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1.
计算和研究了1976年云南龙陵Ms73、Ms74双主震产生的完全库仑破裂应力变化及其对后续震群序列的动态和静态应力触发作用.结果显示,龙陵第2主震受到了第1主震的动态和静态库仑破裂应力的触发作用.龙陵双主震的13个后续强余震中,发生在龙陵三角形块体内部的强余震,90%都受到了第1或第2主震的动态库仑破裂应力触发或静态库仑破裂应力触发作用,发生在三角形块体外部的强余震,2/3受到了第2主震的动态库仑破裂应力触发作用.从触发作用的强度和范围上看,第2主震的动态和静态库仑破裂应力触发作用都大于第1主震.就近场而言,受到龙陵双主震的动态和静态库仑破裂应力触发作用的余震数目相当,但动态库仑破裂应力的触发作用范围大于静态库仑破裂应力. 相似文献
2.
在离散波数法基础上计算2008年3月21日新疆于田MS7.3地震造成的近场区域完全库仑应力变化, 分析该变化对余震发生所产生的影响, 得到了此次地震在2008年10月5日乌恰MS6.8地震震中处所产生的动态库仑破裂应力变化. 计算结果表明, 该地震近场区域库仑应力变化图像演化大概持续了60 s, 库仑应力变化对余震的触发率达到90%以上, 其中动态库仑应力变化图像更好地解释了余震的分布. 余震震中处的完全库仑应力变化计算结果表明, 其动态库仑应力变化远远大于静态库仑应力变化. 于田MS7.3地震在乌恰MS6.8地震震中处造成的最大动态库仑应力变化为0.12 MPa, 说明后者可能受到了于田MS7.3地震的动态应力触发作用, 但不显著;而静态库仑应力则对其影响很小. 相似文献
3.
Based on the discrete wavenumber method, we calculate the fields of dynamic Coulomb rupture stress changes and static stress
changes caused by M6.5 earthquake in Wuding, and study their relationship with the subsequent aftershocks. The results show that the spatial
distribution patterns of the positive region of dynamic stress peak value and static stress peak value are similarly asymmetric,
which are basically identical with distribution features of aftershock. The dynamic stress peak value and the static stress
in the positive region are more than 0.1 MPa and 0.01 MPa of the triggering threshold, respectively, which indicates that
the dynamic and static stresses are helpful for the occurrence of aftershock. This suggests that both influences of dynamic
and static stresses should be considered other than only either of them when studying aftershock triggering in near field.
Foundation item: National Natural Science Foundation of China (40364001) and Joint Seismological Science Foundation of China (605014). 相似文献
4.
选取IRIS远震台站波形数据,反演了云南漾濞MS6.4地震震源破裂过程,计算了断层破裂在近场产生的动态库仑破裂应力变化,并讨论了主震对近场余震活动的动态应力触发作用。结果显示:动态库仑应力演化过程与震源破裂特征反演结果一致,其大小分布与地震序列分布的疏密程度也具有较好的相关性。主震产生的静态和动态库仑破裂应力均促进余震的发生,但相比静态应力,余震位于库仑破裂应力正值区域的比例提高了21%,余震与动态库仑应力变化的正负区域有更好的一致性,动态应力能更好地解释震后余震分布的空间特征。垂直于地震序列主干10 km处出现小震丛集,该现象可能是由主震产生的动态库仑破裂应力占主导作用所致。定量分析主震对余震的动态应力触发结果显示,主震后一周内MS4.0以上的8次余震接收点均受到了动态库仑破裂应力的触发作用。 相似文献
5.
在离散波数法（DWN）基础上,计算了武定M6.5地震断层破裂在周围介质中产生的位移时程（位移理论地震图）和动态位移场;进行弹性动力学转换后,求得应变时程和动态应变场;最后得到了武定M6.5地震所产生的动态库仑破裂应力变化量和动态库仑破裂应力变化场,进而研究其与后续余震的关系. 结果表明,动态应力最大峰值和静态应力的正区均呈非对称性分布,两者的分布特征与余震的分布特征基本一致. 在动态应力峰值为正的确定区应力值超过了0.1 MPa触发阈值, 在静态应力值为正的确定区应力值超过了0.01 MPa触发阈值. 这说明动态应力和静态应力均有助于余震的发生. 相似文献
6.
