2017 Vol. 39 No. 1
2017, 39(1): 1-12.
DOI: 10.11939/jass.2017.01.001
Abstract：
The New Zealand earthquake of November 13, 2016, MS8.0 occurred near the Kaikoura area in the South Island, New Zealand, with focal depth of 11 km. The MS8.0 earthquake occurred on the transform boundary faults between the Pacific Plate and the Australian Plate, and the focal mechanism solution shows the earthquake is of thrust type event. Two people were killed, twenty or so people were injured and more than ten buildings were destroyed during this earthquake, so the damage level is not so severe in consideration about the huge magnitude. In this study, we analyzed the dynamic source process according to the source parameters, it can be confirmed that the radiated energy and the apparent stress of the New Zealand earthquake are small and minor. The results indicate a frictional overshoot behavior in the dynamic source process of the earthquake, which is actually with sufficient rupture and more abundant moderate aftershocks. Comparison with the next generation attenuation (NGA) relationship indicates that the observed horizontal peak ground acceleration (PGA) of the strong ground motion is generally small. The ground motion observations show that the recordings of New Zealand MS8.0 earthquake are less than the New Zealand MW6.1 earthquake in 2011 with nearly 200 deaths. In addition, we studied the characteristics of the observed PGAs at the six near-fault stations, which are located in the area less than 10 km to the main fault. The relatively high ground motion of the six stations may be produced by the higher slip around the asperity area rather than the initial rupture position on the main plane. In fact, the less damage level of New Zealand MS8.0 earthquake may probably result from the smaller strong ground motion and the rare population in the near fault area, with the most severe surface destruction.
The New Zealand earthquake of November 13, 2016, MS8.0 occurred near the Kaikoura area in the South Island, New Zealand, with focal depth of 11 km. The MS8.0 earthquake occurred on the transform boundary faults between the Pacific Plate and the Australian Plate, and the focal mechanism solution shows the earthquake is of thrust type event. Two people were killed, twenty or so people were injured and more than ten buildings were destroyed during this earthquake, so the damage level is not so severe in consideration about the huge magnitude. In this study, we analyzed the dynamic source process according to the source parameters, it can be confirmed that the radiated energy and the apparent stress of the New Zealand earthquake are small and minor. The results indicate a frictional overshoot behavior in the dynamic source process of the earthquake, which is actually with sufficient rupture and more abundant moderate aftershocks. Comparison with the next generation attenuation (NGA) relationship indicates that the observed horizontal peak ground acceleration (PGA) of the strong ground motion is generally small. The ground motion observations show that the recordings of New Zealand MS8.0 earthquake are less than the New Zealand MW6.1 earthquake in 2011 with nearly 200 deaths. In addition, we studied the characteristics of the observed PGAs at the six near-fault stations, which are located in the area less than 10 km to the main fault. The relatively high ground motion of the six stations may be produced by the higher slip around the asperity area rather than the initial rupture position on the main plane. In fact, the less damage level of New Zealand MS8.0 earthquake may probably result from the smaller strong ground motion and the rare population in the near fault area, with the most severe surface destruction.
2017, 39(1): 13-22.
DOI: 10.11939/jass.2017.01.002
Abstract：
In this paper，the focal depths of eleven events of the Shizuishan ML4.4 earthquake sequence were calculated by using the data of first arrival P phases. The results show that the earthquake sequence was composed of shallow earthquakes，which is one reason for the earthquakes felt strongly. Then the focal depth of the sequence was calculated based on double-layer and four-layer velocity models by the method of first arrival P phase. And the above results were compared with the double difference location. Firstly，the comparison of the focal depth obtained by the double difference location method with that by the first arrival P phase method show that the two results are consistent with each other on the whole，but the depth got by the latter method is rela-tively deep. Secondly，the results based on double-layer and four-layer crustal velocity models are in good agreement. The depth of the main shock is 7--8 km，and the depth of the largest aftershock is 6 km. According to the velocity imaging results of Yinchuan basin，it is deduced that the main shock and the largest aftershock occurred in the lower part of the Yinchuan basin basement. In addition，the other aftershocks are small with depth concentrating in 3--5 km，and they occurred mainly on the top of the basement of Yinchuan basin or within overburden layer.
