共查询到19条相似文献，搜索用时 125 毫秒
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青海地区中强地震震源过程的宽频带资料分析 总被引：2，自引：0，他引：2
１９８８年至１９９０年,青海地区发生了４次震级大于６．０的地震,本文利用全球数字地震台网（ＧＤＳＮ）的宽频带波形资料,通过波形模拟,结合地质结造的背影资料对这几个地震的震源破裂和发震构造背景进行了研究。通过台站的视震源时间函数（ａＳＴＦ）和视时间差（ａＴＤ）的分析,特别对震源的复杂性进行了讨论。本文的研究从震源分析的角度进一步支持了青藏高原东北部构造应力的压力轴为接的水平的ＮＥ方向,而随着向青藏高 相似文献
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测定震源深度的意义的初步讨论 总被引：32，自引：5，他引：32
在地震目录中，震源深度是地震学最基本的参数之一，然而它也是一个最不易测准的参数，ＰＤＥ报告中的震源深度以及ＵＳＧＳ和Ｈａｒｖａｒｄ大学的ＣＭＴ反演的矩心深度和利用宽频带波形的深度震相资料获得的震源深度各不相同，其含义也不同，而宽频带波形模拟得到又是一种破裂“核心”的深度。本文对不同测量手段的震源深度的不同物理意义做了初步的探讨。 相似文献
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准实时中小地震震源机制波形自动反演系统的构建及在首都圈地区的应用 总被引：1，自引：0，他引：1
基于Cut And Paste(CAP)全波形拟合反演震源机制解方法, 依托中国地震局地震预测研究所准实时地震波形数据服务系统, 通过接收区域实时连续波形数据, 构建了首都圈地区准实时准自动波形反演系统, 使系统实现当地震大于3.5级时, 可自动、 迅速反演得到震源机制解。 同时考虑到一些台站的地震波形质量或信噪比等因素, 系统也可通过人为干预方式重新反演求得相关结果。 文中详细阐述了震源机制解波形反演系统的运行流程及该系统的基本构建思路, 并对实例进行对比分析, 表明该系统具有较好的实用性。 相似文献
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对山西运城2016年3月12日Ms4.3和27日Ms3.4两次地震的波形特征和震源参数进行对比分析。结果显示,波形一致性很好,PmP波可能由于震源深度的差异,导致在同一台站的特征有所不同;震源机制解非常接近,说明两次地震的应力场作用方式一致。 相似文献
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用余震作为经验格林函数从GDSN长周期波形资料中提取1999年集集地震的震源时间函数 总被引：2，自引：2，他引：2
1999年9月20日17ｈ47minUTC（北京时间9月21日01ｈ47min）中国台湾省南投县集集镇发生Mw7.6地震，随后又发生许多中强余震．我们从这些余震中选择了Mw6.1和Mw6.2两次余震分别作为经验格林函数，并从包括IRIS，GEOSCOPE和CDSN在内的全球数字地震台网的长周期波形资料中提取了主震的震源时间函数．对于发生在9月22日的Mw6.1余震，有26个台站的78条记录的97对震相清晰可用；对于发生在9月25日的Mw6.2余震，有24个台站的72条记录的81对震相清晰可用．对于每个台站，从Ｐ和Ｓ两种震相中提取震源时间函数，分别称之为Ｐ波震源时间函数和Ｓ波震源时间函数．这样，利用两次余震从长周期波形资料中共提取了178个震源时间函数．从这些震源时间函数可以看到，除在特殊方位的几个震源时间函数由于主震和余震的震源机制的差别引起较大的畸变外，大多数台站的震源时间函数都具有相似性；同时，其形状随方位发生一定程度的变化．这两种特征都是对所提取的震源时间函数的稳定性和可靠性的客观反映．通过分析确认，这次地震由两次子事件构成，总持续时间约26ｓ．第二次事件比第一次事件晚大约7ｓ，第一次事件的矩释放率比第二次事件大15％． 相似文献
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Gao Yuan Wu Zhongliang and Zhou HuilanGraduate School of USTC Academia Sinica Beijing ChinaCenter for Analysis Prediction China Seismological Bureau Beijing ChinaInstitute of Geophysics China Seismological Bureau Beijing China 《中国地震研究》1998,(3)
Four earthquakes with M > 6.0 occurred in Qinghai Province, China froth 1988 to 1990. Using broadband data from GDSN, the source ruptures of these earthquakes and tectonic surroundings were studied using waveform modelling combined with background data of geological tectonics. Through the analysis of apparent source time function (aSTF) and apparent time difference (aTD), the complexity of sources was discussed, and in view of source analysis, the result further supports the conclusion that the compressive stress axis of tectonic stress field in northeastern Qinghai-Xizang (Tibetan) plateau is at the NE direction, is nearly horizontal, turns counter-clockwise to the NEE or N to S direction, and is nearly horizontal close to the northern Qinghai-Xizang plateau. 相似文献
