Sample records for accelerographs

  1. Fast Moment Tensor Inversion for Large Earthquakes using the Mexican Accelerographic Network (United States)

    Juarez, A.; Ramirez-Guzman, L.


    The moment tensor calculation that is computed immediately after the occurrence of a major earthquake is limited to the number of unsaturated records in stations near the epicenter and the number of stations that transmit their data in real-time. Accelerographic records, however, are not commonly saturated after major earthquakes. Taking advantage of the wide coverage of the Mexican Accelerographic Network, we use accelerograms observed in real time to compute moment tensor solutions after the occurrence of an earthquake. In our study, we compute the double-couple moment tensor inversion as a least squares problem by minimizing the misfit between synthetic waveforms in three components and observed waveforms. Synthetic Receiver Green's Tensors for each station of the network within the model were previously calculated using a three-dimensional model of South-central Mexico. The database has horizontal spatial resolution of 20 km and a depth spatial resolution of 5 km. Our procedure fits windows containing the P and S waves to compute a fast first-solution. A revised solution is then calculated by fitting the full record. A first solution can be obtained seconds after the P-wave recorded in the station closest to the epicenter. Our results show that it is possible to obtain the moment tensor solution quickly and accurately. Furthermore, we show the resolution and range of uncertainty of the moment tensor solutions compared with that reported by specialized agencies for 30 selected strong earthquakes in Mexico from 2010 to 2014.

  2. Real-time simulation of ground displacement by digital accelerograph record

    Institute of Scientific and Technical Information of China (English)

    金星; 马强; 李山有


    With the development of accelerograph, strong ground motion data can be widely applied to many fields. Especially, it is an important milestone for strong motion observation to expand application fields into earthquake monitoring that real-time simulation of ground displacement can be obtained by strong motion records for determining three earthquake parameters. For the purpose of application, on the basis of principle of seismic response of single-degree-of-freedom (SDOF) system, this paper presents a suit of formula of simulating ground displacement records by using strong ground motion records with the help of simulator of SDOF system. The research results show that the technique is very efficient and can be widely applied to earthquake monitoring.

  3. Calibrating accelerometer sensor on android phone with Accelerograph TDL 303 QS for earthquake online recorder (United States)

    Riantana, R.; Darsono, D.; Triyono, A.; Azimut, H. B.


    Calibration of the android censor was done by placing the device in a mounting at side of accelerograph TDL 303 QS that will be a means of comparison. Leveling of both devices was set same, so that the state of the device can be assumed same anyway. Then applied vibrations in order to have the maximum amplitude value of both censor, so it can be found equality of the coefficient of proportionality both of them. The results on both devices obtain the Peak Ground Acceleration (PGA) as follows, on the x axis (EW) android censor is obtained PGA -2.4478145 gal than at TDL 303 QS obtained PGA -2.5504 gal, the y-axis (NS) on the censor android obtained PGA 3.0066964 gal than at TDL 303 QS obtained PGA 3.2073 gal, the z-axis (UD) on the android censor obtained PGA -14.0702377 gal than at TDL 303 QS obtained PGA -13.2927 gal, A correction value for android accelerometer censor is ± 0.1 gal for the x-axis (EW), ± 0.2 gal for the y-axis (NS), and ± 0.7 gal for the z-axis (UD).

  4. Scaled accelerographs for design of structures in Quetta, Baluchistan, Pakistan (United States)

    Bhatti, Abdul Qadir


    Structural design for seismic excitation is usually based on peak values of forces and deformations over the duration of earthquake. In determining these peak values dynamic analysis is done which requires either response history analysis (RHA), also called time history analysis, or response spectrum analysis (RSA), both of which depend upon ground motion severity. In the past, PGA has been used to describe ground motion severity, because seismic force on a rigid body is proportional to the ground acceleration. However, it has been pointed out that single highest peak on accelerograms is a very unreliable description of the accelerograms as a whole. In this study, we are considering 0.2- and 1-s spectral acceleration. Seismic loading has been defined in terms of design spectrum and time history which will lead us to two methods of dynamic analysis. Design spectrum for Quetta will be constructed incorporating the parameters of ASCE 7-05/IBC 2006/2009, which is being used by modern codes and regulation of the world like IBC 2006/2009, ASCE 7-05, ATC-40, FEMA-356 and others. A suite of time history representing design earthquake will also be prepared, this will be a helpful tool to carryout time history dynamic analysis of structures in Quetta.

  5. Design and Realization of the Dynamoelectric Accelerograph Control System of X-Aeroengine Oil Pump Modulator%某航空发动机油泵调节器电动油门控制系统设计与实现

    Institute of Scientific and Technical Information of China (English)

    蔡开龙; 赵东运; 谢寿生


    提出了一种某航空发动机油泵调节器电动油门控制系统的设计方案.介绍了电动油门控制系统工作原理和各组成部分的设计过程,给出了油门手柄角位移信号α与模拟电压信号Ux 的对应关系,分析了计算机控制系统控制步进电机工作的过程,通过步进电机与油泵调节器的联轴器设计实现了油门手柄对油泵调节器油门开度的控制.试验证明:本文提出的电动油门控制系统的设计方案行之有效,它能有效地调节油门开度的大小,而且调节的精度较高.

  6. Strong Motion Earthquake Data Values of Digitized Strong-Motion Accelerograms, 1933-1994 (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Strong Motion Earthquake Data Values of Digitized Strong-Motion Accelerograms is a database of over 15,000 digitized and processed accelerograph records from...

  7. Study to Determine Seismic Response of Sonic Boom-Coupled Rayleigh Waves (United States)


    are compiled from the microtremor measurements carried out by Instituto de Ingenieria , UNAM and scientists from Japan (for a total of 181 sites...the accelerographs operated by Instituto de Ingenieria , UNAM. Using this new data and results from the analysis of previous accelerograms we present

  8. Estimation of Sedimentary Thickness in Kachchh Basin, Gujarat Using SP Converted Phase (United States)

    Chopra, Sumer; Rao, K. M.; Rastogi, B. K.


    An inexpensive method using natural earthquake data is utilized for determining the sedimentary thickness in Kachchh. The Institute of Seismological Research (ISR) is operating a network of broadband seismographs and strong motion accelerographs in Gujarat. We used data from 13 broadband seismographs and two strong motion accelerographs in the study. The stations are within 5 to 80 km from the epicenters. In this study the S-to-P converted phase, SP, is used. This phase is generated due to large impedance contrast between sediments and basement. This phase is clear in the vertical component. The difference in the travel times of S and SP phases and velocities of P and S waves is used for determining the sedimentary layer thickness. The thickness of sediments beneath each of these 15 stations was determined covering an area of 23,500 sq km.

  9. Strong Motion Studies in the Mines of Kolar Gold Fields (United States)


    Soil Dyn. And Earthq.Eng. 10: (8), 423–428. Uhrhammer, R.A. and Bolt, B.A. (1991). “ the Seismic magnitude of the 1989 Loma Prieta Main Shock...rockburst is its Richter’s local magnitude. It was not possible from the records of geophone due to saturation effect . A strong-motion accelerograph has...magnitude. However, it has not been possible from the records of conventional seismographs due to saturation effect . The rockbursts had been

  10. Strong-motion data from the two Pingtung, Taiwan, earthquakes of 26 December 2006 (United States)

    Wu, C.-F.; Lee, W.H.K.; Boore, D.M.


    1016 strong-motion records at 527 free-field stations and 131 records at 42 strong-motion arrays at buildings and bridges were obtained for the Pingtung earthquake doublet from the Taiwan Central Weather Bureau's dense, digital strong-motion network. We carried out standard processing of these strong-motion records at free-field stations. A data set, including the originally recorded files, processed data files, and supporting software and information, is archived online http:// We have not yet completed the processing of the strong-motion array data at buildings and bridges. However, some preliminary results and the strong-motion array data recorded at the second nearest instrumented building to the Pingtung earthquake doublet are shown. This paper is intended to document our data processing procedures and the online archived data files, so that researchers can efficiently use the data. We also include two preliminary analyses: (1) a comparison of ground motions recorded by multiple accelerographs at a common site, the TAP 117 station in Taipei, and (2) attenuation of the horizontal ground motions (peak acceleration and response spectra at periods of 0.2, 1.0, and 3.0 s) with respect to distance. Our comparison study of multiple recordings at TAP 117 indicates that waveform coherence among 20- and 24-bit accelerograph records is much higher as compared to records from 16-bit or 12-bit accelerographs, suggesting that the former are of better quality. For the 20- and 24-bit accelerographs, waveform coherence is nearly 1 over the frequency range 1 to 8 Hz for all components, and is greater than about 0.9 from 8 to 20 Hz for the horizontal component, but only from 8 to 12 Hz for the vertical component. Plots of pseudo-acceleration response spectra (PSA) as a function of distance, however, show no clear indication for a difference related to the performance level of the accelerographs. The ground-motions of the first

  11. The 2001 Mw7.7 Bhuj, India Earthquake and Eastern North American Ground-Motion Attenuation Relations: Seismic Hazard Implications (United States)

    Cramer, C. H.; Bhattacharya, S. N.; Kumar, A.


    It has been suggested that the Mw7.7 2001 Bhuj, India earthquake occurred in a stable continental region with ground-motion attenuation properties similar to eastern North America (ENA). No strong motion recordings for M7 or greater earthquakes have been recorded in ENA, so, if the two regions share similar properties, then observations from the Bhuj earthquake provide important information for hazard assessments in ENA as well as India. This thesis can be tested using seismic data for the Bhuj mainshock. The Indian Meteorological Department recorded accelerograph and broadband seismograph data at distances of 500 to 1800 km. Accelerograph and engineering seismoscope data were recorded at distances of 40 to 1100 km by the Department of Earthquake Engineering at the Indian Institute of Technology, Roorkee. We have processed the accelerograph and broadband data for response spectral accelerations and corrected them to a common NEHRP site class using Joyner and Boore (2000) site factors. The geologic conditions at each recording site were determined using the geologic map of India and categorized as Quaternary sediments, Tertiary sediments, or hard rock. Comparisons were then made to available ENA ground-motion attenuation relations. For peak ground acceleration (PGA) and 1.0 s spectral acceleration (Sa), the geologically-corrected Bhuj data generally fall among the ENA ground-motion attenuation relations. The Bhuj mainshock ground-motion data agree with the collective predictions of the ENA relations given the random uncertainty in ground-motion measurements of a factor of two or more plus the ground-motion attenuation relation modeling uncertainty. From an engineering perspective, this comparison supports the thesis that seismic-wave attenuation in stable continental India is similar to eastern North America.