In this paper，the focal depths of eleven events of the Shizuishan ML4.4 earthquake sequence were calculated by using the data of first arrival P phases. The results show that the earthquake sequence was composed of shallow earthquakes，which is one reason for the earthquakes felt strongly. Then the focal depth of the sequence was calculated based on double-layer and four-layer velocity models by the method of first arrival P phase. And the above results were compared with the double difference location. Firstly，the comparison of the focal depth obtained by the double difference location method with that by the first arrival P phase method show that the two results are consistent with each other on the whole，but the depth got by the latter method is rela-tively deep. Secondly，the results based on double-layer and four-layer crustal velocity models are in good agreement. The depth of the main shock is 7--8 km，and the depth of the largest aftershock is 6 km. According to the velocity imaging results of Yinchuan basin，it is deduced that the main shock and the largest aftershock occurred in the lower part of the Yinchuan basin basement. In addition，the other aftershocks are small with depth concentrating in 3--5 km，and they occurred mainly on the top of the basement of Yinchuan basin or within overburden layer.
2017, 39(1): 23-33.
DOI: 10.11939/jass.2017.01.003
Abstract：
Based on the ML≥1.0 earthquake catalogue of Xinfengjiang Reservoir area in Heyuan of Guangdong Province during the period from 2009 to 2015，this paper delineates three NW-trending small earthquake dense zones in dam-gorge region. According to the principle that the small earthquake clustering occurs in and around active fault plane，this paper calculated the fault plane parameters of the three dense zones including the strike，dip，dip angle，length，depth and geographic position by using both simulated annealing algorithm and Gauss-Newtonian nonlinear inversion algorithm，and finally got the geometric shape of the NW-trending faults. The results show that the three faults are NW--NNW trending in the depth range of 3--12 km，and are of left-lateral strike-slip with a little vertical slip component. Furthermore，the analyses of inversion results combined with previous data indicate that，the Baitian-Shuangtang fault，one of the three NW-trending faults，was proved to be the seismogenic fault of MS6.1 Xinfengjiang earthquake in 1962，and from Baitian to Shuangtang，the Heyuan fault is interrupted with gap of 5 km，and the gap is filled with part of the Baitian-Shuantang fault. The junction area of endpoints and tangent points of the three faults intersected near the reservoir dam，which leads to stress concentration more easily there，and becomes the most active seismic region in the reservoir.
Based on the ML≥1.0 earthquake catalogue of Xinfengjiang Reservoir area in Heyuan of Guangdong Province during the period from 2009 to 2015，this paper delineates three NW-trending small earthquake dense zones in dam-gorge region. According to the principle that the small earthquake clustering occurs in and around active fault plane，this paper calculated the fault plane parameters of the three dense zones including the strike，dip，dip angle，length，depth and geographic position by using both simulated annealing algorithm and Gauss-Newtonian nonlinear inversion algorithm，and finally got the geometric shape of the NW-trending faults. The results show that the three faults are NW--NNW trending in the depth range of 3--12 km，and are of left-lateral strike-slip with a little vertical slip component. Furthermore，the analyses of inversion results combined with previous data indicate that，the Baitian-Shuangtang fault，one of the three NW-trending faults，was proved to be the seismogenic fault of MS6.1 Xinfengjiang earthquake in 1962，and from Baitian to Shuangtang，the Heyuan fault is interrupted with gap of 5 km，and the gap is filled with part of the Baitian-Shuantang fault. The junction area of endpoints and tangent points of the three faults intersected near the reservoir dam，which leads to stress concentration more easily there，and becomes the most active seismic region in the reservoir.
2017, 39(1): 34-46.
