共查询到19条相似文献,搜索用时 343 毫秒
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结合观测井孔的水文地质条件、大气降水资料 ,深入剖析了华北地区水位、水氡的中期和转折型短期异常变化的直接原因 ,认为水位异常是由于降水量的增大与减少造成的 ,其形成机制主要为降水渗入补给 ;水氡异常的形成原因主要为降水渗入 -混合机制。进而提出“深浅构造的互动作用” ,用以解释流体异常与地震的关系 ,其论点是 :降水、地下水变化可诱发 (活化 )浅层的构造变动 ,而浅层构造活动又引发深部构造活动和地震的发生 ;反之 ,深部构造的活动和地震的孕育 ,使浅层岩石的应力增强 ,在降水、地下水的诱发作用下 ,可导致浅层的构造活动。降水引起的地下水异常是一种广义的地震前兆 相似文献
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依据地下流体存在趋势性异常和短临异常的基本观测事实, 提出“应力-应变效应说与水诱发异常说并重”的地下流体地震预报研究的科学思路。按照这一思路, 对地震地下流体观测的布网与选井原则提出了新的补充意见; 认为降水及其相关的地表水、地下水及大范围抽水等是地形变、地应变、地应力、水化及地电阻率等多种前兆异常产生的调制与诱发因素, 因而需要对原来的干扰因素的内涵作修正; 对地下流体前兆异常做了新定义及主要特征的归纳; 对于今后的工作, 提出了加强对地下流体短临前兆异常重现性的研究、加强对浅层地下流体的调制与诱发作用的研究以及积极促进地震地下流体学与其他相关学科的交叉与融合等建议。 相似文献
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地震临震预测预报的地应力方法 总被引:1,自引:0,他引:1
地震的发生与地球自转和极移的惯性力的作用密切相关,在惯性力的作用下地壳岩石内产生应力应变。用四方位地应变传感器观测水平地应力应变变化规律和临震前兆信息-地应力应变剧烈变化和地壳岩石出现微观断裂滑移及微观弹塑性应变应变波群,再根据主压应力作用方向和地质构造断裂带分布情况作综合分析,可以在临震前10 ̄72小时内初步预报出地震的时间、方向、地点和震级。对于震中距400公里内的中强地震预报对应率较高,根据 相似文献
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地下流体附加力源的研究新思路 总被引:5,自引:2,他引:5
提出地下流体储量变化是地震和多种前兆发生的附加力源的新观点,认为多种天然的和人为的因素所引起的地下流体储量变化。是一种附加力源。它通过流体载荷、孔隙压力、动水压力及化学腐蚀等作用,促进地壳的构造变形,并导致多种地震前兆异常的产生;而流体载荷和构造变形,又可促进地震的孕育和发生。对于降水、地表水、开采等因素造成的异常变化,不能简单地当做干扰来加以排除,它本身包含有大量的地震前兆信息。论述了该思路的科 相似文献
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Evelvn A.Roeloffs 《地震译文集》1990,9(1):22-36,56
本评论总结了作为地震前兆的地下水、石油或气体流量或压力异常的各种报告。在距震中数百公里的地方,曾观测到压力,流量的增加或降低,前兆持续时间从不到一天至一年以上。虽然在许多已发表的水文异常报告中没有记载排除非构造影响后的信息,一些最新研究明确地评价了大气压力,降雨量和地下水及石油的开发可能带来的影响。在中国1976年唐山地震和日本1978年伊豆大岛地震之前出现的一些异常,在本文中专门作了详细介绍,有必要作进一步检验。地下承压含水层的承压水位变化是定量表征地壳应变变化最有说服力的一种水文前兆。因承压水位 对固体潮汐的响应可测定了承压水位与地壳应变间的比例系数。该系数将控制着流体压力对任何地壳应力场的响应,流体流动的储集层是否完全处于这个地壳应力场中无关紧要。地下水位的变化对一些独立构造事件的反映,例如地震和非地震的断层蠕动,证明根据固体潮做出的校正值,可用于构造成因的地壳应变。地震产生的几种模式,可预测未来破裂平面上某一部分的加速稳定滑动。假若前兆滑动力矩低于或等于临震的力矩,那么震时体积应变就是前兆体积应变的上限。虽然地壳应变从多数承压水位异常报告中作出的只能是一种粗略的估算,但许多异常都出现在距震中150公里范围内的事实似乎与上述应变界限一致。与此相反,水位异常出现的震中距范围要比上述界限大几个数量级。显然,尽管水位监测能够提供地震产生过程的信息,但是要深入发展则取决于对数据的进一步积累与处理。 相似文献
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地下水中逸出气氡的研究:水化地震前兆新项目探索 总被引:4,自引:1,他引:4
本文通过对地下水中溶解氡和逸出氡的对比观测及其地震前兆的研究,阐明了地下水中逸出气氡对地壳岩石的变化具有较高的灵敏度,逸出气氡能够反映地壳岩石的潮汐变化。1989年大同阳高6.1级地震逸出气氡的变化突出、幅度大,表明它对地下应力微小变化能起到放大的作用。因此,逸出气氡作为新的地震前兆观测项目,具有广阔的发展前景。 相似文献
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地下水动态映震机制的试验与观测研究 总被引:3,自引:1,他引:3
本文根据一系列室内外试验与观测研究结果,论述了震前地下水位动态异常信息形成的四个基本环节:①地壳应力活动与含水层应力状态的变化,②含水层变形破坏与孔隙压力的变化;③孔压变化信息在井—含水层系统中的传递;④孔压变化信息在井孔地下水动态中的表现。在此基础上,提出了地下水动态映震特性的若干观点。 相似文献
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三向受压状态下地壳岩体的张性变形和张性破裂 总被引:2,自引:0,他引:2
本文叙述了处于三向受压状态的地壳岩体产生张性变形和张性破裂的原理,并以珠江三角洲地区为例说明:①岩体内应力集中点的浅部,可产生张性变形和张性破裂;②地质考察所观察到的张性或张剪性断裂,其断裂面上作用的正应力未必是拉应力,极有可能是压应力,但却一定是拉应变;③张性破裂引起的地震,震级较小,一般在4.5级以下,④地震引起的张性地裂缝的走向,就是震源应力场的主压应力方向。 相似文献
