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1976年唐山7.8级地震前气象要素的异常变化 总被引：2，自引：0，他引：2
系统研究了唐山地震前气象要素的异常变化。地震前约一个月时间，震中及附近地区月平均气压变化幅度最大，月平均气压距平中心区域与震中区吻合，沿区域构造带方向出现气压变化最大梯度区，临震前几天气民较大幅度的升、降变化过程，升压脊 区域构造瞳向吻合。地震前一年，丰润、唐山一带年平均气温距平值最大，地震前一天，气温２４小时变温的升温中心在唐山，升温脊受区域构造带控制。０．８ｍ地温亦有明显的升温异常变化。１９７ 相似文献
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门源、共和地震前甘青交界地区浅层地温异常时空分布特征 总被引：5，自引：0，他引：5
本文研究了１９８６年门源６．４级地震和１９９０年共和７．０级地震地，１９８０－１９９０年青海省东北部甘青交界地区浅层地温场的时空分布特征。主要结论如下：门源地震前，１９８９年出现以青海湖为中心的浅层地温增温区，其中从湟源－门源－带形成椭圆形地温高值区，１９８６年访温区地温下降；共和地震和前从１９８７年出现大面积、长时间浅层地温增高区。增温幅度较大的地区集中在青海省湟源－共和－兴海－线。距震中区较远 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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地下水诱发的浅层前兆异常及其机理与有关的地震预报问题(1) 总被引：17，自引：1，他引：16
依照“源、场、外”相结合的地震科学研究思路,提出地下水诱发浅层前兆异常机理。认为降水等因素造成的地下水动态变化,可产生一种作用于地壳岩石的附加流体力;地震前,通过多种流体力作用,引起已经积累较高应力的地壳应力－－应变场调整变化,并使岩石强度改变,从而促进与诱发浅层地壳的构造变动;其结果是派生或伴生出地形变、地应力、水化学及地电阻率等多种浅层前兆异常。在降水、地下水的多种周期变化成分中,只有那些能与地壳应力－应变过程产生力学耦合的周期变化,才能调制与诱发出异常,这一部分变化可做为广义的地震前兆。孔隙压力、动水压力以及化学腐蚀等原理,是该异常机理的理论基础。列举出六方面的事实做为该机理直接的或间接的证据。 相似文献
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山西大同—阳高6．1级地震形变异常的再研究 总被引：3，自引：1，他引：3
在对山西大同－阳高1989年6．1地震的震例总结中，共收集了23项形变异常，经过对资料的整理研究，又发现了13项。经过进一步总结形变异常的演化特征及物理机制，表明形变异常在震前具有多样性，震源区出现了闭锁现象。中期趋势异常主要受区域应力场的控制，短临异常反映了震源应力场的变化，异常的空间分布是震源应力场和区域应力场相互作用的结果。 相似文献
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利用2013~2017年3期GPS观测资料,获得精河6.6级地震前震中附近区域水平运动速率、主应变率、面膨胀率及最大剪应变率,并结合区域构造背景分析该区域变形动态特征。结果表明:震前震中附近区域速度场速率逐渐增大,发震断裂两盘构造运动速率不均,震中附近区域GPS测点的速率和运动方向存在差异,反应了地壳应变能量积累。震中区域主压应变率变化反映出应力调整过程,沿断层走向的张压转换的形变高梯度带、最大剪应变梯度带可为地震预测提供参考。 相似文献
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在分析地震活动性、地壳形变和其它前兆资料基础上指出，１９９０年景泰６．２级地震前后甘肃东南部地区的区域异常具有变化速率小，起始时间不同步，异常反映的力学性质不一致等特征，其中以异常变化速率小最为显著。该特征与地壳形变及地震活动性异常变化有较好的一致性。通过分析，认为景泰６．２级地震前甘肃东南部地区出现的群体异常是共和７．０级地震和景泰６．２级地震的区域性前兆，震后该区持续的异常变化反映了强震后大范围内的应力调整过程。甘肃东南部地区构造环境特殊，该地区可能是南北地震带第５、第６强震组的共同调整区之一。 相似文献
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Wang Ruobai 《中国地震研究》2005,19(3):327-337
INTRODUCTIONThe Zhangjiakou-Penglai fault zone has drawnextensive attentionfromseismologists and geologistssince it was determinedinthe1980’s(Zheng Binghua,et al.,1981).Ma Xingyuan,et al.(1989)consideredit asthe north boundaryof North China sub-block.Int… 相似文献
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Regional tectonic deformation setting before the Ms8.1 earthquake in the west of the Kunlun Mountains Pass 总被引：1，自引：0，他引：1
This paper gives a preliminarily study of the regional tectonic deformation setting before the Ms8.1 earthquake that occurred in the west of the Kunlun Mountains Pass; in the study, the data of the velocity field of crustal horizontal movement during 1991-2000 observed by GPS in and around the Qinghai-Tibet block and those of gravity reiteration in 1998 and 2000 were used. Analysis shows that the preparation and occurrence of this large earthquake are related to the horizontal movement and deformation setting in a large region and might be attributed to the block activity on a relatively large scale. Within the Qinghai-Tibet block, the region of left-lateral shear deformation is of a very large extent. This large earthquake occurred right in such a place where the left-lateral shear strain along the fault strike had the highest rate and the planar dilatation strain was tensile, which was on the margin of negative value region of abnormal gravity variation. The regional tectonic deformation setting can help the huge left-lateral strike-slip rupture to develop. 相似文献
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邢台地震前地壳形变异常的可能性物理机制 总被引：4，自引：0，他引：4
将地壳介质视为麦克斯威尔体 ,运用差分法和三维有限元方法 ,探讨了邢台分层地壳结构模型 （含高速体和低速体及深大断裂 ）中深部断裂加速蠕滑时 ,平均应力、水平最大剪应力和地表面垂直位移随时间演化的特征 ,计算结果表明 :（1 ）在地壳中上部 1 1km处 ,深部断裂的加速蠕滑急剧加速了水平最大剪应力的增加速率 ,可达数百倍 ,深部断裂的加速蠕滑是邢台强地震成核过程的开始 ,可实现地壳下部的能量向地壳中上部快速转移 ;（2 ）深部断裂的加速蠕滑引起的地面垂直位移变化与邢台地震震前的地表面垂直位移变化非常一致 .说明邢台地震震前地壳表面垂直方向的位移不仅与岩石的膨胀有关 ,而且可能与地壳内深部断裂的加速蠕滑密切相关 . 相似文献
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The orbit perturbation of meteorologic satellite is used for the inversion of stress drop dynamic field of regional crustal
structure. Rapid scanning over vast area is carried out to obtain short term earthquake-generating precursor field of seismic
source and near-source districts in order to predict the three earthquake elements: epicenter, magnitude and commencement
time of earthquake with the same effect as weather forecast. Taking the strong earthquakes that occurred in recent years in