DOI: 10.11939/jass.2017.01.004
Abstract：
SAM (systematic analysis method of shear-wave splitting) has been applied to numerous waveform data recorded by near-field mobile seismic stations of Yingjiang MS6.1 earthquake sequence occurred on May 30， 2014. The results showed that the polarization of fast shear-wave of the earthquake sequence was consistent with regional principal compressive stress of NS trending. The polarization of fast shear-wave has a counterclockwise deflection at the station KAC， and dispersion decrease at the station MNO due to the adjustment of stress state in seismic region after the main shock. Influenced by faults of the studied area， the polarization of fast shear-wave at the station MNO presents a more discrete state compared to that of KAC. The time-delays of slow shear-wave at the stations KAC and MNO both present the feature of sudden contraction before the main shock and increase after the event， which means release and enhancement of crustal stress before and after the earthquake， and also indicates constant occurrence of aftershocks. The oscillation of time-delay curves suggests that the occurrence of aftershocks is accompanied by continuous adjustment of crustal stress in seismic region.
SAM (systematic analysis method of shear-wave splitting) has been applied to numerous waveform data recorded by near-field mobile seismic stations of Yingjiang MS6.1 earthquake sequence occurred on May 30， 2014. The results showed that the polarization of fast shear-wave of the earthquake sequence was consistent with regional principal compressive stress of NS trending. The polarization of fast shear-wave has a counterclockwise deflection at the station KAC， and dispersion decrease at the station MNO due to the adjustment of stress state in seismic region after the main shock. Influenced by faults of the studied area， the polarization of fast shear-wave at the station MNO presents a more discrete state compared to that of KAC. The time-delays of slow shear-wave at the stations KAC and MNO both present the feature of sudden contraction before the main shock and increase after the event， which means release and enhancement of crustal stress before and after the earthquake， and also indicates constant occurrence of aftershocks. The oscillation of time-delay curves suggests that the occurrence of aftershocks is accompanied by continuous adjustment of crustal stress in seismic region.
2017, 39(1): 47-63.
DOI: 10.11939/jass.2017.01.005
Abstract：
In this paper， the geomagnetic preferred planes， Parkinson vectors and their errors at 36 geomagnetic stations of the Chinese mainland are calcu-lated with the methods of geomagnetic difference-vector and complex transfer function. The results show that for these observatories in the southern portion of North China， Central China and South China (containing Guiyang and Shao-yang) and the coastal observatories， the lengths of Parkinson vectors increase as the period decreases， which indicates the conductivity structure in shallow is more horizontally inhomogeneous. However， for the observatories of western China， such as Lhasa， Tonghai， Xichang， Chengdu， the lengths of Parkinson vectors increase as the period increases， which indicates in the deeper there are more clearly horizontal differences in conductivity. On the Chinese mainland， there are obviously some convergence and radiation regions of Parkinson vectors， among Parkinson vectors of the stations in Qinghai-Tibetan Plateau and around the Bohai Sea cohesive; however those in the Ordos block diffuse. For the coastal observatories exists a more clearly seacoast-effect. For the stable blocks， such as North China plain， the lengths of Parkinson vectors are shorter， suggesting that the conductivity structure of these blocks are close to layered levelly. In addition， the inclination and dip angle of the preferred plane inferred from difference-vector algorithm are almost consistent with those calculated from Parkinson vector formula， and agree well with those obtained from transfer function.
In this paper， the geomagnetic preferred planes， Parkinson vectors and their errors at 36 geomagnetic stations of the Chinese mainland are calcu-lated with the methods of geomagnetic difference-vector and complex transfer function. The results show that for these observatories in the southern portion of North China， Central China and South China (containing Guiyang and Shao-yang) and the coastal observatories， the lengths of Parkinson vectors increase as the period decreases， which indicates the conductivity structure in shallow is more horizontally inhomogeneous. However， for the observatories of western China， such as Lhasa， Tonghai， Xichang， Chengdu， the lengths of Parkinson vectors increase as the period increases， which indicates in the deeper there are more clearly horizontal differences in conductivity. On the Chinese mainland， there are obviously some convergence and radiation regions of Parkinson vectors， among Parkinson vectors of the stations in Qinghai-Tibetan Plateau and around the Bohai Sea cohesive; however those in the Ordos block diffuse. For the coastal observatories exists a more clearly seacoast-effect. For the stable blocks， such as North China plain， the lengths of Parkinson vectors are shorter， suggesting that the conductivity structure of these blocks are close to layered levelly. In addition， the inclination and dip angle of the preferred plane inferred from difference-vector algorithm are almost consistent with those calculated from Parkinson vector formula， and agree well with those obtained from transfer function.
