DATABASE OF LANDSLIDES TRIGGERED BY 2015 GORKHA(NEPAL) M_W7.8 EARTHQUAKE     

XU Chong  TIAN Ying-ying  SHEN Ling-ling  MA Si-yuan  XU Xi-wei  ZHOU Ben-gang  HUANG Xue-qiang  MA Jun-xue  CHEN Xi 《地震地质》2018,40(5):1115-1128

In this study, a detailed database of landslides triggered by the 25 April 2015 Gorkha (Nepal)M_W7.8 earthquake is constructed based on visual interpretation of pre- and post-earthquake high-resolution satellite images and field reconnaissance. Results show the earthquake triggered at least 47 200 landslides, which have a NWW direction spatial distribution, similar with the location and strike of the seismogenic fault. The landslides are of a total area about 110km² and an oval distribution area about 35 700km². On the basis of a scale relationship between landslide area (A)and volume (V), V=1.314 7×A^{1.208 5}, the total volume of the coseismic landslides is estimated to be about 9.64×10⁸m³. In the oval landslide distribution area, the landslide number density, area density, and volume density were calculated and the results are 1.32km^-2, 0.31%, and 0.027m, respectively. This study provides a detailed and objective inventory of landslides triggered by the Gorkha earthquake, which provides very important and essential basic data for study of mechanics of coseismic landslides, spatial pattern, distribution law, and hazard assessment. In addition, the landslide database related to an individual earthquake also provides an important earthquake case in a subduction zone for studying landslides related to multiple earthquakes from a global perspective.  相似文献   

GEODETIC AND TELESEISMIC CONSTRAINTS ON SLIP DISTRIBUTION OF 2015 M_W6.4 PISHAN EARTHQUAKE          下载免费PDF全文

CHEN Yun-guo  HE Ping  DING Kai-hua  LI Shui-ping  WANG Qi 《地震地质》2019,41(1):137-149

On July 3^rd, 2015, a M_W6.4 earthquake occurred on Pishan County, Xinjiang, located in the front of western Kunlun thrust belt, which is the largest earthquake(M_W6.0~7.0)in the past 40 years in this region. In this study, we collected both the near-filed geodetic coseismic deformation observations including 4 GPS sites and one high-resolution ALOS-2 InSAR imagery, and far-field teleseismic P waveforms from 25 stations provided by IRIS/USGS, to invert the fault parameters(strike and dip)and coseismic rupture model of 2015 M_W6.4 Pishan earthquake. Using the finite fault theory, a non-linear simulated annealing algorithm was employed to resolve our joint inversion problem. The strike (120°~130°) and dip angle(35°~40°)of optimal models are different from that of some previous studies, and the dip change is strongly constrained by combined data than that of strike. In fixing the geometric parameters of optimal fault model, we also considered data weight(5)(geodetic data/teleseismic P waveforms)and constrained weight from moment and smooth factor(2.5). Clearly, our results indicate that the slip distribution mainly concentrates in the depth range from 9 to 16km and a length range of 20km along the strike direction, which is similar to the spatial distribution of the relocated aftershocks. The maximum slip is~95cm. The seismic moment release is 5.45×10¹⁸N·m, corresponding to M_W6.42. Compared with the single data set, geodetic data or teleseismic waveform, our joint inversion model could simultaneously constrain the seismic moment and slip distribution well, thus avoiding effectively a lower-resolution rupture distribution determined by teleseismic-only inversion and a bias released moment estimated by the geodetic-only inversion. Importantly, we should consider both the near-field geodetic data and far-field teleseismic data in retrieving the rupture model for accurately describing the seismogenic structure of active fault in western Kunlun region.  相似文献   

COSEISMIC DISPLACEMENT FIELD OF THE WENCHUAN EARTHQUAKE DERIVED FROM STRONG MOTION RECORDS AND APPLICATION IN SLIP INVERSION          下载免费PDF全文

LIU Xiao-dong  SHAN Xin-jian  ZHANG Ying-feng  YIN Hao  QU Chun-yan 《地震地质》2019,41(4):1027-1041

