Application of the Load/Unload Response Ratio Theory to Predictions of Moderate Earthquakes (7.0>M≥6.0)

The variation in load/unload response ratio before some moderate earthquakes is analyzed based on the theory of the load/unload response ratio.The results show that the load-unload response ratio increases noticeably before moderate earthquakes,and there are three kinds of patterns in which the load/unload response ratio varies and the duration of noticeable increase in load/unload response ratio ranges from half a year to two years.     

1996年北京顺义Ms4.0地震的前兆特征及解释

通过对顺义地震的序列特征、地震活动与加卸载响应比等前兆异常的时空演化等方面的研究,认为顺义的地震为一次非前光性震群;震前存在地震条带、３级以上地震东移、南北向小震条带、响应经异常地震活动异常以及以顺义板桥水位为主要的破年变等前光异常,这些前光异常的时空演化过程表现出与中强地震类似的具有一定力学基础的三阶段特征,这些结果对北京及邻区的中等以上地震的预测研究与短临跟踪工作都具有重要参考作用。     

The tempo-spatial evolution characteristics of the load/unload response ratio before strong earthquakes in California of America and its predicting implications

IntroductionThetheoryoftheload/unloadresponseratio(LURR)hasbeenproposedabouttenyears(YIN,YIN,1991).Thetheoreticalstudieshavebeendevelopedfromtheoreticalanalysistorockexperimentandnumericalsimulation(SHI,etal,1994;WANG,etal,1999).IncharacteristicsoftheLURRanomalies,atfirst,weonlyanalyzedthevariationoftheload/unloadresponseratio(LURR)versustimeinthefixedregions(YIN,etal,1994;YIN,etal,1995).Thenwestudiedthetempo-spatialevolutionfeaturesoftheLURRintheseismogenicprocessanddevelopedthe…     

中强地震前承压井水位固体潮和地震活动响应比的变化

以山西省大同—阳高２次地震与忻州地震为例,利用尹详础教授的加卸载响应比理论,研究了山西承压井水位与含水层固体潮体应变的响应比、地震活动的响应比变化特征。表明,在多数地震前,井水位的响应比有大于背景值１、地震活动大于背景值２的高值异常变化,且具有突变特点。说明响应比方法对山西省中强地震有较好的预报效能     

The spatial temporal evolution characteristics of the load／unload response ratio（LURR） and its implications for predicting the three elements of earthquakes

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祁连山地震带两次中强地震前的加卸载响应比异常

研究了祁连山地震带两次中强地震前的加卸载响应比异常特征，讨论了基于天然地震序列的样本条件对加卸载响应比计算结果的影响，提出处理序列中4．0级以上地震的新方法。     

The Experimental Simulation of Rocks on Load/Unload Response Ratio for Earthquake Prediction

The load/unload experiments on rock failure under pressure have been carried out in Material Test System (MTS) in the Laboratory for Non-linear Mechanics of Continuous Media (LNM), Institute of Mechanics, Chinese Academy of Sciences, and load/unload response ratio (LURR) values with strain as response (i.e. inverse elastic constant as response rate) have been obtained. The experimental results are in accordance with theoretical results and those in real earthquakes: LURR rises just before rock failure. So LURR can be used as the precursor of rock failure and earthquake prediction.     

加卸载响应比理论在包头西MS6.4地震预报中的应用

用加卸载响应比理论对包头西 MS6 .4 地震前加卸载响应比随时间的变化进行了较详细的研究.结果表明,震前加卸载响应比有较明显的上升异常.异常出现的时间和异常幅度大小不但与所选择的区域和震级下限有关,而且还与发震构造和控震构造有关.异常与地震的对应关系表现为:上升异常出现、转折并恢复到正常值附近时发震.异常持续时间,短的1 a 以上,最长4 a 左右.     