Abstract：
The present paper analyzes the relationship between the apparent resistivity change and major aftershock activities based on magnetotelluric measurements data from May 3 to 24， 2013． A group of self-power and cross-power spectra are obtained with the robust method and coherence limit based on characteristics of magnetotelluric method. Then the spectra causing apparent resistivity and phase curve unsmooth are removed according to their shape， and the high-quality data are obtained after removing disturbed data． The results show that the apparent resistivity tended to increase gradually with maximum change by 27% during the measurement period but not in a monotonous manner． The yx polarized apparent resistivity ρayx reached its maximum after nearly every main aftershock cluster, but among each clusters the minimum resistivity appeared. Finally the analyses on earthquake generating mechanisms indicate that the earthquake resistivity effect is due to the change in pore fluid in micro fractures， therefore it is speculated that the increase trend of the resistivity during the period of Lushan aftershocks is caused by stress recovery and porosity recovery after the Lushan earthquake.
The present paper analyzes the relationship between the apparent resistivity change and major aftershock activities based on magnetotelluric measurements data from May 3 to 24， 2013． A group of self-power and cross-power spectra are obtained with the robust method and coherence limit based on characteristics of magnetotelluric method. Then the spectra causing apparent resistivity and phase curve unsmooth are removed according to their shape， and the high-quality data are obtained after removing disturbed data． The results show that the apparent resistivity tended to increase gradually with maximum change by 27% during the measurement period but not in a monotonous manner． The yx polarized apparent resistivity ρayx reached its maximum after nearly every main aftershock cluster, but among each clusters the minimum resistivity appeared. Finally the analyses on earthquake generating mechanisms indicate that the earthquake resistivity effect is due to the change in pore fluid in micro fractures， therefore it is speculated that the increase trend of the resistivity during the period of Lushan aftershocks is caused by stress recovery and porosity recovery after the Lushan earthquake.
2017, 39(1): 78-84.
DOI: 10.11939/jass.2017.01.007
Abstract：
In this study, we quantitatively analyzed and determined groundwater types of well-aquifer system for the wells Banqiao, Dahuichang, Huanghua, Dadianzi, Fengzhen and Sanhaodi by using water level, barometric pressure and theoretical earth tide. Furthermore, combining with step response function of water level to barometric pressure in convolutional regression, barometric coefficient and tidal factor of M2 wave are comparatively analyzed for each well in the studied period. The results show that: ① an obvious exponential relationship exists between lag time and step response function with “e” as the bottom, and the sign symbol of the coefficient before the base “e” could determine groundwater types of well-aquifer system; ② step response function is growing with lag time increase for artesian wells, and the larger the optimal step response function value is, the larger barometric coefficient and tidal factor of M2 wave are, and the reverse is also true; ③ step response function decreases with latency increase for phreatic and half artesian wells, and because of hydraulic characteristics of aquifer, borehole structures and frequency of solid tidal waves, the relationship between the optimal step response function and barometric coefficient, tidal factor of M2 wave is inconspicuous.