探讨了断层间相互作用产生的同震库仑应力改变及对地震的触发与延缓效应，并以鲜水河断裂带不同断裂段时间上连续发生的4次MS6.0以上地震为例，计算和分析了每次地震发生后，在周围其它断裂上产生的同震库仑应力改变及其对后续地震的触发，以及1973年炉霍MS7.6地震和1981年道孚MS6.9地震发生后，在其周围最易破坏失稳的微破裂上产生的同震库仑应力改变及对余震活动的影响．在其它条件保持不变的情况下，将这4次地震的累积触震与缓震效应加以定量考虑，对鲜水河断裂带各断裂段的地震潜势进行了重新计算，并与已有预测结果进行对比分析，检验和评估了鲜水河断裂带断层间相互作用触震与缓震效应的重要性．结果表明:鲜水河断裂带每次地震都发生于受其先前发生的地震影响而产生同震库仑应力增加的断裂段上，不同断层间相互作用的触震和缓震效应导致地震复发概率的改变可高达30.5％以上， 主震后的余震大多发生于同震库仑应力增加较高的微破裂上． 相似文献
7.
采用文献[1]计算地震产生的静态应变场的解析表达式,对云南禄劝地震的15次余震,计算了主震在余震节面上产生的正应力和静态库仑破裂应力变化。分析了正应力变化和静态库仑破裂应力变化是否对余震有触发作用。结果表明,主震产生的正应力变化和库仑破裂应力变化并没有明显的证据“有利于”余震的发生。另外,还比较了运用与主震相同的余震机制和反演得到的余震机制在库仑破裂模型中计算结果的差异。使用反演的余震机制得出的结果稍优于假定余震与主震有相同震源机制得到的结果。 相似文献
8.
汶川8.0级地震的余震触发作用和对断层的应力加卸载作用 总被引：1，自引：0，他引：1
采用可变滑动震源模型,计算和研究了汶川M_S 8.0地震产生的应力变化及对后续6次强余震的应力触发作用,并定量分析了汶川地震对附近活动断裂带的库仑应力加卸载作用。结果显示:汶川地震产生的库仑破裂应力变化分布图案复杂性强,主要由发震断裂复杂的空间展布形态以及震源断层活动具有逆冲兼右旋走滑两种性质决定。汶川地震产生的库仑破裂应力变化对多数强余震存在一定的触发作用。汶川地震的发生对附近的断裂带有不同程度的影响,其中青川断裂中段和北段、岷江断裂南段和灌县-江油断裂南段,主要是以强烈的库仑破裂应力加载作用占主导地位,有利于强余震序列的孕育、加速以至于发生;东昆仑断裂带和鲜水河断裂带受到了轻微的应力加载作用;龙泉山断裂带、华莹山断裂带和西秦岭北缘断裂带主要受到了轻微的卸载作用。 相似文献
9.
选用Hayes和Guangfu Shao等给出的震源破裂模型(2011年3月网上公布)、哈佛CMT目录和日本F-net目录给出的余震目录,使用Coulomb3.2软件,对2011年3月11日发生在日本本州东海岸附近海域的M_W9.0地震序列间的静态库仑应力触发关系进行了初步研究。结果表明:1)3月9日发生的M_W7.2前震破裂分布产生的库仑应力对随后发生的M_W9.0主震存在触发作用;2)M_W9.0主震对余震的触发统计结果表明,选用不同的主震模型、余震目录、等效摩擦系数和震源机制解中不同的节面作为接收断层面时,会得到不同的触发统计结果,该研究得到的主震对余震的触发率最小为56.8%,最大为75.3%;3)利用震源机制解计算库仑应力时,理论上震源机制解的2个节面上的剪切应力是相同的,但在实际计算中可能由于2个节面的非正交或震源机制解结果的取整,导致2个节面上计算出的剪切应力不同,但一般差异很小。由于节面的选取对接收断层面上的剪切应力有一定影响,而对接收断层面上正应力的影响较大,因而会影响到库仑应力的计算结果,因此讨论某个具体余震是否被触发或统计余震触发率时,对接收断层面的选取应加以注意。 相似文献
10.
