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1.
Large earthquakes are often made up of several subevents. Thus the cumulative damage is higher than for single event earthquakes. Many procedures have been developed to simulate earthquake ground motion occurring from a single energy release; however, procedures to model accelerograms with several periods of strong shaking and to relate the modelling parameters to physical variables have not been developed.In this research, a database of strong motion accelerograms from multiple event earthquakes (including the 1978 Miyagiken-Oki earthquake) the 1968 Tokachi-Oki earthquake, the 1983 Nihonkai-Chubu earthquake, and the 1985 Michoacan earthquake) was modelled by an ARMA process, after first processing the records with multivariate variance and frequency stabilizing transformations. The modelling parameters were related to the time, magnitude and location of each subevent and to the site conditions using a regression analysis. 相似文献
2.
K. AfifChaouch B. Tiliouine M. Hammoutene R. Sigbjörnsson R. Rupakhety 《Bulletin of Earthquake Engineering》2016,14(4):1195-1217
Spatial variability of ground motions has significant influence on dynamic response of extended structures such as bridges and tunnels. In this study, the widely used finite-source ground motion simulation approach, the so-called Empirical Green’s Function (EGF) method, is extended to synthesize seismic motions across an array of stations located at bedrock in the epicentral region of the 1980 El-Asnam region (North-West Algeria). The target event being simulated is the October 10 1980 \( M_{s} = 7.2 \) Earthquake, and the EGF is obtained from the ground motion recorded at Sogedia Factory station during the 8 November 1980 \( M_{L} = 5.6 \) aftershock. Coherency functions are then estimated from the simulated ground accelerations. A parametric study investigating the influence of shear wave velocity, earthquake magnitude, and epicentral distance is conducted by simulating ground acceleration for different scenarios using the Hybrid Green’s Function method. The main finding of the study is that finite source effects can cause significant loss in coherency at bedrock in the near-field. In the far-field, the source effect alone does not seem to produce incoherent motion, which implies that scattering and local site effects could be dominating there. Furthermore, coherency functions are found to be more sensitive to inter-station separation in the near-field than in the far-field. Increasing shear wave velocity seems to increase coherency functions, and larger earthquakes seem to produce more incoherent motion than smaller ones. The simulation method presented here produces incoherent motion mainly due to the finite source effect, while path effects are partially accounted for through the EGF, and local site effects are not considered. In this sense, the estimated coherency functions represent that of plane waves. A parametric model of plane wave coherency is calibrated and presented based on the simulation results. The results indicate that the parametric model can be used as a first approximation, and at least an upper bound of lagged coherency in the near-field region of the El-Asnam Earthquake scenario. This model could be useful in random vibration analysis or generation of spatially variable ground motion for time history analysis of lifeline structures in the study area. 相似文献
3.
Jérome Salichon Carine Kohrs-Sansorny Etienne Bertrand Françoise Courboulex 《Journal of Seismology》2010,14(3):523-541
The southern Alps–Ligurian basin junction is one of the most seismically active zone of the western Europe. A constant microseismicity
and moderate size events (3.5 < M < 5) are regularly recorded. The last reported historical event took place in February 1887
and reached an estimated magnitude between 6 and 6.5, causing human losses and extensive damages (intensity X, Medvedev–Sponheuer–Karnik).
Such an event, occurring nowadays, could have critical consequences given the high density of population living on the French
and Italian Riviera. We study the case of an offshore Mw 6.3 earthquake located at the place where two moderate size events
(Mw 4.5) occurred recently and where a morphotectonic feature has been detected by a bathymetric survey. We used a stochastic
empirical Green’s functions (EGFs) summation method to produce a population of realistic accelerograms on rock and soil sites
in the city of Nice. The ground motion simulations are calibrated on a rock site with a set of ground motion prediction equations
(GMPEs) in order to estimate a reasonable stress-drop ratio between the February 25th, 2001, Mw 4.5, event taken as an EGF
and the target earthquake. Our results show that the combination of the GMPEs and EGF techniques is an interesting tool for
site-specific strong ground motion estimation. 相似文献
4.
