An eyewitness account of the Bhuj earthquake     

M. K. Gupta 《Journal of Earth System Science》2003,112(3):347-352

The occurrence of a severe earthquake is a rare event with its effect localized in a limited region. There are no prior indications of its occurrence too; hence experiencing such an event is just a matter of chance, which the author had by virtue of his posting at Bhuj. This paper presents a detailed account of observations made in the wake of the Bhuj earthquake of January 26th 2001, describing physical and mental reactions during the earthquake, the post-quake scenario, the nature and cause of damage to buildings, the trend of aftershocks, various deformities, including ruptures and fissures on the surface of the earth, etc. which may be useful for a detailed study of the seismological activity in the region.  相似文献   

2013年甘肃岷县—漳县M 6.6地震序列精定位研究     

梁姗姗  徐志国  杜广宝  刘敬光  张广伟 《地震地磁观测与研究》2017,38(2):12-16

采用双差定位法对2013年7月22日甘肃岷县—漳县交界地区M 6.6地震及主震后48小时内388次余震序列进行重新定位,得到350个精定位地震数据。结果表明,余震优势展布以北东向较大倾角的铲状结构为特征,长约12 km,以主震为中心两侧对称分布;震源深度主要集中在4—10 km范围内,但余震震级由10 km左右深度的3—4级向3 km深度之上近地表的2—3级迁移变化;余震分布清晰呈现双层结构,较深层分布在4—10 km深度,而较浅层分布3 km深度之上,2层之间地震分布较少。分析认为,浅层地震可能为本次地震地表破坏较强原因之一。震源深度剖面显示,破裂面向NE倾斜,推测此次地震的发震断裂为临潭—宕昌断裂。  相似文献   

The 2003 M_w 7.2 Fiordland subduction earthquake, New Zealand: aftershock distribution, main shock fault plane and static stress changes on the overlying Alpine Fault     

Peter McGinty  Russell Robinson 《Geophysical Journal International》2007,169(2):579-592

The 2003 August 21 Fiordland earthquake ( M _L7.0, M _W7.2) was the largest earthquake to occur in New Zealand for 35 yr and the fifth of M6+ associated with shallow subduction in Fiordland in the last 15 yr. The aftershocks are diffuse and do not distinguish between the two possible main shock fault planes implied by the Harvard CMT solution, one corresponding to subduction interface thrusting and the other corresponding to steeply seaward dipping thrusting. The distinction is important for calculating the induced stress changes on the overlying Alpine Fault which has a history of very large earthquakes, the last possibly in 1717. We have relocated the aftershocks, using data from temporary seismographs in the epicentral region and the double difference technique. We then use the correlation between aftershock hypocentres and regions of positive changes in Coulomb Failure Stress (CFS) due to various candidate main shock fault planes to argue for concentrated slip on the shallow landward dipping subduction interface. Average changes in CFS on the offshore segments of the Alpine Fault are then negative, retarding any future large events. In our models the change in CFS is evaluated on faults of optimal orientation in the regional stress field as determined by inversion of P -wave polarities.  相似文献   

A damage mechanics model for power-law creep and earthquake aftershock and foreshock sequences   总被引：2，自引：0，他引：2  

Ian G. Main 《Geophysical Journal International》2000,142(1):151-161

  相似文献   

强震动记录编目——以汶川余震流动观测记录为例   总被引：2，自引：2，他引：0  

任叶飞  温瑞智  周宝峰 《震灾防御技术》2011,6(4):406-415

相比技术较成熟的测震编目工作,我国强震动记录编目工作技术亟待完善,缺乏规范化的编目流程及方便实用的编目软件,处理数据经验不足.本文以汶川余震流动观测中获取的强震动记录编目为例,阐述了合理的强震动记录编目方法,通过对万余条强震动数据处理的结果表明,该方法提高了强震动记录编目的效率及可靠性.同时本文对强震动记录编目的标准化...  相似文献   

A novel method for discovering spatio-temporal clusters of different sizes,shapes, and densities in the presence of noise     

