THE COSEISMIC SOURCE SLIP AND COULOMB STRESS TRIGGERING OF 2015 NEPAL GORKHA M_W7.9 AND KODARIM_W7.3 EARTHQUAKE BASED ON InSAR MEASUREMENTS          下载免费PDF全文

ZHANG Ying-feng  ZHANG Guo-hong  SHAN Xin-jian  WEN Shao-yan 《地震地质》2017,39(1):104-116

According to the structure of the Himalayan orogenic belt, a low-angle antilistric thrust-slip fault model is used to simulate the ramp on the rupture portion of the Main Himalayan Fault. Based on descending Alos -2 and Sentinal -1 data, we invert for the coseismic slip models of the Gorkha earthquake and its largest aftershock, Kodari earthquake. In contrast to the inversion using Alos -2 or Sentinal -1 separately, the joint inversion of both data sets has stronger constraint for the deep slip and can obtain more details in Gorkha earthquake. The rupture depth obtained by joint inversion can be as deep as 24km underground, cutting across the locking line to the transition of locked and the creeping zone. The largest slip is as large as 4.5m appearing 17km underground and the dip angle is between 3°and 10°. Gorkha and Kodari earthquakes have the similar focal mechanisms, both of which are mainly thrusting, and yet some right-lateral slip component in Gorkha earthquake. The inversion results reveal that slip models of the Nepal mainshock and its largest aftershock are complementary in space and the Kodari earthquake occurs in the gaps of slip in Gorkha earthquake. The epicenter of the Kodari earthquake is just right in the transitive zone of the positive and negative Coulomb stress change, where the Coulomb stress change can reach 0.4MPa. We thus argue that Kodari earthquake has been triggered by the Gorkha earthquake.  相似文献   

THE STATIC STRESS TRIGGERING INFLUENCES OF THE 2015 M_W6.4 PISHAN,XINJIANG EARTHQUAKE ON THE NEIGHBORING AREAS          下载免费PDF全文

JIN Zhi-tong  WAN Yong-ge  HUANG Ji-chao  LI Xiang  ZHANG Shan-shan 《地震地质》2017,39(5):1017-1029

Based on the rupture models of the 2015 Pishan M_W6.4 earthquake and half space homogeneous elastic model, the Coulomb stress changes generated by the earthquake are calculated on the active faults near the earthquake region. The horizontal stress changes and the displacement field are estimated on the area around the epicenter. Results show that:(1)The Coulomb stress is decreased in the west of the western Kunlun frontal thrust fault(9.5×10³Pa), and increased in the east of the western Kunlun frontal thrust fault and the middle of the Kangxiwa faults. More attention should be taken to the seismic rick of the east of the western Kunlun frontal thrust fault; (2)Based on the analysis on the location of the aftershocks, it is found that most of the aftershocks are triggered by the earthquake. In the region of increased Coulomb attraction, the aftershock distribution is more intensive, and in the area of the Coulomb stress reduction, the distribution of aftershocks is relatively sparse; (3)The horizontal area stress increases in the north and south of the earthquake(most part of the Qaidam Basin and the northwest of the Qinghai-Tibet plateau), and decreases in the east and west of the earthquake(northern part of the Qinghai-Tibet plateau and eastern part of the Pamir Mountains). In the epicenter area, the principal compressive stress presents nearly NS direction and the principal extensional stress presents nearly EW direction. The principal compressive stress shows an outward radiation pattern centered on the epicenter with the principal extensional stress along the direction of concentric circles. The principal compressive stress presents NW direction to the west of the epicenter, and NE to the east of the epicenter. With the increase of radius, the stress level gradually decays with 10⁷Pa in the epicenter and hundreds Pa in the Maidan Fault which is in the north of the Qaidam Basin.  相似文献   

云南地震的潮汐应力触发机制及相关天体位置图像   总被引：15，自引：5，他引：10       下载免费PDF全文

吴小平  黄雍  冒蔚  胡家富  蒋骏  康国发  胡毅力 《地球物理学报》2005,48(3):574-583

通过计算云南163个地震震源处沿地震主应力方向的潮汐应力分量,分析了地震的潮汐应力触发力学机制.结果表明,所研究的地震中有62%受到了潮汐应力的触发作用. 在此基础上,对受到潮汐应力触发的地震发震时的天体位置特征进行了研究,得到了具有潮汐应力触发物理基础的地震时的月日黄经差、月日赤纬和月日天顶距的分布图像.图像显示,云南地区的地震在新月期间和上下弦附近较易受到潮汐应力的触发;受到潮汐应力触发作用的地震发震时刻的月日赤纬有明显的密集分布条带特征,地震频次在月、日天顶距分别为30°～140°和20°～140°范围内为平均优势分布区间.  相似文献   