运用经验格林函数法模拟了2008年5月12日汶川8.0级大地震的近场强地面运动.拟合过程中,首先参考其他学者反演结果给出的滑动量分布的特征,确定强震动生成区的大致范围;然后利用Somerville等(1999)提出的地震矩与凹凸体面积间的经验关系式确定强震动生成区(SMGA)细小划分的初值,继而利用遗传优化算法确定以上两者的最优值及其他震源参数.数值模拟波形同实际地震观测记录在时间域和频率域分别进行了比较,结果显示,在所选取的18个观测台中,多数台站的数值模拟结果同实际观测结果符合得很好,特别是大于1 Hz的高频部分.我们发现断层面上有5个强震动生成区,其中两个的位置与其他学者反演的滑动量集中分布区相一致,但强震动生成区规模和上升时间比Somerville等(1999)获得的定标率外延的估计值要小. 相似文献
5.
Marleine Brax Mathieu Causse Pierre-Yves Bard 《Bulletin of Earthquake Engineering》2016,14(12):3317-3341
The strike slip Yammouneh fault is the longest fault in Lebanon, crossing the territory from South to North. It was responsible for major historical earthquakes like the 1202 A.D. earthquake, estimated to Ms7.6. This paper presents a site-specific estimation of the ground motion caused by a potential Mw7.5 earthquake on the Yammouneh fault, similar to the 1202 event, for various sites within the Beirut area. The empirical Green’s function technique EGF is used to estimate the median and the standard deviations of the seismic ground motion at the reference station BHL, taking into account epistemic and aleatory uncertainties related to source parameters. These uncertainties were quantified through a sensitivity analysis of the position of the rupture nucleation Xnuc, the slip roughness parameter K, the corner frequency fc and the magnitude Mc of the EGF. The rock ground motion is then transferred to various other sites within the Beirut area, using instrumental Fourier transfer functions. Site amplification factors are next deduced by computing the ratio between response spectra at sediment sites and at a reference rock station. Considering the limits of the EGF method in the near field of extended sources, the EGF approach is considered only up to a magnitude Mw of 6.5. Selected Ground Motion Predictive Equations are then used to simulate a Mw7.5 event at a reference station. By applying the amplification factors, the response spectra at the different sites of Beirut are also calculated and compared with the actual response spectra used in the Lebanese regulations. 相似文献
6.
7.
An earthquake ofM
S=6.9 occurred at the Gonghe, Qinghai Province, China on April 26, 1990. Three larger aftershocks took place at the same region,M
S=5.5 on May 7, 1990,M
S=6.0 on Jan. 3, 1994 andM
S=5.7 on Feb. 16, 1994. The long-period recordings of the main shock from China Digital Seismograph Network (CD-SN) are deconvolved
for the source time functions by the correspondent recordings of the three aftershocks as empirical Green’s functions (EGFs).
No matter which aftershock is taken as EGF, the relative source time functions (RSTFs) obtained are nearly identical. The
RSTFs suggest theM
S=6.9 event consists of at least two subevents with approximately equal size whose occurrence times are about 30 s apart, the
first one has a duration of 12 s and a rise time of about 5 s, and the second one has a duration of 17 s and a rise time of
about 8 s. Comparing the RSTFs obtained from P- and SH-phases respectively, we notice that those from SH-phases are a slightly
more complex than those from P-phases, implying other finer subevents exist during the process of the main shock. It is interesting
that the results from the EGF deconvolution of long-period wavform data are in good agreement with the results from the moment
tensor inversion and from the EGF deconvolution of broadband waveform data. Additionally, the two larger aftershocks are deconvolved
for their RSTFs. The deconvolution results show that the processes of theM
S=6.0 event on Jan. 3, 1994 and theM
S=5.7 event on Feb. 16, 1994 are quite simple, both RSTFs are single impulses.
The RSTFs of theM
S=6.9 main shock obtained from different stations are noticed to be azimuthally dependent, whose shapes are a slightly different
with different stations. However, the RSTFs of the two smaller aftershocks are not azimuthally dependent. The integrations
of RSTFs over the processes are quite close to each other, i. e., the scalar seismic moments estimated from different stations
are in good agreement.