Static stress changes as a triggering mechanism of a shallow earthquake: case study of the 1999 Chi-Chi (Taiwan) earthquake 总被引：2，自引：0，他引：2
Jeng-Cheng WangChiou-Fen Shieh Tao-Ming Chang 《Physics of the Earth and Planetary Interiors》2003,135(1):17-25
The role of static stress changes in triggering an earthquake has long been debated in the fields of geophysics and fault mechanics. Valuable data sets for the study of static triggering were provided within the 1-year period following the devastating 1999 Chi-Chi (Taiwan) earthquake (MW=7.6), during which more than 20,000 aftershocks occurred. In this study, stress waves generated by the Chi-Chi earthquake were calculated using a source rupture model in conjunction with a layered elastic model. Static (permanent) stress changes were extracted from the long-period offsets in the stressgrams. Correlations between the calculated stress changes and seismicity were analyzed at different depths and over varying time intervals to ascertain the impact effects of stress changes on triggering aftershocks. Correlations between prior seismicity rates and static stress changes imposed by the Chi-Chi event were low, while correlations between late seismicity rates and static stress changes were much higher. This indicates that static stress changes did affect the occurrence of the Chi-Chi aftershock sequence. The percentage of early aftershocks at shallow depths (0-10 km) in static stress-enhanced areas within 2 weeks of the main shock was high but decreased considerably at greater depths (>10 km) and over longer time periods. It is concluded that static stress changes at depths of 0-10 km played a major role in triggering crustal aftershocks, especially those that occurred within 2 weeks of the main shock. In the deeper crust, static stress changes may have been modified by viscous flow, and at later times, perturbed by earlier, larger aftershocks. Although the correlations between seismicity rate changes and static stress changes are imperfect, a region that was anti-triggered is detected when these two results are compared. Static stress changes are presumably not the only aftershock triggering mechanism, but they definitively play a major role in triggering shallow aftershocks. 相似文献
11.
On May 12, 2008, a magnitude 7.9 earthquake ruptured the Longmenshan fault system in Sichuan Province, China, collapsing buildings
and killing tens of thousands people. As predicted, aftershocks may last for at least one year, and moreover, large aftershocks
are likely to occur. Therefore, it is critical to outline the areas with potential aftershocks before reconstruction and re-settling
people as to avoid future disasters. It is demonstrated that the redistribution of stress induced by an earthquake should
trigger successive seismic activity. Based on static stress triggering theory, we calculated the coseismic stress changes
on major faults induced by the Wenchuan earthquake, with elastic dislocation theory and the multilayered crustal model. We
also discuss the stress distribution and its significance for future seismic activity under the impact of the Wenchuan earthquake.
It is shown that coulomb failure stress (CFS) increases obviously on the Daofu-Kangding segment of the Xianshuihe Fault, the
Maqu and Nanping segment of the Eastern Kunlun Fault, the Qingchuan Fault, southern segment of the Minjiang Fault, Pengxian-Guanxian
Fault, Jiangyou-Guangyuan Fault, and Jiangyou-Guanxian Fault. The increased stress raises the probability of earthquake occurrence
on these faults. Since these areas are highly populated, earthquake monitoring and early disaster alarm system are needed.
CFS increases with a magnitude of 0.03–0.06 MPa on the Qingchuan Fault, which is close to the northern end of the rapture
of Wenchuan earthquake. The occurrence of some strong aftershocks, including three events with magnitude higher than 5.0,
indicates that the seismic activities have been triggered by the main shock. Aftershocks seem to migrate northwards. Since
the CFS change on the Lueyang-Mianxian Fault located on the NEE of the Qingchuan Fault is rather small (±0.01 MPa), the migration
of aftershocks might be terminated in the area near Hanzhong City. The CFS change on the western Qinling Fault is around 10
Pa, and the impact of static triggering can be neglected. The increment of CFS on the Pengxian-Guanxian Fault and Beichuan-Yingxiu
Fault southwest to the main rupture is 0.005–0.015 MPa, which would facilitate earthquake triggering in these areas. Very
few aftershocks in these areas indicate that the accumulated stress has not been released sufficiently. High seismic risk
is predicated in these areas due to co-seismic CFS loading. The Wenchuan earthquake released the accumulated CFS on the Fubianhe
Fault, the Huya Fault, the Ha’nan-Qingshanwan Fault, and the Diebu-Bailongjiang Fault. The decrement of CFS changes on the
Longquanshan Fault east to Chengdu City is about 0.002 MPa. The seismic activity will be depressed by decrement of CFS on
these faults.
Supported by Knowledge Innovation Program of Chinese Academy of Sciences (Grant No. KZCX-SW-153), National Natural Science
Foundation of China (Grant Nos. 40574011 and 40474028) 相似文献
12.
