In some countries with seismicity,an adequate detection network is essential to assess seismic hazards.The Instituto Geografico Nacional(National Geographic Institute/IGN)of Spain manages a strong motion network distr...In some countries with seismicity,an adequate detection network is essential to assess seismic hazards.The Instituto Geografico Nacional(National Geographic Institute/IGN)of Spain manages a strong motion network distributed throughout the whole country and an earthquake detection network composed of velocity stations.This paper aims at studying the development of the strong motion network of the Spanish National Seismic Network(focusing on mainland Spain and the Balearics)in the last three decades.A Geographic Information System(GIS)has been implemented to integrate the attributes from the IGN’s database concerning the earthquake catalogue,seismograph and accelerometer networks,which enabled to analyse the data and map the distribution of detection equipments in the region.The irregularly distributed Spanish strong motion network was greatly expanded from 1990 to 2010.In the past decade,it developed at a slower rate,but more modern technology was implemented.展开更多
In regions of complex geology and tectonic assembly, strong motion seismic arrival time records can be used to test the plausibility of existing hypothesis about the origin of lithological and tectonic features and ho...In regions of complex geology and tectonic assembly, strong motion seismic arrival time records can be used to test the plausibility of existing hypothesis about the origin of lithological and tectonic features and how they are related in space and time. In this study we use differential travel time residuals at some strong motion accelerographic stations in the Medellin-Aburra Valley, in the northern Central Cordillera of the Colombian Andes, to discuss some aspects of the geological configuration. We based our work on the hypothesis that the differences between seismic travel time residuals among pairs of stations are a function of the differences in the surface geology and the near-surface upper crustal configuration. Our results are consistent with the volcanic rocks of the Quebradagrande Complex being less mafic, more weathered or more tectonically affected than previously thought, with the presence of a relatively thin dunite body on top of the metamorphic basement, and with a large lateral heterogeneity in the mainly mafic San Diego Stock.展开更多
The National Strong Motion Observation Network System (NSMONS) of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and...The National Strong Motion Observation Network System (NSMONS) of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and a network management system. During the Wenchuan Earthquake, over 1,400 components of acceleration records were obtained from 460 permanent free-field stations and three arrays for topographical effect and structural response observation in the network system from the main shock, and over 20,000 components of acceleration records from strong aftershocks occurred before August 1, 2008 were also obtained by permanent free-field stations of the NSMONS and 59 mobile instruments quickly deployed after the main shock. The strong motion recordings from the main shock and strong aftershocks are summarized in this paper. In the ground motion recordings, there are over 560 components with peak ground acceleration (PGA) over 10 Gal, the largest being 957.7 Gal. The largest PGA recorded during the aftershock exceeds 300 Gal.展开更多
Local site conditions play an important role in the effective application of strong motion recordings.In the China National Strong Motion Observation Network System(NSMONS),some of the stations do not provide boreho...Local site conditions play an important role in the effective application of strong motion recordings.In the China National Strong Motion Observation Network System(NSMONS),some of the stations do not provide borehole information,and correspondingly,do not assign the site classes yet.In this paper,site classification methodologies for free-field strong motion stations are reviewed and the limitations and uncertainties of the horizontal-to-vertical spectral ratio(HVSR) methods are discussed.Then,a new method for site classification based on the entropy weight theory is proposed.The proposed method avoids the head or tail joggle phenomenon by providing the objective and subjective weights.The method was applied to aftershock recordings from the 2008 Wenchuan earthquake,and 54 free-field NSMONS stations were selected for site classification and the mean HVSRs were calculated.The results show that the improved HVSR method proposed in this paper has a higher success rate and could be adopted in NSMONS.展开更多
