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提出了地震前兆研究是地震预测研究的基础,其研究的对象是个案. 地震前兆研究受到的最大限制,是对个案的观测严重不足. 龙门山断裂带西南段仍然存在发生强震的危险性,应该不失时机地在那里建立密集的钻孔应变观测网. 四分量钻孔应变仪是我国发明的、 已经可以与地震仪和GPS相提并论的观测仪器. 对地震前兆研究而言,钻孔应变观测在理论和实践两方面都具有优越性. 本文认为: 钻孔应变观测点应该建在应力集中的构造部位; 应该在钻孔选点和仪器安装两方面采取措施以保证观测点建设的成功; 四分量钻孔应变观测最重要的是数据自洽; 钻孔应变观测不必追求很深; 观测点建设不必进行绝对应力测量. 相似文献
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唐山地震前,地震主断裂附近的陡河站和赵各庄站都观测到垂直于该断裂方向的地应力张性跳动,根据地震前跨该断裂的水准观测数据,认为这是地壳沿该断裂的局部凸起使地表附近沿该方向出现张性裂隙的反映。在其扩展的过程中,测量元件与张裂隙前沿的相对位置将发生变化。通过对张裂隙前沿附近应力场的分析,不仅可以说明当裂隙前沿在元件附近经过时与裂隙垂直的元件测值为什么突然上升后又下降恢复到原来的水平,而且可以说明另外两个与该元件呈60°交角的元件的同时刻测值变化不大的原因。 相似文献
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一、引言地震是当地壳内的应力积累超过岩石破裂强度引起大范围的岩体破裂造成的。因此,对地应力(应变)及其变化的观测一直受到人们的特别关注。我国用钻孔地应力-应变观测进行地震预报,是1966年在李四光的倡导下开展起来的,已经有30多年的历史。30多年来,经过众多研究人员的不懈努力,钻孔地应力-应变观测在理论上和技术上不断改进,日臻完善。最近10多年来,钻孔地应力(应变)观测系 相似文献
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Observations of remote coseismic stress step-changes 总被引:2,自引:0,他引:2
The study on stress triggering and stress shadow is a frontier subject of current seismologic research. One of the problems presently encountered is the lack of reliable observation of real coseismic stress changes at locations remote to the epicenter. At Changping Station near Beijing, coseismic step-changes were recorded for the Mw6.3 Zhangbei quake on 10 January, 1998 and the Mw5.8 Zhangbei quake on 11 March, 1999, by a RZB borehole component strainmeter. Based on analyses of these recordings, this paper shows observed coseismic step-changes of the horizontal component of strain tensor. The strain step-changes reach the order of 10?8 and, correspondingly, stress step-changes reach as high as 10?4 MPa. The results are significantly higher than linear elastic theoretical values. However, as self-checking can be carried out with the 4 groups of data recorded by the 4-component strainmeter, it has proved that the results are reliable. 相似文献
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Application of observed strain steps to the study of remote earthquake stress triggering 总被引:1,自引:0,他引:1
IntroductionModernseismologysuggeststhatearthquakesarecausedbyfaultslippingtriggeredbytec-tonicstressesaccumulatedtoacertainextent;andthefaultslip,inturn,releasesstresses.Infact,whenanintensivequakeoccurs,thefracturingoftheseismogenicfaultdoesnotleadtothereleaseofallthestressesbut,accordingtothegeometricrelationsamongthefaults,releasesstressesonsomeofthefaultstomakethemmorestable,whileaccumulatesstressesonotherfaultstomakethemtendtoslip.Asanapproximation,thestrengthofthefaulttobeysByerleylawby… 相似文献
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