGS and USBM. No potential for fossil fuel or geothermal resources was identified

Unravelling the collapse mechanisms at a Jurassic caldera of the Chon Aike silicic LIP in Southern Patagonia (47 deg. 15 'S, 71 deg. 40'W), Argentina

International Nuclear Information System (INIS)

Sruoga, P; Japas, S; Salani, F; Kleiman, L; Graffigna, M

2008-01-01

La Peligrosa Caldera is located at Sierra Colorada (47 0 15'S, 71 0 40' W) in the Chon-Aike silicic LIP. It represents an unique window to understand the eruptive mechanisms that prevailed throughout the ignimbritic flare-up in Southern Patagonia during middle to late Jurassic times. Key pieces of lithologic and structural evidences are taken into account to reconstruct the volcanic structure.

Unravelling the collapse mechanisms at a Jurassic caldera of the Chon Aike silicic LIP in Southern Patagonia (47° 15 'S, 71° 40'W), Argentina

Science.gov (United States)

Sruoga, P.; Japas, S.; Salani, F.; Kleiman, L.; Graffigna, M.

2008-10-01

La Peligrosa Caldera is located at Sierra Colorada (47° 15'S, 71° 40' W) in the Chon-Aike silicic LIP. It represents an unique window to understand the eruptive mechanisms that prevailed throughout the ignimbritic flare-up in Southern Patagonia during middle to late Jurassic times. Key pieces of lithologic and structural evidences are taken into account to reconstruct the volcanic structure.

Aggregate supply and demand modeling using GIS methods for the front range urban corridor, Colorado

Science.gov (United States)

Karakas, Ahmet; Turner, Keith

2004-07-01

The combined use of allocation modeling and geographical information system (GIS) technologies for providing quantitative assessments of aggregate supply and demand is evaluated using representative data for the Front Range Urban Corridor (FRUC) in Colorado. The FRUC extends from the Colorado-Wyoming border to south of Colorado Springs, and includes Denver and the major urban growth regions of Colorado. In this area, aggregate demand is high and is increasing in response to population growth. Neighborhood opposition to the establishment of new pits and quarries and the depletion of many deposits are limiting aggregate supplies. Many sources are already covered by urban development or eliminated from production by zoning. Transport of aggregate by rail from distant resources may be required in the future. Two allocation-modeling procedures are tested in this study. Network analysis procedures provided within the ARC/INFO software, are unsatisfactory. Further aggregate allocation modeling used a model specifically designed for this task; a modified version of an existing Colorado School of Mines allocation model allows for more realistic market analyses. This study evaluated four scenarios. The entire region was evaluated with a scenario reflecting the current market and by a second scenario in which some existing suppliers were closed down and new potential suppliers were activated. The conditions within the Denver metropolitan area were studied before and after the introduction of three possible rail-to-truck aggregate distribution centers. GIS techniques are helpful in developing the required database to describe the Front Range Urban Corridor aggregate market conditions. GIS methods allow the digital representation of the regional road network, and the development of a distance matrix relating all suppliers and purchasers.

Source signature of volatile organic compounds from oil and natural gas operations in northeastern Colorado.

Science.gov (United States)

Gilman, J B; Lerner, B M; Kuster, W C; de Gouw, J A

2013-02-05

An extensive set of volatile organic compounds (VOCs) was measured at the Boulder Atmospheric Observatory (BAO) in winter 2011 in order to investigate the composition and influence of VOC emissions from oil and natural gas (O&NG) operations in northeastern Colorado. BAO is 30 km north of Denver and is in the southwestern section of Wattenberg Field, one of Colorado's most productive O&NG fields. We compare VOC concentrations at BAO to those of other U.S. cities and summertime measurements at two additional sites in northeastern Colorado, as well as the composition of raw natural gas from Wattenberg Field. These comparisons show that (i) the VOC source signature associated with O&NG operations can be clearly differentiated from urban sources dominated by vehicular exhaust, and (ii) VOCs emitted from O&NG operations are evident at all three measurement sites in northeastern Colorado. At BAO, the reactivity of VOCs with the hydroxyl radical (OH) was dominated by C(2)-C(6) alkanes due to their remarkably large abundances (e.g., mean propane = 27.2 ppbv). Through statistical regression analysis, we estimate that on average 55 ± 18% of the VOC-OH reactivity was attributable to emissions from O&NG operations indicating that these emissions are a significant source of ozone precursors.

Colorado Handbook for State-Funded Student Assistance Programs. Revised.

Science.gov (United States)

Colorado Commission on Higher Education, Denver.