Finally the scalar seismic moments of the three aftershocks are compared. The relative scalar seismic moment of the three
aftershocks deduced from the relative scalar seismic moments of theM
S=6.9 main shock are very close to those inverted directly from the EGF deconvolution. The relative scalar seismic moment of
theM
S=6.9 main shock calculated using the three aftershocks as EGF are 22 (theM
S=6.0 aftershock being EGF), 26 (theM
S=5.7 aftershock being EGF) and 66 (theM
S=5.5 aftershock being EGF), respectively. Deducing from those results, the relative scalar sesimic moments of theM
S=6.0 to theM
S=5.7 events, theM
S=6.0 to theM
S=5.5 events and theM
S=5.7 to theM
S=5.5 events are 1.18, 3.00 and 2.54, respectively. The correspondent relative scalar seismic moments calculated directly from
the waveform recordings are 1.15, 3.43, and 3.05.
Contribution No. 96B0007, Institute of Geophysics, SSB, China. 相似文献
8.
An earthquake ofM S=6.9 occurred at the Gonghe, Qinghai Province, China on April 26, 1990. Three larger aftershocks took place at the same region,M S=5.5 on May 7, 1990,M S=6.0 on Jan. 3, 1994 andM S=5.7 on Feb. 16, 1994. The long-period recordings of the main shock from China Digital Seismograph Network (CD-SN) are deconvolved for the source time functions by the correspondent recordings of the three aftershocks as empirical Green’s functions (EGFs). No matter which aftershock is taken as EGF, the relative source time functions (RSTFs) obtained are nearly identical. The RSTFs suggest theM S=6.9 event consists of at least two subevents with approximately equal size whose occurrence times are about 30 s apart, the first one has a duration of 12 s and a rise time of about 5 s, and the second one has a duration of 17 s and a rise time of about 8 s. Comparing the RSTFs obtained from P- and SH-phases respectively, we notice that those from SH-phases are a slightly more complex than those from P-phases, implying other finer subevents exist during the process of the main shock. It is interesting that the results from the EGF deconvolution of long-period wavform data are in good agreement with the results from the moment tensor inversion and from the EGF deconvolution of broadband waveform data. Additionally, the two larger aftershocks are deconvolved for their RSTFs. The deconvolution results show that the processes of theM S=6.0 event on Jan. 3, 1994 and theM S=5.7 event on Feb. 16, 1994 are quite simple, both RSTFs are single impulses. The RSTFs of theM S=6.9 main shock obtained from different stations are noticed to be azimuthally dependent, whose shapes are a slightly different with different stations. However, the RSTFs of the two smaller aftershocks are not azimuthally dependent. The integrations of RSTFs over the processes are quite close to each other, i. e., the scalar seismic moments estimated from different stations are in good agreement. Finally the scalar seismic moments of the three aftershocks are compared. The relative scalar seismic moment of the three aftershocks deduced from the relative scalar seismic moments of theM S=6.9 main shock are very close to those inverted directly from the EGF deconvolution. The relative scalar seismic moment of theM S=6.9 main shock calculated using the three aftershocks as EGF are 22 (theM S=6.0 aftershock being EGF), 26 (theM S=5.7 aftershock being EGF) and 66 (theM S=5.5 aftershock being EGF), respectively. Deducing from those results, the relative scalar sesimic moments of theM S=6.0 to theM S=5.7 events, theM S=6.0 to theM S=5.5 events and theM S=5.7 to theM S=5.5 events are 1.18, 3.00 and 2.54, respectively. The correspondent relative scalar seismic moments calculated directly from the waveform recordings are 1.15, 3.43, and 3.05. 相似文献
9.
