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通过对2013年1月至11月四川长宁地区M≥4.0地震震相的分析得出,在震中距大于260 km时,四川数字地震台网部分台站可记录到较为清晰的sPn震相。本文采用sPn和Pn震相确定震源深度的方法,分别对长宁地区2个M≥4.0地震的震源深度进行了重新计算,2次地震的震源深度较浅,均小于3 km,是较为精确的震源深度值。 相似文献
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采用黑龙江地震台网记录的地震波形,基于sPn震相,计算2005—2021年黑龙江省区域内发生的11次M≥4.0近震的震源深度。分析发现,在研究区域内,可精确识别单台震中距在3°—7°范围内的地震记录波形的sPn震相。计算多台站震源深度,发现其平均值与黑龙江地震台网采用HypoSat方法测定的震源深度结果基本一致,仅3个地震的误差较大。分析认为,采用sPn震相方法测定黑龙江地区近震的震源深度准确度较高,可为日常跟踪分析工作提供依据。 相似文献
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sPn震相计算近震震源深度研究 总被引:4,自引:2,他引:4
震源深度是描述震源信息的基本参数之一,也是目前最难测准的参数之一。近震深度震相sPn与Pn震相到时差与震中距无关,是测定地壳内地震震源深度的主要依据之一。sPn与Pn到时差测定地壳内近震深度的方法简洁、准确,可以在日常地震速报中应用。 相似文献
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运用Pn震相对齐的方法分析了发生在中国台湾地区地震的sPn震相,总结了该地区地震sPn震相的一些特征,用sPn震相计算了震源深度并与单纯型定位法结果进行了对比。结果表明,在该地区地震中,sPn震相特征明显;应用该方法可以较准确地测定台湾浅源地震的震源深度。 相似文献
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本文推导了sPn与Pn波走时差与震源深度的方程,方程中sPn与Pn波的走时差与震中距无关,只与震源深度和区域地壳模型有关.根据该方程,提出用sPn与Pn的走时差来测定地震深度.2008年8月30日和8月31日在四川省攀枝花和会理交界处分别发生了Ms6.1、Ms5.6两次地震.但是,在四川省地震台网地震目录中缺少8月30... 相似文献
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利用sPn和Pn震相走时差计算的2014年2月28日石嘴山M_L4.4地震的震源深度为7.21±0.277km;分析不同震源深度下民勤台的理论波形与观测波形拟合结果,得到震源深度为7~8km。研究认为,石嘴山M_L4.4地震属于浅源地震,震源浅和沉积层较厚是此次地震震感较强的主要原因。另外,合理选取地震波形数据和震相识别方法,可有效提高s Pn震相测定震源深度的可靠性。为便于应用,本文还给出了宁夏地区地震震源分别位于上地壳和下地壳时sPn和Pn震相走时差与震源深度的对应关系表。 相似文献
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用sPn震相测定近震震源深度 总被引:10,自引:5,他引:10
用近震深度震相sPn与Pn波的到时差测定近震深度,方法以求简捷准确。为此,对我国部分地区台网记录的sPn震相进行了初步分析研究,通过研制的计算sPn走时程序运算,给出华北、山西、华东、西北及四川地区的sPn-Pn走时差对应震源深(h)表和sPn-Pn求震源深度列线图。经过震例检验,该表比较适合本地区的走时特性。为应用sPn震相测准我国部分地区震源深度,提供了有利工具。 相似文献
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新疆乌鲁木齐地区震源深度分布与断层关系研究 总被引:2,自引:0,他引:2
采用新疆维吾尔自治区地震局精度较高的常规地震目录和双差定位目录,对乌鲁木齐地区震源深度的分布特征及与断层的关系进行了研究。结果表明,乌鲁木齐地区的平均震源深度随震级的增加而加深,并形成3个分布层。震源绝大多数分布在上地壳1~35km深度范围内,优势集中在上地壳16~25km深度范围内。平均震源深度的空间分布特征与断层的展布密切相关,乌鲁木齐市附近的3组断裂所夹持的地块震源深度最浅,深度处于17~21km之间,而在周边一些深大断裂上震源深度较深。不同构造部位的震源深度剖面显示,清水河子断裂、齐古断裂、依连哈比尔尕等断裂的断裂面处于无震蠕滑或闭锁状态,地震主要发生在其下的滑脱层中;而在霍尔果斯、西山、二道沟等断裂上,震源深度从滑脱层延伸到断裂面上,反映出断裂未完全闭锁时的弱运动状态,显示这些断裂为新的活动断裂。震源深度的分布还与乌鲁木齐地区复杂的地壳结构有关,地震多分布在低速体之上或低速体和高速体之间的夹层中 相似文献
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通过对中国绝大部分地区 1970年以来有仪器测定震源深度的地震资料进行详细分析 ,提出了“地震地热说”的假说并对分析结果作出解释 ,得出了一个关于中国强震活动大形势的全新观念 ,认为中国强震活动受到地壳深部 4个“热点”(吉林、新疆兴都库什、台湾和西藏日喀则等中深源震区 ) 70年代强震活动的牵引 ,完成了一个由地震活动高潮期 ( 1970 ?~ 1982 )、调整期 ( 1983~ 1992 )和消减期 ( 1993~ 1999?)所组成的地震链全过程。目前消减期尚未结束 ,但从 1999年 4月 8日吉林7 0级深震开始 ,新的一轮地震链过程可能已在酝酿之中 相似文献
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In this paper,we derived the relationships between the travel time difference of sPn and Pn and the local earthquake focal depth.In these equations,the travel time difference of sPn and Pn is not related to the epicentral distance,but depends only on the regional crustal mode and the focal depth.According to the equations,we provided a simple and accurate method to determine local earthquake focal depth by using the travel time difference between phase sPn and Pn.This method has been used to determine the f... 相似文献
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On July 31th, 2016, a magnitude 5.4 earthquake struck Cangwu Country, Guangxi Zhuang Autonomous Region, it was the largest earthquake recorded by Guangxi Seismological Network since it set up. The number of people affected by the earthquake had reached 20 000, and the direct economic losses caused by the earthquake were nearly 100 million Yuan.