  12. Estimation of source parameters of Chamoli Earthquake, India

    Indian Academy of Sciences (India)

    Y Pandey; R Dharmaraju; P K S Chauhan


    The devastating earthquake (mb = 6.6) at Chamoli, Garhwal Himalaya, which occurred in the morning hours on 29th March 1999, was recorded on Delhi Strong Motion Accelerograph (DSMA) Network operated by the Central Building Research Institute, Roorkee. In this paper the source parameters of this event calculated from the Strong Motion Data are presented. The seismic moment for this event has been found to be of the order of 1025 and the moment mag- nitude has been calculated in the range of 6.53-6.69 at different stations. The stress drop and source radius for the earthquake are also calculated.

  13. The August 1st, 2014 ( M w 5.3) Moderate Earthquake: Evidence for an Active Thrust Fault in the Bay of Algiers (Algeria) (United States)

    Benfedda, A.; Abbes, K.; Bouziane, D.; Bouhadad, Y.; Slimani, A.; Larbes, S.; Haddouche, D.; Bezzeghoud, M.


    On August 1st, 2014, a moderate-sized earthquake struck the capital city of Algiers at 05:11:17.6 (GMT+1). The earthquake caused the death of six peoples and injured 420, mainly following a panic movement among the population. Following the main shock, we surveyed the aftershock activity using a portable seismological network (short period), installed from August 2nd, 2014 to August 21st, 2015. In this work, first, we determined the main shock epicenter using the accelerograms recorded by the Algerian accelerograph network (under the coordination of the National Center of Applied Research in Earthquake Engineering-CGS). We calculated the focal mechanism of the main shock, using the inversion of the accelerograph waveforms in displacement that provides a reverse fault with a slight right-lateral component of slip and a compression axis striking NNW-SSE. The obtained scalar seismic moment ( M o = 1.25 × 1017 Nm) corresponds to a moment magnitude of M w = 5.3. Second, the analysis of the obtained aftershock swarm, of the survey, suggests an offshore ENE-WSW, trending and NNW dipping, causative active fault in the bay of Algiers, which may likely correspond to an offshore unknown segment of the Sahel active fault.

  14. Update of Earthquake Strong-Motion Instrumentation at Lawrence Livermore National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Robert C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)


    Following the January 1980 earthquake that was felt at Lawrence Livermore National Laboratory (LLNL), a network of strong-motion accelerographs was installed at LLNL. Prior to the 1980 earthquake, there were no accelerographs installed. The ground motion from the 1980 earthquake was estimated from USGS instruments around the Laboratory to be between 0.2 – 0.3 g horizontal peak ground acceleration. These instruments were located at the Veterans Hospital, 5 miles southwest of LLNL, and in San Ramon, about 12 miles west of LLNL. In 2011, the Department of Energy (DOE) requested to know the status of our seismic instruments. We conducted a survey of our instrumentation systems and responded to DOE in a letter. During this survey, it was found that the recorders in Buildings 111 and 332 were not operational. The instruments on Nova had been removed, and only three of the 10 NIF instruments installed in 2005 were operational (two were damaged and five had been removed from operation at the request of the program). After the survey, it was clear that the site seismic instrumentation had degraded substantially and would benefit from an overhaul and more attention to ongoing maintenance. LLNL management decided to update the LLNL seismic instrumentation system. The updated system is documented in this report.

  15. Seismic Safety Margins Research Program, Phase I. Project II: seismic input. Compilation, assessment and expansion of the strong earthquake ground motion data base

    Energy Technology Data Exchange (ETDEWEB)

    Crouse, C B; Hileman, J A; Turner, B E; Martin, G R


    A catalog has been prepared which contains information for: (1) world-wide, ground-motion accelerograms, (2) the accelerograph sites where these records were obtained, and (3) the seismological parameters of the causative earthquakes. The catalog is limited to data for those accelerograms which have been digitized and published. In addition, the quality and completeness of these data are assessed. This catalog is unique because it is the only publication which contains comprehensive information on the recording conditions of all known digitized accelerograms. However, information for many accelerograms is missing. Although some literature may have been overlooked, most of the missing data has not been published. Nevertheless, the catalog provides a convenient reference and useful tool for earthquake engineering research and applications.

  16. INL Seismic Monitoring Annual Report: January 1, 2009 – December 31, 2009

    Energy Technology Data Exchange (ETDEWEB)

    N. S. Carpenter; S. J. Payne; J. M. Hodges; R. G. Berg


    The Idaho National Laboratory (INL) has accumulated 37 years of earthquake data (1972-2009). This report covers the earthquake activity from January 1, 2009 through December 31, 2009 and is a continuation of previous annual reports on earthquake activity surrounding the eastern Snake River Plain (ESRP) and within and near the INL. It discusses the earthquake activity that has occurred around the local region and within a 161-km radius around the INL centered at 43? 39.00' N, 112? 47.00' W). It discusses the seismic station and strong motion accelerograph instrumentation used to record earthquake data and how they were analyzed. It also includes a brief discussion of continuous GPS (Global Positioning System) stations co-located at INL seismic stations.


    Shiba, Yukio

    "Ground response spectrum" is proposed in this paper. "Ground response spectrum" is the graph which is so drawn as to read the maximum values of dynamic responses of subsurface ground to a seismic accelerograph, such as particle acceleration, velocity, displacement on the surface and shear strain caused in the ground. The calculation method of the spectrum is the same as the ordinary response spectrum except the use of simple one-dimensional continuum of linear viscoelastic medium; instead a single-degree-of-freedom oscillation system is used in the calculation of ordinary response spectrum. A few examples of the "ground response spectrum" are presented and special feature and usefulness of the spectrum is discussed in this paper.

  18. Proposal of Screening Method of Sleep Disordered Breathing Using Fiber Grating Vision Sensor (United States)

    Aoki, Hirooki; Nakamura, Hidetoshi; Nakajima, Masato

    Every conventional respiration monitoring technique requires at least one sensor to be attached to the body of the subject during measurement, thereby imposing a sense of restraint that results in aversion against measurements that would last over consecutive days. To solve this problem, we developed a respiration monitoring system for sleepers, and it uses a fiber-grating vision sensor, which is a type of active image sensor to achieve non-contact respiration monitoring. In this paper, we verified the effectiveness of the system, and proposed screening method of the sleep disordered breathing. It was shown that our system could equivalently measure the respiration with thermistor and accelerograph. And, the respiratory condition of sleepers can be grasped by our screening method in one look, and it seems to be useful for the support of the screening of sleep disordered breathing.

  19. Cross-correlations of ambient noise recorded by accelerometers. (United States)

    Rábade García, S. E.; Ramirez-Guzman, L.


    We investigate the ambient noise cross-correlations obtained by using properly corrected accelerometric recordings, and determine velocity structure in central Mexico based on a dispersion analysis. The data used comprise ten months of continuous recordings - from April 2013 to January 2014 - of ambient seismic noise at stations operated by the National Seismological Service of Mexico and the Engineering Strong Ground Motion Network of the National Autonomous University of Mexico (UNAM). The vertical component of ambient noise was base-line corrected, filtered, and properly integrated before extracting Green's functions (GF), which were compared successfully against GF obtained using recordings from broadband velocity sensors. In order to obtain dispersion curves, we estimated group and phase velocities applying the FTAN analysis technique and obtained s-wave velocity profiles at selected regions. We conclude and highlight that the use of widely deployed accelerographs to conduct regional studies using ambient noise tomography is feasible

  20. Catalog of strong motion stations in Eastern North America (United States)

    Busby, R. W.


    The catalog contains information on all strong motion stations operating in Eastern North America known to the National Center for Earthquake Engineering Research (NCEER). The location, coordinates, installation dates, type of instrument, operator, structure type and size, and site geology are listed for each station. The format of the catalog is patterned after the United States Geological Survey (USGS) Open-File Report 81-664, 'Western Hemisphere Strong-Motion Accelerograph Station List-1980' but the entries have been updated as of January 1990. There are 237 stations listed in the catalog which include 414 recording instruments. One third of these stations are intended to record free-field ground motion while the rest are associated with large engineered structures. The relationship of station location to seismicity is shown in a series of figures and a method is described to predict peak acceleration levels from an earthquake where the magnitude and distance to station are known.

  1. Seismic Strong Motion Array Project (SSMAP) to Record Future Large Earthquakes in the Nicoya Peninsula area, Costa Rica (United States)

    Simila, G.; Lafromboise, E.; McNally, K.; Quintereo, R.; Segura, J.