During the great Wenchuan earthquake, about 460 permanent free-field stations in National Strong Motion Observation Network System (NSMONS) of China captured the main shock acceleration records. These records can be...During the great Wenchuan earthquake, about 460 permanent free-field stations in National Strong Motion Observation Network System (NSMONS) of China captured the main shock acceleration records. These records can be applied to site effect analyses, and then the site classification of those permanent stations can be carried out firstly, which will served as the fundamental information for further research. In this paper, the site of near-fault stations is classified by horizontal-to-vertical spectral ratio (HVSR) method according to the site class description of Japan earthquake resistant design code and response spectral shapes (RSS) method following the site class description of the 1997 Uniform Building Code (UBC) provisions. Then based on the detailed borehole data of those free-field stations, the equivalent shear wave velocity and overburden thickness are calculated and the site classifications are given by Chinese code for seismic design of buildings. Furthermore, for the stations having successful microtremor test data, the site dominant periods are computed to verify the results of site classification. Finally, combined with all the above results, the recommended site classes of near-fault permanent free-field stations are given.展开更多
A random synthesis procedure based on finite fault model is adopted for near field strong ground motion simulation in this paper. The fault plane of the source is divided into a number of sub-sources, the whole moment...A random synthesis procedure based on finite fault model is adopted for near field strong ground motion simulation in this paper. The fault plane of the source is divided into a number of sub-sources, the whole moment magnitude is also divided into more sub-events. The Fourier spectrum of ground motion caused by a sub-event in given sub-source, then can be derived by means of taking the point source spectrum, attenuation with distance, energy dissipation, and near surface effect, into account. A time history is synthesized from this amplitude spectrum and a random phase spectrum, and being combined with an envelope function. The ground motion is worked out by superposition of all time histories from each sub-event in each sub-source, with time lags determining by the differences between the triggering times of sub-events and distances of the sub-sources. From the example of simulations at 21 near field points in a scenario earthquake with 4 dip angles of the fault plane, it is illustrated that the procedure can describe the rupture directivity and hanging wall effect very well. To validate the procedure, the response spectra and time histories recorded at three near fault stations MCN, LV3 and PCD during the Northridge earthquake in 1994, are compared with the simulated ones.展开更多
The county town of Beichuan county, China, experienced catastrophic destruction due to landslides induce by the 2008 Wenchuan earthquake. In consideration of the special location of the county town, this paper selecte...The county town of Beichuan county, China, experienced catastrophic destruction due to landslides induce by the 2008 Wenchuan earthquake. In consideration of the special location of the county town, this paper selected the landslides induced in the town as representative of large-scale near-rupture landslides, and quantitatively analyzed why the landslide damage was so destructive in the town by using strong motion data obtained from the Wenchuan earthquake in the Longmenshan area. Three methods were employed to estimate the landslide damage using strong motion data. (1) Peak ground accelerations (PGAs) on the hanging wall were used to evaluate the PGAs on the landslide sites in the town. The evaluated average PGAs were all greater than I g, indicating that the ground motion intensity was very strong during the earthquake. (2) Acceleration time histories, from another station with similar geological conditions to the town, were used to evaluate the critical acceleration changing range, and the estimated values showed the geological conditions were very susceptible to earthquakes. (3) Acceleration time histories, from two stations on the hanging and foot walls of the rupture, and near the town, were used to calculate the Newmark displacements, and all the evaluated displacements indicated that landslides were very likely. The results show that the slopes, susceptible to earthquakes in the Beichuan county town, were easily triggered under such strong ground-motion intensity and developed into large-scale catastrophic events.展开更多
In this paper, the mobile strong ground motion observation for the destructive earthquake is introduced. Considering the characteristics and its spatial distributions of aftershock, 59 strong ground motion instruments...In this paper, the mobile strong ground motion observation for the destructive earthquake is introduced. Considering the characteristics and its spatial distributions of aftershock, 59 strong ground motion instruments were installed along the Longrnenshan fault area, and more than 2 000 records have been accumulated. It shows that it is necessary to perform the mobile strong ground motion observation after the destructive earthquake, and the precious collected data could be applied for further research.展开更多
With the recent development of digital Micro Electro Mechanical System (MEMS) sensors, the cost of monitoring and detecting seismic events in real time can be greatly reduced. Ability of MEMS accelerograph to record...With the recent development of digital Micro Electro Mechanical System (MEMS) sensors, the cost of monitoring and detecting seismic events in real time can be greatly reduced. Ability of MEMS accelerograph to record a seismic event depends upon the efficiency of triggering algorithm, apart from the sensor's sensitivity. There are several classic triggering algorithms developed to detect seismic events, ranging from basic amplitude threshold to more sophisticated pattern recognition. Algorithms based on STA/LTA are reported to be computationally efficient for real time monitoring. In this paper, we analyzed several STA/LTA algorithms to check their efficiency and suitability using data obtained from the Quake Catcher Network (network of MEMS accelerometer stations). We found that most of the STA/LTA algorithms are suitable for use with MEMS accelerometer data to accurately detect seismic events. However, the efficiency of any particular algorithm is found to be dependent on the parameter set used (i.e., window width of STA, LTA and threshold level).展开更多