Prediction and verification of earthquakes induced by the Xiluodu hydropower station reservoir

Research has been conducted on reservoir-induced earthquakes in China since the Xinfengjiang reservoir-induced earthquakes in the 1960s. Regulations now require the risk of reservoir-induced earthquakes to be evaluated in the pre-research stage of all hydropower projects. Although nearly 40 cases of reservoir-induced earthquakes have been reported in China, analyses comparing the changes in seismic activity following reservoir impoundment with predictions are rare. In this study, we compared seismic activities observed in the reservoir area before and after the impoundment of the Xiluodu hydropower station in terms of the spatial distribution, frequency, and focal depths of the earthquakes, and clarified the correlation between their frequency/timing and reservoir level after impoundment. We then concluded that the seismic events in the head region were karst-type earthquakes, while those in the second segment of the reservoir were tectonic earthquakes. The spatial distribution of the earthquake epicenters and the seismic intensities validated some of the results for the reservoir-induced seismic risk assessment for the Xiluodu hydropower station, indicating that the proposed earthquake triggers and predictive models are reasonable. This study can provide a valuable reference for investigating the mechanism (s) of reservoir-induced earthquakes, revising reservoir-induced earthquake hazard assessment codes, and predicting the hazard zones of reservoir-induced seismicity under similar conditions.     

加卸载响应比在震后趋势估计和震前中短期预测中的应用

以加卸载响应比方法在青藏高原北部地区几次中强地震预报中的应用为例 ,讨论了天然地震序列下样本条件对加卸载响应比Y值的影响 ,探讨了该方法在震后趋势估计和震前中短期预测应用中的若干问题 ,以探索提高响应比方法预测地震的成功率 .     

井水位气压加卸载响应比

将加卸载响应比的理论和方法引入到地下水位资料中．根据承压井水位的气压效应，将地球表面大气压的随机变化做为加载和卸载的力源，从理论上论征可以应用大气压变化而引起的井水位变化来计算加卸载响应比，并给出了计算方法．以此方法计算了1995年9月20日山东苍山Ms5．3地震前后鲁14井、鲁15井水位的气压加卸载响应比，分析了其变化特征。     

天津地区井水位固体潮观测的加卸载响应比变化与附近地震关系的研究

用加卸载响应比的方法,处理了天津地区2002年以来静海地震台井、宝坻地震台井、高村井和张道口地震台深井地下水位固体潮观测数据,并以加卸载响应比计算值的2倍方差作为异常判定指标,将天津及周边地区发生的M_L≥4.0地震参数与井水位固体潮响应比异常变化对比分析。结果表明:该区4口地下水位固体潮井的加卸载响应比异常变化与附近的地震活动有较好的对应关系。从而证明,利用井水位固体潮观测的加卸载响应比是一种能有效识别和提取地震前兆的方法。     

新疆中强地震前加卸载响应比时空演化特征分析与检验

加卸载响应比是一种刻画震源区介质损伤程度的物理学参数,它通过随时间的变化来反映地震孕育的过程来进行地震预测。通过对1990—1999年新疆地区部分中强地震前加卸载响应比时空演化特征进行分析,并基于该理论得到孕震积分的概念应用于震例中。结果表明:中强震震前在震中附近可能存在多个高加卸载响应比值区,它们大致围成椭圆状或环状,地震通常发生在异常高值波动或减弱的过程中;异常峰值至发震时间比理论时间要短,这可能表明新疆地区构造活动剧烈,孕震周期较短。     

水库诱发地震震级预测的统计研究

于收集到的全球102例水库及已发地震的资料,应用隶属函数方法综合分析了水库基本属性、震中区岩性、库坝区基本烈度和震中区断层类型等与水库诱发地震之间的关系,从统计学角度给出了水库诱发最大地震震级的判定方法．通过回溯检验和费舍尔判别检验给出了预测震级的相对误差和正确识别率,总体预测效果较好,可为将来水库的设防和最大地震震级的判定提供统计学上的依据．      

上海地区地磁场加卸载响应比与地震

应用地磁场加卸载响应比方法,计算处理了佘山地震台１９８１～１９９７年和崇明地震台１９８３～１９９７年的地磁场垂直分量日变幅资料,研究了１９８０年以来上海邻区发生的３次中强地震前的响应比值Ｐ（Ｚ）的变化特征,找出了该方法适用于上海地区的地震中短期判定指标,以指导地震趋势判断和提高综合预测水平     

地震预报可能性的物理分析

分析了岩石的破裂过程,认为地震是非线性系统失稳的结果,加卸载响应比反映了岩体趋近应力峰值的程度,其异常仅标志着某地区具有发生地震的危险性,指出临震预报的困难在于地震往往发生在应力峰值之后,同时还讨论了临震预报的可能性。     