NVST多通道成像观测系统的数据同步采集     

李玉艳  陈宇超  杨磊  柳光乾 《天文研究与技术》2015,(3)

为了在1 m红外太阳望远镜多通道高分辨率成像观测系统中实现多个波段太阳图像的同步高分辨率统计重建,需要1 m太阳望远镜多个观测通道图像采集系统同步。研究了如何采用CCD相机外触发工作模式、计算机PCI总线硬件中断技术和全球定位系统时间相结合实现1 m太阳望远镜多个观测通道图像的同步采集,并在现有的Hα和Ti O两个成像观测通道上搭建实验平台。通过一系列的波形时序测试,数据记录和分析等实验证明本文所采用的这一数据同步采集技术能满足1 m太阳望远镜多个观测通道图像的同步采集要求。  相似文献   

The large aftershocks triggered by the 2011 Mw 9.0 Tohoku-Oki earthquake,Japan     

《Journal of Asian Earth Sciences》2013

The Mw 9.0 Tohoku-Oki earthquake that occurred off the Pacific coast of Japan on March 11, 2011, was followed by thousands of aftershocks, both near the plate interface and in the crust of inland eastern Japan. In this paper, we report on two large, shallow crustal earthquakes that occurred near the Ibaraki-Fukushima prefecture border, where the background seismicity was low prior to the 2011 Tohoku-Oki earthquake. Using densely spaced geodetic observations (GPS and InSAR datasets), we found that two large aftershocks in the Iwaki and Kita-Ibarake regions (hereafter referred to as the Iwaki earthquake and the Kita-Ibarake earthquake) produced 2.1 m and 0.44 m of motion in the line-of-sight (LOS), respectively. The azimuth-offset method was used to obtain the preliminary location of the fault traces. The InSAR-based maximum offset and trace of the faults that produced the Iwaki earthquake are consistent with field observations. The fault location and geometry of these two earthquakes are constrained by a rectangular dislocation model in a multilayered elastic half-space, which indicates that the maximum slips for the two earthquakes are 3.28 m and 0.98 m, respectively. The Coulomb stress changes were calculated for the faults following the 2011 Mw 9.0 Tohoku-Oki earthquake based on the modeled slip along the fault planes. The resulting Coulomb stress changes indicate that the stresses on the faults increased by up to 1.1 MPa and 0.7 MPa in the Iwaki and Kita-Ibarake regions, respectively, suggesting that the Tohoku-Oki earthquake triggered the two aftershocks, supporting the results of seismic tomography.  相似文献   

汶川地震余震活动固体潮调制的统计分析   总被引：1，自引：1，他引：0  

李金  蒋海昆 《中国地震研究》2013,27(1):23-38

A statistical analysis on the Wenchuan aftershock activity triggered by tidal forces is systematically studied based on Schusters test, including earthquakes triggered by tidal force, tidal stress and tidal coulomb failure stress. The results show that a group of strong aftershocks which occurred at the end of July to early August in 2008 at the north of Wenchuan were obviously triggered by earth tide, the same conclusion is drawn by Schusters smooth test of the tidal force, tidal stress and tidal coulomb failure stress. In addition, the Wenchuan aftershock activity is obviously triggered by fortnight tide. In the north, the aftershocks happened more frequently in the first and last quarters of the moon, and in the south, the aftershocks happened more frequently in the first and last quarters of the moon and during the full moon.  相似文献   

