Rupture process of the M_s 7.0 Lushan earthquake, 2013     

LIU ChengLi  ZHENG Yong  GE Can  XIONG Xiong  HSU HouTze 《中国科学:地球科学(英文版)》2013,(7):1187-1192

On April 20, 2013 at 8:02 am, a magnitude 7.0 earthquake occurred in Lushan County, Sichuan Province, China, which induces massive landslides, causes great losses to life and property. Based on the locations of aftershocks provided by the China Earthquake Network Center and the characteristic of Longmenshan active faults system, combined with the current preliminary focal mechanism solution, the fault rupture direction is determined. With the finite fault inversion method, we invert the rupture process of the Lushan M s 7.0 earthquake by teleseismic waveforms data. The inversion results indicate that the main shock is dominated by thrust fault component and the rupture initiated at depth of 15 km, and most of slip ruptured around the hypocenter with the peak slip of about 1.5 m. Most of rupture slips released at the first 20 s and the main rupture occurred at the first 10 s after the onsets of the mainshock. Most of seismic energy released near the hypocenter with a length of 28 km, especially on both sides of the hypocenter with the range of 20 km, and the seismic energy released relatively smaller in other areas. There is a large area with weak slip between the main rupture and another two asperities on both sides of the hypocenter; it may imply that the accumulated strain on the rupture fault has not been completely released. Therefore, there is a significant possibility of having strong aftershocks in the areas where energy is not fully released. This is also the main reason why there are a lot of moderate to strong aftershocks in the Lushan aftershock sequence. In addition, there is an earthquake vacant zone with a length of about 50 km between the Wenchuan M w 7.9 earthquake and this event, which is of high earthquake risk and is deserved to be paid close attention to.  相似文献   

Crustal and upper mantle structure and the deep seismogenic environment in the source regions of the Lushan earthquake and the Wenchuan earthquake   总被引：11，自引：0，他引：11  

ZHENG Yong  GE Can  XIE ZuJun  YANG YingJie  XIONG Xiong  HSU HouTze 《中国科学:地球科学(英文版)》2013,(7):1158-1168

Following the M w 7.9 Wenchuan earthquake, the M w 6.6 Lushan earthquake is another devastating earthquake that struck the Longmenshan Fault Zone (LFZ) and caused severe damages. In this study, we collected continuous broadband ambient noise seismic data and earthquake event data from Chinese provincial digital seismic network, and then utilized ambient noise tomography method and receiver function method to obtain high resolution shear wave velocity structure, crustal thickness, and Poisson ratio in the earthquake source region and its surroundings. Based on the tomography images and the receiver function results, we further analyzed the deep seismogenic environment of the LFZ and its neighborhood. We reveal three main findings: (1) There is big contrast of the shear wave velocities across the LFZ. (2) Both the Lushan earthquake and the Wenchuan earthquake occurred in the regions where crustal shear wave velocity and crustal thickness change dramatically. The rupture faults and the aftershock zones are also concentrated in the areas where the lateral gradients of crustal seismic wave speed and crustal thickness change significantly, and the focal depths of the earthquakes are concentrated in the transitional depths where shear wave velocities change dramatically from laterally uniform to laterally non-uniform. (3) The Wenchuan earthquake and its aftershocks occurred in low Poisson ratio region, while the Lushan earthquake sequences are located in high Poisson ratio zone. We proposed that the effect of the dramatic lateral variation of shear wave velocity, and the gravity potential energy differences caused by the big contrast in the topography and the crustal thickness across the LFZ may constitute the seismogenic environment for the strong earthquakes in the LFZ, and the Poisson ratio difference between the rocks in the south and north segments of the Longmenshan Fault zone may explain the 5 years delay of the occurrence of the Lushan earthquake than the Wenchuan earthquake.  相似文献   