The development of high-rate GNSS seismology and seismic observation methods has provided technical support for acquiring the near-field real-time displacement time series during earthquake. But in practice, the limited number of GNSS continuous stations hardly meets the requirement of near-field quasi-real-time coseismic displacement observation, while the macroseismographs could be an important complement. Compared with high-rate GNSS, macroseismograph has better sensitivity, higher resolution(100~200Hz)and larger dynamic range, and the most importantly, lower cost. However, baseline drift exists in strong-motion data, which limits its widespread use. This paper aims to prove the feasibility and reliability of strong motion data in acquiring seismic displacement sequences, as a supplement to high-rate GNSS. In this study, we have analyzed the strong-motion data of Wenchuan M_S8.0 earthquake in Longmenshan fault zone, based on the automatic scheme for empirical baseline correction proposed by Wang et al., which fits the uncorrected displacement by polynomial to obtain the fitting parameters, and then the baseline correction is completed in the velocity sequence. Through correction processing and quadratic integration, the static coseismic displacement field and displacement time series are obtained. Comparison of the displacement time series from the strong motions with the result of high-rate GPS shows a good coincidence. We have worked out the coseismic displacement field in the large area of Wenchuan earthquake using GPS data and strong motion data. The coseismic displacement fields calculated from GPS and strong motions are consistent with each other in terms of magnitude, direction and distribution patterns. High-precision coseismic deformation can provide better data constraint for fault slip inversion. To verify the influence of strong-motion data on slip distribution in Wenchuan earthquake, we used strong motion, GPS and InSAR data to estimate the stress drop, moment magnitude and coseismic slip model, and our results agreed with those of the previous studies. In addition, the inversion results of different data are different and complementary to some extent. The use of strong-motion data supplements the slip of the fault in the 180km segment and the 270~300km segment, thus making the inversion results of fault slip more comprehensive. From this result, we can draw the following conclusions:1)Based on the robust baseline correction method, the use of strong motion data, as an important complement to high-rate GNSS, can obtain reliable surface displacement after the earthquake. 2)The strong motion data provide an effective method to study the coseismic displacement sequence, the surface rupture process and quick seismogenic parameters acquisition. 3)The combination of multiple data can significantly improve the data coverage and give play to the advantages of different data. Therefore, it is suggested to combine multiple data(GPS, strong motion, InSAR, etc.)for joint inversion to improve the stability of fault slip model.  相似文献   

九寨沟Ms7.0地震的同震形变场误差研究及断层滑动分布反演     

庄春晓  王仕祥  王仲想 《测绘与空间地理信息》2020,(3):211-214,224

北京时间2017年8月8日四川省九寨沟发生Ms7.0级地震。为了提高断层滑动分布反演的可靠性,本文利用升降轨InSAR数据联合反演断层滑动分布,再根据模拟形变值二次反演,对比反演结果来探讨升降轨形变场误差和确定断层滑动分布的结果。结果表明,九寨沟升轨同震形变场的质量较好,降轨形变场受余震、震后粘弹性松弛效应影响明显,利用模拟形变值二次反演确定的断层滑动分布可靠性更高。  相似文献   

PBO钻孔应变同震响应分析     

陈燚飞  吕品姬 《大地测量与地球动力学》2019,39(7):765-770

以2017-09-08墨西哥8.1 级地震为例，分析14个PBO综合钻孔应变仪和地震仪同址记录的地震波信号，结果表明，应变仪记录的地震波符合射线传播规律。对不同震中距的站点进行基于S变换的应变仪与地震仪的同震响应特征分析，二者同震响应一致性较好，应变仪频段主要在0.25 Hz以下。取震后1 h应变数据进行分析发现，同震阶段应变主方向指向震中。  相似文献   

1948年川西理塘 M7. 3地震地表破裂特征及Riedel剪切构造分析     

刘亢  李岩峰  郭辉文  张迎峰 《地质学报》2021,95(8):2346-2360

1948年川西理塘M7. 3地震是川滇菱形块体内部近一个世纪以来发生的震级最大的走滑型地震。在对此次同震地表破裂进行详细调查基础上,利用差分GPS对同震地表破裂带进行了精确测量与统计分析。结果揭示该地表破裂的现存长度为36 km,北端始于无量河以北,往东南沿藏坝盆地北东缘、德巫盆地东南缘,延伸至德巫乡北,分为南、北两段,而在交德附近存在约3 km长的地表破裂空区。对同震地表破裂的线密度和同震水平位错量进行分段统计后揭示,此次地震的宏观震中应位于德巫盆地中部交德东南约4~5 km处。对理塘同震地表破裂的Riedel剪切分析结果指示,该破裂带主要由R剪切组成,以发育雁列状排列的挤压鼓包(Push- up)为主要特征,伴有少量R′剪切与T裂缝,缺少P型与X型剪切。其中R剪切占95%以上,其在藏坝段(北段)的优势方向为318°,德巫段(南段)为315°,整条地表破裂带的R剪切平均方向为316°。同时发现,此次地震形成的雁列状挤压鼓包主要以平缓的“弧形”为主,这与1981年道孚MS 6. 9地震和2010年玉树MS 7. 1地震地表破裂带中出现大量反“S”形挤压鼓包有所不同,推断与走滑断裂滑动速率密切相关。沿强滑动速率走滑断层地震破裂带的Riedel剪切发育会更为完善,挤压鼓包也更发育,易形成反“S”形,反之则以平缓的“弧形”为特征。综合分析认为,1948年理塘同震地表破裂带的展布主要受藏坝盆地与德巫盆地控制,而且藏坝段(北段)与德巫段(南段)的R剪切方向存在偏差,这可能与两个拉分盆地的发育程度有关。  相似文献   