矿井地质灾害要素与地质灾源体辨识评价     

夏玉成  王锐  马丽 《中国煤炭地质》2019,(2):51-55

矿井地质灾害严重威胁人民生命财产安全,深入认识成灾机理与相关要素,准确辨识地质灾源体并评价其致灾危险度,是煤矿防灾减灾保障安全开采不可或缺的基础性工作。本文通过分析矿井地质灾害典型案例,认为矿井地质灾源体是在煤矿采掘过程中具有发生矿井地质灾害潜在危险的地质体,包括煤层及其围岩以及存在其中的地下水与瓦斯等,具有地源性、隐蔽性、触发性、可控性等主要特征;矿井地质灾源体是矿井地质灾害的内因,煤矿采掘活动是触发矿井地质灾害的外因,地质影响因素和人为影响因素可能提高或降低矿井地质灾害的危险程度;并提出了辩识地质灾源体和评价其致灾危险度的具体方法。  相似文献   

Correlation between tides and seismicity in Northwestern South America: The case of Colombia     

《Journal of South American Earth Sciences》2019

We present the first systematic exploration of earth tides-seismicity correlation in northwestern South America, with a special emphasis in Colombia. For this purpose, we use a dataset of ∼167,000 earthquakes, gathered by the Colombian Seismological Network between 1993 and 2017. Most of the events are intermediate-depth earthquakes from the Bucaramanga seismic nest and the Cauca seismic cluster. For this purpose, we implemented a novel approach for the calculation of tidal phases that considers the relative positions of the Earth-Moon-Sun system at the time of the events. After applying the standard Schuster test to the whole dataset and to several earthquake samples (classified by time, location, magnitude and depth), we found strong correlation anomalies with the diurnal and monthly components of the tide (global log(p) values around −7.0 for the diurnal constituent and −12.1 for the monthly constituent), especially for the intermediate depth events. These anomalies suggest that around 16% of the deep earthquakes in Colombia may be triggered by tides, especially when the monthly phase is between 350°-10°. We attribute our positive results, which favor the tidal-triggering hypothesis, in contrast to previous negative ones to: 1) the size of our dataset, and 2) the method we used to calculate tidal phases. Anyone willing to reproduce our results or to apply our methodology to custom datasets can use the public information system tQuakes that we developed for this work.  相似文献   

Ms 8.7印尼地震面波在云南产生的远场动态即刻触发特征          下载免费PDF全文

解朝娣;  吴小平;  何家斌;  付虹;  杨周胜; 《地球物理学进展》2007,22(2)

通过云南区域数字测震台网对2004年12月26日Ms 8.7印尼大震的波形记录，着重考查了大地震面波在到达云南26个台站后的1小时传播过程中对云南及周边地区产生的远场动态触发效应，发现在面波作用的短短1小时内，云南的西部地区有明显的地震即刻触发现象，并对这些现象的特征及其相关因素进行了讨论.  相似文献   

地震触发研究中库仑应力随摩擦系数增加而增大的矛盾及其解决   总被引：2，自引：1，他引：1       下载免费PDF全文

朱守彪  缪淼 《地球物理学报》2016,59(1):169-173

近年来,通过计算库仑破裂应力变化研究地震触发及断层的相互作用,进而估计地震灾害已经成为国际上研究的热点.研究中,为考察库仑模型触发地震的效果,计算时往往要改变模型参数进行检验,特别是让有效摩擦系数从0.0到0.8之间变化.许多研究人员的计算结果表明,库仑破裂应力随着摩擦系数的增加而增大,即断层上摩擦系数的增大可以导致触发地震能力的提高.这显然与我们的常识相违背:摩擦总是阻碍断层滑动、抑制地震发生的,即断层面上的摩擦越大,地震越是难以被触发.文中通过对库仑破裂应力的计算公式进行详细分析后发现,之所以出现摩擦越大,地震越容易被触发的现象,其原因是研究者在计算中没有考虑在构造应力作用的环境里,摩擦系数本身的变化所带来的附加库仑应力变化.若某个地震使一个位于地下15km的典型断层面上的正应力增加2 MPa,如果只考虑静岩压力,当摩擦系数从0.3增大到0.4后,传统库仑破裂应力变化为0.8 MPa;而综合库仑应力变化则大约为-39.2 MPa.所以,若从整体上来分析断层在地震位错及摩擦系数变化所造成的综合库仑应力改变,就不可能出现库仑应力随摩擦系数增加而增加的不正常现象.由此可见,今后在利用库仑模型研究地震触发问题时,应综合考虑构造应力场及摩擦系数本身变化所带来的库仑应力变化.  相似文献