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1996年11月19日新疆和田地区发生了ML=7.1地震. 在这次地震发生前,观测到了地震的超低频（ULF）电磁辐射前兆. 电磁辐射前兆的特点是电位漂移、极化椭圆主轴的垂直方向指向震中和大幅度的电磁辐射. 本文根据电磁辐射特征建立了地震电磁辐射前兆垂直电偶极子模型,并且给出了观测结果的物理解释. 偶极子产生一个不稳定的静电场使水平分量的电位日均值发生明显漂移,震前电偶极子中电荷复合放电产生的随机弱电磁噪声造成在ULF频段上水平分量偏振主轴方向偏转. 喀什台站和安西台站观测到的电势比值与模型估计值相近,从水平分量判断出偶极子间电流方向向下,与垂直电偶极子模型一致. 相似文献
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本文对１９８９年山西大同－阳高６．１级地震的前兆过程及其场、源特征进行了综合研究，结果表明，大同－阳高地震震前较为丰富的前兆现象是震源应力场与区域应力场共同作用的结果，估计大同地震的震源区尺度为２０－３０ｋｍ，孕震区范围约２００ｋｍ。最早的异常（震前３－４年）表现为大同盆地沉降速率加大，且出现在震源区，然后扩展至孕震区边缘，在孕震区边缘（１５０－２００ｋｍ）存在中、短期异常的突出集中区，在孕震过程 相似文献
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中国及其周邻地区中深源地震的活动特征分析 总被引：2，自引：0，他引：2
根据USGS最新的7万多条地震资料，分析了中国及其周邻地区的地震深度特征，特别是4个中深源震区的深度特征。结果表明：中国及其周邻四大中深源地震区多位于各板块的交界带上，地震活动强度最大的地区为吉林——日本深震区，其次为台湾中深震区，中印缅交界区和新疆——兴都库什中深震区的地震强度相当；并且后面两的地震频次在55km，110km和220km左右深度出现了多震层位式的高值；由深度资料推断板块间的作用方式来看，太平洋板块向欧亚大陆的挤压是一个由浅入深的过程，在不同的部位有不同的俯冲角度，印度板块向欧亚大陆的推挤，表现为前垂直插入后之中，俯冲现象不明显。 相似文献
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断层强度是反映孕震区状态的一个基本特性，其时间变化会增大或降低最终触发地震事件的可能性。虽然有人提出断层强度变化能解释各种不同现象，如地震活动的远距离影响，但实际中还没有现场监测这种重要特性的手段。 相似文献
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七十年代初,中外地震工作者先后发现震前有震源电磁辐射现象。由于震源电磁波信息对于地震的临震预报有意义,引起一些多震国家的关注。国内外的现场观测和岩石破裂模拟实验的结果表明,孕震区的电磁辐射伴随岩石块体破裂过程而产生;在一定的距离和接收频段上能够记录到震源辐射的电磁波;只要震前电磁辐射现象存在,就必然存在它的辐射源,这个辐射源可能就是正在孕育中的震源体本身。只要震源电磁辐射的这种波具有电磁波特性,就可以运用测向技术测定辐射源与观测点之间的相对方位角,然后通过几个不同的观测点在地图上交 相似文献
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本文简要评述了近年来震前电磁辐射研究的新进展和发展方向,以及今后的重点研究课题.已取得的初步结果表明,新发现的震前电磁辐射现象是一种客观存在,并可能是具有良好应用前景的短临前兆.鉴于地震电磁辐射机制及其空间耦合与时间变化过程的复杂性,必须深入探索电磁辐射前兆现象与孕震过程之间的内在联系,使观测工作与理论研究很好地结合起来,并结合多种前兆进行综合诊断. 相似文献
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强地震前，在震区产生先兆电磁现象已经得到了越来越多的测量记录证实，地面直接电磁辐射异常和电离层异常扰动是地震前最显著的前兆现象，而且具有较稳定的时间尺度。除了卫星观测方法外，地震先兆电磁信息的观测方法有多种。根据接收的信号来源途径不同，地面观测方法可划分为：①被动观测：在地面观测附近孕震区直接辐射的ULF／ELF／VLF的电磁波; 相似文献
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大量的观测研究结果表明，近场地震发生前极低频电磁异常信息既丰富又强烈．为探索对其规律性认识，本文通过对地震电偶极子的形成及传播规律研究后指出，震前垂直向极低频电场异常具有穿透能力强、干扰少、信息突出及易于提取和接收等优点，是探索地震可靠短临前兆信息的重要方面；进而通过对极低频准静场观测资料的频谱分析结果得出，近场地震前电磁异常的频谱大都集中在周期为数分钟至数十分钟的极低频段，异常信息频谱与震中距存在一定的相关关系，且震前极低频电磁异常与孕震区的空间分布范围存在明显的相关关系，地震渗滤电场异常信息及频谱的幅度与震级大小无明显相关． 相似文献
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Elsayed Fergany 《Journal of Seismology》2018,22(1):251-262
This work intends to assess deterministic seismic hazard and risk analysis in terms of the maximum expected intensity map of the Egyptian Nile basin sector. Seismic source zone model of Egypt was delineated based on updated compatible earthquake catalog in 2015, focal mechanisms, and the common tectonic elements. Four effective seismic source zones were identified along the Nile basin. The observed macroseismic intensity data along the basin was