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1.
This paper introduces relative and absolute gravity change observations in the eastern portion of the Tibetan Plateau. We analyze and discuss a change that occurred in 2010 in the gravity along the eastern margin of the plateau and the relationship between this change and the 2013 Lushan M S7.0 earthquake. Our results show that: (1) before the Lushan M S7.0 earthquake, gravity anomalies along the eastern margin of the Tibetan Plateau changed drastically. The Lushan earthquake occurred at the bend of the high gradient zone of gravity variation along the southern edge of the Longmenshan fault zone. (2) The 2013 Lushan earthquake occurred less than 100 km away from the epicenter of the 2008 Wenchuan earthquake. Lushan and Wenchuan are located at the center of a four-quadrant section with different gravity anomalies, which may suggest that restoration after the Wenchuan earthquake may have played a role in causing the Lushan earthquake. (3) A medium-term prediction based on changes in gravity anomalies was made before the Lushan M S7.0 earthquake, in particular, a prediction of epicenter location.  相似文献   

2.
利用2008年汶川M8.0地震获得的强震动记录数据,根据《仪器地震烈度计算暂行规程》计算得到各台站处的仪器地震烈度值,分析仪器地震烈度与宏观地震烈度的对应关系,研究该仪器烈度计算方法的适用性。结果表明,利用该算法所得的仪器烈度值与宏观烈度完全吻合的比率为47.5%,偏差±1度以内的比率为89.1%,说明二者对应情况较为理想,仪器烈度可在一定程度上客观反映实际的震害情况;在各宏观烈度区内仪器烈度值虽然具有一定的离散性,但其均值与宏观烈度区值的偏差相对较小,均控制在±0.3度以内。另外,文中还绘制了汶川地震仪器烈度分布图,虽然与宏观烈度在整体分布上具有一定的对应关系,但受多种因素的影响,仪器烈度分布与宏观烈度分布不可能完全一致。仪器烈度与宏观烈度的概念和属性有所差异,发挥的作用也不尽相同,不应混淆和相互替代。  相似文献   

3.
On October 27, 2004, a moderate size earthquake occurred in the Vrancea seismogenic region (Romania). The Vrancea seismic zone is an area of concentrated seismicity at intermediate depths beneath the bending area of the southeastern Carpathians. The 2004 M w?=?6 Vrancea subcrustal earthquake is the largest seismic event recorded in Romania since the 1990 earthquakes. With a maximum macroseismic intensity of VII Medvedev–Sponheuer–Kárník (MSK-64) scale, the seismic event was felt to a distance of 600 km from the epicentre. This earthquake caused no serious damage and human injuries. The main purpose of this paper is to present the macroseismic map of the earthquake based on the MSK-64 intensity scale. After the evaluation of the macroseismic effects of this earthquake, an intensity dataset has been obtained for 475 sites in the Romanian territory. Also, the maximum horizontal accelerations recorded in the area by the K2 network are compared to the intensity values.  相似文献   

4.
Comparison between accelerometric and macroseismic observations is made for three M w?=?4.5 earthquakes, which occurred in north-eastern France and south-western Germany in 2003 and 2004. Scalar and spectral instrumental parameters are processed from the accelerometric data recorded by nine accelerometric stations located between 29 and 180 km from the epicentres. Macroseismic data are based on French Internet reports. In addition to the single questionnaire intensity, analysis of the internal correlation between the encoded answers highlights four predominant fields of questions bearing different physical meanings: (1) “vibratory motions of small objects”, (2) “displacement and fall of objects”, (3) “acoustic noise” and (4) “personal feelings”. Best correlations between macroseismic and instrumental observations are obtained when the macroseismic parameters are averaged over 10-km-radius circles around each station. Macroseismic intensities predicted by published peak ground velocity (PGV)–intensity relationships agree with our observed intensities, contrary to those based on peak ground acceleration (PGA). Correlation between the macroseismic and instrumental data for intensities between II and V (EMS-98) is better for PGV than for PGA. Correlation with the response spectra exhibits clear frequency dependence for all macroseismic parameters. Horizontal and vertical components are significantly correlated with the macroseismic parameters between 1 and 10 Hz, a range corresponding to both natural frequencies of most buildings and high energy content in the seismic ground motion. Between 10 and 25 Hz, a clear lack of correlation between macroseismic and instrumental observations exists. It could be due to a combination of the decrease in the energy signal above 10 Hz, a high level of anthropogenic noise and an increase in variability in soil conditions. Above 25 Hz, the correlation coefficients between the acceleration response spectra and the macroseismic parameters are close to the PGA correlation level.  相似文献   