唐山两次中级地震前后地下水位固体潮加卸载响应比的变化

本文将加卸载响应比的理论和方法引入到地下水位潮汐资料计算中来,从岩石的应变与应力的非线性响应分析了井水位固体潮加卸载响应比的物理。     

2014年鲁甸MS6.5地震前后地震活动性

2014年 8月3日在云南省鲁甸县发生M_S6.5地震,造成了巨大的人员伤亡和财产损失.关于鲁甸地震的起因,特别是鲁甸地震与溪洛渡水库之间的关系存在一些争议.分析中强地震前后地震活动性的变化可以为判断主震起源提供一定的依据.然而,由于鲁甸地震震中附近固定台站数目少、台站距离震中远及主震后尾波干扰等因素的影响,会造成地震目录的缺失,从而可能影响地震活动性的可靠分析.为了获得更加完备的地震目录,本文采用模板匹配方法对鲁甸地震前后小地震进行了搜索和识别.以台网目录中的541个事件作为模板,在主震之前33天到主震后5天的连续波形中识别出991个未在目录中列出的地震,使余震的完备震级从1.8降低到1.3.根据检测目录得到主震前33天内的b值为1.04±0.18,余震的b值在震后5天内由0.5左右逐渐上升至0.9附近并保持稳定;根据2009年到主震发生前的台网目录得到该区域的背景b值为0.93±0.04.即鲁甸地震前后区域地震活动b值均与背景b值接近,这与典型水库诱发的中强震具有的b值特征不相符.同时通过进一步分析台网目录,未发现溪洛渡水库蓄水前后研究区域内的地震活动性存在明显变化,这也与典型水库诱发地震区域的地震活动性特征不相符.综合以上结果,我们认为2014年鲁甸M_S6.5地震不具有典型水库诱发地震的特征.     

山西中强地震前波速比异常研究

本文分析了大同－阳高６．１级（１９８９），５．８级（１９９１），忻州５．、１级（１９９１），侯马５．１级（１９８９）以及太原，运城１９８９－１９９１年几个４．０级左右地震前后的２０２次小震资料。结果表明：这些主震前都存在明显的地震波速异常变化，纵横波速比Ｖｐ／Ｖｓ表面为下降－回升的异常形态，负异常持续时间与震级大小相关；主震在岁异常结束后发生，滞后时间随区域地震震源深度增大而延长。同时，主震前还存     

Reservoir-induced seismicity in the Longtan reservoir, southwestern China

A pronounced increase in seismicity started in and around Longtan reservoir, southwestern China after October 1, 2006 when it began the impoundment, and by the end of May 14, 2010, about 3,233 earthquakes with ?0.6?≤?M _L?≤?4.2 had been located. This seismicity which occurred in five clusters mainly concentrated in the areas where few earthquakes had occurred before the first filling. There were four water filling periods in the Longtan reservoir, and the observed reservoir-induced seismicity (RIS) shows a strong correlation with the filling cycles. After the first filling, there appears to be an instant undrained response due to an elastic response to the reservoir load in the third and fourth cluster. Then, this seismicity is followed by a delayed, drained response due to pore pressure diffusion, with the seismicity migrating outwards in one or more directions in the second and third filling period. The seismic diffusivity (α _s) we estimated is about 4.54?×?10⁵?cm²/s. The activity levels in the five clusters are different due to differences in the structures and permeabilities of the faults. The delayed seismic response to the filling in the third cluster was due to the combined effects of the lack of local fault intersecting the reservoir and lower permeability of the rock. The b value we obtained for reservoir-induced events was significantly different and higher than that of pre-impoundment natural tectonic earthquakes in the Longtan reservoir. The results of relocated earthquakes based on double difference earthquake location algorithm showed that their focal depths were mainly shallower than about 10 km and the distribution of relocated RIS in four clusters had no relation with these intersecting faults in the Longtan reservoir except the fifth cluster. All these characteristics of RIS in the Longtan reservoir indicate that they may relate to the coupled poroelastic response that includes both pore pressure diffusion and an undrained response, but the pore pressure diffusion and the water permeation appear to play a more important role on inducing the earthquakes in Longtan reservoir.