After the earthquake, USGS provided a global earthquake catalog showing that the focal depth of Cangwu earthquake was about 24.5km. However, the result given by the Global Centroid Moment Tensor showed the focal depth of this earthquake was 15.6km. However, the result obtained by Xu Xiaofeng et al. using CAP method was 5.1km. It was clear that the focal depths of Cangwu earthquake given by different institutions were quite different from each other. However, accurate focal depth of the earthquake has important significance for exploring the tectonic mechanism near the epicenter, so it is necessary to further determine the more accurate depth of the Cangwu earthquake.
In order to further accurately determine the focal depth of Cangwu earthquake, we used the global search method for travel-time residual to calculate the focal depth of this earthquake and its error range, based on the regional velocity model, which is a one-dimensional velocity model of the Xianggui tectonic belt produced by the comprehensive geophysical profile. Then, we inverted the focal mechanism of this earthquake with the CAP method. Based on this, the focal depth of Cangwu MS5.4 earthquake was further determined by the method of the Rayleigh surface wave amplitude spectrum and the sPL phase, respectively.
Computed results reveal that the focal depth of this earthquake and its error range from the travel-time residual global search method is about(13±3)km, the focal depth inverted by CAP method is about 10km, the focal depth from sPL phase is about 10km, and the focal depth from Rayleigh surface wave amplitude spectrum is about 9~10km. Finally, we confirmed that the focal depth of Cangwu MS5.4 earthquake is about 10km, which indicates that this earthquake still occurred in the upper crust. In the case of low network density, the sPL phase and Rayleigh wave amplitude spectrum recorded by only 1 or 2 broadband stations could be used to obtain more accurate focal depth.
The focal depth's accuracy of Cangwu MS5.4 earthquake in the USGS global earthquake catalog has yet to be improved. In the future, we should consider the error of the source parameters when using the USGS global earthquake catalog for other related research. 相似文献
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根据震源指标几何扩散率n和近场吸收系数a/km^2都随实际地震而异的性质,导出了完整震源深度公式,并获得K-G问题的通解。对此通解及震源深度公式分别提出3种算法,效果都较好,利用计算所得震源类型,结合宏观场粗略地探索了震源几何学,为直接观察震源的钻孔设计提供了依据。 相似文献
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TwoMS4.5 earthquakes happened in Yongning, a county of Yinchuan in Ningxia on June 22, 2010 and November 20, 2012, which were both strongly felt in Yinchuan and its vicinities. In order to understand the seismogenic structure better, we collected the regional earthquake waveform data of Ningxia and nearby seismic networks. Locating main shocks and aftershocks distribution by Hyp2000 and inversing the focal mechanism and depth by TDMT, we got results as follows: for the June 22 earthquake, nodal plane Ⅰ: strike 208, dip 89, and rake -164; nodal plane Ⅱ: strike 117, dip 74, and rake -2. For the November 20 earthquake: nodal plane Ⅰ: strike 284, dip 79, and rake 12, nodal plane II strike 192, dip 79, and rake 169. By means of reference to Snoke method, it is known that the main fractures of the two earthquakes are both strike slip faults with NNE-trending and NNW-dipping, while the former has a small amount of tension component and the latter has a small amount of thrust component. And the moment magnitudes of them areMW4.5 andMW4.3. According to Hyp2000 location, TDMT moment tensor fitting error and sPn depth phases, we consider that the focal depths of the two earthquakes are 22km and 8km, both are shallow-focus ones. Though the epicenters of the two earthquakes are 13km apart from each other, the former one is deeper, the reason is that the November 20 earthquake was controlled by the major fault of Yinchuan Fault, while the June 22 earthquake was controlled by south branch of Yinchuan Fault. 相似文献