5.
The eastern margin of Tibetan Plateau is one of the most active zones of tectonic deformation and seismicity in China. To monitor strain buildup and benefit seismic risk assessment, we constructed 14 survey-mode global position system(GPS) stations throughout the northwest of Longmenshan fault. A new GPS field over 1999–2011 is derived from measurements of the newly built and pre-existing stations in this region. Sequentially,two strain rate fields, one preceding and the other following the 2008 MW7.9 Wenchuan earthquake, are obtained using the Gausian weighting approach. Strain field over1999–2007 shows distinct strain partitioning prior to the2008 MW7.9 Wenchuan earthquake, with compression spreading over around Longmenshan area. Strain field derived from the two measurements in 2009 and 2011 shows that the area around Longmenshan continues to be under striking compression, as the pattern preceding the Wenchuan earthquake, implying a causative factor of the sequent of 2013 MW6.7 Lushan earthquake. Our GPSderived dilatation shows that both the Wenchuan and Lushan earthquakes occurred within the domain of pronounced contraction. The GPS velocities demonstrate that the Longriba fault underwent slight motion with the faultnormal and-parallel rates at 1.0 ± 2.5 mm and 0.3 ± 2.2 mm/a; the Longmenshan fault displayed slow activity, with a fault-normal rate at 0.8 ± 2.5 mm/a, and a fault-parallel rate at 1.8 ± 1.7 mm/a. Longriba fault is on a par with Longmenshan fault in strain partitioning to accommodate the southeastward motion of eastern margin of the Tibetan Plateau. Integrated analysis of principal strain tensors, mean principal stress, and fast directions of mantle anisotropy shows that west of Sichuan is characterized as mechanically strong crust-mantle coupling.  相似文献   

6.
Ma  Qiang  Wang  Fuchen  Tao  Dongwang  Xie  Quancai  Liu  Heyi  Jiang  Peng 《Journal of Seismology》2021,25(6):1537-1555

Ground motion amplification induced by topography plays a vital role in engineering seismology. A topographic array of 8 accelerographs has been operating along the ridge in Xishan Park since 2007. The topographic site effects in Zigong city are studied based on the strong motion data of 2008 Ms 8.0 Wenchuan earthquake (the epicentral distance?=?225 km) and 2019 Ms 5.2 Zizhong earthquake (the epicentral distance?=?29 km). We compare the peak ground acceleration (PGA) of the two earthquakes and find that the PGA of Station 7#, which locates on a relatively steep slope, is amplified by 4.41 times comparing with the reference station in Zizhong earthquake, while this value is only 1.62 in Wenchuan earthquake. Fourier amplitude spectrum shows that the high frequency content of Zizhong earthquake is more abundant because of its smaller epicentral distance. By using the standard spectral ratio (SSR) method, we conclude that the amplification occurs because high-frequency ground motion is likely to resonate at small-scale features. Finally, the 3D numerical simulations are used to verify these conclusions. Our work indicates that more sophisticated numerical models need to be established for more accurate topographic site effects quantification. In addition, the influence of nearby topographic features should be considered when selecting reference stations.

  相似文献   

7.
A new 3D velocity model of the crust and upper mantle in the southeastern (SE) margin of the Tibetan plateau was obtained by joint inversion of body- and surface-wave data. For the body-wave data, we used 7190 events recorded by 102 stations in the SE margin of the Tibetan plateau. The surface-wave data consist of Rayleigh wave phase velocity dispersion curves obtained from ambient noise cross-correlation analysis recorded by a dense array in the SE margin of the Tibetan plateau. The joint inversion clearly improves the v S model because it is constrained by both data types. The results show that at around 10 km depth there are two low-velocity anomalies embedded within three high-velocity bodies along the Longmenshan fault system. These high-velocity bodies correspond well with the Precambrian massifs, and the two located to the northeast of 2013 M S 7.0 Lushan earthquake are associated with high fault slip areas during the 2008 Wenchuan earthquake. The aftershock gap between 2013 Lushan earthquake and 2008 Wenchuan earthquake is associated with low-velocity anomalies, which also acts as a barrier zone for ruptures of two earthquakes. Generally large earthquakes (M ≥ 5) in the region occurring from 2008 to 2015 are located around the high-velocity zones, indicating that they may act as asperities for these large earthquakes. Joint inversion results also clearly show that there exist low-velocity or weak zones in the mid-lower crust, which are not evenly distributed beneath the SE margin of Tibetan plateau.  相似文献   