Taking Tianjin as an example, this paper proposed a methodology and process for evaluating near-fault strong ground motions from future earthquakes to mitigate earthquake damage for the metropolitan area and important...Taking Tianjin as an example, this paper proposed a methodology and process for evaluating near-fault strong ground motions from future earthquakes to mitigate earthquake damage for the metropolitan area and important engineering structures. The result of strong ground motion was predicted for Tianjin main faults by the hybrid method which mainly con- sists of 3D finite difference method and stochastic Green's function. Simulation is performed for 3D structures of Tianjin re- gion and characterized asperity models. The characterized asperity model describing source heterogeneity is introduced fol- lowing the fault information from the project of Tianjin Active Faults and Seismic Hazard Assessment. We simulated the worst case that two earthquakes separately occur. The results indicate that the fault position, rupture process and the sedi- mentary deposits of the basin significantly affect amplification of the simulated ground motion. Our results also demonstrate the possibility of practical simulating wave propagation including basin induced surface waves in broad frequency-band, for seismic hazard analysis near the fault from future earthquakes in urbanized areas.展开更多
Objectives of this task are to conduct research on seismic hazards,and to provide relevant input on the expected levels of these hazards to other tasks.Other tasks requiring this input include those dealing with inven...Objectives of this task are to conduct research on seismic hazards,and to provide relevant input on the expected levels of these hazards to other tasks.Other tasks requiring this input include those dealing with inventory,fragility curves, rehabilitation strategies and demonstration projects.The corresponding input is provided in various formats depending on the intended use:as peak ground motion parameters and/or response spectral values for a given magnitude,epicentral distance and site conditions;or as time histories for scenario earthquakes that are selected based on the disaggregated seismic hazard mapped by the U.S.Geological Survey and are incorporated in building codes.The user community for this research is both academic researchers and practicing engineers who may use the seismic input generated by the synthesis techniques that are developed under this task for a variety of applications.These include ground motions for scenario earthquakes,for developing fragility curves and in specifying ground motion input for critical facilities (such as hospitals) located in the eastern U.S.展开更多
On the assumption that seismic source is simplified as linear rupture fault with finite length, this paper qualitatively studies the seismic source effects on space correlation of strong ground motion. Based on expand...On the assumption that seismic source is simplified as linear rupture fault with finite length, this paper qualitatively studies the seismic source effects on space correlation of strong ground motion. Based on expanding expression of Fourier spectrum of strong ground motion with space coordinate variables, this paper also gives a expression of describing correlation of strong ground motion field. According to far-field condition, the theoretical formula of the expression can be obtained. Furthermore, this paper presents a theoretical formula of estimation the radius of strong ground motion field, which depends on expansion condition of Fourier spectrum of strong ground motion, with space variables. At last, taking one earthquake as an example, this paper gives three-dimension patterns of radius of the field with epicenter distance and azimuth as well as frequency.展开更多
Seismic hazard assessment based on urban active faults can provide scientific bases for city planning and project construction, while numerical simulation of strong ground motion is an important method for seismic haz...Seismic hazard assessment based on urban active faults can provide scientific bases for city planning and project construction, while numerical simulation of strong ground motion is an important method for seismic hazard prediction and assessment. A 3-D physical model in conformity with real strata configuration of (mainly) the Quaternary is a prerequisite to ensure the reliability of the simulation results. In this paper, we give a detailed account of the technical scheme and process for creating a 3-D physical model in Kunming basin. The data used are synthe- sized from seismogeological data, borehole data, topographic data, digital elevation mode (DEM) data, seismic exploration results and wave velocity measurements. Strafigraphic division is based mainly on shear wave velocity, with strata sequence taken into consideration. The model construction is finally accomplished with ArcGIS and many relevant programming techniques via layer-by-layer stacking (in depth direction) of the adjacent medium interfaces (meshes). Meanwhile, a database of 3-D physical models is set up, which provides model data and parameters for strong ground motion simulation. Some processing methods and significant issues are also addressed in the paper in accordance with different types of exploration and experimental data.展开更多