云南西双版纳(曼桂)目击陨石的热变质和冲击变质研究     

罗业鑫  陈景有  梁伯健  廖世勇  李晔  李少林  吴蕴华  王英  邓志培  梅苞  徐伟彪 《天文学报》2019,60(5):1-14

曼桂陨石是新近(2018年6月1日)陨落在云南西双版纳地区的目击球粒陨石,其中的主要矿物为橄榄石(Fa_(24.3±0.6))、斜方辉石(Fs_(20.6±0.5)Wo_(0.4±0.2))、长石(An_(11-12)Or_(2-4))、铁镍金属和陨硫铁,次要矿物为铬铁矿、白磷钙矿等.橄榄石和辉石的化学成分表明曼桂陨石属于L型普通球粒陨石.陨石中球粒很少且轮廓不清晰,基质矿物普遍经历过重结晶,重结晶矿物颗粒粒径较大,高钙辉石粒径25–30μm,长石颗粒大多超过50μm,说明该陨石属于6型岩石类型.橄榄石和辉石颗粒中发育有波状消光、嵌晶块状消光现象、平面裂隙和面状变形构造,长石熔长石化并不完全,陨石中观察到宽度不等且纵横交错的冲击熔融脉,表明曼桂普通球粒陨石受到的冲击变质作用可以达到S5级以上.通过熔融脉中的矿物组合推断出熔融脉中矿物经历的压力在15–16 GPa左右.  相似文献   

插值公式、相关系数和采样间隔对GRACE Follow-On 星间加速度精度的影响   总被引：2，自引：0，他引：2       下载免费PDF全文

郑伟  许厚泽  钟敏  员美娟 《地球物理学报》2012,55(3):822-832

本文基于星间加速度法开展了插值公式、相关系数和采样间隔对GRACE Follow-On星间加速度精度影响的研究. 模拟结果表明:1)适当增加数值微分公式的插值点数可有效提高插值精度. 基于9点Newton插值公式,星间加速度的插值误差为4.401×10^-13 m·s^-2,分别基于7点、5点和3点插值公式,插值误差增加了1.192倍、6.912倍和274.029倍. 2)适当增大相关系数可有效降低星间加速度的误差. 基于相关系数0.99,星间加速度方差为3.777×10^-24 m²·s^-4,分别基于相关系数0.90、0.70、0.50和0.00,方差增加了9.780倍、22.404倍、26.217倍和26.820倍. 3)随着采样间隔增大,星间加速度方差逐渐降低,但卫星观测值的空间分辨率也同时降低,因此合理选取采样间隔有利于地球重力场精度的提高. 4)基于9点Newton插值公式、相关系数(K波段测量系统星间距离和星间速度0.85、GPS轨道位置和轨道速度0.95、星载加速度计非保守力0.90)和采样间隔10 s,利用预处理共轭梯度迭代法,精确和快速反演了120阶GRACE Follow-On地球重力场,在120阶处累计大地水准面精度为4.602×10^-4 m.  相似文献   

Theoretical and Experimental Study of Breaking Wave on Sloping Bottoms     

YANG Kuei-Sen  CHEN Yang-Yih  LI Meng-Syue  HSU Hung-Chu 《海洋工程》2013,27(6):737-750

This paper studies the continuous evolution of breaking wave for the surface water waves propagating on a sloping beach. A Lagrangian asymptotic solution is derived. According to the solution coupled with the wave breaking criteria and the equations of water particles motion, the wave deformation and the continuous wave breaking processes for the progressive water waves propagating on a sloping bottom can be derived. A series of experiments are also conducted to compare with the theoretical solution. The results show that the present solution can reasonably describe the plunging or spilling wave breaking phenomenon.  相似文献   

Refractory inclusions and aluminum‐rich chondrules in Sayh al Uhaymir 290 CH chondrite: Petrography and mineralogy     