used to develop intensity prediction equation defined in terms of moment magnitude. Expected maximum intensity map was proven based on the developed intensity prediction equation, identified effective seismic source zones, and maximum expected magnitude for each zone along the basin. The earthquake hazard and risk analysis was discussed and analyzed in view of the maximum expected moment magnitude and the maximum expected intensity values for each effective source zone. Moderate expected magnitudes are expected to put high risk at Cairo and Aswan regions. The results of this study could be a recommendation for the planners in charge to mitigate the seismic risk at these strategic zones of Egypt. 相似文献
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《地震学报(英文版)》1996,9(3):447-454
In order to investigate the physical mechanism of seismo-electromagnetic signals, many scholars from China and other countries
have carried out laboratory and field experiments of rock samples by loading them up to fracture in recent ten-odd years.
In each of these experiments, the phenomenon of electromagnetic radiation was observed during the process of rock sample fracture.
However, the experimental results can not explain the non-synchronous electromagnetic radiation in actual observation records.
In these records, some stations displayed anomalies but some others did not, and the signals of different frequency bands
observed by the same station did not occur simultaneously. This has brought about many difficulties to the application of
electromagnetic radiation in earthquake prediction. The experimental result of this paper can explain the phenomenon of non-synchronous
electromagnetic radiation. In the experiment of this paper, rock samples are uniaxially compressed up to fracture. The antennas
of different frequency bands are installed two meters away from the rock sample in different directions. The electromagnetic
signals during the whole process of rock sample fracture are recorded synchronously by a 14-channel tape recorder. The experimental
results are as follows: (1) signals of the four frequency bands: VLF, MF, HF and VHF, are all recorded during the main fracturing
process of rock samples, but signals of different frequencies may somtimes occur non-synchronously; (2) the intensity of electromagnetic
radiation is the highest at the moment when the main fracture occurs, but signals in different directions are of different
intensities. The above results are consistent with the non-synchronous electromagnetic radiation observed in real earthquakes.
It seems possible to predict the orientation of future seismic source by the electromagnetic method of the LF or VLF frequency
bands.
Contribution No. 95A0075, Institute of Geophysics, SSB, China.