M. Cocco C. Chiarabba M. Di Bona G. Selvaggi L. Margheriti A. Frepoli F. P. Lucente A. Basili D. Jongmans M. Campillo 《Journal of Seismology》1999,3(1):105-117
The analysis of the Irpinia earthquake of 3 April 1996 (ML = 4.9), based on strong motion and short period local data, shows that it was a normal faulting event located within the epicentral area of the MS 6.9, 1980, earthquake. It was located at 40.67° N and 15.42° E at a depth of 8 km. The local magnitude (4.9) has been computed from the VBB stations of the MedNet network. The moment magnitude is Mw = 5.1 and the seismic moment estimated from the ground acceleration spectra is 5.0 1023 dyne cm. Spectral analysis of the strong motion recordings yields a Brune stress drop of 111 bars and a corner frequency of 1 Hz. The source radius associated to these values of seismic moment and stress drop is 1.3 km. The focal mechanism has two nodal planes having strike 297°, dip 74°, rake 290° and strike 64°, dip 25° and rake 220°, respectively. A fault plane solution with strike 295° ± 5°, dip 70° ± 5°, and rake 280° ± 10° is consistent with the S-wave polarization computed from the strong motion data recorded at Rionero in Vulture. We discuss the geometry and the dimensions of the fault which ruptured during the 1996 mainshock, its location and the aftershock distribution with respect to the rupture history of the 1980 Irpinia earthquake. The distribution of seismicity and the fault geometry of the 1996 earthquake suggest that the region between the two faults that ruptured during the first subevents of the 1980 event cannot be considered as a strong barrier (high strength zone), as it might be thought looking at the source model and at the sequence of historical earthquakes revealed by paleoseismological investigations. 相似文献
10.
11.
文中通过收集整理三河-平谷8级地震的历史记录、野外地质调查和区域地震等资料,建立了该地震的震源模型;以穿过研究区的12条测线和区域第四纪、新近纪、古近纪沉积等厚度图等资料为基础,建立了北京地区的传播介质模型;利用哈尔滨工程力学研究所的近断层强地震动有限元程序和40节点的高性能并行计算机计算了北京地区震后60s内地表各点的地震动速度时程和峰值速度。为检验模拟结果的质量,我们取2排测点的速度时程和水平向峰值速度等值线图进行了分析,发现计算结果与历史地震记录及实际地震观测资料吻合良好,说明了我们的模拟结果的可信性和模拟方法的客观性 相似文献
12.
Another look at the 1993 and 1995 Gulf of Aqaba earthquakes from the analysis of teleseismic waveforms 总被引：3，自引：0，他引：3
In this work we estimated the source process and the source parameters of the 1993 and 1995 Gulf of Aqaba earthquakes. To
investigate the source process of both events, we inverted the teleseismic P- and SH-waveform data using an iterative technique in which the rupture is modeled as a series of point source subevents with varying
mechanisms. The main source process of the 1993 event can be explained by two subevents with essentially the same mechanism.
These two subevents had different focal depths. The second subevent was about 5 s later than the first one and about 70% of
the moment rate released with the second one. The total rupture duration time was about 12 s. Our solution for the 1995 Gulf
of Aqaba earthquake indicated that the event consists of three subevents with various fault geometries and about 60% of the
moment released by the second subevent. The first subevent occurred at a depth of 13 km, and was followed after 9 s by the
second one at a depth of 11 km; the third subevent, at a depth of 9 km occurred 19 s after the second one. The total duration
of the earthquake rupture process was about 18.7 s. The obtained mechanisms for the 1993 and 1995 Gulf of Aqaba earthquakes
are well correlated with the structural setting of the Gulf of Aqaba. 相似文献
13.
Ronan Pavic Martin G. Koller Pierre-Yves Bard Corinne Lacave-Lachet 《Journal of Seismology》2000,4(1):59-77
An assessment of uncertainties for ground motion predictions with the aid of the empirical Green's function (EGF) technique is presented. The main input parameters were identified, and their respective uncertainties were assessed by means of an international expert inquiry. The repercussion of these input uncertainties on the final ground motion estimates were investigated by means of the Latin Hypercube Sampling technique. The mean ground motion estimates (response spectra) and their standard deviations were compared with results obtained from empirical attenuation laws. The most sensitive input parameter turned out to be the seismic moment corresponding to the EGF. In general, if the source parameters are well determined, equivalent uncertainties, statistically speaking, can be expected from the EGF technique and from the application of attenuation laws. Therefore, if EGFs with well known source parameters are available, the EGF technique seems to be preferable: site effects are automatically taken into account, and physically realistic acceleration time histories can be obtained. However, further investigations on the reliability of the EGF technique should be performed, and finally, it is recalled that the EGF technique is based on the assumption of linearity. If conditions are such that this assumption cannot be maintained, the EGF technique should be combined with non-linear geotechnical methods. 相似文献
14.
