共查询到19条相似文献，搜索用时 343 毫秒
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对2001～2006年兰州—天水—武都地区5期重力场时变资料进行小波分解,结合2003年11月岷县5.2级地震、2004年9月岷县5.0级地震以及2006年6月武都、文县间5.0级地震进行分析。探讨了无震年份、有震年份及较长时段的重力场时变资料小波分解结果与地震活动之间的关系,结果表明:用小波分解方法可有效分离重力场时变的不同波长成分;该地区不同层次的重力场时变异常反映了一定尺度意义上不同深度的介质密度的动态变化分布,说明兰州—天水—武都地区中深部地质构造活动所引起的重力异常变化的2阶、3阶小波细节对2003、2004、2006年3次MS≥5.0地震反应明显。 相似文献
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兰州-天水-武都地区重力场变化及其与地震的关系 总被引：2，自引：1，他引：1
应用流动重力观测资料,研究分析了南北地震带北段兰州—天水—武都地区重力场的时空变化特征．结果表明,以１０５° Ｅ 为界,其东西二侧重力场变化明显不同．据此判断,沿１０５° Ｅ 在地壳的深部存在一条 Ｎ Ｓ 向活动构造．１９９０ 年以来在甘肃省境内发生的３ 次５ 级以上地震前,兰州岸门村和永登树屏２ 个测点的重力点值出现了明显异常 相似文献
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利用四川地区2010 ～ 2013 年流动重力观测数据作出的重力场动态变化图像和重力段差时序变化图像,对芦山7. 0 级地震前后的重力场动态演化特征进行了研究,结果表明:震前重力场经历了约3 年的重力增大和约1 年的减小变化,重力变化呈“上升→加速上升→减速上升→加速下降→减速下降”特征; 芦山地震发生在重力场变化由下降转为上升的回调过程中;震后重力场变化以较快的速度恢复到接近震前状况,并出现重力正值变化异常区域;临震前震中区域重力场变化数值较小,构造带活动速度变慢。 相似文献
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利用青藏高原东北缘2011-2013年期间的流动重力观测资料,系统分析了区域重力场动态变化及其与2013年7月22 H岷县漳县6.6级地震发生的关系.结果表明:1)测区内重力场异常变化与主要断裂带在空间上关系密切,反映沿主要断裂带(段)在2011-2013年期间发生了引起地表重力变化效应的构造活动或变形.2)岷县漳县6.6级地震前,测区内先出现了较大空间范围的区域性重力异常,后在震源区附近产生了局部重力异常及重力变化高梯度带,其中,甘肃临夏与岷县一带重力差异变化达150×10 8ms-2以上;这些可能反映岷县漳县地震前,区域及震源区附近均产生与该地震孕育、发生有关的构造运动或应力增强作用.3)重力场1a尺度动态变化图像和差分动态演化图像均反映岷县漳县6.6级地震孕育过程的最后2a出现较显著的流动重力异常变化,地震发生在NE向重力变化高梯度带上、重力变化零值线附近和等值线的拐弯部位.4)基于流动重力异常变化在岷县漳县6.6级地震前做过一定程度的中期预测,尤其是地点判定. 相似文献
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AbstractThe relation between the gravity variation features and M_S=8.1 earthquake in Qinghai-Xizang monitoring area isanalyzed preliminarily,by using spatial dynamic variation results of regional gravity field from absolute gravityand relative gravity observation in 1998 and 2000.The results show that:1)M_S=8.1 earthquake in Kulun mountainpass western occurred in the gravity variation high gradient near gravity's high negative variation; 2)The maintectonic deformation and energy accumulation before M_S=8.1 earthquake are distributed at south side of theepicenter;3)The range of gravity’s high negative variation at east of the M_s=8.1 earthquake epicenter relativelycoincides with that rupture region according to field geology investigation; 4)Gravity variation distribution in highnegative value region is just consistent with the second shear strain’s high value region of strain field obtainedfrom GPS observation. 相似文献
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利用成都地区1996~2008年绝对重力和相对重力观测资料获得区域重力场时空动态变化结果,系统分析了龙门山断裂带重力场变化特征及其与汶川8.0级地震的关系.①重力变化与龙门山断裂构造活动存在密切空间联系,重力测量较好地反映了伴随活动断层的物质迁移和构造变形引起的地表重力变化效应.②成都地区重力场动态图像较完整地反映了2008年5月12日汶川8.0级地震孕育、发生过程中出现的流动重力前兆信息.③映秀及北川重力点值时序变化累积量达120×10-8m·s-2,较好地反映了汶川地震前映秀和北川两个极震区附近的重力测点随时间的剧烈波动性上升变化.④汶川地震前,龙门山断裂带东侧的四川盆地相对稳定,而较显著的重力变化发生在龙门山断裂带西侧的川西高原上. 相似文献
