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The spatial characteristic of the short－term and imminent anomalies of waterradonbe┐foreearthquakeinthemainlandofChina 总被引：1，自引：0，他引：1
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The changes of radon concentration in underground water (water radon) recorded at about 200 stations in 32 earthquakes occurred in the mainland of China are studied in this paper. The result shows that the spatial distribution of short-term and imminent anomalies of water radon before earthquake seems to be mainly related to the active master fault nearby the hypocenter of an earthquake and the earthquake-generating mechanism. Finally, some understandings on the mechanism of the anomalies and the imminent earthquake prediction are set forth. 相似文献
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地下流体中强震源兆、场兆和强震远兆特征及其物理成因 总被引：22，自引：1，他引：21
初步分析了乌鲁木齐9、10号泉地下流体中强震源兆、场兆及强震远兆特征。结果表明,中强震源兆具体表现为震前1~ 2年观测点的绝大多数主测项出现同步性高值异常,临震前可能出现转折或反向,震后恢复正常;绝大多数中强震场兆则表现为观测点仅有部分测项出现短期异常变化;而强震场兆则表现为观测点少数映震性能较好的几个测项出现同步性较好的中期前兆异常;强震(群)远兆则主要表现为个别映震较好的测项出现前兆异常。并对震兆形成的原因进行了初步探讨。 相似文献
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卡方检验在华北强震前的应用 总被引：1，自引：0，他引：1
用卡方检验的数理统计方法,结合华北地区活断层、震源机制解等地震地质构造,对华北地区3次强震前的地震活动进行了时间及空间上的检验.认为,卡方检验不仅揭示了中强震前地震的丛集特性,而且体现了强震与地震地质背景之间的密切关系,揭示了构造体系与地震的某些联系. 相似文献
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归纳了自1975年以后华北地区13次中强以上地震的地壳形变短临前兆异常60例。统计地壳形变短临异常与地震的定性关系，发现距震中较远的台站异常出现较早，较近的台站异常出现较晚，地震的震级与异常的空间展布范围成正比，异常往往倾向震中或背向震中。跨断层的位移型形变异常形态有两大类：一类是趋势性异常变化，另一类是高频波动。本文提出了将连续型形变转化为应变的方法。从1989年10月16日大同－阳高61级地 震和1991年3月26日大同－阳高5．8缓地震的实例可见，地震往往发生在高应变区或其附 近，异常量级可达10－6。 相似文献
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震前多种前兆异常形态特征及预测意义 总被引：1，自引：0，他引：1
对1970年以来华北地区31次MS≥5.0地震前多种前兆异常形态特征进行了系统研究, 结果认为: ① 在强震前短临阶段, 普遍存在垂直形变和水位异常形态的四象限性分布, 且这种象限分布特征与主震震源机制解具有一定的相关性。 即在压缩区, 垂直形变上升, 水位亦上升。 在膨胀区, 垂直形变和水位都下降; ② 地倾斜异常在近源区与远源区具有明显的差异, 其中多数强震前表现为距离震中近的台站向与震中相反的方向倾斜, 而远离震中的台站, 其倾斜方向指向震中; ③ 地电阻率异常形态以下降为主; 多数水化异常(气体)表现为短期上升而临震转平或下降; 电磁波通常为短临异常。 基于上述前兆异常形态特征, 特别是垂直形变和水位异常形态的四象限分布特点, 提出了根据前兆场异常特征判断发震地点和孕震状态的思路。 相似文献
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新疆地下流体源兆、 场兆、 大震远兆特征的统计与分析 总被引：7，自引：0，他引：7
以20多年来新疆地区的18个地下流体监测点的资料为基础, 沿着“异常与震中”这一主线, 对新疆地区的16次5级地震、 4次 7级以上地震及1个6级强震群的前兆异常特征进行了定量的统计与分析。 结果表明, 源、 场、 远兆异常有如下特征: 异常空间展布不均, 源兆空间内异常监测点展布"密集"、 异常比例可达90%; 而场兆空间展布“稀疏”、 “分散”, 异常比例一般在45%～53%; 而远兆则是更加“稀疏”和“零星”, 异常比例统计为25%。 异常起始时间不同, 源兆异常时间以中期为主; 中强震场兆异常时间以中短期、 特别是短期为主; 强震场兆以中期异常为主; 而强震远兆则也以中期异常为主。 异常形态不同, 源兆中期异常及强震场兆中期异常一般是趋势性大幅度升高变化为主, 且以化学测项为多, 油气探井以井喷形式予以表现; 而中强震场兆异常, 一般表现为幅度明显的短期内的负异常、 脉冲突跳、 短期内的高值上升、 阶变及年变化规律被打破等; 强震远兆特征则基本上表现为少数测点、 测项的大幅度中期异常及个别测项的临震大幅度突跳现象, 油气探井则也以剧烈井喷形式予以表现。 相似文献
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对2018年4月6日无为ML4.1地震前的地下流体前兆异常特征以及该地震的震源机制解进行了分析, 结果表明, 无为地震前的异常分布在距震中64~233 km范围内, 这些异常在时间进程上, 可分为中期趋势背景异常和短临异常, 主要以中期趋势背景异常为主。 这些中期趋势背景异常均表现为水位的破年变变化。 从空间演化上看, 2018年安徽无为ML4.1地震前出现的中期趋势背景异常沿着长江破碎带有序分布。 这种比较明显的异常群体性特征为地震预测提供了较好的依据。 震源机制解结果显示, 节面I的走向为NE向, 节面Ⅱ的走向NW向。 反演的震源机制的P轴(主压轴)方向为NE向(70°), 倾角近水平(7°)。 无为地震震源机制解所得主压应力作用方向与无为地震前异常展布方向相同。 这说明地震孕育过程中区域应力加载作用和流体前兆响应具有密切关系。 相似文献
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THE COMPREHENSIVE ANALYSIS AND RESEARCH OF RECENT GRAVITY AND CRUSTAL DEFORMATION IN NORTHEASTERN EDGE OF THE TIBETAN PLATEAU 
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下载免费PDF全文 ZHU Yi-qing LIANG Wei-feng HAO Ming ZHAO Ling-qiang HAO Qing-hua ZHANG Guo-qing LIU Lian 《地震地质》2017,39(4):768-780