2021年2月13日,日本福岛近海发生MS7.1地震,震中距海岸线约70 km,震源深度接近60 km,造成了较大范围的震害影响。考虑地震应急及地震动强度特征预测的应用前景等,利用经验格林函数法快速估计了本次地震的高频地震动（1.0～20.0 Hz）空间分布特征及加速度时程,并结合实际地形、场地覆盖层等信息对部分台站地震动模拟结果进行修正,最终获得较可靠的地震动预测结果。研究结果表明,在具备合适小震记录时（余震及前震）,可较准确地再现大震的高频地震动主要特征,模拟结果与真实记录拟合较好;地震动模拟过程中需考虑盆地等特殊地形及覆盖土层对地震动的放大作用影响,这也是未来利用经验格林函数法合成大震时需重点考虑的因素。 相似文献
15.
A method of body-wave inversion is developed in an attempt to extract the information about asperities or barriers in a fault zone. A sequence of point sources, each being characterized with the seismic moment, the onset time and the location, are iteratively derived from observed records at multi-stations, where the two-dimensional extent of the source location is taken into account. A modification is made of the iterative method of Kikuchi and Kanamori on the formulation of inversion procedure to facilitate the computation.Using this method, we analyse long period P waves of the Tokachi-Oki earthquake of 1968 (Mw = 8.2) and obtain several significant subevents with time durations of ～ 10 s. Their spatio-temporal distribution shows that the rupture process consists of three characteristic stages: (A) a stage of introductory rupture, (B) a stage of main rupture and (C) a stage of aftershocks. The main rupture takes place in the form of clustering around a few sites of the fault plane. The largest subevent occurs in the northwestern corner. The stress drop associated with this event is estimated to be ～ 200 bars, one order of magnitude higher than the stress drop averaged over the entire fault plane. The sum of the seismic moments of the individual subevents amounts to 2.3 × 1028 dyn. cm which approximately coincides with the one estimated from the analysis of long-period surface waves. This implies that the source of the Tokachi-Oki earthquake consists of several major subevents with time durations of ～ 10 s in addition to other minor subevents. 相似文献
16.
Characteristics of amplitude and duration for near fault strong ground motion from the 1999 Chi-Chi, Taiwan Earthquake 总被引：2，自引：0，他引：2
A great number of free-field ground motion records are obtained during the 1999 Chi-Chi, Taiwan, earthquake. Records from 130 near fault free-field stations within 55 km to the causative fault surface are used as database, and characteristics of earthquake peak ground acceleration, velocity, displacement and duration are analyzed. According to this study, near fault ground motions are strongly affected by distance to fault, fault rupture directivity, site condition, as well as thrust of hanging wall. Compared with empirical strong ground motion attenuation relations used in China, US and Japan, the PGAs and PGVs recorded in this earthquake are not as large as what we have expected for a large earthquake as magnitude 7.6. However, the largest PGV and PGD worldwide were recorded in this event, which are 292 cm/s and 867 cm, respectively. Caused by nonlinear site effects of soil, peaks and corresponding ratios on E-class site were markedly different from those on other sites. Just as observed in historic earthquakes, fault rupture directivity effects caused significant differences between peaks of ground motion of two horizontal components, but took very slight effects on the duration of ground motion. The significant velocity pulses associated with large PGVs and PGDs, as well as large permanent displacements, which may result from the large thrust of the hanging wall, became the outstanding character of this event. Based on this study, we point out that 3D waveform modeling is needed to understand and predict near fault ground motion of large earthquakes. 相似文献
17.