8.
Vertical records are critically important when determining the rupture model of an earthquake, especially a thrust earthquake. Due to the relatively low fitness level of near-field vertical displacements, the precision of previous rupture models is relatively low, and the seismic hazard evaluated thereafter should be further updated. In this study, we applied three-component displacement records from GPS stations in and around the source region of the 2013 MW6.6 Lushan earthquake to re-investigate the rupture model.To improve the resolution of the rupture model, records from both continuous and campaign GPS stations were gathered, and secular deformations of the GPS movements were removed from the records of the campaign stations to ensure their reliability. The rupture model was derived by the steepest descent method(SDM), which is based on a layered velocity structure. The peak slip value was about 0.75 m, with a seismic moment release of 9.89 × 10~(18) N·m, which was equivalent to an M_W6.6 event. The inferred fault geometry coincided well with the aftershock distribution of the Lushan earthquake. Unlike previous rupture models, a secondary slip asperity existed at a shallow depth and even touched the ground surface. Based on the distribution of the co-seismic ruptures of the Lushan and Wenchuan earthquakes, post-seismic relaxation of the Wenchuan earthquake, and tectonic loading process, we proposed that the seismic hazard is quite high and still needs special attention in the seismic gap between the two earthquakes.  相似文献   

9.
The generalized inversion of S-wave amplitude spectra from the free-field strong motion recordings of the China National Strong Motion Observation Network System (NSMONS) are used to evaluate the site effects in the Wenchuan area. In this regard, a total of 602 recordings from 96 aftershocks of the Wenchuan earthquake with magnitudes of M3.7-M6.5 were selected as a dataset. These recordings were obtained from 28 stations at a hypocenter distance ranging from 30 km to 150 km. The inversion results have been verified as reliable by comparing the site response at station 62WUD using the Generalized Inversion Technique (GIT) and the Standard Spectral Ratio method (SSR). For all 28 stations, the site predominant frequency F p and the average site amplification in different frequency bands of 1.0–5.0 Hz, 5.0–10.0 Hz and 1.0–10.0 Hz have been calculated based on the inversion results. Compared with the results from the horizontal-to-vertical spectral ratio (HVSR) method, it shows that the HVSR method can reasonably estimate the site predominant frequency but underestimates the site amplification. The linear fitting between the average site amplification for each frequency band and the V s20 (the average uppermost-20 m shear wave velocity) shows good correlation. A distance measurement called the asperity distance D Aspt is proposed to reasonably characterize the source-to-site distance for large earthquakes. Finally, the inversed site response is used to identify the soil nonlinearity in the main shock and aftershocks of Wenchuan earthquake. In ten of the 28 stations analyzed in the main shock, the soil behaved nonlinearly, where the ground motion level is apparently beyond a threshold of PGA > 300 cm/s2 or PGV > 20 cm/s, and only one station coded 51SFB has evidence of soil nonlinear behavior in the aftershocks.  相似文献   

10.
A disastrous earthquake with a magnitude M S = 8.0 (M W = 7.9), in China called “the 5.12 Wenchuan earthquake,” occurred on May 12, 2008, in Sichuan province on the border between the Sino-Tibetan Mountains and the Sichuan depression. The instrumental epicenter was registered in the southeastern part of Wenchuan county, and the hypocenter depth was 14 km. As the strongest and most destructive earthquake within mainland China, it caused numerous human losses and destruction of buildings and infrastructure. The seismic effect from the main shock and aftershocks was felt in many counties, towns, and villages, though Sichuan province suffered the most. The maximum intensity of the shocks was estimated at 11 degrees, according to the Chinese macroseismic scale. In the process of source opening, from the southern part of Wenchuan county to the vicinities of Quingchuan, a seismic fault system with a total length up to 240 km out-cropped on the earth’s surface, confined to the Longmenshan fault belt. The seismic fault system disturbed the original ground, resulting in the collapse or damage to various constructions, such as buildings, homes, bridges, roads, etc. Fault offsets had a dextral strike-slip and thrust kinematic combination. The earthquake generated several tens of thousands of landslides, rockfalls, and debris flows. Many dammed ponds appeared in the epicentral zone due to the activation of landslides. Thus, the geological effects turned out to be the most destructive factor in this case. At the same time, the seismic intensity of surface shaking was abnormally low even in direct proximity to the seismic fault system. Usually it was no more than 7–8 degrees. This macroseismic phenomenon may turn out to be rather typical for many major earthquakes.  相似文献   

