Response spectral attenuation relationships for Singapore and the Malay Peninsula due to distant Sumatran‐fault earthquakes     

Kusnowidjaja Megawati  Tso‐Chien Pan  Kazuki Koketsu 《地震工程与结构动力学》2003,32(14):2241-2265

As part of the effort to assess the seismic hazards of Singapore and the Malay Peninsula, representative ground motion prediction models have to be established. Seven existing attenuation relationships developed for shallow crustal earthquakes in stable continent and active tectonic regions are examined, and they are found to consistently over‐predict the ground motions of Sumatran‐fault earthquakes recently recorded in Singapore. This may be attributed to the differences in the regional crustal structures and distance ranges considered. Since the number of recorded ground motions in the region is very limited, a new set of attenuation relationships is derived based on synthetic seismograms. The uncertainties in rupture parameters, such as stress drop, focal depth, dip and rake angles, are defined according to the regional geological and tectonic settings as well as the ruptures of previous earthquakes. Ground motions are simulated for earthquakes with Mw ranging from 4.0 to 8.0, within a distance range from 174 to 1379km. Besides magnitude and distance, source‐to‐station azimuth is found to influence the amplitudes of the ground motions simulated. Thus, the azimuth is taken as an independent variable in the derived ground motion attenuation relationships. The Sumatran‐fault segments that have the potential to generate a specified level of response spectral accelerations in Singapore and Kuala Lumpur are identified based on the newly derived ground motion models. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

青岛市地震前兆观测系统的映震能力     

潘元生  刘静  王晋生 《地震地磁观测与研究》2003,24(4):19-25

概述了青岛市地震前兆观测系统，结合1992年以来青岛周边地区发生的4次Ms≥5．0地震分析了前兆观测的映震能力，以期对青岛市地震监测预报提供参考。  相似文献   

含弱层岩石破裂前兆规律的数值模拟分析   总被引：3，自引：0，他引：3  

梁正召  唐春安  杨天鸿  焦明若 《地震》2003,23(3):65-70

利用数值模拟软件RFPA^2D模拟了含断层带岩体的破裂过程及其应力、位移和声发射前兆的复杂性和规律性。模拟结果表明。应力和位移在同一点的变化情况不同。不同点在同一时刻的位移和应力也不同。应力、位移和声发射在时间和空间上的分布呈现出一系列复杂图像。但是这些复杂变化并不是随机的。都遵循相同的物理过程和一定的演化规律。应力和位移的变化量比应力和位移本身更重要。同时这些变化的大小和断层结构紧密相关。而单一物理量的异常并不一定预示着必然的破裂。  相似文献   

地磁日变规律的破坏与地震的关系研究   总被引：3，自引：3，他引：3  

王亶文 《地震地磁观测与研究》2003,24(1):1-6

2001年11月14日昆仑山8.1级地震前，震中距为400km的格尔木台地磁垂直分量Z的日变形态发生异常，1998年1月10日张北Ms6.2地震前，北京台和静海台Z的日变形态也有异常。但是，2000年1月15日云南姚安Ms6.5地震和1月27日丘北Ms5.5地震前，通海台的Z分量无异常。这可能与地震的复杂性有关。  相似文献   

综合治理是地震前兆台站防雷保护的必由之路     

陈德福 《国际地震动态》1998,(4):17-19

雷电灾害是气象自然灾害的一个组成部分。地震前兆台站的防雷问题是一个十分重要的问题,然而防雷技术目前在国际上尚未过关。经过多年的研究与实践,该文作者及其同事认为,综合治理是地震前兆台站防雷保护的必由之路。  相似文献   

Study of the Ability of the Magnetotelluric Method to Monitor Earthquakes     

Jin Guangwen  Sun Jie  and Wang JijunInstitute of Geology  SSB  Beijing  China 《中国地震研究》1998,(2)

Most earthquakes on the Chinese mainland have occurred within the depth range of 10-25 km,which is usually called the seismogenic layer.According to the rule of penetration depth,the precursor of the electric anomaly,which is transferred from the seismogenic layer to the Earth's surface,should be very weak,but the ability to monitor earthquakes can be greatly improved if the field precursor effect is taken into consideration because of expansion of the electric anomaly area.The results of one-and two-dimensional modeling computations are consistent with the observed fact that the apparent resistivity decreases before earthquakes.This provides good evidence for our inference.The corresponding physical mechanism is that the conductivity of the anomaly area may be increased by the rock dilatation and fluid permeation due to the stress effect during the developing process of earthquakes.  相似文献   

Variation of Electromagnetic Tornogram Before and After Earthquakes     

Sun Cichang  Wang Xusheng  Liu Qingfang  Tao Yulu  Yu Ping  and Feng RuiInstitute of Geophysics  SSB  Beijing  China Department of Geophysics  Peking University  Beijing  China Seismnlogical Bureau of Hunan Province  Changsha  China Center for Seismological Data  Information  SSB  Beijing  China 《中国地震研究》1998,(2)

Cross-well electromagnetic tomography has been used to monitor the changes of the abso rption coefficient of electromagnetic waves before and after earthquakes for 5 years at Dahuichang fault since 1992.It has been found that 3 months before the occurrence of moderately strong earthquakes(ML≥4.0,△<210 km),several special changes in tomogram appeared as follows:The mean-value of the absorption coefficient dropped about 10% compared with the annually decreasing tendency; the mean difference of pixels suddenly decreased or increased in different directions; and the entropy of the paragenic matrix in a tomogram decreased and the number of low absorption pixels increased.It is inferred that such changes in electromagnetic tomograms are attributed to the variation of micro-cracks and porosity in rocks.Electromagnetic tomography can be studied as a new technique to detect earthquake precursors.  相似文献   

张北6.2级地震震兆特征的综合分析   总被引：1，自引：0，他引：1  

张清荣  平建军 《华北地震科学》1998,16(3):15-27

介绍了１９９８年１月１０日张北６．２级地震前的地震活动情况和前兆观测异常现象,并从实际观测资料出发,综合分析了前兆异常的总体特征,以及伴随地震孕育过程而表现出来的各各前兆场的时、空、强变化特征及其它们之间的相互联系,以追踪方式探讨了长、中、短、临的阶段性变化,通过对所掌握的河北省各种前兆资料进行剖析,可知张北地震前前兆资料的变化,在一定程度上能够反映出一些有意义的震兆信息,但以此给出准确的短临预报  相似文献   

非潮汐变形中地震信息的检测     

牛安福  李旭东  吴静  柯丽君 《大地测量与地球动力学》1998,(1)

根据过程的线性与非线性、平稳与非平稳、确定与随机等特征,讨论了非潮汐变形的非稳态模型和异常的幅度与频度特征,运用Ｆ检验和动态场分析系统理论,对异常的合成、定量化及识别准则进行了研究。所提出的新的“异常”概念包含了动态过程的幅度和频度信息。结果表明,异常出现后,在一定区域范围和时间段,绝大多数情况下伴有地震或震群发生。  相似文献   

贺兰山东麓断裂带流动短水准测量资料分析     

马禾青  柴炽章 《大地测量与地球动力学》1998,(2)

分析了宁夏流动短水准测量资料,结果表明在大多数宁夏及其邻近地区的中强地震前有高信度的地震异常出现。  相似文献