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Inversion for the seismic fault rupture history is an important way to study the nature of the earthquake source. In this paper, we have selected two Taiwan earthquakes that occurred closely in time and located in the same region, inversed the distribution of the slip amplitudes, rakes, risetimes and the rupture times on the fault planes by using GDSN broad-band and long-period records and the adaptive hybrid global search algorithm, and compared the two events. The slip rate of every subfault calculated provides information about the distribution of tectonic stress and fault strength. To the former event (MS=6.0), the maximum slip amplitude 2.4 m and the minimum risetime 1.2 s are both located at the hypocentre. The latter earthquake (MS=6.6) consisted of two subevents and the second source has 4 s delay. The maximum slip amplitude 0.9 m located near hypocentre is corresponding to the minimum risetime 1.4 s, and the corresponding maximum slip rate 0.7 m.s-1 is similar to the peak value of other large slip rate areas. We consider that the latter event has more complicated temporal-spatial distribution than the former. 相似文献
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在分析区域地震活动和构造环境及利用ＧＤＳＮ的宽频带波形资料分析震源破裂特征的基础上,结合余震资料,讨论了１９８８～１９９０年发生在四川和青海的９次强震的震源破裂和余震分布特征,分析了四川、青海、西藏相邻区域内的地震能量迁移,并用单键群分析方法对１９７０年以来的地震活动总体图象进行了研究。结果表明,这些地震的震源性质与构造应力环境相符,但青海地震的震源都具有较大的逆掩分量,与过去的走滑震源性质不同,而四川地震的震源Ｐ轴不接近水平方向与当地的“Ｙ”字形复杂构造有关 相似文献
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The source process of February 3, 1996 Lijiang earthquake in Yunnan was studied by body waveform inversion using teleseismic
data from IRIS. Two normal double-couple subevents with different strikes were obtained. The difference of the onset time
between these two subevents, which are 15 km apart in space, is 7 s. The total seismic moment is 3.81 × 1018 Nm (M
w=6.3). The total fault area S is about 720 km2 from the aftershock data and the average dislocation is about ū=0.18 m. Considering both the result of inversion and tectonic environment around the source, the first rupture might result
from the extension along the NNW directed Zhongdian-Yongsheng fault belt where an earthquake of M=6.4 occurred in 1966. Then, the second started along the NE directed the eastern foot of Snow Mountain fault where rupture
seemed to be able to propagate more easily. 相似文献
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昆仑山口西8.1级地震前青藏块体边界断层异常活动 总被引：5，自引：0，他引：5
系统分析了青藏块体边界断层的形变资料，研究了断层活动的动态过程及空间分布。结果表明，昆仑山口西8．1级地震前孕震影响范围达到青藏块体的周边地区；发震断层所在的构造带震前断层活动最为剧烈；加强对构造块体断层整体活动的宏观动态比较和分析，有助于判定未来强震发生的危险地段；震后应力将转移并集中到西秦岭构造带及其邻近地区。 相似文献
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In terms of seismically radiated energy or moment release, the earthquake of 20 January 1990 in the Manjil Basin-Alborz Mountain region of Iran is the second largest strike-slip earthquake to have occurred in an intracontinental setting in the past decade. It caused enormous loss of life and the virtual destruction of several cities. Despite a very large meizoseismal area, the identification of the causative faults has been hampered by the lack of reliable earthquake locations and conflicting field reports of