In this study, we systematically analyzed the relationship between regional gravity changes, 3D crustal deformation, regional tectonic environment and strong earthquakes based on the relative gravity measurements(2011-2014), GPS data and the background vertical deformation from the leveling measurements conducted from 1970 to 2011. Subsequently, we further characterized the temporal-spatial patterns and discussed the mechanism of regional gravity changes and the crustal deformation. The results can be summarized as follows:1)The regional gravity changes, the GPS-derived horizontal deformation and the vertical deformational obtained from leveling data showed a close spatial relationship:The gravity increased along with the direction of horizontal movement, and the gravity decreased with the crustal uplift and vice versa, which reflects the inherited characteristics of neotectonic activities. 2)The crustal deformation was closely related to the active faults. The contour lines of gravity changes and vertical deformation were generally along with the Qilian-Haiyuan Fault(the strike is NWW), and the crustal horizontal deformation showed left-lateral strike slip motion near the Qilian-Haiyuan Fault. 3)The strong earthquakes usually occur in the active faults where intensive gravity change and vertical and/or horizontal deformation occurred. The extrusion deformation, surface compression rate and gravity changes were obvious near the epicenter of 2016 Menyuan earthquake. The 2013 Minxian-Zhangxian MS6.6 earthquake occurred in the direction-turning area of intense gravity gradient zone and the transitional area of surface compression and vertical deformation. The first author of this paper has made a medium-term forecast before the Minxian and Menyuan earthquakes, especially the location of the earthquake. Based on the above understandings, we emphasized that:there are still possibilities of strong or huge earthquakes within medium-long term in the areas of crustal deformation anomalies in the study region. 相似文献
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LIMITATION OF CURRENT TECTONIC DEFORMATION MODES IN THE WESTERN MARGIN OF ORDOS BASED ON SEISMIC ACTIVITY CHARACTERISTICS 下载免费PDF全文
下载免费PDF全文 ZHAN Hui-li ZHANG Dong-li HE Xiao-hui SHEN Xu-zhang ZHENG Wen-jun LI Zhi-gang 《地震地质》1979,42(2):346-365
Due to the interaction between the Tibetan plateau, the Alxa block and the Ordos block, the western margin of Ordos(33.5°~39°N, 104°~108°E)has complex tectonic features and deformation patterns with strong tectonic activities and active faults. Active faults with different strikes and characteristics have been developed, including the Haiyuan Fault, the Xiangshan-Tianjingshan Fault, the Liupanshan Fault, the Yunwushan Fault, the Yantongshan Fault, the eastern Luoshan Fault, the Sanguankou-Niushoushan Fault, the Yellow River Fault, the west Qinling Fault, and the Xiaoguanshan Fault.
In this study, 7 845 earthquakes(M≥1.0)from January 1st, 1990 to June 30th, 2018 were relocated using the double-difference location algorithm, and finally, we got valid locations for 4 417 earthquakes. Meanwhile, we determined focal mechanism solutions for 54 earthquakes(M≥3.5)from February 28th, 2009 to September 2nd, 2017 by the Cut and Paste(CAP)method and collected 15 focal mechanism solutions from previous studies. The spatial distribution law of the earthquake, the main active fault geometry and the regional tectonic stress field characteristics are studied comprehensively.