    The seismic strong motion array project (SSMAP) for the Nicoya Peninsula in northwestern Costa Rica is composed of 10 - 13 sites including Geotech A900/A800 accelerographs (three-component), Ref-Teks (three- component velocity), and Kinemetric Episensors. The main objectives of the array are to: 1) record and locate strong subduction zone mainshocks [and foreshocks, "early aftershocks", and preshocks] in Nicoya Peninsula, at the entrance of the Nicoya Gulf, and in the Papagayo Gulf regions of Costa Rica, and 2) record and locate any moderate to strong upper plate earthquakes triggered by a large subduction zone earthquake in the above regions. Our digital accelerograph array has been deployed as part of our ongoing research on large earthquakes in conjunction with the Earthquake and Volcano Observatory (OVSICORI) at the Universidad Nacional in Costa Rica. The country wide seismographic network has been operating continuously since the 1980's, with the first earthquake bulletin published more than 20 years ago, in 1984. The recording of seismicity and strong motion data for large earthquakes along the Middle America Trench (MAT) has been a major research project priority over these years, and this network spans nearly half the time of a "repeat cycle" (~ 50 years) for large (Ms ~ 7.5- 7.7) earthquakes beneath the Nicoya Peninsula, with the last event in 1950. Our long time co- collaborators include the seismology group OVSICORI, with coordination for this project by Dr. Ronnie Quintero and Mr. Juan Segura. The major goal of our project is to contribute unique scientific information pertaining to a large subduction zone earthquake and its related seismic activity when the next large earthquake occurs in Nicoya. We are now collecting a database of strong motion records for moderate sized events to document this last stage prior to the next large earthquake. A recent event (08/18/06; M=4.3) located 20 km northwest of Samara was recorded by two stations (Playa Carrillo

  2. Potentiation of atracurium by pancuronium during propofol-fentanyl-N2O anesthesia. (United States)

    Nathan, N; Bonada, G; Feiss, P


    At the end of abdominal surgery deep neuromuscular blockade is required for peritoneal closure. Ideally injecting an intermediate acting drug like atracurium after a long acting drug such as pancuronium should deepen the neuromuscular block without the fear of an inadequate reversal at the completion of surgery. Thirty patients ASA I or II status, without known allergy to myorelaxant and without neuromuscular, hepatic or renal failure were included in this study. Anesthesia was induced and maintained with propofol, fentanyl, and N20. Normal core temperature was maintained by active warming of the upper part of the body. Blood electrolytes and the acid-base status were within the normal range. The accelerographic responses to Train-Of-Four supramaximal stimulation (TOF) of the ulnar nerve was monitored at the thumb. After obtaining a stable response with the accelerograph, the patients randomly received pancuronium (0.10, group I, n = 10 and group II, n = 10) or atracurium (0.50, group III, n = 10). An additional dose of atracurium (0.16, group I and III) or pancuronium (0.03, group II) was injected when the first response of TOF stimulation (T1) reached 25% of its initial value. Then the time to obtain a 25% twitch height of T1 (T25), the recovery index (RI 25-75), the delay to obtain 4 responses to TOF and an adequate recovery [TOF ratio of 0.70 (TOF70)] were monitored. Injection of 60% ED95 of atracurium after pancuronium resulted in a similar recovery of neuromuscular function as after 45% ED95 of pancuronium as shown by the same recovery of T25 (66.5 +/- 4.2 min versus 71.4 +/- 7.8 min, group I versus group II, p > 0.05) and TOF70 (131.6 +/- 15.7 min versus 144.0 +/- 17.5, group I versus II, p > 0.05). Nevertheless the RI 25-75 of group I was of intermediate duration between those of group II and III. Electrolytes and acid-base status were similar between groups at the beginning of surgery. Thus this study shows a synergistic

  3. The strong ground motion in Mexico City: array and borehole data analysis. (United States)

    Roullé, A.; Chávez-García, F. J.


    Site response at Mexico City has been intensively studied for the last 15 years, since the disastrous 1985 earthquakes. After those events, more than 100 accelerographs were installed, and their data have been extremely useful in quantifying amplification and in the subsequent upgrading of the building code. However, detailed analysis of the wavefield has been hampered by the lack of absolute time in the records and the large spacing between stations in terms of dominant wavelengths. In 2001, thanks to the support of CONACYT, Mexico, a new dense accelerographic network was installed in the lake bed zone of Mexico City. The entire network, including an existing network of 3 surface and 2 borehole stations operated by CENAPRED, consists in 12 surface and 4 borehole stations (at 30, 102 and 50 meters). Each station has a 18 bits recorder and a GPS receiver so that the complete network is a 3D array with absolute time. The main objective of this array is to provide data that can help us to better understand the wavefield that propagates in Mexico City during large earthquakes. Last year, a small event of magnitude 6.0 was partially recorded by 6 of the 12 surface stations and all the borehole stations. We analysed the surface data using different array processing techniques such as f-k methods and MUSIC algorithm and the borehole ones using a cross-correlation method. For periods inferior to the site resonance period, the soft clay layer with very low propagation velocities (less than 500 m/s) and a possible multipathing rule the wavefield pattern. For the large period range, the dominant surface wave comes from the epicentral direction and propagates with a quicker velocity (more than 1500 m/s) that corresponds to the velocity of deep layers. The analysis of borehole data shows the presence of different quick wavetrains in the short period range that could correspond to the first harmonic modes of Rayleigh waves. To complete this study, four others events recorded in

  4. Liquefaction-induced settlement, site effects and damage in the vicinity of Yalova City during the 1999 Izmit earthquake, Turkey

    Indian Academy of Sciences (India)

    Ferhat Ozcep; Savas Karabulut; Oguz Özel; Tazegul Ozcep; Nazire İmre; Halil Zarif


    Yalova City (Turkey) is in a tectonically active location that is particularly affected by the northern branch of the North Anatolian Fault Zone. Magnitudes 7.4 and 7.2 earthquakes in 1999 caused great destruction in Yalova. The heavy damage to buildings and other civil engineering structures was mainly due to liquefaction-induced settlement and site effects such as resonance and amplification. In the first phase of this study, the soil liquefaction potential index (PL) and the induced soil settlement were estimated. In the second phase, the effects on sites in Yalova soil were investigated using microtremor and earthquake data. The fundamental periods and amplification in soft soil were compared with microtremor data and strong ground motion records obtained by a local array of eight accelerograph stations deployed in Yalova. Thirty-seven ‘single site’ ambient noise measurements were taken in a dense grid of points covering the centre of the city. A comparison between fundamental periods obtained from strong ground motion records and from microtremor measurements showed similarities, in the 0.1–5 Hz range. Finally, soil liquefaction and amplification (or resonance) were divided into regions according to the extent of damage and the geotechnical/geophysical results.

  5. Intermediate-Depth Intraplate Strike-Slip Earthquake Along the Subducted Nazca Plate: Stress Conditions Related to Flat-Slab Transition Zone? (United States)

    Carrizo, D.; Peyrat, S.; Comte, D.; Boroschek, R.


    On October 11th, 2012 an strike-slip intraplate earthquake Mw=5.6 occurred at about 15 km NE of Santiago-Chile, at 107 km depth. This earthquake had a distribution of intensities of about VI MM, around Santiago region. In the past only few similar seismic events had been occurred, the majority of them without reported intensities. The location, the focal mechanism, and the depth of this earthquake, make it particularly interesting because the processes responsible for this kind of ruptures is still an open question. Moreover, it was also recorded by a local strong motion networks, allowing for the first time the possibility to study this kind of earthquakes using seismic and accelerographic data. We study the nature of this event using the aftershocks recorded by the Chilean Seismological Network and with a joint inversion of local strong-motion and teleseimic data, to understand the kinematic of rupture. Preliminary results suggest a singular stress condition in the subducted plate related to the transition from flat to normal subduction, which could be accommodated by strike-slip faulting. The strong motion analysis reveals high horizontal accelerations in agreement with high angle fault planes. Understand the tectonic setting associated to this type of earthquakes represents a relevant goal for seismic risk evaluation in the most populated Chilean region.

  6. The Speed Control of Diesel Generator Based on the SPWM Drive of Stepping Motor%基于步进电动机SPWM驱动的发电机调速控制

    Institute of Scientific and Technical Information of China (English)

    沈锐; 卢刚; 李声晋; 孟凡军


    Aiming at the narrow bound and sensitivity of a diesel generator accelerograph, the stepping motor was driven with SPWM method,which achieved the even speed control of the diesel generator between 700 r/min and 3 800 r/min. Experimentations validated the feasibility and accuracy of the design proposal and the dynamic response and general performance of the diesel generator were improved.%针对某柴油发电机油门调整范围窄而精度要求高的特点,以SPWM方式驱动油门调整用两相混合式步进电动机,实现了该柴油发电机在700~3 800 r/min内的平滑调速.实验验证了所设计方案的可行性,改善了柴油发电机的动态响应,提高了系统的综合性能.

  7. Performance of several low-cost accelerometers (United States)

    Evans, J.R.; Allen, R.M.; Chung, A. I.; Cochran, E.S.; Guy, R.; Hellweg, M.; Lawrence, J. F.


    Several groups are implementing low‐cost host‐operated systems of strong‐motion accelerographs to support the somewhat divergent needs of seismologists and earthquake engineers. The Advanced National Seismic System Technical Implementation Committee (ANSS TIC, 2002), managed by the U.S. Geological Survey (USGS) in cooperation with other network operators, is exploring the efficacy of such systems if used in ANSS networks. To this end, ANSS convened a working group to explore available Class C strong‐motion accelerometers (defined later), and to consider operational and quality control issues, and the means of annotating, storing, and using such data in ANSS networks. The working group members are largely coincident with our author list, and this report informs instrument‐performance matters in the working group’s report to ANSS. Present examples of operational networks of such devices are the Community Seismic Network (CSN;, operated by the California Institute of Technology, and Quake‐Catcher Network (QCN; Cochran et al., 2009;; November 2013), jointly operated by Stanford University and the USGS. Several similar efforts are in development at other institutions. The overarching goals of such efforts are to add spatial density to existing Class‐A and Class‐B (see next paragraph) networks at low cost, and to include many additional people so they become invested in the issues of earthquakes, their measurement, and the damage they cause.

  8. Instrumental Intensity as a Tool for Post-Earthquake Damage Assessment: Validation for the Strong Vrancea Earthquakes of August 1986 and May 1990

    Directory of Open Access Journals (Sweden)

    Ioan Sorin BORCIA


    Full Text Available The frequency-dependent spectrum based seismic intensity, also called instrumental intensity, is calculated basically from the integration of the square values of spectral acceleration ordinates. The values of the instrumental intensity are calibrated to match the values of the EMS-98 intensity scale, providing a promising analytical indicator for estimating the destructive potential of earthquakes. Previous studies have shown that the proposed index could be used as a basis for the development of a new improved seismic intensity scale. The paper presents a set of maps describing the spatial distribution of instrumental intensity ordinates for three seismic events recorded in 1986 and 1990. These events, generated by the Vrancea source, are the strongest earthquakes in Romania for which accelerographic data was recorded at multiple stations. Intensity maps were generated for separate significant frequency bands, in order to reveal the destructiveness of the considered earthquakes for different building categories. Results were compared and correlated with previous studies on Vrancea earthquakes and with information provided by building damage reports from the considered earthquakes.

