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991.
992.
通过回忆共和地震前出现的反常现象,认为地震发生前有预兆,并通过这些预兆使人们提高警惕,做好地震预报、地震应急的准备工作。 相似文献
993.
地震前兆数据库软件的使用 总被引:2,自引:0,他引:2
新疆地震前兆台网中心通过远程拨号的方式采集各台点的数字化数据,运用前兆通讯、数据服务等软件实现数据的格式转换、入库及基本数据查询等前兆数据库的各种操作,方便了分析人员的使用。初步建立起地震前兆数据库。 相似文献
994.
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
995.
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
996.
997.
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
998.
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
999.
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
1000.
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