The notion of equivalent dispersion of strong seismic waves is further illuminated and a frequency-dependentstochastic model of the Fourier phase of strong earthquake ground motion is presented for use in statistical ...The notion of equivalent dispersion of strong seismic waves is further illuminated and a frequency-dependentstochastic model of the Fourier phase of strong earthquake ground motion is presented for use in statistical estimates of the Fourier phase. The non-stationary features of design ground motions synthesized using the phasemodel in combination with the empirical attenuation model of amplitude spectra of strong ground motion are ableto be consistent with those of observed records in the sense of statistics.展开更多
A method to predict near-field strong ground motions for scenario earthquakes on active faults is proposed. First, macro-source parameters characterizing the entire source area, i.e., global source parameters, includi...A method to predict near-field strong ground motions for scenario earthquakes on active faults is proposed. First, macro-source parameters characterizing the entire source area, i.e., global source parameters, including fault length, fault width, rupture area, average slip on the fault plane, etc., are estimated by seismogeology survey, seismicity and seismic scaling laws. Second, slip distributions characterizing heterogeneity or roughness on the fault plane, i.e., local source parameters, are reproduced/evaluated by the hybrid slip model. Finally, the finite fault source model, developed from both the global and local source parameters, is combined with the stochastically synthetic technique of ground motion using the dynamic comer frequency based on seismology. The proposed method is applied to simulate the acceleration time histories on three base-rock stations during the 1994 Northridge earthquake. Comparisons between the predicted and recorded acceleration time histories show that the method is feasible and practicable.展开更多
The catalogs of ground motion parameters for earthquake-prone regions of Kazakhstan used for modeling seismic effects in seismic hazard assessment and microzonation are presented.
The M6.2 earthquake in Jishishan,Gansu Province,on December 18,2023,caused extraordinary earthquake disasters.It was located in the northern part of the north−south seismic zone,which is a key area for earthquake moni...The M6.2 earthquake in Jishishan,Gansu Province,on December 18,2023,caused extraordinary earthquake disasters.It was located in the northern part of the north−south seismic zone,which is a key area for earthquake monitoring in China.The newly built dense strong motion stations in this area provide unprecedented conditions for high-precision earthquake relocation,especially the earthquake focal depth.This paper uses the newly built strong motion and traditional broadband seismic networks to relocate the source locations of the M3.0 and above aftershocks and to invert their focal mechanisms.The horizontal error of earthquake location is estimated to be 0.5−1 km,and the vertical error is 1−2 km.The focal depth range of aftershocks is 9.6−14.6 km,distributed in a 12-km-long strip with SSE direction.Aftershocks in the south are more concentrated horizontally and vertically,while aftershocks in the north are more scattered.The focal mechanisms of the main shock and aftershocks are relatively consistent,and the P-axis orientation is consistent with the regional strain direction.There is a seismic blank area of M3.0 and above,about 3−5 km between the main shock and aftershocks.It is suggested that the energy released by the main shock rupture is concentrated in this area.Based on the earthquake location and focal mechanism of the main shock,it is inferred that the Northern Lajishan fault zone is the seismogenic structure of the main shock,and the main shock did not occur on the main fault,but on a secondary fault.The initial rupture depth and centroid depth of the main shock were 12.8 and 14.0 km,respectively.The source rupture depth may not be the main reason for the severe earthquake disaster.展开更多
文摘In some countries with seismicity,an adequate detection network is essential to assess seismic hazards.The Instituto Geografico Nacional(National Geographic Institute/IGN)of Spain manages a strong motion network distributed throughout the whole country and an earthquake detection network composed of velocity stations.This paper aims at studying the development of the strong motion network of the Spanish National Seismic Network(focusing on mainland Spain and the Balearics)in the last three decades.A Geographic Information System(GIS)has been implemented to integrate the attributes from the IGN’s database concerning the earthquake catalogue,seismograph and accelerometer networks,which enabled to analyse the data and map the distribution of detection equipments in the region.The irregularly distributed Spanish strong motion network was greatly expanded from 1990 to 2010.In the past decade,it developed at a slower rate,but more modern technology was implemented.