11.
A series of housing collapses and other serious damage was caused by the 2008 Wenchuan MS 8.0 earthquake in the seismic intensity Ⅵ areas of the Loess Plateau, which is hundreds of kilometers away from the epicenter, and which showed a remarkable seismic intensity anomaly. The seismic disasters are closely related to the seismic response characteristics of the site, therefore, the systematic study of the far-field seismic response law of the Wenchuan earthquake in the Loess Plateau is of great significance to prevent the far-field disaster of great earthquake. In this paper, the seismic acceleration records of several bedrock stations and loess stations from the seismogenic fault of the Wenchuan earthquake to the Loess Plateau were collected, and the attenuation law of ground motion along the propagation path and the characteristics of seismic response on the loess site are studied, and the mechanism of amplification effect of ground motion is analyzed based on the dynamic feature parameters of the loess site obtained through the HVSR method. Taking a typical loess site of thick deposit as the prototype, a series of shaking table tests of dynamic response of loess site models with different thicknesses were carried out. Amplification effect, spectral characteristics of acceleration in model sites were analyzed under the action of a far-field seismic wave of the Wenchuan earthquake. The results show that seismic attenuation on the propagation path along the NE strike of the seismogenic fault to the Loess Plateau is slower than that in other directions, and the predominant period range of ground motion on bedrock site of the Loess Plateau presents broadband characteristics. Because the natural periods of loess sites with thick deposits are within the predominant period range of bedrock input wave, loess sites appear significant amplification effect of ground motion, the horizontal acceleration of ground motion exceeds 0.1 ?g, the seismic intensity reaches 7°. The thicker the loess deposit is, the more significant the change of spectral characteristics of ground motion on loess sites, and the narrower the predominant period range of ground motion becomes, and the closer it is to the natural period of loess sites. Therefore, for some old houses on thick loess sites, the poor seismic performance and strong seismic response eventually led to their collapses and damages because their natural periods are very close to the predominant period of ground motion of the Wenchuan earthquake on thick loess sites; For these damaged high-rise buildings, the resonance effect might be the main reason for their damages because their natural periods are included in the predominant period range of ground motion of the Wenchuan earthquake on thick loess sites.These research results would provide a basis for seismic disasters prediction and evaluation and seismic design of construction engineering in the Loess Plateau.  相似文献   

12.
宋金  蒋海昆  孟令媛  臧阳 《中国地震》2017,33(2):219-228
本文采用分层粘弹性介质模型计算了汶川地震对芦山震中产生的库仑应力加载的影响,进而结合Dieterich(1994)提出的速率状态摩擦定律给出芦山附近区域6级地震累积发震概率随时间的变化。结果显示,2013年芦山7.0级地震时其累积发震概率达18%,说明汶川地震产生的应力扰动加速了芦山地震的发生。本文还计算了汶川、芦山2次地震对其间"破裂空段"处产生的累积库仑应力扰动的影响,结合背景地震发生率,给出了"破裂空段"处6级地震累积发震概率变化。虽然计算结果可能受到大邑地震、介质模型参数的选取和背景地震发生概率等因素影响而存在一定误差,但"破裂空段"在2次强震应力加载下累积发震概率是不断增大的,因此我们认为"破裂空段"处发生中强地震的紧迫性不断增强。  相似文献   