The paper is translated by Prof.Jie-Fan HUANG, Peking University from the Chinese into English version. 相似文献
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福建及邻区水平基岩加速度反应谱衰减关系 总被引：1，自引：0，他引：1
收集福建及邻区内既有仪器测定震级又有宏观烈度调查资料的28次破坏性地震资料,并对上述资料进行烈度等效处理、近远场补点、数据加权处理,加强对大震近场与远场的控制,建立了适合本区的地震烈度衰减关系;利用最新得出的美国西部基岩水平向地震加速度反应谱衰减关系,采用转换方法建立了本区的基岩水平向地震加速度反应谱衰减关系;并与华南地区的地震动参数衰减关系进行了对比,其结果更加符合该区近代地震震害分布的地域性特征.所得结果可应用于该区的地震安全性评价、震害预测、损失快速评估等防震减灾领域. 相似文献
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本文应用位错模型地震震源波谱理论和观测资料,论证了远场体波质点位移或速度最大值（地震震级）决定于彼此独立的两个震源动力学参数地震矩M0和体波波谱特征频率f0。因此,仅以地震矩表征地震强度或仅以断层尺度（体波波谱特征频率）分类地震大小,只在另一个震源参数保持为常数时才有可能。体波波谱特征频率携带着震源体波脉冲持续时间的信息。据此,探讨了地震震级的物理含义。 相似文献
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This paper applies the Seismic Hazard Analysis method for the cities of China to research on the probability of earthquake occurrence in the Daduhe drainage area, where the cascade dam system is located. This research is based on the potential seismic source scheme of the Seismic Ground Motion Parameter Zonation Map of China （2001）, and uses Poisson distribution as an earthquake occurrence model. Earthquake magnitude obeys truncated exponential distribution. The spatial distribution function of the potential seismic source zone is taken as the first-class spatial probability distribution, and the homogeneous probability distribution in the potential seismic source zone as the second-class spatial probability distribution. Considering the seismic intensity attenuation relationship of western China, we compute the occurrence probability of an earthquake around magnitude 6.0 （5.5 - 6.5）, 7.0 （6.5 - 7.5） and over 7.5 in the Daduhe drainage area, where 22 series cascade dams will be built. The results can be used for hydropower plant planning, hydropower dam site selection and seismic fortification. 相似文献
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Huang Qinghua Ikeya Motoji and Huang PeihuaDepartment of Earth Space Sciences Graduate School of Science Osaka University Osaka Japan Department of Earth Space Sciences University of Science Technology of China Hefei China 《中国地震研究》1997,(1)
Electric field effect on animals has been studied to investigate its relation with seismic anomalous animal behaviors(SAABs)in China.Freshwater eel,crucian carp,catfish,and soft-shelled turtle responded to the threshold electric field of 1-10 V/m,while duck,goose,cat,sheep,pig,dog,and chicken all responded to the ground electric field of about tens of V/m,depending on the species as well as on individuals.Most of the behaviors caused by electric field were similar to those reported as SAABs such as alignment,sudden movement,panic,and convulsion.The intensity of electric field due to a major earthquake would have been over these threshold values.Numerical estimation based on an electromagnetic model of a fault has been made to induce SAABs as electric shocks to pulsed electric fields in electro-physiology.The seismic electric signals(SES)intensity might be estimated from the observation of SAABs. 相似文献
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A model has been developed to simulate the statistical and mechanical nature of rupture on a heterogeneous strike-slip fault. The model is based on the progressive failure of circular asperities of varying sizes and strengths along a fault plane subjected to a constant far-field shear displacement rate. The basis of the model is a deformation and stress intensity factory solution for a single circular asperity under a unidirectional shear stress. The individual asperities are unified through the fault stiffness and the far-field stress and displacement. During fault deformation asperities can fail and reheal, resulting in changes in the local stresses in the asperities, stress drops, and changes in the stiffness of the fault. Depending on how the stress is redistributed following asperity failure and on the strenghts of the neighboring asperities an earthquake event can be the failure of one or more asperities. Following an earthquake event seismic source parameters such as the stress drop, energy change, and moment magnitude are calculated. Results from the model show a very realistic pattern of earthquake rupture, with reasonable source parameters, the proper magnitude-frequency behavior, and the development of characteristic earthquakes. Also the progression ofb-values in the model gives some insight into the phenomenon of self-organized criticality. 相似文献
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利用“十五”数字化后山西地震台网记录的612次 ML ≥2．0地震，使用中国地震局地震预测研究所推广的中小地震新参数计算软件，计算其中148次事件的震源新参数，对地震矩、矩震级、震源破裂尺度、应力降、拐角频率等参数间的定标关系做初步研究，得出 ML 震级与地震矩、矩震级间存在较好的线性正相关；震级与震源尺度间存在多项式关系；与应力降的对数呈显著正相关，当大于 ML 4．0后，随着震级的增大，释放的应力降略有变缓；与拐角频率的对数呈负相关。 相似文献