surface displacement. Using broadband data from global networks of digitally recording seismographs, we analyse broadband seismic waveforms to derive characteristics of the rupture process. Complexities in waveforms generated by the earthquake indicate that the main shock consisted of a tiny precursory subevent followed in the next 20 seconds by a series of four major subevents with depths ranging from 10 to 15 km. The focal mechanisms of the major subevents, which are predominantly strike-slip, have a common nodal plane striking about 285°–295°. Based on the coincidence of this strike with the dominant tectonic fabric of the region we presume that the EW striking planes are the fault planes. The first major subevent nucleated slightly south of the initial precursor. The second subevent occurred northwest of the initial precursor. The last two subevents moved progressively southeastward of the first subevent in a direction collinear with the predominant strike of the fault planes. The offsets in the relative locations and the temporal delays of the rupture subevents indicate heterogeneous distribution of fracture strength and the involvement of multiple faults. The spatial distribution of teleseismic aftershocks, which at first appears uncorrelated with meizoseismal contours, can be decomposed into stages. The initial activity, being within and on the periphery of the rupture zone, correlates in shape and length with meizoseismal lines. In the second stage of activity the aftershock zone expands and appears to cluster about the geomorphic and geologic features several tens of kilometres from the rupture zone. The activity is interpreted as a regional response to quasistatic stress migration along zones of tectonic weakness. The radiated energy of the main shock and the estimate of seismic moment yields an apparent stress of 20 bars. High apparent stress may be typical of strike slip earthquakes occurring in intracontinental environments undergoing continental collision. 相似文献
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昆仑Ms 8.1地震前青藏块体北、东缘水平运动变形的关联特征 总被引：2，自引：0，他引：2
青藏块体东北缘和川滇GPS监测区1991(1993)、1999和2001年高精度GPS观测资料揭示：2001年11月14日昆仑Ms8．1地震前，青藏块体北、东缘构造区域水平运动变形场动态演变具有一定的关联性特征。即：在继承性运动总体背景下，临近大震发生时两区域运动强度同步减弱且变形状态发生变化。结合地质构造分析研究认为，昆仑Ms8．1地震前，青藏块体边界运动变形的关联性变化与大震孕育后期大范围应力应变快速积累所形成的扰动应力场有关；随着块体内部大震的发生、应变能的大量释放和构造应力场的调整，可能会促使块体边界地带具有较高应变积累的相关构造部位(尤其是未被历史强震破裂贯通的地带)的应力应变的进一步积累或破裂释放。 相似文献
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2017年8月9日的新疆精河MS6.6地震是近年来天山北缘发生的最大地震,震中位于由多条逆冲断层组成的库松木契克断裂带内.由于震源较深、构造形变复杂、区域地震台站相对稀疏,仅根据震源机制解、余震分布和InSAR观测结果等难以直接判定发震构造.本文针对倾滑型地震发展了一种基于区域地震波形的破裂方向性测定方法,利用余震作为参考地震进行路径校正,根据主震和参考地震的波形时移差和Pn-Pg到时差分别确定主震在水平方向和深度方向的破裂尺度,进而推断同震破裂的延展方向和延伸尺度.本文在反演了主震的点源参数后,应用新发展的方法测定了地震的破裂方向性.点源反演结果显示,精河地震是一个发生在中地壳的高角度逆冲地震,矩震级约6.2,质心深度21km,震源持续时间5.5s,两个双力偶节面分别为102°/45°/106°(NP1)和259°/47°/74°(NP2).破裂方向性分析结果显示,地震的破裂面为南倾的NP1节面,地震沿着破裂起始点向西南方向、向下破裂,总破裂长度约11.5km,其中,沿深度的破裂范围约7km,沿水平的破裂范围约9km,平均破裂速度约2.1km·s-1.综合区域地质资料、卫星影像等判定本次地震的发震断层为精河南断层,地震可能只破裂了断层的下段(17~25km),并未破出地表. 相似文献