文摘In regions of complex geology and tectonic assembly, strong motion seismic arrival time records can be used to test the plausibility of existing hypothesis about the origin of lithological and tectonic features and how they are related in space and time. In this study we use differential travel time residuals at some strong motion accelerographic stations in the Medellin-Aburra Valley, in the northern Central Cordillera of the Colombian Andes, to discuss some aspects of the geological configuration. We based our work on the hypothesis that the differences between seismic travel time residuals among pairs of stations are a function of the differences in the surface geology and the near-surface upper crustal configuration. Our results are consistent with the volcanic rocks of the Quebradagrande Complex being less mafic, more weathered or more tectonically affected than previously thought, with the presence of a relatively thin dunite body on top of the metamorphic basement, and with a large lateral heterogeneity in the mainly mafic San Diego Stock.
基金NSFC Under Grant No. 90715038MOST of China Under Grant No. 2006BAC13B02
文摘The National Strong Motion Observation Network System (NSMONS) of China is briefly introduced in this paper. The NSMONS consists of permanent free-field stations, special observation arrays, mobile observatories and a network management system. During the Wenchuan Earthquake, over 1,400 components of acceleration records were obtained from 460 permanent free-field stations and three arrays for topographical effect and structural response observation in the network system from the main shock, and over 20,000 components of acceleration records from strong aftershocks occurred before August 1, 2008 were also obtained by permanent free-field stations of the NSMONS and 59 mobile instruments quickly deployed after the main shock. The strong motion recordings from the main shock and strong aftershocks are summarized in this paper. In the ground motion recordings, there are over 560 components with peak ground acceleration (PGA) over 10 Gal, the largest being 957.7 Gal. The largest PGA recorded during the aftershock exceeds 300 Gal.
基金National Key Technology R&D Program Under Grant No.2009BAK55B05Nonprofit Industry Research Project of CEA Under Grant No.201108003Science Foundation of Institute of Engineering Mechanics,CEA Under Grant No.2010C01
文摘Local site conditions play an important role in the effective application of strong motion recordings.In the China National Strong Motion Observation Network System(NSMONS),some of the stations do not provide borehole information,and correspondingly,do not assign the site classes yet.In this paper,site classification methodologies for free-field strong motion stations are reviewed and the limitations and uncertainties of the horizontal-to-vertical spectral ratio(HVSR) methods are discussed.Then,a new method for site classification based on the entropy weight theory is proposed.The proposed method avoids the head or tail joggle phenomenon by providing the objective and subjective weights.The method was applied to aftershock recordings from the 2008 Wenchuan earthquake,and 54 free-field NSMONS stations were selected for site classification and the mean HVSRs were calculated.The results show that the improved HVSR method proposed in this paper has a higher success rate and could be adopted in NSMONS.