  9. Technical guidelines for the implementation of the Advanced National Seismic System (United States)

    Committee, ANSS Technical Integration


    The Advanced National Seismic System (ANSS) is a major national initiative led by the US Geological Survey that serves the needs of the earthquake monitoring, engineering, and research communities as well as national, state, and local governments, emergency response organizations, and the general public. Legislation authorizing the ANSS was passed in 2000, and low levels of funding for planning and initial purchases of new seismic instrumentation have been appropriated beginning in FY2000. When fully operational, the ANSS will be an advanced monitoring system (modern digital seismographs and accelerographs, communications networks, data collection and processing centers, and well-trained personnel) distributed across the United States that operates with high performance standards, gathers critical technical data, and effectively provides timely and reliable earthquake products, information, and services to meet the Nation’s needs. The ANSS will automatically broadcast timely and authoritative products describing the occurrence of earthquakes, earthquake source properties, the distribution of ground shaking, and, where feasible, broadcast early warnings and alerts for the onset of strong ground shaking. Most importantly, the ANSS will provide earthquake data, derived products, and information to the public, emergency responders, officials, engineers, educators, researchers, and other ANSS partners rapidly and in forms that are useful for their needs.

  10. Sediment Thicknesses and Qs vs. Qp Relations in the Kachchh Rift Basin, Gujarat, India Using Sp Converted Phases (United States)

    Mandal, Prantik


    Delineation of the top sedimentary structure and its Qs vs. Qp relationship using the travel-time difference of direct S and converted Sp phase is key to understanding the seismic hazard of any sedimentary basin area. We constructed filtered displacement waveforms from local ETNA Episensor acceleration recordings as well as local velocity recordings of aftershocks of the 2001 Bhuj earthquake recorded by the Kachchh seismological network of the National Geophysical Research Institute (NGRI), Hyderabad, India during 2001 2004. Stations are within 15 70km of epicenters, and the resulting displacement waveforms are generally simple, displaying prominent P, Sp, and S wave pulses. Particle motion of P and S waves suggest near-vertical raypaths consistent with preliminary depth estimates. The direct S wave on the horizontal component is characterized by lower frequency content than the converted Sp phase on the vertical component. This difference in frequency content between S and Sp phases can be explained in terms of different attenuation effects for P and S waves in the unconsolidated sediments. The Sp phase is generated by S-to-P phase conversion at the base of Mesozoic sediments of the Kachchh basin. Travel-time inversion (VELEST) of 2565 P and 2380 S arrivals from 658 well located aftershocks recorded at 8 14 three-component local seismic stations led to 1 D velocity models indicated very slow sediments in the upper 0 2 km depth range (Vp: 2.92 km/s and Vs: 0.90 km/s) and an increasing trend of velocities with depth at 2 40 km depth. The estimated sediment thicknesses beneath 12 accelerograph and 6 seismograph sites from the estimated velocity model and the travel-time difference between S and converted Sp phases reaches a maximum of (1.534 ± 0.117) km beneath Bandri (near the location of 2001 Bhuj mainshock) and attains a minimum sediment thickness of (0.858 ± 0.104) km beneath Ramvav and Burudia. The spectral ratios between Sp and S from 159 three

  11. Requirements for Verifying Wave-Wave Coupling at Texcoco, Valley of Mexico (United States)

    Stephenson, W. R.


    A late-arriving monochromatic wave has been identified at the Texcoco accelerograph array in the Valley of Mexico, for the 2001 October 8 Coyuca, Guerrero (M 6.1) earthquake. Because this wave propagates nearly towards the epicentre, it must be locally-generated, and its combination of low velocity (160m/s phase, 60m/s group) long delay (85sec after s-wave arrival), distance from the basin margin (about 8km), and relatively high amplitude, are not consistent with current beliefs about wave attenuation in the lacustrine mud in which the wave travels. Three possibilities must be considered; that the mud does not attenuate motion as much as believed; that most of the wave energy does not travel in the mud; or that the observed wave is coupled to a less-attenuated wave so that energy lost in the mud is continually being replaced by wave-wave coupling. Wave-wave coupling is a likely mechanism because the monochromatic motion is at a frequency that differs from the readily-evaluated "layer frequency", ruling out the layer as the main determinant of frequency. Instead it is possible that the observed frequency is that at which a Rayleigh wave travels at the speed of a wave in a material below the surface (28m thick) layer. In order for wave-wave coupling to be unambiguously confirmed it is necessary to identify a layer of material which will support a wave at the observed velocity of 160m/s. Such a wave is unlikely to be a p-wave because p-waves in the profile are likely to have velocities in excess of 1500m/s. SCPT testing will readily determine whether an s-wave velocity of 160m/s is present in the profile. In the case of coupling of a Rayleigh wave to an acoustic wave it is relatively easy to identify the two waves and to ascertain that they travel at the same speed, on account of the widely differing nature of the two waves. A pressure detector will not respond to the Rayleigh wave, even though a seismometer will respond to the pressure wave. The situation is more

  12. Theoretical design and field deployment of a dense strong motion instrument network for the Alpine Fault, South Island, New Zealand. (United States)

    Francois, C.; Berril, J.; Pettinga, J.


    A dense network of strong motion seismometers is being developed in order to investigate the complexities of the upper crustal rupture process and propagation of major seismogenic sources such as the Alpine Fault and strands of the Marlborough Fault System defining the South Island sector of the Australia-Pacific plate boundary zone. The proposed network is designed as a dense array of approximately 20 accelerographs using the University of Canterbury 12-bit CUSP instrument, now nearing development completion. It will be deployed straddling the Alpine Fault in the central West Coast region of the South Island, and coverage will extend across the region at the Alpine-Hope Fault junction also. The array layout is being designed utilizing the frequency-analysis MUSIC method (Multiple Signal Characterization) developed by Goldstein and Archuleta (1991a&b). Synthetic strong-motion records were computed using an empirical Green's function synthetic seismogram program EMPSYN (Hutchings, 1987). The process of finding an optimal network configuration is dependent on the geometry of the array (study of the frequency analysis performance of the modelled earthquake data for various proposed array configurations), and on the instrument site conditions (geology, communications, accessibility, isolation etc). References Goldstein, P. and R. J. Archuleta (1991a). "Deterministic frequency-wavenumber methods and direct measurements of rupture propagation during earthquakes using a dense array; data analysis." Journal of Geophysical Research, B, Solid Earth and Planets 96(4): 6187-6198. Goldstein, P. and R. J. Archuleta (1991b). "Deterministic frequency-wavenumber methods and direct measurements of rupture propagation during earthquakes using a dense array; theory and methods." Journal of Geophysical Research, B, Solid Earth and Planets 96(4): 6173-6185. Hutchings, L. J. (1987). "Modelling strong earthquake ground motion with empirical Green's function", Ph.D. thesis, Department of

  13. Explosion source strong ground motions in the Mississippi embayment (United States)

    Langston, C.A.; Bodin, P.; Powell, C.; Withers, M.; Horton, S.; Mooney, W.


    Two strong-motion arrays were deployed for the October 2002 Embayment Seismic Excitation Experiment to study the spatial variation of strong ground motions in the deep, unconsolidated sediments of the Mississippi embayment because there are no comparable strong-motion data from natural earthquakes in the area. Each linear array consisted of eight three-component K2 accelerographs spaced 15 m apart situated 1.2 and 2.5 kin from 2268-kg and 1134-kg borehole explosion sources, respectively. The array data show distinct body-wave and surface-wave arrivals that propagate within the thick, unconsolidated sedimentary column, the high-velocity basement rocks, and small-scale structure near the surface. Time-domain coherence of body-wave and surface-wave arrivals is computed for acceleration, velocity, and displacement time windows. Coherence is high for relatively low-frequency verticalcomponent Rayleigh waves and high-frequency P waves propagating across the array. Prominent high-frequency PS conversions seen on radial components, a proxy for the direct S wave from earthquake sources, lose coherence quickly over the 105-m length of the array. Transverse component signals are least coherent for any ground motion and appear to be highly scattered. Horizontal phase velocity is computed by using the ratio of particle velocity to estimates of the strain based on a plane-wave-propagation model. The resulting time-dependent phase-velocity map is a useful way to infer the propagation mechanisms of individual seismic phases and time windows of three-component waveforms. Displacement gradient analysis is a complementary technique for processing general spatial-array data to obtain horizontal slowness information.

  14. The Engineering Strong Ground Motion Network of the National Autonomous University of Mexico (United States)

    Velasco Miranda, J. M.; Ramirez-Guzman, L.; Aguilar Calderon, L. A.; Almora Mata, D.; Ayala Hernandez, M.; Castro Parra, G.; Molina Avila, I.; Mora, A.; Torres Noguez, M.; Vazquez Larquet, R.


    The coverage, design, operation and monitoring capabilities of the strong ground motion program at the Institute of Engineering (IE) of the National Autonomous University of Mexico (UNAM) is presented. Started in 1952, the seismic instrumentation intended initially to bolster earthquake engineering projects in Mexico City has evolved into the largest strong ground motion monitoring system in the region. Today, it provides information not only to engineering projects, but also to the near real-time risk mitigation systems of the country, and enhances the general understanding of the effects and causes of earthquakes in Mexico. The IE network includes more than 100 free-field stations and several buildings, covering the largest urban centers and zones of significant seismicity in Central Mexico. Of those stations, approximately one-fourth send the observed acceleration to a processing center in Mexico City continuously, and the rest require either periodic visits for the manual recovery of the data or remote interrogation, for later processing and cataloging. In this research, we document the procedures and telecommunications systems used systematically to recover information. Additionally, we analyze the spatial distribution of the free-field accelerographs, the quality of the instrumentation, and the recorded ground motions. The evaluation criteria are based on the: 1) uncertainty in the generation of ground motion parameter maps due to the spatial distribution of the stations, 2) potential of the array to provide localization and magnitude estimates for earthquakes with magnitudes greater than Mw 5, and 3) adequacy of the network for the development of Ground Motion Prediction Equations due to intra-plate and intra-slab earthquakes. We conclude that the monitoring system requires a new redistribution, additional stations, and a substantial improvement in the instrumentation and telecommunications. Finally, we present an integral plan to improve the current network

  15. The Beni Haoua, Algeria, Mw 4.9 earthquake: source parameters, engineering, and seismotectonic implications (United States)