In this study, we quantitatively analyzed and determined groundwater types of well-aquifer system for the wells Banqiao, Dahuichang, Huanghua, Dadianzi, Fengzhen and Sanhaodi by using water level, barometric pressure and theoretical earth tide. Furthermore, combining with step response function of water level to barometric pressure in convolutional regression, barometric coefficient and tidal factor of M2 wave are comparatively analyzed for each well in the studied period. The results show that: ① an obvious exponential relationship exists between lag time and step response function with “e” as the bottom, and the sign symbol of the coefficient before the base “e” could determine groundwater types of well-aquifer system; ② step response function is growing with lag time increase for artesian wells, and the larger the optimal step response function value is, the larger barometric coefficient and tidal factor of M2 wave are, and the reverse is also true; ③ step response function decreases with latency increase for phreatic and half artesian wells, and because of hydraulic characteristics of aquifer, borehole structures and frequency of solid tidal waves, the relationship between the optimal step response function and barometric coefficient, tidal factor of M2 wave is inconspicuous.
2017, 39(1): 85-101.
DOI: 10.11939/jass.2017.01.008
Abstract：
The concentration and flux of soil gases were measured at 35 profiles across 18 faults in the capital area of China from June to July of 2015， and the geochemical characteristics and sources of soil gases Rn， Hg and CO2 in the area were also investigated. The results showed that the average concentrations of Rn， Hg and CO2 varied from 3.2 to 45.0 kBq/m3， 3.9 to 24.9 ng/m3 and 0.154% to 2.175%， respectively. The average flux values of Rn， Hg and CO2 ranged from 3.8 to 152.1 mBq/(m2·s)， 0.1 to 42.6 ng/(m2·h) and 8.5 to 89.4 g/(m2·d)， respectively. There is an obvious spatial distribution feature of soil gases that both the concentration and flux values in the eastern region were higher than those in the western region within the studied area， which could be attributed to the increased tectonic stress， the decreased crustal thickness， the increased thickness of sediments and earthquake activity from west to east. These spatial geochemical characteristics in the studied area might be mainly controlled by the upper crustal material structure， deep gas supply and seismic activity， and also additionally affected to some degree by the natural environment and soil types.
The concentration and flux of soil gases were measured at 35 profiles across 18 faults in the capital area of China from June to July of 2015， and the geochemical characteristics and sources of soil gases Rn， Hg and CO2 in the area were also investigated. The results showed that the average concentrations of Rn， Hg and CO2 varied from 3.2 to 45.0 kBq/m3， 3.9 to 24.9 ng/m3 and 0.154% to 2.175%， respectively. The average flux values of Rn， Hg and CO2 ranged from 3.8 to 152.1 mBq/(m2·s)， 0.1 to 42.6 ng/(m2·h) and 8.5 to 89.4 g/(m2·d)， respectively. There is an obvious spatial distribution feature of soil gases that both the concentration and flux values in the eastern region were higher than those in the western region within the studied area， which could be attributed to the increased tectonic stress， the decreased crustal thickness， the increased thickness of sediments and earthquake activity from west to east. These spatial geochemical characteristics in the studied area might be mainly controlled by the upper crustal material structure， deep gas supply and seismic activity， and also additionally affected to some degree by the natural environment and soil types.
2017, 39(1): 102-110.
DOI: 10.11939/jass.2017.01.009
Abstract：
Combining the operation status of the earthquake early warning (EEW) system in Fujian Province， this paper discusses the feasibility of the Pd-τc compatibility criterion in discrimination of triggered events， based on seismic records of KiK-net in Japan and seismic monitoring networks of Fujian Province， in which both spontaneous earthquakes and artificial explosion events are included. The results show that， for large local earthquakes and false triggering events， Pd-τc criterion is quite reliable with less error. Also， teleseismic earthquake events may be roughly judged by the criterion. But artificial explosions and/or small magnitude local earthquakes cannot be effectively distinguished only by this criterion. Furthermore， based on the Pd-τc compatibility test results， this paper sets an intensity test standard by the parameter Pd=10-3 cm， by which those destructive earthquakes can be identified more accurately. The present method will help to improve the reliability of triggered events discrimination， promote processing efficiency of the whole EEW system， eventually generate more accurate seismic alert message.