《International Journal of Digital Earth》2013,6(2):138-157

The discovery of spatio-temporal clusters in complex spatio-temporal data-sets has been a challenging issue in the domain of spatio-temporal data mining and knowledge discovery. In this paper, a novel spatio-temporal clustering method based on spatio-temporal shared nearest neighbors (STSNN) is proposed to detect spatio-temporal clusters of different sizes, shapes, and densities in spatio-temporal databases with a large amount of noise. The concepts of windowed distance and shared nearest neighbor are utilized to define a novel spatio-temporal density for a spatio-temporal entity with definite mathematical meanings. Then, the density-based clustering strategy is employed to uncover spatio-temporal clusters. The spatio-temporal clustering algorithm developed in this paper is easily implemented and less sensitive to density variation among spatio-temporal entities. Experiments are undertaken on several simulated data-sets to demonstrate the effectiveness and advantage of the STSNN algorithm. Also, the real-world applications on two seismic databases show that the STSNN algorithm has the ability to uncover foreshocks and aftershocks effectively.  相似文献   

Calculation of Calibration Functions and Explosive Aftershock Magnitudes in the Near Field     

Li Xuezheng  Wang Haijun  Lei Jun 《中国地震研究》2003,17(4):305-314

The current calibration function used in calculating the magnitude of natural earthquakes within 5km is a constant; a fact that causes several serious difficulties for the calculation of the magnitude of small and shallow-focus earthquakes. According to the attenuation law of explosions and the propagation theory of elastic waves, the calibration function is calculated for near field quakes from 0kin to 5kin. Magnitudes of two aftershock sequences are calculated. The magnitudes of most explosion earthquakes are small, ranging mainly from magnitude -0.5 to 1.0. The M-t chart of the explosive aftershocks is completely different from that of strong earthquake aftershocks. It not only shows positive columnar lines indieatJng large magnitudes but also short negative columnar lines indicating small magnitudes.  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   

预报能力评分R值的应用     

吴平静  马莉  赵树贤 《国际地震动态》2012,(10):30-32

许绍燮院士1973年提出的预报能力评分R值,除了用于地震预报效能评价外,还可用于判断物理量的聚集程度和关联信息评价。本文给出了3个应用实例:余震序列响应周期扫描,确定太阳风磁场优势聚集方向,余震序列与其震前太阳风磁场方位的关联性评价。  相似文献   

玉树M_S7.1级地震部分余震重新定位及发震构造分析   总被引：4，自引：0，他引：4       下载免费PDF全文

刘巧霞  杨卓欣  莘海亮  李源  沙成宁 《地球物理学报》2012,55(1):146-154

综合利用玉树震区应急流动台站观测数据和青海地震台网固定台站观测数据,依据最新的人工地震宽角反射/折射剖面的速度模型,采用Hypo2000地震定位法,对2010年4月18日至4月29日期间玉树震区发生的部分余震进行了重新定位.重新定位后,震源位置的水平和垂直方向平均误差分别为1.35 km和4.68 km,走时残差为0.49 s.震源深度分布范围为1.48～19.85 km,平均震源深度为10.28 km.定位研究结果表明:玉树地震余震沿北西-南东向的甘孜-玉树断裂带的北支,即玉树-隆宝断裂分布,长约97 km.余震分布特征在主震(微观震中)两侧存在差异,可能反映了两侧构造特征存在差异.截止到4月29日,主震东南仍是应力的主要释放区域,余震强度大且活动密集的区域位于主震东南距主震约5 km、横向范围约20 km.主震破裂区的大部分应力在主震过程中得以释放,主震时应力未释放的区域成为主要的余震分布区.余震的连续发生可能已造成主震破裂区相互连通,且破裂范围向西北方向扩展.玉树主震及余震的发震构造为甘孜-玉树断裂的北支,即玉树-隆宝断裂段,断层性质为北东倾向的高角度左旋走滑断层.发震断层的倾角和宽度在帮洞两侧有所不同,帮洞以东发震断层宽度约为12 km,倾角约为83°;而帮洞以西发震断层宽度约为6.5 km,断层倾角约减缓为63°.  相似文献