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Extraction of groundwater or hydrocarbons causes pore pressure gradients and soil deformation due to poroelastic coupling. Recent studies show that high-resolution engineering tiltmeters installed at shallow depth between 2 and 10 m resolve this deformation. Models using poroelasticity can describe the relationship between fluid extraction, pore pressure gradients and induced tilt for homogeneous and layered sedimentary half spaces. Faults intersecting a stack of sedimentary layers, for example in the Lower-Rhine-Embayment, are of fundamental impact to the groundwater flow system of an area. However, the fault’s hydromechanical effect on pump induced tilt and the pore pressure regime is still poorly investigated. We chose a comparatively simple approach to quantify anomalous pump induced tilt and pore pressure observed near a fault and close to the surface in a sedimentary subsoil. A PC-based Finite Element software is used to model poroelastic deformation, i.e. modelling vertical tilt and excess pore pressure in response to fluid extraction through a singular well. We compare numerical solutions for models with and without faults and show that a fault can modify symmetry and amplitude of the deformation field by more than a magnitude. We conclude that tilt and pore pressure measurements also at shallow depth can thus be biased by large subsurface structures like faults. Vice versa, these measurements may provide means to quantify hydromechanical effects caused by subsurface structures. However, depending on the geological setting, i.e. if pathways are established by a fault, the anomaly caused by the fault can also be small and hard to detect. Therefore, faults and geological structures like material boundaries have to be considered in poroelastic models carefully. For tilt surveys with a limited number of instruments in geologically well constrained areas these models allow the preselection of potential positions for tiltmeters where prominent field anomalies are expected. 相似文献
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地下水位与应变的相关性分析 总被引:3,自引:2,他引:3
根据弹性动态理论,变形介质中流体的动态,是由封闭含水层所受压力变化引起的。利用川-18井水位与仁和台钻孔应变资料,使用最大相关系数方法进行分析,结果表明在强震的孕育、发展的某一阶段,测点处的应力-应变场对于水位的变化起主导作用,这种相关性也可以作为异常判据。 相似文献
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高邮-宝应M4.9级地震是江苏陆地22年来发生的最大的地震。在震前2年发现省内流体井水位出现了群体性准同步变化,表现为震中区井水位的同步下降。本文重点分析了江苏省流体井水位变化特征,消除了气压、降雨和地下水开采的影响,用异常幅度与年变幅度比值、从属函数两种方法定量提取了震前异常变化,根据水位资料及其变化机理总结了震前水位的群体性异常特征,认为在弱震区井水位的群体性变化是分析判定地震前兆异常的有效指标。水位的群体性异常反映了震前区域应力场的调整,震源区为应力变化的集中区。 相似文献
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2004年印尼8.7级强震前昌黎台的远场电性异常特征探讨 总被引:1,自引:0,他引:1
分析了在2004年12月26日印尼8.7级地震前河北昌黎台记录到的自然电位及电场异常, 结果显示昌黎台自电位、 电场正常时段观测到的半日、 半月潮汐波周期变化在震前1个多月发生畸变, 周期消失, 变化幅度相应减小, 震后快速恢复, 且潮汐波记录比震前正常时段更加清晰。 该台地电阻率的观测结果显示起始下降变化比较平缓, 震前一周左右, 变化加剧, 出现多次阶变。 究其原因, 在强震发生前断层的蠕滑作用导致孔隙压力变化, 产生一种可以在岩石中传播的应变波, 由于台站下方岩土层对小应变信号具有很好的放大作用, 所以记录到了这种小幅度的应变波, 也就是远场的静态应变效应。 随着地震临近, 应力作用加强, 远程应变波引起台站下方水位、 水化学性质以及岩石孔隙度、 渗透率等的改变, 导致电阻率、 电场大幅度的阶变, 这反映了远场应变波的动态效应。 当然就异常幅度而言, 应变波的效应还嫌弱一些, 因此昌黎台异常变化可能还叠加了震源区激发的电磁波。 相似文献