Combining the operation status of the earthquake early warning (EEW) system in Fujian Province， this paper discusses the feasibility of the Pd-τc compatibility criterion in discrimination of triggered events， based on seismic records of KiK-net in Japan and seismic monitoring networks of Fujian Province， in which both spontaneous earthquakes and artificial explosion events are included. The results show that， for large local earthquakes and false triggering events， Pd-τc criterion is quite reliable with less error. Also， teleseismic earthquake events may be roughly judged by the criterion. But artificial explosions and/or small magnitude local earthquakes cannot be effectively distinguished only by this criterion. Furthermore， based on the Pd-τc compatibility test results， this paper sets an intensity test standard by the parameter Pd=10-3 cm， by which those destructive earthquakes can be identified more accurately. The present method will help to improve the reliability of triggered events discrimination， promote processing efficiency of the whole EEW system， eventually generate more accurate seismic alert message.
Abstract：
Based on the indirect boundary element method (IBEM) with high precision, this paper solves the seismic response of a three-dimensional sedimentary basins both in the frequency domain and time domain. Taking the scattering of plane P and SV waves around an semi-ellipsoidal three-dimensional sedimentary basin as an example, the amplification effects of incident angle, wave type, incident frequency, length-width ratio and depth-width ratio of the basin on the ground motion are investigated in detail. The numerical results show that the basin shape has a significant impact on the amplification effect of seismic waves and the spatial distribution characteristics, and the detail effect also strongly depends on the frequency band of incident wave. In particular, as the basin depth increases, edge-generated surface waves become dominant, significant ground motion amplification effect can be observed for a wider band, and amplification area is mainly located in the middle of basin. The seismic wave focusing effect within the circular basin seems most significant, while that within long-narrow basin seems relatively weak, and multiple wave-focused areas appear within the basin for incident high-frequency waves. The amplification mechanism of basin effect on ground motion is different for different types of waves: for incident P waves, significant amplification of vertical displacement in the middle of basin can be mainly attributed to the focusing of surface waves generated from the basin edge; as for SV wave incidence, the surface wave focusing effect is relatively weak, but when the basin is deep, constructive interference of transmitted body waves and edge surface waves tend to result in a considerable amplification effect. For the wave-velocity ratio 1/2 between the alluvial basin and the bedrock, amplification factors of P and SV waves can reach up to 25, 15, respectively in frequency domain, and to 4.0, 3.7, respectively in time domain (Ricker waves). As for the low frequency waves, the displacement amplitude decreases from the basin center to basin edge, and the amplification is not obvious for the shallow basin. In addition, the angle of incidence also has significant impact on the amplitude and spatial distribution characteristics of ground motion.
Based on the indirect boundary element method (IBEM) with high precision, this paper solves the seismic response of a three-dimensional sedimentary basins both in the frequency domain and time domain. Taking the scattering of plane P and SV waves around an semi-ellipsoidal three-dimensional sedimentary basin as an example, the amplification effects of incident angle, wave type, incident frequency, length-width ratio and depth-width ratio of the basin on the ground motion are investigated in detail. The numerical results show that the basin shape has a significant impact on the amplification effect of seismic waves and the spatial distribution characteristics, and the detail effect also strongly depends on the frequency band of incident wave. In particular, as the basin depth increases, edge-generated surface waves become dominant, significant ground motion amplification effect can be observed for a wider band, and amplification area is mainly located in the middle of basin. The seismic wave focusing effect within the circular basin seems most significant, while that within long-narrow basin seems relatively weak, and multiple wave-focused areas appear within the basin for incident high-frequency waves. The amplification mechanism of basin effect on ground motion is different for different types of waves: for incident P waves, significant amplification of vertical displacement in the middle of basin can be mainly attributed to the focusing of surface waves generated from the basin edge; as for SV wave incidence, the surface wave focusing effect is relatively weak, but when the basin is deep, constructive interference of transmitted body waves and edge surface waves tend to result in a considerable amplification effect. For the wave-velocity ratio 1/2 between the alluvial basin and the bedrock, amplification factors of P and SV waves can reach up to 25, 15, respectively in frequency domain, and to 4.0, 3.7, respectively in time domain (Ricker waves). As for the low frequency waves, the displacement amplitude decreases from the basin center to basin edge, and the amplification is not obvious for the shallow basin. In addition, the angle of incidence also has significant impact on the amplitude and spatial distribution characteristics of ground motion.