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Xianshuihe Fault, a main strong earthquake activity belt in southwest China, begins from Ganzi in the northwest, passes through Luhuo, Daofu, and Kangding, and then extents along the Dadu River valley. The fault is divided into two parts at Shimian, one part turns to south and converses to Anninghe Fault extending further to south, the other part, continuing to extend to southeast, cutting through Xiaoxiangling and then changing to Daliangshan Faults in the north of the Yuexi Basin, has the length of about 400km. Since 1700AD, there have happened 22 earthquakes larger than magnitude 6.0 and 8 earthquakes larger than magnitude 7.0. In this paper, we systematically collated and computed the gravity repetition measurement data along the Xianshuihe fault zone since 1988, and by referring to the anomaly index of gravity field of the predecessor achievements, analyzed the spatial-temporal variation of the regional gravity field and the relation to the occurrence of ≥ MS5.0 earthquakes. The mechanism of the regional gravity changes is further studied, and also the implication of strong earthquake risk because of the dynamic variation of gravity field in the near future is discussed.The results show that:1)The mobile gravity observation has the ability to detect crustal activity and MS ≥ 5.0 earthquake events. 2)There is definite correspondence between interannual gravitational field change and the 8 earthquakes among the 13 MS ≥ 5.0 earthquakes occurring in the surveying area since 1988, which can be determined according to the change of interannual gravitational field. Three M ≥ 6.0 earthquakes occurred 3~4 years after the abnormal image was developed, 4 earthquakes that occurred in the region of no data available were not determined. 3)A significant feature of the spatial-temporal variation of the regional gravity is a north-south run-through image before 2004, and characterized by the alternatively positive or negative variation in different year, the earthquakes of MS ≥ 5.0 occurring in this period were not distributed along the fault. Gravity variation magnitude indicates that there were two similar crustal material movement waves before 2004, corresponding to the course of earthquake space-time distribution from strong to weak in the study area. After 2010, the variation image shows that the local positive and negative zones are concurrent within a year, different from the image before 2004, and earthquakes of MS ≥ 5.0 basically occurred on the fault. It is believed that the variation of gravity field since 1988 and the seismic distribution fit with the geodynamic mode of strong and weak stages of the northeast motion of Indian plate. According to the conclusion we can try to optimize gravity anomaly index. After the Kangding earthquake in 2014, the north segment of Moxi Fault was still subject to negative high value changes till 2017 and then the gravity variation was further developed to a four quadrant distribution image. Based on the analysis of this paper and the previous variation trend of gravity field, we believe that the north segment of Moxi Fault has the background of medium-long term, strong or large earthquake risk. 相似文献