the NW of Yunnan as examples, direct deduction has been made for Lijiang and Wuding earthquakes, and curves of dynamic characteristics
of stress drop before and after earthquakes as well as abnormal fluctuations of precursor stress drop and commencement time
of earthquake have been plotted. 相似文献
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8.1级震后青藏块体东北部水平形变态势与地震有序活动研究 总被引：2，自引：0，他引：2
青藏块体东北部2003年最新GPS复测揭示：昆仑山口西8．1级地震后本区水平运动变形较前变异显,以甘青块体西部出现的与NE向挤压背景相反的张性运动变形为主要标志,且区域总体应变幅度增大。结合地震有序活动分析认为：本区目前的水平运动变形态势,与8．1级大震及随后青藏块体中西部发育的NE向中强以上地震条带在较短时间内释放了大量的压应变,使得青藏块体北部区域NE向推挤的应力场失衡(西侧的区域应力场强度衰减、东侧的应力场增强)密切相关;因而青藏块体北部大区域应力场趋于平衡过程将有利于块体东北边缘应力应变加速积累和破裂错动。 相似文献
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This paper gives a preliminarily study of the regional tectonic deformation setting before the Ms8.1 earthquake that occurred in the west of the Kunlun Mountains Pass; in the study, the data of the velocity field of crustal horizontal movement during 1991-2000 observed by GPS in and around the Qinghai-Tibet block and those of gravity reiteration in 1998 and 2000 were used. Analysis shows that the preparation and occurrence of this large earthquake are related to the horizontal movement and deformation setting in a large region and might be attributed to the block activity on a relatively large scale. Within the Qinghai-Tibet block, the region of left-lateral shear deformation is of a very large extent. This large earthquake occurred right in such a place where the left-lateral shear strain along the fault strike had the highest rate and the planar dilatation strain was tensile, which was on the margin of negative value region of abnormal gravity variation. The regional tectonic deformation setting can help the huge left-lateral strike-slip rupture to develop. 相似文献
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In order to study the characteristics of crustal deformation around the epicenter before the 2016 MS6.4 Menyuan earthquake, the GPS continuous stations of the period from 2010 to 2016 were selected according to the observation data of the tectonic environment monitoring network in Chinese Mainland. The deformation characteristics of the crust before the earthquake were discussed through inter-station baseline time series analysis and the strain time series analysis in the epicentral region. The results show that a trend turn of the baseline movement state around the epicenter region occurred after 2014, and the movement after 2014 reflects an obvious decreasing trend of compressional deformation. During this period, the stress field energy was in a certain accumulation state. Since the beginning of 2014, the EW-component linear strain and surface strain rate weakened gradually before the earthquake. It shows that there was an obvious deformation deficit at the epicentral area in the past two years, which indicates that the region accumulated a high degree of strain energy before the earthquake. Therefore, there was a significant background change in the area before the earthquake. The results of the study can provide basic research data for understanding the seismogenic process and mechanism of this earthquake. 相似文献
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This paper gives a preliminarily study of the regional tectonic deformation setting before the Ms8.1 earthquake that occurred in the west of the Kunlun Mountains Pass; in the study, the data of the velocity field of crustal horizontal movement during 1991-2000 observed by GPS in and around the Qinghai-Tibet block and those of gravity reiteration in 1998 and 2000 were used. Analysis shows that the preparation and occurrence of this large earthquake are related to the horizontal movement and deformation setting in a large region and might be attributed to the block activity on a relatively large scale. Within the Qinghai-Tibet block, the region of left-lateral shear deformation is of a very large extent. This large earthquake occurred right in such a place where the left-lateral shear strain along the fault strike had the highest rate and the planar dilatation strain was tensile, which was on the margin of negative value region of abnormal gravity variation. The regional tectonic deformation setting can help the huge left-lateral strike-slip rupture to develop.
相似文献20.
CHARACTERISTICS OF SATELLITE GRAVITY FIELD AND SEISMOGENIC MECHANISM IN THE LONGMENSHAN FAULT ZONE 
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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