Abstract：
For investigating the rupture directivity effect of the central Italy MW6.2 earthquake on August 24， 2016， more than 150 strong motion stations are separated into two groups， which are SE and NW， according to the fault strike. Comparing the PGA， PGV， pseudo-acceleration response spectrum (PSA) and significant duration DSR of two groups， the results show that: the observed PGAs, PGVs and PSAs of NW group are larger than those of SE group; the residuals between the observed and predicted PGAs and PGVs are significantly correlated with the azimuth; the observed DSR of NW group is smaller than that of SE group. From these observations we deduce that the rupture directivity effect exists in this earthquake. Furthermore， the inversion for source rupture parameters using PGAs and PGVs, respectively， shows that the rupture is bilateral， and the MW6.2 earthquake predominantly ruptured in the direction 345°--360°， accounting for 70%--80% of the total rupture， and the rupture velocity is 2.2--2.5 km/s. These results validate the conclusion that the differences of ground motion parameters between two groups of stations might be caused by the rupture directivity effect.
For investigating the rupture directivity effect of the central Italy MW6.2 earthquake on August 24， 2016， more than 150 strong motion stations are separated into two groups， which are SE and NW， according to the fault strike. Comparing the PGA， PGV， pseudo-acceleration response spectrum (PSA) and significant duration DSR of two groups， the results show that: the observed PGAs, PGVs and PSAs of NW group are larger than those of SE group; the residuals between the observed and predicted PGAs and PGVs are significantly correlated with the azimuth; the observed DSR of NW group is smaller than that of SE group. From these observations we deduce that the rupture directivity effect exists in this earthquake. Furthermore， the inversion for source rupture parameters using PGAs and PGVs, respectively， shows that the rupture is bilateral， and the MW6.2 earthquake predominantly ruptured in the direction 345°--360°， accounting for 70%--80% of the total rupture， and the rupture velocity is 2.2--2.5 km/s. These results validate the conclusion that the differences of ground motion parameters between two groups of stations might be caused by the rupture directivity effect.
2017, 39(1): 143-154.
DOI: 10.11939/jass.2017.01.012
Abstract：
With strong earthquake observation data improved greatly in quantity and quality in China, strong ground motion records after the destructive earthquake have been converted tentatively into the instrumental intensity. With the help of strong ground motion records and the expression method of rapid evaluation model for earthquake damage and losses， this paper proposed a rapid evaluation method of earthquake casualty， which combines the probability density ofinstrumental intensity with the life loss function. By the probability density of the instrumental intensity， combined with the research results of the building vulnerability in Sichuan region， a rapid evaluation function of seismic life loss and seismic damage related to the earthquake intensity is established. Finally， the Wenchuan earthquake strong ground motion records have been evaluated， and the results by the rapid assessment method in this paper were consistent with the actual seismic damages， which proves the feasibility of the method. Therefore the rapid assessment method can provide reliable information quickly for earthquake emergency rescue.
With strong earthquake observation data improved greatly in quantity and quality in China, strong ground motion records after the destructive earthquake have been converted tentatively into the instrumental intensity. With the help of strong ground motion records and the expression method of rapid evaluation model for earthquake damage and losses， this paper proposed a rapid evaluation method of earthquake casualty， which combines the probability density ofinstrumental intensity with the life loss function. By the probability density of the instrumental intensity， combined with the research results of the building vulnerability in Sichuan region， a rapid evaluation function of seismic life loss and seismic damage related to the earthquake intensity is established. Finally， the Wenchuan earthquake strong ground motion records have been evaluated， and the results by the rapid assessment method in this paper were consistent with the actual seismic damages， which proves the feasibility of the method. Therefore the rapid assessment method can provide reliable information quickly for earthquake emergency rescue.
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