13.
We model the macroseismic damage distribution of four important intermediate-depth earthquakes of the southern Aegean Sea subduction zone, namely the destructive 1926 M?=?7.7 Rhodes and 1935 M?=?6.9 Crete earthquakes, the unique 1956 M?=?6.9 Amorgos aftershock (recently proposed to be triggered by a shallow event), and the more recent 2002 M?=?5.9 Milos earthquake, which all exhibit spatially anomalous macroseismic patterns. Macroseismic data for these events are collected from published macroseismic databases and compared with the spatial distribution of seismic motions obtained from stochastic simulation, converted to macroseismic intensity (Modified Mercalli scale, IMM). For this conversion, we present an updated correlation between macroseismic intensities and peak measures of seismic motions (PGA and PGV) for the intermediate-depth earthquakes of the southern Aegean Sea. Input model parameters for the simulations, such as fault dimensions, stress parameters, and attenuation parameters (e.g. back-arc/along anelastic attenuation) are adopted from previous work performed in the area. Site-effects on the observed seismic motions are approximated using generic transfer functions proposed for the broader Aegean Sea area on the basis of VS30 values from topographic slope proxies. The results are in very good agreement with the observed anomalous damage patterns, for which the largest intensities are often observed at distances >?100 km from the earthquake epicenters. We also consider two additional “prediction” but realistic intermediate-depth earthquake scenarios, and model their macroseismic distributions, to assess their expected damage impact in the broader southern Aegean area. The results suggest that intermediate-depth events, especially north of central Crete, have a prominent effect on a wide area of the outer Hellenic arc, with a very important impact on modern urban centers along northern Crete coasts (e.g. city of Heraklion), in excellent agreement with the available historical information.  相似文献   

14.
Immediately following the M S7.0 Lushan earthquake on April 20, 2013, using high-pass and low-pass filtering on the digital seismic stations in the Shanxi Province, located about 870–1,452 km from the earthquake epicenter, we detected some earthquakes at a time corresponding to the first arrival of surface waves in high-pass filtering waveform. The earthquakes were especially noticed at stations in Youyu (YUY), Shanzizao (SZZ), Shanghuangzhuang (SHZ), and Zhenchuan (ZCH), which are located in a volcanic region in the Shanxi Province,but they were not listed in the Shanxi seismic observation report. These earthquakes occurred 4–50 min after the passage of the maximum amplitude Rayleigh wave, and the periods of the surface waves were mainly between 15 and 20 s following. The Coulomb stresses caused by the Rayleigh waves that acted on the four stations was about 0.001 MPa, which is a little lower than the threshold value of dynamic triggering, therefore, we may conclude that the Datong volcanic region is more sensitive to the Coulomb stress change. To verify, if the similar phenomena are widespread, we used the same filtering to observe contrastively continuous waveform data before, and 5 h after, the M S7.0 Lushan earthquake and M S9.0 Tohoku earthquake in 2011. The results show that the similar phenomena occur before the earthquakes, but the seismicity rates after the earthquakes are remarkably increased. Since these weak earthquakes are quite small, it is hard to get clear phase arrival time from three or more stations to locate them. In addition, the travel time differences between P waves and S waves (S–P) are all less than 4 s, that means the events should occur in 34 km around the stations in the volcanic region. The stress of initial dynamic triggering of the M S9.0 Tohoku earthquake was about 0.09 MPa, which is much higher than the threshold value of dynamic triggering stress. The earthquakes after the M S9.0 Tohoku earthquake are related to dynamic triggering stress, but the events before the earthquake cannot be linked to seismic events, but may be related to the background seismicity or from other kinds of local sources, such as anthropogenic sources (i.e., explosions). Using two teleseismic filtering, the small background earthquakes in the Datong volcanic region occur frequently, thus we postulate that previous catalog does not apply bandpass filter to pick out the weak earthquakes, and some of the observed weak events were not triggered by changes in the dynamic stress field.  相似文献   

15.
The 2003 Ml = 5.4 Rambervillers earthquake, north-east of France, is the largest seismic event recorded north of the Alps since the 1992 Ms = 5.3, I0 = VII, Roermond earthquake, Netherlands. With a maximum macroseismic intensity of VI-VII EMS-98, the 2003 event was broadly felt to a distance of 300 km from the epicentre. It provides a unique opportunity to test and compare the different procedures used in France, Germany and Switzerland when evaluating macroseismic intensities. The main purpose of this paper is to present a common transfrontier macroseismic map based on the EMS-98 intensity scale. Maximum horizontal accelerations recorded in the area are compared to the intensity values, and we propose to use a differential technique to re-estimate the magnitude of the 1682 Remiremont, I0 = VIII, earthquake, which occurred 40 km south of Rambervillers.  相似文献   

16.
The epicentral zone and settlements that suffered from the M S = 6.1 earthquake in the northwest Amur oblast are examined. Only secondary seismic dislocations were revealed and mapped in detail. The inspection of settlements and inhabitansts inquiry allowed estimation of the intensity of the macroseismic effect based on the MSK-64 scale. These forthwith primary factual data give an idea on the shaking intensity at the distant and nearest zones and precise location of the earthquake focus. The map of isoseists of the highest (7–8) intensity is drawn.  相似文献   