    Abbes, Khadidja; Dorbath, Louis; Dorbath, Catherine; Djeddi, Mohamed; Ousadou, Farida; Maouche, Said; Benkaci, Nassima; Slimani, Abdennasser; Larbes, Said; Bouziane, Djillali


    A moderate Mw 4.9 earthquake struck the Beni Haoua (Algeria) coastal area on April 25, 2012. The mainshock was largely recorded by the accelerograph network of the Centre National de Recherche Appliquée en Génie Parasismique (CGS). The same day the earthquake occurred, eight mobile short period stations were deployed through the epicentral area. In this study, we use accelerogram and seismogram data recorded by these two networks. We combined the focal mechanism built from the first motion of P waves and from waveform inversion, and the distribution of aftershocks to well constrain the source parameters. The mainshock is located with a shallow focal depth, ˜9 km, and the focal mechanism shows a nearly pure left lateral strike slip motion, with total seismic moment of 2.8 × 1016 N.m (Mw = 4.9). The aftershocks mainly cluster on a narrow NS strip, starting at the coast up to 3-4 km inland. This cluster, almost vertical, is concentrated between 6 and 10 km depth. The second part of this work concerns the damage distribution and estimated intensity in the epicentral area. The damage distribution is discussed in connection with the observed maximum strong motion. The acceleration response spectrum with 5 % damping of the mainshock and aftershocks give the maximum amplitude in high frequency which directly affects the performance of the high-frequency structures. Finally, we tie this earthquake with the seismotectonic of the region, leading to conclude that it occurred on a N-S transform zone between two major compressional fault zones oriented NE-SW.

  16. The development and present status of seismic research work in Jamaica, West Indies (United States)

    Jackson, Trevor A.


    Jamaica is located near the northern boundary of the Caribbean Plate and is within a seismically active zone. Historic records of earthquakes date back to the sixteenth century during the early period of European settlement and colonization. During the last four centuries more than 4000 lives have been lost as a result of local seismic events and there are at least 55 documented cases in which there was an earthquake of intensity VI or greater on the Modified Mercalli Scale. The Seismic Research Unit of the University of the West Indies first began its operation in Jamaica in 1963 with the installation of three short period vertical-component seismometers. Since 1963 the number of stations has increased and there is now a network of five short-period vertical-component seismometers linked by radio telemetry to the base recording station at the Mona Campus of the University of the West Indies. Seismic events are recorded on 600-m reels of magnetic tape and the position of each event is located by first replaying and then transcribing the data on the tape for the five stations onto strip chart. P and S arrival times are then read into an IBM-PC and the magnitude and epicentre determined by using the 'JCA-HYPO' program, based on a four-layer model for Jamaica. In addition to the network of seismic stations there are six strong motion accelerographs, which are deployed in high-rise buildings in urban and rural Jamaica. Since their installation in the mid-1970s only one earthquake, in 1978, yielded a good strong motion record. In 1983 the Jamaica Bureau of Standards introduced a National Building Code for engineers in which it recommended that structures be designed according to the code of the Structural Engineers' Association of California.

  17. Initiation of a Database of CEUS Ground Motions for NGA East (United States)

    Cramer, C. H.


    The Nuclear Regulatory Commission has funded the first stage of development of a database of central and eastern US (CEUS) broadband and accelerograph records, along the lines of the existing Next Generation Attenuation (NGA) database for active tectonic areas. This database will form the foundation of an NGA East project for the development of CEUS ground-motion prediction equations that include the effects of soils. This initial effort covers the development of a database design and the beginning of data collection to populate the database. It also includes some processing for important source parameters (Brune corner frequency and stress drop) and site parameters (kappa, Vs30). Besides collecting appropriate earthquake recordings and information, existing information about site conditions at recording sites will also be gathered, including geology and geotechnical information. The long-range goal of the database development is to complete the database and make it available in 2010. The database design is centered on CEUS ground motion information needs but is built on the Pacific Earthquake Engineering Research Center's (PEER) NGA experience. Documentation from the PEER NGA website was reviewed and relevant fields incorporated into the CEUS database design. CEUS database tables include ones for earthquake, station, component, record, and references. As was done for NGA, a CEUS ground- motion flat file of key information will be extracted from the CEUS database for use in attenuation relation development. A short report on the CEUS database and several initial design-definition files are available at Comments and suggestions on the database design can be sent to the author. More details will be presented in a poster at the meeting.

  18. Source characteristics of moderate size events using empirical Green funclions: an application to some Guerrero (Mexico subduction zone earthquakes

    Directory of Open Access Journals (Sweden)

    S. K. Singh


    Full Text Available The records of an aftershock (M ~ 4 of a moderate size event (M = 5.9 which occurred along the subduction zone of Guerrero (Mexico, are used as empirical Green functions (EGF to determine the source characteristics of the mainshock and of its smaller size (M = 5.5 foreshock. The data consist of accelerograms recorded by the Guerrero Accelerograph Array, a high dynamic range strong motion array. The three events appear to be located close to each other at distances much smaller than the source to receiver distances. The fault mechanism of the mainshock is computed by non-linear inversion of P polarity readings and S wave polarizations determined at two near source stations. The foreshock and aftershock fault mechanisms are similar to that of the mainshock as inferred from long period data and shear wave polarization analysis. The maximum likelihood solution is well constrained, indicating a typical shallow dipping thrust fault mechanism, with the P-axis approximately oriented in a SSW direction. The source time functions (STFs of the mainshock and foreshock events are determined using a new method of deconvolution of the EGF records at three strong motion sites. In this method the STF of the large event is approximated by a superposition of pseudo triangular pulses whose parameters are determined by a non-linear inversion in frequency domain. The source time function of the mainshock shows the presence of two separate pulses, which can be related to multiple rupture episodes. The relative location of mainshock sub-events is done by using plots of isochrones computed from measurementes of the time delay between pulses on the STF records at each station. The first sub-event is located no more than 2.5-3 km away from the other along the fault strike. The STF retrieved from foreshock records shows single pulse waveforms. The computed STFs are used to estimate seismic moments, source radii and stress release of the events assuming a circular fault

  19. Storey building early monitoring based on rapid seismic response analysis (United States)

    Julius, Musa, Admiral; Sunardi, Bambang; Rudyanto, Ariska


    Within the last decade, advances in the acquisition, processing and transmission of data from seismic monitoring has contributed to the growth in the number structures instrumented with such systems. An equally important factor for such growth can be attributed to the demands by stakeholders to find rapid answers to important questions related to the functionality or state of "health" of structures during and immediately of a seismic events. Consequently, this study aims to monitor the storey building based on seismic response i. e. earthquake and tremor analysis at short time lapse using accelerographs data. This study used one of storey building (X) in Jakarta city that suffered the effects of Kebumen earthquake January 25th 2014, Pandeglang earthquake July 9th 2014, and Lebak earthquake November 8th 2014. Tremors used in this study are tremors after the three following earthquakes. Data processing used to determine peak ground acceleration (PGA), peak ground velocity (PGV), peak ground displacement (PGD), spectral acceleration (SA), spectral velocity (SV), spectral displacement (SD), A/V ratio, acceleration amplification and effective duration (te). Then determine the natural frequency (f0) and peak of H/V ratio using H/V ratio method.The earthquakes data processing result shows the value of peak ground motion, spectrum response, A/V ratio and acceleration amplification increases with height, while the value of the effective duration give a different viewpoint of building dynamic because duration of Kebumen earthquake shows the highest energy in the highest floor but Pandeglang and Lebak earthquake in the lowest floor. Then, tremors data processing result one month after each earthquakes shows the natural frequency of building in constant value. Increasing of peak ground motion, spectrum response, A/V ratio, acceleration amplification, then decrease of effective duration following the increase of building floors shows that the building construction supports the

  20. Determinación de las características mecánicas de los muros de fábrica de ladrillo en la arquitectura doméstica sevillana de los siglos XVIII Y XIX

    Directory of Open Access Journals (Sweden)

    Rubio, P.


    Full Text Available The main aim consists on improving the information technology tools in order to make models of the real situation (constructive, geometrical, resistant of the structural elements, as well as getting the restoration or support proposals. We have developed the work in some stages: – Analysis,inspection, measurement, and evolution of the building. – Extraction and analysis in laboratory of small samples of masonry walls to determine the strength parameters of materials. – Experimental studie for determination of a model and obtaining the compression stresses of the masonry walls studied. – The monitoring instrumentation which has been used is an accelerograph to evaluate the rigidity of the walls. – Application of Finite Elements Method in order to obtain the stresses distribution before and after any change in the building. The final aim is to be able to compare the results from the laboratory and the stresses distribution from the F.E.M., in order to decide the best way of getting the restoration.El resultado del trabajo permite manejar datos geométricos, constructivos y mecánicos objetivos en el momento de la recuperación de los muros estudiados y los edificios referidos. Las fases seguidas para el desarrollo del método han sido: – Análisis de edificios objeto de rehabilitación: características constructivas del muro a estudiar, levantamiento de lesiones. – Extracción y análisis en laboratorio de pequeñas muestras de la fábrica para la determinación de las características resistentes de sus materiales. – Trabajo experimental en laboratorio para elaboración de un modelo que permita la obtención de la resistencia a compresión de la fábrica estudiada. – Aplicación del acelerógrafo para medir la rigidez del edificio in situ, aproximándonos al módulo de elasticidad del muro de fábrica. – Obtención de conclusiones con la comparación de valores máximos de tensiones obtenidos para una fábrica no fisurada

  1. Source Parameters of the 8 October, 2005 Mw7.6 Kashmir Earthquake (United States)

    Mandal, Prantik; Chadha, R. K.; Kumar, N.; Raju, I. P.; Satyamurty, C.