Aicheng ZHANG  Weibiao HSU 《Meteoritics & planetary science》2009,44(6):787-804

Abstract— Here we report the petrography, mineralogy, and bulk compositions of Ca,Al‐rich inclusions (CAIs), amoeboid olivine aggregate (AOA), and Al‐rich chondrules (ARCs) in Sayh al Uhaymir (SaU) 290 CH chondrite. Eighty‐two CAIs (0.1% of the section surface area) were found. They are hibonite‐rich (9%), grossite‐rich (18%), melilite ± spinel‐rich (48%), fassaite ± spinel‐rich (15%), and fassaite‐anorthite‐rich (10%) refractory inclusions. Most CAIs are rounded in shape and small in size (average = 40 μm). They are more refractory than those of other groups of chondrites. CAIs in SaU 290 might have experienced higher peak heating temperatures, which could be due to the formation region closer to the center of protoplanetary disk or have formed earlier than those of other groups of chondrites. In SaU 290, refractory inclusions with a layered texture could have formed by gas‐solid condensation from the solar nebula and those with an igneous texture could have crystallized from melt droplets or experienced subsequent melting of pre‐existing condensates from the solar nebula. One refractory inclusion represents an evaporation product of pre‐existing refractory solid on the basis of its layered texture and melting temperature of constituting minerals. Only one AOA is observed (75 μm across). It consists of olivine, Al‐diopside, anorthite, and minor spinel with a layered texture. CAIs and AOA show no significant low‐temperature aqueous alteration. ARCs in SaU 290 consist of diopside, forsterite, anorthite, Al‐enstatite, spinel, and mesostasis or glass. They can be divided into diopside‐rich, Al‐enstatite‐rich, glass‐rich, and anorthite‐rich chondrules. Bulk compositions of most ARCs are consistent with a mixture origin of CAIs and ferromagnesian chondrules. Anorthite and Al‐enstatite do not coexist in a given ARC, implying a kinetic effect on their formation.  相似文献   

青藏地区大地水准面形态及其与构造动力学的关系   总被引：2，自引：1，他引：2       下载免费PDF全文

陆洋  许厚泽 《地球物理学报》1996,39(2):203-210

利用密合法求解青藏地区大地水准面模型，研究青藏地区大地水准面主要特征及其与该区内部构造和活动的相关性．表明青藏地区大地水准而异常与青藏高原隆起的形状极为相似，大地水准面整体负异常与下地幔相关，形状起伏与上地幔相对应，岩石层反映的大地水准而异常与青藏高原活动构造有较好的对应关系．  相似文献   

应用地理信息系统辅助山坡地潜在崩山灾害评估模式之建立   总被引：2，自引：0，他引：2  

朱子豪  齐士峥  杨乃夷  许秋玲 《国土资源遥感》2001,12(4):13-19,68

山坡地开发具有潜在的自然危险因子,人工开挖也会触动这些因子,因此,要做好土地管理工作,需从分析潜在崩山灾害类型以及开发区位两方面考虑。地形分析在工程、灾害评估等方面广为应用,本研究以张石角(1987)提出的“简确工程地质灾害调查与评估法”为依据,以山坡地丙种建地作为评估对象,利用地理信息系统所提供的空间分析及数据库功能,完成台湾省中、北部地区大范围的山坡地潜在灾害评估工作,其成果也将为政府部门所采用.  相似文献   

曾文水库保护带泰山滑坡之调查与治理   总被引：1，自引：0，他引：1  

许中立  李金来 《山地学报》2002,20(4):411-420

崩塌与滑坡灾害之治理，首重破坏诱因了了解与破坏机制之调查。再根据调查观测所得之资料与参数，着手进行设计适当之防治对策，方能得到良好的治理成效。泰山滑坡位于台湾南部极重要之曾文水库的保护带。其边坡由陆陆续续的崩陷而逐渐演变为坍滑，甚至造成交通中断受阻。调查发现本区为属浅层滑动，滑动区平面类似酒瓶状，主要原因为长期受到雨水之漫流与渗透软化的影响，加上蚀沟之切割淘刷作用，使得边坡容易失去支撑而滑动。经施以经济有效的蚀沟控制工程兴建多座潜坝，跌水与排水设施后，发现确定提高了边坡之稳定性，地区产业因而可以持续动作，是一次相当成功的治理案例模式，但由于施工便道之开 当，遂再度诱发部份边坡的坍滑，故尔后之维护管理工作极为重要。  相似文献   

海洋潮汐对重力潮汐观测的影响   总被引：11，自引：4，他引：11       下载免费PDF全文

许厚泽  陈振邦  杨怀冰 《地球物理学报》1982,25(2):120-129

本文论述了海潮对重力固体潮观测的影响,把整个褶积计算分为近洋区及远洋区两部分,其中近洋区采用格林函数进行数值积分的方法,远洋区则利用全球海潮潮高的球函数展开式。着重讨论了远洋区的实施方案,导出了必要的工作公式,并就加速远洋区级数收敛问题作了探讨。利用导得的公式,计算了M₂海洋潮波对中国境内重力观测的影响。  相似文献