大地震发生后,估计后续地震发展趋势是人们关心的问题.目前,学术界经常利用大地震造成的库仑应力变化研讨大震对后续地震的影响,但库仑应力的计算和应用中尚有一些问题被忽视而有待探讨.本文修正了传统的库仑应力计算中沿地震破裂面滑动方向计算剪应力变化的近似方法,考虑震后主应力方向可能改变对剪应力变化量计算的影响,对改进方法和传统方法获得的结果进行了对比分析.本文基于龙门山地区背景应力场测量资料,根据不同研究者反演的地震破裂模型,计算了汶川地震造成的静态库仑应力变化,考察了不同地震破裂模型下库仑应力分布差异.在断层面附近,使用改进方法与传统方法计算的库仑应力分布差异相当大;利用多个地震破裂模型计算大地震库仑应力判断大震后余震发展趋势时,要注意破裂模型不确定性对危险性估计的影响. 相似文献
13.
We calculated the Coulomb failure stress change generated by the 1976 Tangshan earthquake that is projected onto the fault planes and slip directions of large subsequent aftershocks.Results of previous studies on the seismic fail-ure distribution,crustal velocity and viscosity structures of the Tangshan earthquake are used as model constraints.Effects of the local pore fluid pressure and impact of soft medium near the fault are also considered.Our result shows that the subsequent Luanxian and Ninghe earthquakes occurred in the regions with a positive Coulomb fail-ure stress produced by the Tangshan earthquake.To study the triggering effect of the Tangshan,Luanxian,and Ninghe earthquakes on the follow-up small earthquakes,we first evaluate the possible focal mechanisms of small earthquakes according to the regional stress field and co-seismic slip distributions derived from previous studies,assuming the amplitude of regional tectonic stress as 10 MPa.By projecting the stress changes generated by the above three earthquakes onto the possible fault planes and slip directions of small earthquakes,we find that the "butterfly" distribution pattern of increased Coulomb failure stress is consistent with the spatial distribution of follow-up earthquakes,and 95% of the aftershocks occurred in regions where Coulomb failure stresses increase,indicating that the former large earthquakes modulated occurrences of follow-up earthquakes in the Tangshan earthquake sequence.This result has some significance in rapid assessment of aftershock hazard after a large earthquake.If detailed failure distribution,seismogenic fault in the focal area and their slip features can be rapidly determined after a large earthquake,our algorithm can be used to predict the locations of large aftershocks. 相似文献
14.
2010年4月14日青海省玉树藏族自治州发生MS7.1级地震.和传统的板内地震相比,玉树MS7.1级地震的余震具有数量少、震级大的特点.研究玉树地震主震与余震之间的关系,对于我们了解余震的发震机理具有十分重要的参考价值.本文利用弹性位错理论和分层岩石圈模型,计算玉树地震引起的同震及震后黏弹松弛应力场变化,讨论MS7.1级玉树地震对余震分布的影响以及与2011年囊谦MS5.2级地震之间的触发关系.结果显示,玉树地震导致了四处明显的库仑应力增强的扇区,2010年4月13日至6月17日的870次ML>1.0级余震主要分布于主震破裂面附近区域以及破裂面东北端的应力增强扇区.分析玉树地震对余震分布的影响时,有效摩擦系数以及计算深度的选取对计算结果的影响较小,是否考虑区域构造应力场的影响较大.考虑区域构造应力场时,占总数86.7%的余震位于库仑应力增强区,地震应力触发理论较好地解释了余震的分布.选取囊谦地震震源机制解的两个节面作为库仑应力计算中的接收断层参数,并且考虑不同黏滞系数下的玉树地震同震及震后黏弹松弛效应,模型计算结果均表明囊谦地震位于玉树地震所导致应力影区,仅依靠地震的静态、震后黏弹松弛应力触发理论,无法解释囊谦地震的发生,说明该次地震可能是一次独立的事件. 相似文献
15.
地震静态触发研究在全世界范围内广泛开展,并取得显著成效;但是否所有的大地震,地震静态触发都有很好的效果,对此目前还不甚清楚.本文通过计算最近发生在俯冲带上的三次特大地震(2011年日本东北地震(Mw=9.1)、2010年智利地震(Mw=8.8)与2004年苏门答腊—安达曼地震(Mw=9.0))所产生的静态库仑应力变化,考察主震库仑应力变化对其后续余震空间分布的影响,从而研究俯冲带上特大地震对地震的触发效果.计算结果显示:对于2011年日本东北地震,仅有47%的后续余震发生在库仑应力增加的区域;2010年智利地震也只有47.6%的余震位置处于库仑应力变化的正值区;2004年苏门答腊地震触发了49.8%的后续余震.文中通过进一步改变模型参数(如:采用不同的有效摩擦系数,使用不同作者给出的震源模型等)进行计算,结果表明这三大地震对后续余震的触发比例仍然不高(最好情况下,触发比例也不超过60%).但对于板内地震(如:2008年汶川地震,1999年集集地震),主震对后续余震的触发比例超过85%.由此可以推知,对于俯冲带上的特大地震,地震静态触发效果不显著.因此,对于俯冲带上大地震的触发问题,还需深入研究. 相似文献
16.