    During the last six years, the National Geophysical Research Institute, Hyderabad has established a semi-permanent seismological network of 5 broadband seismographs and 10 accelerographs in the Kachchh seismic zone, Gujarat, with the prime objective to monitor the continued aftershock activity of the 2001 Mw7.7 Bhuj mainshock. The reliable and accurate broadband data for the Mw 7.6 (8 Oct., 2005) Kashmir earthquake and its aftershocks from this network, as well as from the Hyderabad Geoscope station, enabled us to estimate the group velocity dispersion characteristics and the one-dimensional regional shear-velocity structure of peninsular India. Firstly, we measure Rayleigh- and Love-wave group velocity dispersion curves in the range of 8 to 35 sec and invert these curves to estimate the crustal and upper mantle structure below the western part of peninsular India. Our best model suggests a two-layered crust: The upper crust is 13.8-km thick with a shear velocity (Vs) of 3.2 km/s; the corresponding values for the lower crust are 24.9 km and 3.7 km/sec. The shear velocity for the upper mantle is found to be 4.65 km/sec. Based on this structure, we perform a moment tensor (MT) inversion of the bandpass (0.05 0.02 Hz) filtered seismograms of the Kashmir earthquake. The best fit is obtained for a source located at a depth of 30 km, with a seismic moment, Mo, of 1.6 × 1027 dyne-cm, and a focal mechanism with strike 19.5°, dip 42°, and rake 167°. The long-period magnitude (MA ~ Mw) of this earthquake is estimated to be 7.31. An analysis of well-developed sPn and sSn regional crustal phases from the bandpassed (0.02 0.25 Hz) seismograms of this earthquake at four stations in Kachchh suggests a focal depth of 30.8 km.

  2. Source Parameters of the Deadly Mw 7.6 Kashmir Earthquake of 8 October, 2005 (United States)

    Mandal, Prantik; Chadha, R. K.; Kumar, N.; Raju, I. P.; Satyamurty, C.


    During the last six years, National Geophysical Research Institute, Hyderabad has established a semi-permanent seismological network of 5 8 broadband seismographs and 10 20 accelerographs in the Kachchh seismic zone, Gujarat with a prime objective to monitor the continued aftershock activity of the 2001 Mw 7.7 Bhuj mainshock. The reliable and accurate broadband data for the 8 October Mw 7.6 2005 Kashmir earthquake and its aftershocks from this network as well as Hyderabad Geoscope station enabled us to estimate the group velocity dispersion characteristics and one-dimensional regional shear velocity structure of the Peninsular India. Firstly, we measure Rayleigh-and Love-wave group velocity dispersion curves in the period range of 8 to 35 sec and invert these curves to estimate the crustal and upper mantle structure below the western part of Peninsular India. Our best model suggests a two-layered crust: The upper crust is 13.8 km thick with a shear velocity (Vs) of 3.2 km/s; the corresponding values for the lower crust are 24.9 km and 3.7 km/sec. The shear velocity for the upper mantle is found to be 4.65 km/sec. Based on this structure, we perform a moment tensor (MT) inversion of the bandpass (0.05 0.02 Hz) filtered seismograms of the Kashmir earthquake. The best fit is obtained for a source located at a depth of 30 km, with a seismic moment, Mo, of 1.6 × 1027 dyne-cm, and a focal mechanism with strike 19.5°, dip 42°, and rake 167°. The long-period magnitude (MA ~ Mw) of this earthquake is estimated to be 7.31. An analysis of well-developed sPn and sSn regional crustal phases from the bandpassed (0.02 0.25 Hz) seismograms of this earthquake at four stations in Kachchh suggests a focal depth of 30.8 km.

  3. Aceleraciones del terremoto de sámara del 05 de setiembre del 2012

    Directory of Open Access Journals (Sweden)

    Schmidt D., Víctor


    Full Text Available Presenta un análisis detallado de los registros de aceleración en el terremoto de Sámara, en la provincia de Guanacaste, Costa Rica. Toma en cuenta datos de los acelerógrafos del Laboratorio de Ingeniería Sísmica (LIS de la Universidad de Costa Rica, colocados a nivel nacional. Presenta una relación entre las aceleraciones máximas y su equivalencia en la escala de intensidad Mercalli, siendo la estación de Nosara la que tiene el registro de aceleración más intenso en la historia instrumental del país. Hace una interpretación de al menos cuatro estados de liberación de energía. Muestra una comparación con otros sismos a nivel mundial, con valores de aceleración alta. Analiza los espectros de respuesta en componentes norte-sur y este oeste, la forma en que decae la aceleración pico con la distancia y compara las Intensidades Arias (IA. Expone los daños ocurridos en algunos edificios públicos y hace una comparación de los daños en el Hospital Monseñor Sanabria, de Puntarenas, por el sismo de Cóbano y el de Sámara It presents a detailed analyses of the acceleration records in the Sámara earthquake, in Guanacaste, Costa Rica. It considers data from the accelerographs from the Seismic Engineering Lab (Laboratorio de Ingeniería Sísmica - LIS from the University of Costa Rica, located nationally. It presents a relation between maximum accelerations and their equivalent on the Mercalli intensity scale. The Nosara station is the one that has the most intense acceleration record in the instrumental history of the country. It interprets at least four stages of energy liberation. It shows a comparison with other earthquakes worldwide with high acceleration values. It analyses response spectrum in components North-South and East-West, the way in which the acceleration peak decreases with the distance and compares the Arias Intensities (IA. It presents the damages in some of the public buildings and compares the damages at the Monse

  4. Seismicity in northeast edge of the Mexican Volcanic Belt (MVB), activation of an undocumented fault: the Peñamiller earthquake sequence of 2011, Queretaro, Mexico (United States)

    Clemente-Chavez, A.; Figueroa-Soto, A.; Zúñiga, F. R.; Arroyo, M.; Montiel, M.; Chavez, O.


    The Peñamiller town, in the Queretaro state, Mexico is located at the northeast border of the seismogenic zone known as the Mexican Volcanic Belt (MVB), which covers a central fringe of Mexico with east-west orientation. In this town, a sequence of small earthquakes occurred during the end of 2010 and beginning of 2011. Seismicity frequent in of the continental regimen of central Mexico are not common, however, it is known that there are precedents of large earthquakes (Mw magnitude greater than 6.0) occurring in this zone. In order to enrich seismic information, which has not been analyzed nor documented until this moment, is presented this work. This will contribute to gain more insight into the tectonic situation of the central Mexico region. Twenty-four shallow earthquakes records of the Peñamiller, Queretaro seismic sequence of 2011 were recorded by a provisional accelerograph network from the Universidad Autonoma de Queretaro (UAQ). The data were analysed in order to determine the source locations and for the estimation of the source parameters. The study was carried out through an inversion process and by spectral analysis. The results show that the largest earthquake, occurred on 8 February 2011 at 19:53:48.6 UTC, had a moment magnitude Mw = 3.5, and was located at latitude 21.039° and longitude -99.752°, at a depth of 5.6 km. This zone is located less than 7 km away in south-east direction from downtown Peñamiller. The focal mechanisms are mostly normal faults with a small lateral component. This feature is consistent with the extensional regimen of the southern extension of the Basin and Range (BR) province. The source area of the largest event was estimated to have a radius of 0.5 km, which corresponds to a normal fault with azimuth of 174° and an almost pure dip slip; this caused Peak Ground Acceleration (PGA) of up to 100 cm s-2 in the horizontal direction. It is evident that the shallow earthquakes induced by crustal faulting can present a

  5. Ground Motion Prediction Trends For Eastern North America Based on the Next Generation Attenuation East Ground Motion Database (United States)

    Cramer, C. H.; Kutliroff, J.; Dangkua, D.


    A five-year Next Generation Attenuation (NGA) East project to develop new ground motion prediction equations for stable continental regions (SCRs), including eastern North America (ENA), has begun at the Pacific Earthquake Engineering Research (PEER) Center funded by the Nuclear Regulatory Commission (NRC), the U.S. Geological Survey (USGS), the Electric Power Research Institute (EPRI), and the Department of Energy (DOE). The initial effort focused on database design and collection of appropriate M>4 ENA broadband and accelerograph records to populate the database. Ongoing work has focused on adding records from smaller ENA earthquakes and from other SCRs such as Europe, Australia, and India. Currently, over 6500 horizontal and vertical component records from 60 ENA earthquakes have been collected and prepared (instrument response removed, filtering to acceptable-signal band, determining peak and spectral parameter values, quality assurance, etc.) for the database. Geologic Survey of Canada (GSC) strong motion recordings, previously not available, have also been added to the NGA East database. The additional earthquakes increase the number of ground motion recordings in the 10 - 100 km range, particularly from the 2008 M5.2 Mt. Carmel, IL event, and the 2005 M4.7 Riviere du Loup and 2010 M5.0 Val des Bois earthquakes in Quebec, Canada. The goal is to complete the ENA database and make it available in 2011 followed by a SCR database in 2012. Comparisons of ground motion observations from four recent M5 ENA earthquakes with current ENA ground motion prediction equations (GMPEs) suggest that current GMPEs, as a group, reasonably agree with M5 observations at short periods, particularly at distances less than 200 km. However, at one second, current GMPEs over predict M5 ground motion observations. The 2001 M7.6 Bhuj, India, earthquake provides some constraint at large magnitudes, as geology and regional attenuation is analogous to ENA. Cramer and Kumar, 2003, have

  6. Local network deployed around the Kozloduy NPP - a useful tool for seismological monitoring (United States)

    Solakov, Dimcho; Simeonova, Stela; Dimitrova, Liliya; Slavcheva, Krasimira; Raykova, Plamena; Popova, Maria; Georgiev, Ivan


    Processor (SNDP) software package. Strong motion accelerographs and GPS instrumentation are installed permanently within the near region. The equipment is periodically upgraded and calibrated to provide adequate information in line with updated international operational practice. The results of the 17 years of operation of LSN "Kozloduy" are presented in the present study. The multiple studies carried out indicate that LSN jointly with NOTSSI provide reliable registration of weak seismicity in the near (30 km) region of NPP site. Earthquakes recorded within and near the network are carefully analyzed in connection with seismotectonic studies of the near region. The seismological database acquired is homogeneous for the entire region to the extent possible or, at a minimum, is sufficiently complete for characterizing, from a seismotectonic point of view, features relevant to the site.