基金supported by the projects from the Ministry of Science and Technology of China (No.2009BK55B00)China Earthquake Administration (CEA) (No. 200808026)Institute of Engineering Mechanics of CEA (No. 0618001)
文摘During the great Wenchuan earthquake, about 460 permanent free-field stations in National Strong Motion Observation Network System (NSMONS) of China captured the main shock acceleration records. These records can be applied to site effect analyses, and then the site classification of those permanent stations can be carried out firstly, which will served as the fundamental information for further research. In this paper, the site of near-fault stations is classified by horizontal-to-vertical spectral ratio (HVSR) method according to the site class description of Japan earthquake resistant design code and response spectral shapes (RSS) method following the site class description of the 1997 Uniform Building Code (UBC) provisions. Then based on the detailed borehole data of those free-field stations, the equivalent shear wave velocity and overburden thickness are calculated and the site classifications are given by Chinese code for seismic design of buildings. Furthermore, for the stations having successful microtremor test data, the site dominant periods are computed to verify the results of site classification. Finally, combined with all the above results, the recommended site classes of near-fault permanent free-field stations are given.
基金Earthquake Science Foundation under Contract No.201009
文摘A random synthesis procedure based on finite fault model is adopted for near field strong ground motion simulation in this paper. The fault plane of the source is divided into a number of sub-sources, the whole moment magnitude is also divided into more sub-events. The Fourier spectrum of ground motion caused by a sub-event in given sub-source, then can be derived by means of taking the point source spectrum, attenuation with distance, energy dissipation, and near surface effect, into account. A time history is synthesized from this amplitude spectrum and a random phase spectrum, and being combined with an envelope function. The ground motion is worked out by superposition of all time histories from each sub-event in each sub-source, with time lags determining by the differences between the triggering times of sub-events and distances of the sub-sources. From the example of simulations at 21 near field points in a scenario earthquake with 4 dip angles of the fault plane, it is illustrated that the procedure can describe the rupture directivity and hanging wall effect very well. To validate the procedure, the response spectra and time histories recorded at three near fault stations MCN, LV3 and PCD during the Northridge earthquake in 1994, are compared with the simulated ones.
基金supported by the National Science and Technology Supporting Item of China (No. 2012BAK15B06)the project from Institute of Crustal Dynamics, China Earthquake Administration (No. ZDJ2010-28)
文摘The county town of Beichuan county, China, experienced catastrophic destruction due to landslides induce by the 2008 Wenchuan earthquake. In consideration of the special location of the county town, this paper selected the landslides induced in the town as representative of large-scale near-rupture landslides, and quantitatively analyzed why the landslide damage was so destructive in the town by using strong motion data obtained from the Wenchuan earthquake in the Longmenshan area. Three methods were employed to estimate the landslide damage using strong motion data. (1) Peak ground accelerations (PGAs) on the hanging wall were used to evaluate the PGAs on the landslide sites in the town. The evaluated average PGAs were all greater than I g, indicating that the ground motion intensity was very strong during the earthquake. (2) Acceleration time histories, from another station with similar geological conditions to the town, were used to evaluate the critical acceleration changing range, and the estimated values showed the geological conditions were very susceptible to earthquakes. (3) Acceleration time histories, from two stations on the hanging and foot walls of the rupture, and near the town, were used to calculate the Newmark displacements, and all the evaluated displacements indicated that landslides were very likely. The results show that the slopes, susceptible to earthquakes in the Beichuan county town, were easily triggered under such strong ground-motion intensity and developed into large-scale catastrophic events.
基金supported by MOST of China under Grant No. 2006BAC13B02CEA under Grant No. 200808026 IEM/CEA under Grant No. 0618001
文摘In this paper, the mobile strong ground motion observation for the destructive earthquake is introduced. Considering the characteristics and its spatial distributions of aftershock, 59 strong ground motion instruments were installed along the Longrnenshan fault area, and more than 2 000 records have been accumulated. It shows that it is necessary to perform the mobile strong ground motion observation after the destructive earthquake, and the precious collected data could be applied for further research.