2010年1月12日海地 Mw7.0地震InSAR同震形变观测及同震滑动分布反演          下载免费PDF全文

薛莲  孙建宝  沈正康 《地震地质》2011,33(1):157-174

2010年1月12日GMT时间21时53分,在海地境内(72.57°W,18.44°N)发生了Mw7.0地震.文中利用干涉合成孔径雷达(InSAR)方法获得了覆盖整个震区的高精度形变观测资料,用以研究该地震的发震机理.采用ALOs PALSAR数据,分析了轨道、大气等误差源对干涉信号的影响,最终获得了雷达视线向(LOS...  相似文献   

2008年大柴旦M_w6.3级地震的InSAR同震形变观测及断层参数反演     

刘洋  许才军  温扬茂  何平 《测绘学报》2015,44(11):1202-1209

2008年11月10日,青海省大柴旦地区发生了Mw6.3级地震。本文利用EnviSat卫星升降轨SAR数据和差分干涉测量技术提取了同震形变场,基于均匀位错模型反演确定了地震断层参数,然后利用格网迭代搜索法确定了较优断层倾角,同时基于非均匀位错模型获得了精细滑动分布。结果表明,地震使得上盘区域沿降轨、升轨视线向分别产生最大约8.5cm、10cm的抬升;较优断层倾角为47.9°;地震滑动未延伸至地表,主要发生在地下8.2~23.7km深度范围内,最大和平均滑动量为0.5m和0.19m,平均滑动角为104.9°。反演的地震矩为3.74×1018 N·m,矩震级为Mw6.35。  相似文献   

2011日本东北大地震前震余震重力效应分析     

龚正  许才军 《测绘科学》2015,(12):59-62

针对2011年日本东北大地震(Tohoku-Oki地震)发生前后较短时间内的多次较大前震和余震和主震混在一起,不利于提取出主震同震信号的问题,该文利用弹性位错理论模拟计算了Tohoku-Oki地震一次较大前震和两次较大余震的同震重力变化,讨论了这3次地震单独和综合的重力效应,并与主震重力变化对比分析,认为这3次前震和余震引起的重力变化数值较大,影响范围广,会直接影响到Tohoku-Oki地震主震的同震重力信号提取,所以需要作为重要误差考虑。  相似文献   

菲律宾棉兰老岛2019年4次M_W>6.0地震断层运动模型及库仑应力传输研究     

吴少杰  杨莹辉  王泽根  熊凌艳  陈强  陈静  杨超 《大地测量与地球动力学》2022,42(3):240-246

基于雷达干涉测量技术,利用ALOS-2、Sentinel-1卫星升降轨雷达影像,获得2019-10~12发生在菲律宾棉兰老岛的4次M_W>6.0地震的同震形变场,并以此形变结果为约束,反演得到4次地震的断层运动模型。综合分析发现,此次地震序列由3条断裂的破裂引起,其中2019-10-16和2019-10-31的2次地震为同一发震断裂,2019-10-31地震断层破裂区域位于2019-10-16地震断层破裂的东北延伸段,最大滑动量约为1.1 m,约为2019-10-16地震最大滑动量的2倍。2019-10-29地震由一条独立断层破裂引起,断层最大滑动量约为2.0 m。2019-12-15地震由一条东北向倾斜断层破裂引起,断层最大滑动量约为3.0 m。此外,2019-10-16地震引起2019-10-29地震显著滑动区明显的正向库仑应力传输;而2019-10-29地震显著增加了2019-10-31地震震源区域的库仑应力;前3次地震对2019-12-15地震孕震断层的库仑应力传输总和为负值,说明静态库仑应力传输可能不是此次地震触发的主要诱因。  相似文献