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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
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CHARACTERISTICS OF SATELLITE GRAVITY FIELD AND SEISMOGENIC MECHANISM IN THE LONGMENSHAN FAULT ZONE 下载免费PDF全文
Longmenshan fault zone is a famous orogenic belt and seismic zone in the southeastern Tibetan plateau of China. The Wenchuan MS8.0 earthquake on May 12, 2008 and the Ya'an MS7.0 earthquake on April 20, 2013 occurred in the central-southern part of Longmenshan fault zone. Because of its complex geological structures, frequent earthquakes and special geographical locations, it has attracted the attention of many scholars around the world. Satellite gravity field has advantages in studying gravity field and gravity anomaly changes before and after earthquake. It covers wide range, can be updated regularly, without difficulty in terms of geographical restrictions, and is not affected by environmental factors such as weather, terrain and traffic. Therefore, the use of high-precision Earth satellite gravity field data inversion and interpretation of seismic phenomena has become a hot topic in earth science research. In order to understand satellite gravity field characteristics of the Longmenshan earthquake zone in the southeastern Tibetan plateau and its seismogenic mechanism of earthquake disasters, the satellite gravity data was used to present the terrain information of the study area. Then, by solving the regional gravity anomaly of the Moho surface, the crustal thickness of the study area was inverted, and the GPS velocity field data was used to detect the crustal deformation rate and direction of the study area. Combining the tectonic setting of the Longmenshan fault zone and the existing deep seismic sounding results of the previous researchers, the dynamic characteristics of the gravity time-varying field after the earthquake in the Longmenshan earthquake zone was analyzed and the mechanism of the earthquake was explored. The results show that the eastward flow of deep materials in the eastern Tibetan plateau is strongly blocked at the Longmenshan fault zone. The continuous collision and extrusion process result in a "deep drop zone" in the Moho surface, and the long-term stress effect is conducive to the formation of thrust-nappe and strike-slip structures. The Longmenshan earthquake zone was in the large-scale gradient zone of gravity change before the earthquake, the deep plastic fluid material transport velocity differed greatly, the fluid pressure was enhanced, and the rock mechanical strength in the seismic source region was weakened, which contributed to the intrusion of crustal fluid and the upwelling of the asthenosphere. As a result, the continuous accumulation of material and energy eventually led to continuous stress imbalance in the deep part and shear rupture of the deep weak structure, causing the occurrence of the thrust-nappe and strike-slip earthquake. 相似文献