17.
The April 20, 2013 Lushan earthquake which occurred in Sichuan, China had only moderate thrust. However, the computed seismic moments (M 0) for the Lushan earthquake calculated by several institutions differ significantly from 0.4 × 1019 to 1.69 × 1019 Nm, up to four times difference. We evaluate ten computed M 0s by using normal mode observations from superconducting gravimeters in Mainland China. We compute synthetic normal modes on the basis of moment tensor solutions and fit them to the observed normal modes. Comparison of our results indicates that M 0 is the main cause for some large differences between observations and synthetics. We suggest that a moment magnitude of M w6.6, corresponding to a M 0 of 0.97–1.08 × 1019 Nm, characterizes the size and strength of the seismic source of the Lushan earthquake.  相似文献   

18.
Ground motion prediction equations (GMPE) in terms of macroseismic intensity are a prerequisite for intensity-based shake maps and seismic hazard assessment and have the advantage of direct relation to earthquake damage and good data availability also for historical events. In this study, we derive GMPE for macroseismic intensity for the Campania region in southern Italy. This region is highly exposed to the seismic hazard related to the high seismicity with moderate- to large-magnitude earthquakes in the Appenninic belt. The relations are based on physical considerations and are easy to implement for the user. The uncertainties in earthquake source parameters are accounted for through a Monte Carlo approach and results are compared to those obtained through a standard regression scheme. One relation takes into account the finite dimensions of the fault plane and describes the site intensity as a function of Joyner–Boore distance. Additionally, a relation describing the intensity as a function of epicentral distance is derived for implementation in cases where the dimensions of the fault plane are unknown. The relations are based on an extensive dataset of macroseismic intensities for large earthquakes in the Campania region and are valid in the magnitude range M w = 6.3–7.0 for shallow crustal earthquakes. Results indicate that the uncertainties in earthquake source parameters are negligible in comparison to the spread in the intensity data. The GMPE provide a good overall fit to historical earthquakes in the region and can provide the intensities for a future earthquake within 1 intensity unit.  相似文献   

19.
孙冬军  刘芳  毕波 《中国地震》2022,38(1):112-119
本文选取2013年芦山地震和2017年九寨沟地震波形,重新量取垂直向振幅,计算宽频带面波震级MS（BB）,分析各台站实测震级出现方向性差异的原因。其中,通过572个宽频带台站实测芦山地震震级MS（BB）7.1,通过603个宽频带台站实测九寨沟地震震级MS（BB）6.9。芦山地震实测震级大于MS（BB）7.3的台站呈现WN-ES向分布,与断层倾向一致;实测震级小于MS（BB）7.0的台站呈现NE-WS向分布,与其所在断层走向一致。九寨沟地震实测震级大于MS（BB）7.0的台站分布呈现NE向分布,与断层倾向一致;实测震级小于MS（BB）6.8的台站总体分布较为离散,大体呈现NW-SE向分布,与树正断裂走向一致。实测震级偏大的台站方向性分布与多普勒效应和P波辐射花样联系不明显。对比分析芦山地震和九寨沟地震,去除场地响应和仪器自身影响,台站实测震级差异性仍然存在,因此,台站实测震级差异性是由于受到了多普勒效应、辐射花样、仪器和场地响应之外的因素影响。综合考虑地震震级涉及的影响因素,芦山地震和九寨沟地震的台站实测震级差异性可能与地震波的传播路径有关。  相似文献   

20.
Near-field strong ground motions are useful for engineering seismology studies and seismic design, but dense observation networks of damaging earthquakes are still rare. In this study, based on the strong-motion data from the M w 6.6 Lushan earthquake, the ground motion parameters in different spatial regions are systematically analyzed, and the contributions from different effects, like the hanging-wall effect, directivity effect, and attenuation effect are separated to the extent possible. Different engineering parameters from the observed ground motions are compared with the local design response spectra and a new attenuation relation of Western China. General results indicate that the high frequency ground motion, like the peak ground acceleration, on two sides of the fault plane is sensitive to the hanging-wall effect, whereas the low frequency ground motion, like the long period spectral acceleration, in the rupture propagation direction is affected by the directivity effect. Moreover, although the M w 6.6 Lushan earthquake is not a large magnitude event, the spatial difference of ground motion is still obvious; thus, for a thrust faulting earthquake, in addition to the hanging effect, the directivity effect should also be considered.  相似文献   

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