A new finite element model in studying earthquake triggering and continuous evolution of stress field 总被引：2，自引：0，他引：2
In this paper, a new finite element model (FEM) in consideration of regional stress field and an earthquake triggering factor
C are proposed for studying earthquake triggering and stress field evolution in an earthquake sequence. The factor C is defined
as a ratio between the shear stress and the frictional strength on a slip surface, and it can be used to tell if earthquake
is triggered or not. The new FEM and the factor C are used to study the aftershock triggering of the 1976 Tangshan earthquake
sequence. The results indicate that the effects of the stress field and the heterogeneity of the Tangshan earthquake fault
zone on the aftershock triggering are very important. The aftershocks fallen in the earthquake triggering regions predicted
by the new FEM are more than those fallen in the regions of ΔCFS⩾0 predicted by seismic dislocation theory.
Supported by National Natural Science Foundation of China (Grant Nos. 40474013 and 40821062) 相似文献
17.
基于九寨沟MS7.0地震的破裂模型及均匀弹性半空间模型,本文计算了该地震在周围主要活动断层上产生的库仑应力变化、在周围地区产生的应力场和位移场和同震库仑应力变化对余震的触发.结果表明：（1）九寨沟地震造成虎牙断裂中段库仑破裂应力有较大增加,已经超过0.01 MPa的阈值,虎牙断裂北段、塔藏断裂中段和岷江断裂北段北部的库仑破裂应力有较大降低,因此尤其要注意虎牙断裂中段的危险性.（2）水平面应力场在该地震震中东西两侧增加（拉张）,张应力起主要作用.在震中南北两侧降低（压缩）,压应力起主要作用.从水平主压和主张应力方向来看,均呈现出条形磁铁的磁场形态.从剖面上的应力场来看,在上盘的面膨胀区域内,大部分点的主张应力方向与地表是垂直的,在其他区域内,主张应力和主压应力均以震中为中心,向外呈辐射状.（3）从地表水平位移场来看,震中东西两侧物质朝震中位置汇聚,南北两侧物质向外流出,在震中处的最大水平位移量达43 mm.从地表垂直位移场来看,震中南北两侧出现明显的隆升,隆升最大值达56.8 mm.震中东西两侧出现明显的沉降,沉降最大值达74.5 mm.从剖面的位移场来看,九寨沟地震为左旋走滑地震,且有一定的正断成分.由分析可以推测该断层破裂在大致22~26 km的深度上就截止了.并推测下盘物质运动的动力来自震源北东东方向（四川块体）深度在6~30 km的下盘下层物质,上盘物质运动的动力来自震源北西西方向（巴颜喀拉块体）深度在0~6 km的上盘上层物质.（4）通过计算不同深度上主震对余震的触发作用可知,主震后的最大余震受到了主震的触发作用,多数其他余震也受到主震的触发作用.主震的发生促使了库仑应力增加地区余震的发生,抑制了一部分库仑应力减少地区余震的发生. 相似文献
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Based on the discrete wavenumber method, we calculate the fields of dynamic Coulomb rupture stress changes and static stress changes caused by M6.5 earthquake in Wuding, and study their relationship with the subsequent aftershocks. The results show that the spatial distribution patterns of the positive region of dynamic stress peak value and static stress peak value are similarly asymmetric, which are basically identical with distribution features of aftershock. The dynamic stress peak value and the static stress in the positive region are more than 0.1 MPa and 0.01 MPa of the triggering threshold, respectively, which indicates that the dynamic and static stresses are helpful for the occurrence of aftershock. This suggests that both influences of dynamic and static stresses should be considered other than only either of them when studying aftershock triggering in near field. 相似文献
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采用可变滑动震源模型,计算Ms8．1昆仑山口西地震产生的库仑破裂应力变化,解释余震的空间分布特征。以此为基础,分析了此次大地震在周边断层上产生的应力变化及其对地震活动性的影响。结果表明,两个模型和两种方法计算得到的应力变化均呈现相似的分布特征。应力增加区与后续地震活动的对应关系,反映昆仑山口西地震对后续地震活动的触发效应。玛尼断裂带和东昆仑断裂带受应力变化影响最明显。 相似文献