We found that the earthquakes are more spatially concentrated after the relocation, and the epicenters of larger earthquakes(M≥3.5) are located at the edge of main active faults. The average hypocenter depth is about 8km and the seismogenic layer ranges from 0 to 20km. The spatial distributions and geometry structures of the faults and the regional deformation feature are clearly mapped with the relocated earthquakes and vertical profiles. The complex focal mechanism solutions indicate that the arc-shaped tectonic belt consisting of Haiyuan Fault, Xiangshan-Tianjingshan Fault and Yantongshan Fault is dominated by compression and torsion; the Yellow River Fault is mainly by stretching; the west Qinling Fault is characterized by shear and compression. The structural properties of the fault structure are dominated by strike-slip and thrust, with a larger strike-slip component. The near-north-south Yellow River Fault is characterized by high angle NW dipping and normal fault motion.
Based on small earthquake relocation and focal mechanism solution results, and in combination with published active structures and geophysical data in the study area, it is confirmed that the western margin of Ordos is affected by the three blocks of the Tibetan plateau, the Alax and the Ordos, presenting different tectonic deformation modes, and there are also obvious differences in motion among the secondary blocks between the active faults. The area south of the Xiangshan-Tianjingshan Fault has moved southeastward since the early Quaternary; the Yinchuan Basin and the block in the eastern margin of the Yellow River Fault move toward the SE direction. 相似文献
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华北平原周边北西向强震地表地震断层及全新世断裂活动特征 总被引：8，自引：0，他引：8
讨论了华北平原周边１９７５年海城地震，１９３７年荷泽地震及１８３０年磁县地震３次强震的地表地震破裂特征以及这３个地区北西向断裂的全新世活动。研究结果表明，尽管这３次强震地表破裂显示较弱，断续分布，仍反映了存在北西向地表破裂带，活动方式呈左旋走滑兼正倾滑。 相似文献
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本文根据青藏高原东北部震源深度、震源机制及其周边断裂晚更新世晚期以来的运动特征等大量资料分析,讨论了本区地壳浅部块体物质运动的基本特征、西秦岭北缘断裂带构造地貌滞后效应现象及其原因,同时探讨了大闸口内强震成因,成带等问题。 相似文献
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以2000年以来6.4级以上地震为例,研究了腾冲地区潜热通量（SLHF）在这些震例发生前后的变化特征。结果表明：腾冲地区的SLHF动态,不但在其附近发生强地震前常出现异常,而且对周边较远的强地震前也会发生异常反应;异常出现时间大都在震前1个半月以内,汶川地震前异常出现较早,发生在震前2个月之前,这可能与汶川地震震级高影响范围大有关;异常幅值与震级有关,震级越大,异常表现越强。 比如芦山7.0级地震、缅甸7.0级地震和汶川MS 8.0地震前,腾冲地区SLHF异常幅度很大,远远超过最大参考值,而姚安6.5级地震和宁洱6.4级地震前异常幅度就相对小一些。腾冲地区SLHF异常与周围强地震的发生有较好的相关性,一方面与腾冲地区的活动断裂发育、现今构造变形强烈有关,另一方面可能是由于腾冲地区火山活动强烈,温泉广泛发育,水热交换迅速,对周边构造活动感应灵敏所致。 相似文献
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作为强震长期预测基础的地震带、潜在震源区的划分,仍然依据地震构造类比和地震活动重复两原则。现有的强震长期预测方法在构造“稳定”区,即没有活动构造、没有历史地震(包括古地震)资料的条件下,无能为力。通过张北地震资料的分析,高精度地震定位并结合波形数据反演震源机制的结果表明：在稳定而统一的构造应力场的作用下,沿其最大剪切应力方向上的小地震集中成带,并且持续活动、震源机制的优势取向与应力场吻合,小震带便可以看作属于现今活动的震源断层,在地震长期预测工作中可以作为划分潜在震源区的依据。构造“稳定”区发生的强震属于新破裂。 相似文献
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根据地球内部热状况及震源热力学理论,分析了全球地热带与地震活动带之间的密切关系。指出我国1966年—1988年强震(Ms≥7.0)多发生在地热异常区的边缘(两端和两侧)及两个相近热区之间的地热梯度带。认为区域热流动态的分布特征是地震危险区的重要判别指标之一,与构造活动断裂有关的深井,温泉的温度变化可能是地热异常显示的灵敏“窗口”。 相似文献
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Introduction Earthquakes are direct results from tectonic deformation and crustal movements, which usu- ally contain abundant information of crustal stress status and medium property in the deep lithosphere. Seismic activities might reflect accumulation and concentration of crustal stress in the seismogenic process. And different mechanisms of rock ruptures lead to different precursory phe- nomena prior to earthquakes (ZHANG, et al, 2001). Therefore, seismic activities before a strong earthq… 相似文献