Policies and procedures established by the Colorado Commission on Higher Education for the use of state-funded student assistance are presented. Annual budget ranges, sample forms, and instructions are included. In addition to providing definitions and general policy information, the guidelines cover fund application and allocation; accounting,…

Simulating the Probability of Grain Sorghum Maturity before the First Frost in Northeastern Colorado

Directory of Open Access Journals (Sweden)

Gregory S. McMaster

2016-09-01

Full Text Available Expanding grain sorghum [Sorghum bicolor (L. Moench] production northward from southeastern Colorado is thought to be limited by shorter growing seasons due to lower temperatures and earlier frost dates. This study used a simulation model for predicting crop phenology (PhenologyMMS to estimate the probability of reaching physiological maturity before the first fall frost for a variety of agronomic practices in northeastern Colorado. Physiological maturity for seven planting dates (1 May to 12 June, four seedbed moisture conditions affecting seedling emergence (from Optimum to Planted in Dust, and three maturity classes (Early, Medium, and Late were simulated using historical weather data from nine locations for both irrigated and dryland phenological parameters. The probability of reaching maturity before the first frost was slightly higher under dryland conditions, decreased as latitude, longitude, and elevation increased, planting date was delayed, and for later maturity classes. The results provide producers with estimates of the reliability of growing grain sorghum in northeastern Colorado.

Communities defining environmental health: examples from the Colorado (U.S.A.) Healthy Communities Initiative.

Science.gov (United States)

Conner, R F; Tanjasiri, S P

2000-01-01

Communities are increasingly defining 'health' for themselves, then becoming the main actors in actions to improve their health and well being. These community members work from a broad and inclusive definition of 'health' that often incorporates environmental health as a key aspect. They also assume an ecological, or systems, viewpoint that integrates many aspects of the community that affect health and well being, including housing, health, economy, education, transportation, youth and family issues, as well as health and illness care. This paper describes a program that involves 28 large and small, urban and rural communities in the United States state of Colorado that undertook this type of community-based health improvement project. The Colorado Healthy Communities Initiative (CHCI) was designed to bring together citizens in Colorado to work collaboratively to make their communities healthier. This paper describes the program's background, including its principles, processes, and participants, then focuses on the particular aspects of environmental health that communities included in their definitions of a 'healthy community'.

Insights into the 3D architecture of an active caldera ring-fault at Tendürek volcano through modeling of geodetic data

KAUST Repository

Vasyura-Bathke, Hannes

2015-04-28

The three-dimensional assessment of ring-fault geometries and kinematics at active caldera volcanoes is typically limited by sparse field, geodetic or seismological data, or by only partial ring-fault rupture or slip. Here we use a novel combination of spatially dense InSAR time-series data, numerical models and sand-box experiments to determine the three-dimensional geometry and kinematics of a sub-surface ring-fault at Tendürek volcano in Turkey. The InSAR data reveal that the area within the ring-fault not only subsides, but also shows substantial westward-directed lateral movement. The models and experiments explain this as a consequence of a ‘sliding-trapdoor’ ring-fault architecture that is mostly composed of outward-inclined reverse segments, most markedly so on the volcano\\'s western flanks but includes inward-inclined normal segments on its eastern flanks. Furthermore, the model ring-fault exhibits dextral and sinistral strike-slip components that are roughly bilaterally distributed onto its northern and southern segments, respectively. Our more complex numerical model describes the deformation at Tendürek better than an analytical solution for a single rectangular dislocation in a half-space. Comparison to ring-faults defined at Glen Coe, Fernandina and Bárðarbunga calderas suggests that ‘sliding-trapdoor’ ring-fault geometries may be common in nature and should therefore be considered in geological and geophysical interpretations of ring-faults at different scales worldwide.

Construction of calibration pads facility, Walker Field, Grand Junction, Colorado

International Nuclear Information System (INIS)

Ward, D.L.

1978-08-01

A gamma-ray spectrometer facility was completed at Walker Field Airport, Grand Junction, Colorado, in November 1976. This report describes spectrometers and their calibration, the construction of the spectrometer facility, the radioelement concentrations, procedures for using the facilites, and environmental considerations

Colorado River Sewer System Joint Venture to Upgrade Wastewater System

Science.gov (United States)

SAN FRANCISCO -Today, the Colorado River Sewer System Joint Venture, located in Parker, Ariz. entered into an agreement with the EPA to upgrade their wastewater treatment system to meet stringent water quality standards. The cost of the upgrade is ap

Remedial action plan and site design for stabilization of the inactive uranium processing site at Naturita, Colorado

International Nuclear Information System (INIS)

1993-08-01

The uranium processing site near Naturita, Colorado, is one of 24 inactive uranium mill sites designated to be cleaned up by the US Department of Energy (DOE) under the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA), Public Law 95-604. Part of the UMTRCA requires that the US Nuclear Regulatory Commission (NRC) concur with the DOE's remedial action plan (RAP) and certify that the remedial action conducted at the site complies with the standards promulgated by the US Environmental Protection Agency (EPA). Included in the RAP is this Remedial Action Selection Report (RAS), which serves two purposes. First, it describes the activities that are proposed by the DOE to accomplish remediation and long-term stabilization and control of the radioactive materials at the inactive uranium processing site near Naturita, Colorado. Second, this document and the rest of the RAP, upon concurrence and execution by the DOE, the state of Colorado, and the NRC, become Appendix B of the cooperative agreement between the DOE and the State of Colorado

43 CFR 34.6 - Equal opportunity clause.

Science.gov (United States)

2010-10-01

... women in its procurement practices; to assure that applicants for employment are employed, and that employees are treated during employment, without discrimination on the basis of race, creed, color, national..., financial aid, and other benefits without discrimination on the basis of race, creed, color, national origin...