  7. 乳腺癌术前化疗对罗库溴铵肌松效应的影响%Effect of chemotherapy on neuromuscular blocking of rocuronium in patients undergoing brest cancer

    Institute of Scientific and Technical Information of China (English)

    李振江; 蒋晖; 马新军


    Objective To investigate the effect of chemotherapy on neuromuscular blocking of rocuronium in patients undergoing brest cancer. Methods Forty-three femail patients undergoing selective brest cancer operation under general anesthesia were divided into 25 patients who had received chemotherapy before surgery(group A)and 18 cases who had not(group B).The neuromuscular function was monitored by TOF stimulation using accelerograph.The onset time,clinical duration of action and recovery index were recorded after rocuronium 0.6 mg/kg was administered iv.Results The onset times of group A and group B were (93±18) s in and (96±19) s, respectively. The clinical duration of action in group A was (49±16) min. which was longer than(37±19)min in group B(P<0.05).So did the recovery inde)[[(14.2±3.0)min vs.(10.9±2.5)min(P<0.05).Conclusion Chemotherapy before surgery could make the clinical duration of action and recovery of rocuromum in patients with brest cancer.%目的 研究乳腺癌术前化疗对罗库溴铵肌松效应的影响.方法 全麻下肌松监测乳腺癌手术患者43例,分为术前化疗组(A组,25例)和未进行化疗组(B组,18例).两组术前均未用对肌松有影响的药物.用加速度仪监测拇内收肌收缩反应,观察罗库溴铵0.6 mg/kg静注后肌松时效的差异.结果 A、B两组起效时间分别为(93±18)S和(96±19)s,差异无统计学意义;A组临床时效长于B组[(49±16)min vs.(37±13)min],A组恢复指数也长于B组[(14.2±3.0)min vs.(10.9±2.5)min](P<0.05).结论 乳腺癌术前化疗对罗库溴铵的临床作用时效和恢复延长.

  8. The NetQuakes Project - Research-quality Seismic Data Transmitted via the Internet from Citizen-hosted Instruments (Invited) (United States)

    Luetgert, J. H.; Oppenheimer, D. H.; Hamilton, J.


    The USGS seeks accelerograph spacing of 5-10 km in selected urban areas of the US to obtain spatially un-aliased recordings of strong ground motions during large earthquakes. These dense measurements will improve our ability to make rapid post-earthquake assessments of expected damage and contribute to the continuing development of engineering standards for construction. To achieve this goal the USGS and its university partners are deploying “NetQuakes” seismographs, designed to record moderate to large earthquakes from the near field to about 100 km. The instruments have tri-axial Colibrys 2005SF MEMS sensors, clip at 3g, and have 18-bit resolution. These instruments are uniquely designed for deployment in private homes, businesses, public buildings and schools where there is an existing Broadband connection to the Internet. The NetQuakes instruments connect to a local network using WiFi and then via the Internet to USGS servers to a) upload triggered accelerograms in miniSEED format, P arrival times, and computed peak ground motion parameters immediately after an earthquake; b) download software updates; c) respond to requests for log files, execute UNIX scripts, and upload waveforms from long-term memory for quakes with peak motions below the trigger threshold; d) send state-of-health (SOH) information in XML format every 10 minutes; and e) synchronize instrument clocks to 1ms accuracy using the Network Time Protocol. NetQuakes instruments cost little to operate and save about $600/yr/site compared to instruments that transmit data via leased telemetry. After learning about the project through press releases, thousands of citizens have registered to host an instrument at using a Google Map interface that depicts where we seek instrument sites. The website also provides NetQuakes hosts access to waveform images recorded by instruments installed in their building. Since 3/2009, the NetQuakes project has installed over 100

  9. The NetQuakes Project - Seeking a Balance Between Science and Citizens. (United States)

    Luetgert, J. H.; Oppenheimer, D. H.


    The challenge for any system that uses volunteer help to do science is to dependably acquire quality data without unduly burdening the volunteer. The NetQuakes accelerograph and its data acquisition system were created to address the recognized need for more densely sampled strong ground motion recordings in urban areas to provide more accurate ShakeMaps for post-earthquake disaster assessment and to provide data for structural engineers to improve design standards. The recorder has 18 bit resolution with ±3g internal tri-axial MEMS accelerometers. Data are continuously recorded at 200 sps into a 1-2 week ringbuffer. When triggered, a miniSEED file is sent to USGS servers via the Internet. Data can also be recovered from the ringbuffer by a remote request through the NetQuakes servers. Following a power failure, the instrument can run for 36 hours using its internal battery. We rely upon cooperative citizens to host the dataloggers, provide power and Internet connectivity and perform minor servicing. Instrument and battery replacement are simple tasks that can be performed by hosts, thus reducing maintenance costs. Communication with the instrument to acquire data or deliver firmware is accomplished by file transfers using NetQuakes servers. The client instrument initiates all client-server interactions, so it safely resides behind a host's firewall. A connection to the host's LAN, and from there to the public Internet, can be made using WiFi to minimize cabling. Although timing using a cable to an external GPS antenna is possible, it is simpler to use the Network Time Protocol (NTP) to discipline the internal clock. This approach achieves timing accuracy substantially better than a sample interval. Since 2009, we have installed more than 140 NetQuakes instruments in the San Francisco Bay Area and have successfully integrated their data into the near real time data stream of the Northern California Seismic System. An additional 235 NetQuakes instruments have been

  10. Modernization of the Slovenian National Seismic Network (United States)

    Vidrih, R.; Godec, M.; Gosar, A.; Sincic, P.; Tasic, I.; Zivcic, M.


    The Environmental Agency of the Republic of Slovenia, the Seismology Office is responsible for the fast and reliable information about earthquakes, originating in the area of Slovenia and nearby. In the year 2000 the project Modernization of the Slovenian National Seismic Network started. The purpose of a modernized seismic network is to enable fast and accurate automatic location of earthquakes, to determine earthquake parameters and to collect data of local, regional and global earthquakes. The modernized network will be finished in the year 2004 and will consist of 25 Q730 remote broadband data loggers based seismic station subsystems transmitting in real-time data to the Data Center in Ljubljana, where the Seismology Office is located. The remote broadband station subsystems include 16 surface broadband seismometers CMG-40T, 5 broadband seismometers CMG-40T with strong motion accelerographs EpiSensor, 4 borehole broadband seismometers CMG-40T, all with accurate timing provided by GPS receivers. The seismic network will cover the entire Slovenian territory, involving an area of 20,256 km2. The network is planned in this way; more seismic stations will be around bigger urban centres and in regions with greater vulnerability (NW Slovenia, Krsko Brezice region). By the end of the year 2002, three old seismic stations were modernized and ten new seismic stations were built. All seismic stations transmit data to UNIX-based computers running Antelope system software. The data is transmitted in real time using TCP/IP protocols over the Goverment Wide Area Network . Real-time data is also exchanged with seismic networks in the neighbouring countries, where the data are collected from the seismic stations, close to the Slovenian border. A typical seismic station consists of the seismic shaft with the sensor and the data acquisition system and, the service shaft with communication equipment (modem, router) and power supply with a battery box. which provides energy in case

  11. A P-wave based, on-site method for Earthquake Early Warning (United States)

    Zollo, Aldo


    Can we rapidly predict the potential damage of earthquakes by-passing the estimation of its location and magnitude? One possible approach is to predict the expected peak ground shaking at the site and the earthquake magnitude from the initial P-peak amplitude and characteristic period, respectively. The idea, first developed by Wu and Kanamori (2005), is to combine the two parameters for declaring the alert once the real-time measured quantities have passed pre-defined thresholds. Our proposed on-site early warning method generalized this approach, based on the analysis of strong motion data from modern accelerograph networks in Japan, Taiwan and Italy (Zollo et al., 2010). It is based on the real-time measurement of the period (τc) and peak displacement (Pd) parameters at one or more co-located stations at a given target site to be protected against the earthquake effects. By converting these real-time proxies in predicted values of Peak Ground Velocity (PGV) or instrumental intensity (IMM) and magnitude, an alert level is issued at the recording site based on a decisional table with four entries defined upon threshold values of the parameters Pd and Tc. The latter ones are set according to the error bounds estimated on the derived prediction equations. A near-source network of stations running the onsite method can provide the event location and transmit the information about the alert levels recorded at near-source stations to more distant sites, before the arrival of the most destructive phase. The network-based approach allows for the rapid and robust estimation of the Potential Damage Zone (PDZ), that is the area where most of earthquake damage is expected (Colombelli et al., 2012). A new strategy for a P-wave based, on-site earthquake early warning system has been developed and tested on Japanese strong motion data and under testing on Italian data. The key elements are the real-time, continuous measurement of three peak amplitude parameters and their

  12. Median effective dose of cisatracurium priming accelerating onset of neuromuscular block in patients of different genders%不同性别患者预注顺阿曲库铵加快起效的半数有效剂量

    Institute of Scientific and Technical Information of China (English)

    陈益; 田玉科; 廖志品; 李新华; 周碧云; 韩东吉


    Objective To investigate the median effective dose (ED50) of cisatracurium priming accelerating the onset of neuromuscular block in patients of different genders. Methods Ninety ASA Ⅰ or Ⅱ patients aged 18-55 yr undergoing elective abdominal operation under general anesthesia were divided into 2 groups ( n = 45 each): male group (group M) and female group (group F). Neuromuscular block was monitored with accelerograph F (TOF-Watch SX). A single twitch stimulation of ulnar nerve was used to monitor neuromuscular function.Anesthesia was induced with midazolam 0.04 mg/kg and fentanyl 1 μg/kg. Accelerograph F was opened after the patients lost consciousness. The priming dose of cisatracurium was injected intravenously, then fentanyl 5 μg/kg and propofol 2 mg/kg were injected intravenously 3 min later and the left dose of cisatracurium for intubation was injected intravenously 4 min later. Tracheal intubation was performed when the ratio of the single twitch stimulation value to control value (T/Tc). decreased to 10%. Anesthesia was maintained with iv infusion of propofol and remifentanil and inhalation of isoflurane. The priming dose of cisatracurium was determined by up-and-down sequential trial. The initial priming dose was set at 5 μg/kg. The ratio of two successive doses was 1.2. T/Tc, time to 90% block, onset time, maximal neuromuscular block and clinical duration were recorded 4 min after the administration of the priming dose. The ED50 and 95% confidence interval (CI) of cisatracurium priming required to accelerate the onset were caculated. Results Time to 90% block was significantly longer-in group M than in group F (P <0.05). No significant difference was found in the other parameters among the groups. The ED50 and 95% CI of cisatracurium priming required to accelerate the onset were 21.36 μg/kg (95% CI 20.52-22.23 μg/kg)in group M and 14.53 μg/kg (95% CI 13.77-15.33 μg/kg) in group F. The ED50 was significantly higher in group M than in group F