基金IIT Roorkee under the Faculty Initiation Grant No.100556
文摘With the recent development of digital Micro Electro Mechanical System (MEMS) sensors, the cost of monitoring and detecting seismic events in real time can be greatly reduced. Ability of MEMS accelerograph to record a seismic event depends upon the efficiency of triggering algorithm, apart from the sensor's sensitivity. There are several classic triggering algorithms developed to detect seismic events, ranging from basic amplitude threshold to more sophisticated pattern recognition. Algorithms based on STA/LTA are reported to be computationally efficient for real time monitoring. In this paper, we analyzed several STA/LTA algorithms to check their efficiency and suitability using data obtained from the Quake Catcher Network (network of MEMS accelerometer stations). We found that most of the STA/LTA algorithms are suitable for use with MEMS accelerometer data to accurately detect seismic events. However, the efficiency of any particular algorithm is found to be dependent on the parameter set used (i.e., window width of STA, LTA and threshold level).
基金supported by the National Natural Science Foundation of China (40674016)Earthquake Research Fund of Ministry of Science and Technology of China ((2007)203/8-53)
文摘Taking Tianjin as an example, this paper proposed a methodology and process for evaluating near-fault strong ground motions from future earthquakes to mitigate earthquake damage for the metropolitan area and important engineering structures. The result of strong ground motion was predicted for Tianjin main faults by the hybrid method which mainly con- sists of 3D finite difference method and stochastic Green's function. Simulation is performed for 3D structures of Tianjin re- gion and characterized asperity models. The characterized asperity model describing source heterogeneity is introduced fol- lowing the fault information from the project of Tianjin Active Faults and Seismic Hazard Assessment. We simulated the worst case that two earthquakes separately occur. The results indicate that the fault position, rupture process and the sedi- mentary deposits of the basin significantly affect amplification of the simulated ground motion. Our results also demonstrate the possibility of practical simulating wave propagation including basin induced surface waves in broad frequency-band, for seismic hazard analysis near the fault from future earthquakes in urbanized areas.
基金the Earthquake Engineering Research Centers Program of the National Science Foundation under Award Number EEC-9701471 to the Multidisciplinary Center for Earthquake Engineering Research.
文摘Objectives of this task are to conduct research on seismic hazards,and to provide relevant input on the expected levels of these hazards to other tasks.Other tasks requiring this input include those dealing with inventory,fragility curves, rehabilitation strategies and demonstration projects.The corresponding input is provided in various formats depending on the intended use:as peak ground motion parameters and/or response spectral values for a given magnitude,epicentral distance and site conditions;or as time histories for scenario earthquakes that are selected based on the disaggregated seismic hazard mapped by the U.S.Geological Survey and are incorporated in building codes.The user community for this research is both academic researchers and practicing engineers who may use the seismic input generated by the synthesis techniques that are developed under this task for a variety of applications.These include ground motions for scenario earthquakes,for developing fragility curves and in specifying ground motion input for critical facilities (such as hospitals) located in the eastern U.S.
文摘On the assumption that seismic source is simplified as linear rupture fault with finite length, this paper qualitatively studies the seismic source effects on space correlation of strong ground motion. Based on expanding expression of Fourier spectrum of strong ground motion with space coordinate variables, this paper also gives a expression of describing correlation of strong ground motion field. According to far-field condition, the theoretical formula of the expression can be obtained. Furthermore, this paper presents a theoretical formula of estimation the radius of strong ground motion field, which depends on expansion condition of Fourier spectrum of strong ground motion, with space variables. At last, taking one earthquake as an example, this paper gives three-dimension patterns of radius of the field with epicenter distance and azimuth as well as frequency.
基金Urban Active Fault Detection Project sponsored by the National Development andReform Commission of China(2004-1138)National Natural Science Foundation of China(40604005)+1 种基金Joint Seismological Science Foundation of China(A07027)Key Project during the 10th Five-year Plan Period from Earthquake Administration of China(J105B-16).