Complexity of rupture propagation has an important bearing on the state of stress along the earthquake fault plane and on the prediction of strong ground motion in the near-field. By studying far-field body waveforms recorded by WWSSN long-period seismograms it has been possible to investigate the degree of complexity of several Turkish earthquakes. The results, which are obtained by matching synthetic P waveforms to observed data indicate that the July 22, 1967 Mudurnu Valley earthquake (Ms = 7.1) is a complex event which can be explained by the superposition of elementary sources with variable amplitudes and source time sequence history. In this regard, it is very similar to the February 4, 1976 Guatemala earthquake (Ms = 7.5). A comparison of these two events indicates that their source-time series ranges from 5 to ca. 20 s and, regardless of the total moment of the earthquake, the moment of the individual events is bounded at around 5 × 1026 dyn cm. The November 24, 1976 E. Turkey earthquake (Ms = 7.3), on the other hand, has a complexity which cannot be explained by such a simple model; in this respect, it may be more similar to the Tangshan, China, earthquake and as such, may involve significant thrust, normal or other complications to its faulting mechanism than the strike-slip mechanism of the P-wave first-motion data. The source time history for the 1967 Mudurnu Valley event is used to illustrate its significance in modeling strong ground motion in the near field. The complex source-time series of the 1967 event predicts greater amplitudes (2.5 larger) in strong ground motion than a uniform model scaled to the same size for a station 20 km from the fault. Such complexity is clearly important in understanding what strong ground motion to expect in the near-field of these and other continental strike-slip faults such as the San Andreas. 相似文献
18.
IntroductionMoreandmoreobservationssuggestthatmostintermediateandstrongearthquakeshavecomplexsourceprocesses.MostintermediateandstrongearthquakesoccurredincontinentalregionofChinaincludetwoormoreruptureevents.Thesubeventshavetimeintervalfromseveralseconds(suchasthe1990Gonghe,Qinghaiearthquakeandthe1996Lijiang,Yunnanearthquake),severalminutes(suchasthe1976Tangshanearthquake)toseveraldays(suchasthe1966Xingtaiearthquake).Tostudytherelationshipbetweendifferentruptureeventsoccurredsubsequentlyis… 相似文献
19.
Inversion for the seismic fault rupture history is an important way to study the nature of the earthquake source. In this paper, we have selected two Taiwan earthquakes that occurred closely in time and located in the same region, inversed the distribution of the slip amplitudes, rakes, risetimes and the rupture times on the fault planes by using GDSN broad-band and long-period records and the adaptive hybrid global search algorithm, and compared the two events. The slip rate of every subfault calculated provides information about the distribution of tectonic stress and fault strength. To the former event (MS=6.0), the maximum slip amplitude 2.4 m and the minimum risetime 1.2 s are both located at the hypocentre. The latter earthquake (MS=6.6) consisted of two subevents and the second source has 4 s delay. The maximum slip amplitude 0.9 m located near hypocentre is corresponding to the minimum risetime 1.4 s, and the corresponding maximum slip rate 0.7 m.s-1 is similar to the peak value of other large slip rate areas. We consider that the latter event has more complicated temporal-spatial distribution than the former. 相似文献
20.
Geological, geophysical and seismological criteria for local response evaluation in Bucharest urban area 总被引：4，自引：0，他引：4
N. Mndrescu M. Radulian Gh. M&#x;rmureanu 《Soil Dynamics and Earthquake Engineering》2007,27(4):367-393
Vrancea major intermediate-depth earthquakes produced extreme damage in Bucharest city, located at about 165 km epicenter distance. Our purpose is to investigate the influence of local geological conditions upon the seismic motion in Bucharest in case of large (M>7) Vrancea earthquakes. Two input data sets are used: (a) geological, geotechnical and geophysical information, including in situ measurements, and (b) acceleration recordings of Vrancea earthquakes. Local response evaluation based on first dataset is confirmed by the spectral analysis of the earthquake records. Two main features are outlined: non-stationarity of ground motion dynamic amplification from one event to other and inadequacy of limiting the investigation depth to uppermost 30 m to evaluate ground dynamic characteristics. Consequently (1) we cannot extrapolate the ground motion response determined for moderate and small earthquakes to anticipate the effects of the large Vrancea shocks and (2) the local response is controlled by the entire package of Quaternary deposits which are significantly deeper than 30 m depth beneath Bucharest Area. 相似文献