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Using the tendentious accumulation rate of crustal deformation,DC,the spatial distributionfeatures of deformation across fault in the West of China was studied;the regional patterns ofdeformation accumulation induced by fault activity was established and its seismogenicmeaning was discussed.The types of fault deformation evolution in the time domain and thefeatures of change of large extent anomaly in fault deformation which occurred in 1995～1996was analyzed comprehensively.It was indicated definitely that 1995～1996 is the turningpoint of fault network activity in the West of China since the 1990s;it is closely related to thechange of main seismic active regions in the West of China,i.e,the alternation of strong/weak stages and the change of action range of tectonic stress field in the Qinghai-Tibet blockand its environs;and hence it is of medium-and short-term precursor meaning for the changeof the overall pattern of earthquake activity in the West of China in the year 1996.On such abasis,a preliminar 相似文献
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利用南北地震带2014-2017年期间的流动重力观测资料，系统分析了区域重力场变化及其与2017年8月8日四川九寨沟7.0级地震发生的关系.结果表明：①区域重力场异常变化与北西西向塔藏断裂和南北向岷江断裂带在空间上关系密切，反映了沿控震断裂在2013-2017年期间发生了引起地表重力变化效应的地壳变形和构造活动.②九寨沟地震前，测区内出现了大空间范围的区域性重力异常，而震源区附近产生了局部重力异常，沿塔藏断裂带形成了重力变化高梯度带，其中，甘肃玛曲、迭部、青海河南蒙古族自治县、四川若尔盖、九寨沟一带重力差异变化达100×10-8m·s-2以上；这些可能反映九寨沟地震前，区域及震源区附近均产生与该地震孕育、发生有关的构造运动或应力增强作用.③九寨沟地震震中位于重力差异运动剧烈的鞍部等值线附近，与断裂走向基本一致的重力变化高梯度带零值线上，这一观测事实进一步佐证了重力场动态变化图像对强震地点预测具有重要的指示意义. 相似文献
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Jin-Zhao Liu Tong-Qing Wang Zhao-Hui Chen Pin Zhang Chuan-Dong Zhu Shuang-Xi Zhang 《应用地球物理》2018,15(1):137-146
We evaluated 2011–2015 mobile relative gravity data from the Hexi monitoring network that covers the epicenter of the 2016 Menyuan Ms6.4 earthquake, Qinghai Province, China and examined the spatiotemporal characteristics of the gravity field at the focal depth. In addition, we assessed the regional gravity field and its variation the half-year before the earthquake. We use first different interpolation algorithms to build a grid for the gravity data and then introduce potential field interpolation–cutting separation techniques and adaptive noise filtering. The results suggest that the gravity filed at the focal depth of 11.12 km separated from the total gravity field at about–400~150 × 10?8 m/s2 in the second half of 2015, which is larger than that in the same period in 2011 to 2014 (±30 × 10?8 m/s2). Moreover, at the same time, the gravity field changed fast from September 2014 to May 2015 and May 2015 to September 2015, reflecting to some extent material migration deep in the crust before the Menyuan earthquake. 相似文献
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新疆南天山东段地震平静相关问题探讨 总被引：1，自引：0，他引：1
分析了南天山东段地震平静相关问题。得到如下结论：①将平静现象分为震前平静、震后平静．场兆平静、无震平静可能更能客观地反映平静状态;②南天山东段4级地震平静6个月以上具有前兆意义;③5级地震发生前的打破平静现象分为两类,由4级地震打破平静的5级地震其发震位置与4级地震关系密切,由5级地震打破平静的地震一般发生在地震弱活动区或南天山东段5级地震成组活动时期,前兆现象较难捕捉;④南天山东段5级地震最长平静时间为57个月。 相似文献
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利用青藏高原东北缘2011-2015年期间的流动重力观测资料,系统分析了区域重力场变化及其与2016年1月21日青海门源MS6.4地震发生的关系,结合GNSS、水准观测成果和区域地质构造动力环境,进一步研究了区域重力场变化的时空分布特征及其机理.结果表明：（1）测区内重力场异常变化与祁连山断裂带在空间上关系密切,反映沿祁连山断裂带（段）在2011-2015年期间发生了引起地表重力变化效应的构造活动或变形.（2）门源MS6.4地震前,测区内先出现了较大空间范围的区域性重力异常,到临近发震前显示出相对闭锁的现象,且围绕震中区周围出现四象限分布特征的局部重力变化,地震发生在重力反向变化过程中,并出现显著的四象限分布特征的重力异常变化,其中,青海门源与甘肃天祝一带重力差异变化达100×10-8m·s-2以上.（3）区域重力场动态演化大体反映了青藏高原东北缘物质北东流的动态效应,门源震中附近区域地壳受挤压变形显著、面压缩率和重力剧烈变化的特征最为显著.（4）重力场的空间分布及其随时间变化与地壳垂直与水平运动及地质构造活动等观测结果有一定的对应关系,强震易发生在重力变化四象限分布中心地带或正、负异常区过渡的高梯度带上. 相似文献