文摘Seismic hazard assessment based on urban active faults can provide scientific bases for city planning and project construction, while numerical simulation of strong ground motion is an important method for seismic hazard prediction and assessment. A 3-D physical model in conformity with real strata configuration of (mainly) the Quaternary is a prerequisite to ensure the reliability of the simulation results. In this paper, we give a detailed account of the technical scheme and process for creating a 3-D physical model in Kunming basin. The data used are synthe- sized from seismogeological data, borehole data, topographic data, digital elevation mode (DEM) data, seismic exploration results and wave velocity measurements. Strafigraphic division is based mainly on shear wave velocity, with strata sequence taken into consideration. The model construction is finally accomplished with ArcGIS and many relevant programming techniques via layer-by-layer stacking (in depth direction) of the adjacent medium interfaces (meshes). Meanwhile, a database of 3-D physical models is set up, which provides model data and parameters for strong ground motion simulation. Some processing methods and significant issues are also addressed in the paper in accordance with different types of exploration and experimental data.
文摘The notion of equivalent dispersion of strong seismic waves is further illuminated and a frequency-dependentstochastic model of the Fourier phase of strong earthquake ground motion is presented for use in statistical estimates of the Fourier phase. The non-stationary features of design ground motions synthesized using the phasemodel in combination with the empirical attenuation model of amplitude spectra of strong ground motion are ableto be consistent with those of observed records in the sense of statistics.
基金China Postdoctoral Science Foundation UnderGrant No. 2005037650 Heilongjiang Province PostdoctoralScience Foundation China EarthquakeAdministration’s Tenth"Five Year Plans" Project
文摘A method to predict near-field strong ground motions for scenario earthquakes on active faults is proposed. First, macro-source parameters characterizing the entire source area, i.e., global source parameters, including fault length, fault width, rupture area, average slip on the fault plane, etc., are estimated by seismogeology survey, seismicity and seismic scaling laws. Second, slip distributions characterizing heterogeneity or roughness on the fault plane, i.e., local source parameters, are reproduced/evaluated by the hybrid slip model. Finally, the finite fault source model, developed from both the global and local source parameters, is combined with the stochastically synthetic technique of ground motion using the dynamic comer frequency based on seismology. The proposed method is applied to simulate the acceleration time histories on three base-rock stations during the 1994 Northridge earthquake. Comparisons between the predicted and recorded acceleration time histories show that the method is feasible and practicable.
文摘The catalogs of ground motion parameters for earthquake-prone regions of Kazakhstan used for modeling seismic effects in seismic hazard assessment and microzonation are presented.
文摘The M6.2 earthquake in Jishishan,Gansu Province,on December 18,2023,caused extraordinary earthquake disasters.It was located in the northern part of the north−south seismic zone,which is a key area for earthquake monitoring in China.The newly built dense strong motion stations in this area provide unprecedented conditions for high-precision earthquake relocation,especially the earthquake focal depth.This paper uses the newly built strong motion and traditional broadband seismic networks to relocate the source locations of the M3.0 and above aftershocks and to invert their focal mechanisms.The horizontal error of earthquake location is estimated to be 0.5−1 km,and the vertical error is 1−2 km.The focal depth range of aftershocks is 9.6−14.6 km,distributed in a 12-km-long strip with SSE direction.Aftershocks in the south are more concentrated horizontally and vertically,while aftershocks in the north are more scattered.The focal mechanisms of the main shock and aftershocks are relatively consistent,and the P-axis orientation is consistent with the regional strain direction.There is a seismic blank area of M3.0 and above,about 3−5 km between the main shock and aftershocks.It is suggested that the energy released by the main shock rupture is concentrated in this area.Based on the earthquake location and focal mechanism of the main shock,it is inferred that the Northern Lajishan fault zone is the seismogenic structure of the main shock,and the main shock did not occur on the main fault,but on a secondary fault.The initial rupture depth and centroid depth of the main shock were 12.8 and 14.0 km,respectively.The source rupture depth may not be the main reason for the severe earthquake disaster.