  13. Seismicity at the northeast edge of the Mexican Volcanic Belt (MVB and activation of an undocumented fault: the Peñamiller earthquake sequence of 2010–2011, Querétaro, Mexico

    Directory of Open Access Journals (Sweden)

    A. Clemente-Chavez


    Full Text Available The town of Peñamiller in the state of Querétaro, Mexico, is located at the northeast border of the seismogenic zone known as the Mexican Volcanic Belt (MVB, which transects the central part of Mexico with an east–west orientation. In the vicinity of this town, a sequence of small earthquakes occurred during the end of 2010 and beginning of 2011. Seismicity in the continental regimen of central Mexico is not too frequent; however, it is known that there are precedents of large earthquakes (Mw magnitude greater than 6.0 occurring in this zone. Three large earthquakes have occurred in the past 100 yr: the 19 November 1912 (MS = 7.0, the 3 January 1920 (MS = 6.4, and the 29 June 1935 (MS = 6.9 earthquakes. Prior to the instrumental period, the earthquake of 11 February 1875, which took place near the city of Guadalajara, caused widespread damage. The purpose of this article is to contribute to the available seismic information of this region. This will help advance our understanding of the tectonic situation of the central Mexico MVB region. Twenty-four shallow earthquakes of the Peñamiller seismic sequence of 2011 were recorded by a temporary accelerograph network installed by the Universidad Autónoma de Querétaro (UAQ. The data were analyzed in order to determine the source locations and to estimate the source parameters. The study was carried out through an inversion process and by spectral analysis. The results show that the largest earthquake occurred on 8 February 2011 at 19:53:48.6 UTC, had a moment magnitude Mw = 3.5, and was located at latitude 21.039° and longitude −99.752°, at a depth of 5.6 km. This location is less than 7 km away in a south-east direction from downtown Peñamiller. The focal mechanisms are mostly normal faults with small lateral components. These focal mechanisms are consistent with the extensional regimen of the southern extension of the Basin and Range (BR province. The source area of the largest event was

  14. Seismicity at the northeast edge of the Mexican Volcanic Belt (MVB) and activation of an undocumented fault: the Peñamiller earthquake sequence of 2010-2011, Querétaro, Mexico (United States)

    Clemente-Chavez, A.; Figueroa-Soto, A.; Zúñiga, F. R.; Arroyo, M.; Montiel, M.; Chavez, O.


    The town of Peñamiller in the state of Querétaro, Mexico, is located at the northeast border of the seismogenic zone known as the Mexican Volcanic Belt (MVB), which transects the central part of Mexico with an east-west orientation. In the vicinity of this town, a sequence of small earthquakes occurred during the end of 2010 and beginning of 2011. Seismicity in the continental regimen of central Mexico is not too frequent; however, it is known that there are precedents of large earthquakes (Mw magnitude greater than 6.0) occurring in this zone. Three large earthquakes have occurred in the past 100 yr: the 19 November 1912 (MS = 7.0), the 3 January 1920 (MS = 6.4), and the 29 June 1935 (MS = 6.9) earthquakes. Prior to the instrumental period, the earthquake of 11 February 1875, which took place near the city of Guadalajara, caused widespread damage. The purpose of this article is to contribute to the available seismic information of this region. This will help advance our understanding of the tectonic situation of the central Mexico MVB region. Twenty-four shallow earthquakes of the Peñamiller seismic sequence of 2011 were recorded by a temporary accelerograph network installed by the Universidad Autónoma de Querétaro (UAQ). The data were analyzed in order to determine the source locations and to estimate the source parameters. The study was carried out through an inversion process and by spectral analysis. The results show that the largest earthquake occurred on 8 February 2011 at 19:53:48.6 UTC, had a moment magnitude Mw = 3.5, and was located at latitude 21.039° and longitude -99.752°, at a depth of 5.6 km. This location is less than 7 km away in a south-east direction from downtown Peñamiller. The focal mechanisms are mostly normal faults with small lateral components. These focal mechanisms are consistent with the extensional regimen of the southern extension of the Basin and Range (BR) province. The source area of the largest event was estimated to

  15. Comparative study of the amplification of ground motion using seismic noise and recent earthquakes adjacent to the Cerro Prieto volcano, Baja California (United States)

    Vega, F. D.; Vidal-Villegas, A.


    We have chosen an area of approximately 79 km2, centered around the Cerro Prieto volcano, in the Mexicalli valley, Baja California, based on elevated registered acceleration data. The GEO station, located in the Cerro Prieto geothermal field has registered seismic accelerations on the order of 492 gales. The local residents near the study area have reported feeling numerous smaller magnitude earthquakes, compared to those of the nearby populated city of Mexicalli. Does there exist an amplified seismic signal in the area? If so, what is the cause of the amplification? The objective of our study is to answer these questions and determine the subsurface (0-50 m) structure in 4 specific sites. To obtain these answers, we registered seismic noise samples using short period seismometers (1 s), intermediate (5 s) and 16 bit recorders, along a linear profile which crosses the volcano with an 18 degree NE orientation. Furthermore, we analyzed ground-motion data (from 2004-2006), obtained from 24-bit accelerographs. Using both types of data (noise and accelegraphs) we calculated the H/V spectral ratios, and the relative ratios between both sites. To determine the subsurface structure, we used a unidimensional model of the H/V ratios, based on the methodology used by Huerta-Lopez et al., 2005. The H/V spectral ratios from the seismic noise adjacent to the volcano display amplitude of 1 in the frequency range (0.8 - 30 Hz). In contrast, the amplitude in the volcano crater (159 m.a.s.l.) was 6 in the frequency range (0.8 - 3 Hz). The average H/V relative ratio of the crater and the adjacent sites is 4, with frequencies between 0.8 and 1.2 Hz. The S-wave H/V ratios for the VCP acceleration station (110 m.a.s.l.), are near 8, with frequencies between 1 and 2. The H/V spectral ratios from the seismic noise for the geothermal field display amplitude of 4 for frequencies between 0.8 and 1.3 Hz, while the results from the S wave display amplitudes of 5 between 1.5 and 3 Hz. In the

  16. Observations of large earthquakes in the Mexican subduction zone over 110 years (United States)

    Hjörleifsdóttir, Vala; Krishna Singh, Shri; Martínez-Peláez, Liliana; Garza-Girón, Ricardo; Lund, Björn; Ji, Chen


    Fault slip during an earthquake is observed to be highly heterogeneous, with areas of large slip interspersed with areas of smaller or even no slip. The cause of the heterogeneity is debated. One hypothesis is that the frictional properties on the fault are heterogeneous. The parts of the rupture surface that have large slip during earthquakes are coupled more strongly, whereas the areas in between and around creep continuously or episodically. The continuously or episodically creeping areas can partly release strain energy through aseismic slip during the interseismic period, resulting in relatively lower prestress than on the coupled areas. This would lead to subsequent earthquakes having large slip in the same place, or persistent asperities. A second hypothesis is that in the absence of creeping sections, the prestress is governed mainly by the accumulative stress change associated with previous earthquakes. Assuming homogeneous frictional properties on the fault, a larger prestress results in larger slip, i.e. the next earthquake may have large slip where there was little or no slip in the previous earthquake, which translates to non-persistent asperities. The study of earthquake cycles are hampered by short time period for which high quality, broadband seismological and accelerographic records, needed for detailed studies of slip distributions, are available. The earthquake cycle in the Mexican subduction zone is relatively short, with about 30 years between large events in many places. We are therefore entering a period for which we have good records for two subsequent events occurring in the same segment of the subduction zone. In this study we compare seismograms recorded either at the Wiechert seismograph or on a modern broadband seismometer located in Uppsala, Sweden for subsequent earthquakes in the Mexican subduction zone rupturing the same patch. The Wiechert seismograph is unique in the sense that it recorded continuously for more than 80 years

  17. 顺式阿曲库铵与琥珀胆碱用于支撑喉镜检查手术的比较研究%Comparision of Cisatracurium and Succinylcholine in Brace Laryngoscopy Operation

    Institute of Scientific and Technical Information of China (English)

    王宏梗; 陈汝聘; 王艳辉; 施萍萍


    Objective To compare the muscular relaxation effect and side effects of Cisatracurium and Succinylcholine in brace laryngoscopy operation. Methods Sixty adult patients(ASA Ⅰ ~Ⅱ ), agreed to be on electively brace laryngoscopy operation,were divided randomly into three groups(group Cl ,group C2 and group S, n=20 each). All patients in these three groups were injected intravenously with Fen tanil 4 μg/kg and Propofol 2 mg/kg during the induction of general anesthesia,and then be injected intrave nously with muscle relaxant (Cisatracurium 0. 15 mg/kg for group Cl , Cisatracurium 0. 2 mg/kg for group C2 or succinylcholine 1 mg/kg for group S, respectively). After the induction, continuously intravenous injection with Propofol 5~6 mg ? Kg-1 ? H-1 were used until the operation was over. Two minutes before the operations,all patients in group S were injected intravenously with Fentanil 1. 5 jug/kg and succinylcho line 0. 5 mg/kg, Cisatracurium 0. 05 mg/kg just in case depending on the relaxation level. Neuromuscular (N-M) function -was monitored with accelerograph F(TOF-Watch SX, Organon, the netherlands). The degree of muscle relexation was recorded at the time point of the tracheal intubation, brace laryngoscopy, the end of the operation, 15 min after the operation, 30 min after the operation. Brace laryngoscopy con dition was graded according to a criteria set by the surgeons. Heart rate(HR) was especlly recorded be fore and after the second dose of muscle relaxant was injected intravenously. The rates of muscle pain were also recorded 24 h after the operation. Results The degree of muscle relexation at the time point of 15 min after the operation was significantly lower in group S than that in group Cl and group C2 (P 0. 05). HR was stable and none needed the second dose of muscle relaxant in group Cland group C2, however, HR of all of the patients in group S was significantly slower after the second dose of muscle re laxant was injected intravenously than that