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1.
This paper calculates the static Coulomb stress changes generated by four earthquakes in the Yutian area during 2008 ~ 2014 separately, then discusses the triggering influence, their accumulated Coulomb stress changes and their influence on nearby faults. The results indicate that the Ms5. 5 earthquake in 2011 and the Ms7. 3 earthquake in 2014 are both in the regions where the Coulomb stress change is positive, the stress changes are 0. 004MPa and 0. 021MPa, respectively, meaning they are triggered by prior earthquakes. The Ms6. 2 earthquake in 2012 occurred in the place where Coulomb stress change was negative, so it is postponed by the prior earthquakes. The image of Coulomb stress changes of the Ms 7. 3 earthquake in 2014 is in accord with aftershocks （ML ≥ 3. 0 ） distribution, but some regions on the fault where the Coulomb stress change is positive have few aftershocks, and strong aftershocks may occur at these districts in future. In addition, this paper calculates the Coulomb stress change on nearby faults, and finds that the Coulomb stress changes of different elements in the GGC fault are very different, and must receive strong triggered-influence, though the result may be influenced by the input finite fault model, so there is still a large earthquake-risk. The GGN, PLC, PLW and LBW faults were also triggered by the four earthquakes occurring between 2008 ~ 2014. Their maximum Coulomb stress changes all exceed 0. 002MPa, so they also have a strong earthquake hazard. 相似文献
2.
Wang Qiong 《中国地震研究》2007,21(3):255-268
The Bachu-Jiashi earthquake of Ms6.8 occurred on February 24, 2003, about 20km from the southeast of the 1997 - 1998 Jiashi seismic region in Xinjiang, and its aftershocks are rich and strong. Did the 1997 - 1998 Jiashi strong earthquake swarm trigger the Bachu-Jiashi Ms6.8 earthquake？ The Atushi earthquake of Ms6.7 occurred in 1996, and the 1997 - 1998 Jiashi strong earthquake swarm occurred about 70km from the Atushi earthquake 10 months later. Did the Atushi earthquake of Ms6.7 encourage the 1997 - 1998 Jiashi strong earthquake swarm？ There were 9 earthquakes with Ms6.0 from 1996 to 1997 in the Jiashi seismic region, how did they act on each other？ To answer the above questions, the article studies the triggering effect of the activity process of the whole Jiashi earthquake swarm from the 1996 Atushi earthquake of Ms6.7, the 1997 - 1998 Jiashi strong swarm to the 2003 Bachu-Jiashi earthquake of Ms6.8, and analyzes the seismicity characteristics around the Jiashi region. The results show that the 1996 Atushi earthquake of Ms6.7 encouraged the 1997 - 1998 Jiashi strong swarm to some extent, the accumulative Coulomb stress change from the previous M6.0 earthquakes of the Jiashi strong swarm had certain triggering effects on the following M6.0 events, and the Coulomb stress change converted from the Jiashi strong swarm strongly encouraged the 2003 Bachu-Jiashi earthquake with Ms6.8. 相似文献
3.
Immediately following the Ms7.0 Lushan earthquake on April 20, 2013, using high-pass and low- pass filtering on the digital seismic stations in the Shanxi Province, located about 870-1,452 km from the earthquake epicenter, we detected some earthquakes at a time corre- sponding to the first arrival of surface waves in high-pass filtering waveform. The earthquakes were especially noticed at stations in Youyu （YUY）, Shanzizao （SZZ）, Shanghuangzhuang （SHZ）, and Zhenchuan （ZCH）, which are located in a volcanic region in the Shanxi Province,but they were not listed in the Shanxi seismic observation report. These earthquakes occurred 4-50 rain after the passage of the maximum amplitude Rayleigh wave, and the periods of the surface waves were mainly between 15 and 20 s following. The Coulomb stresses caused by the Ray- leigh waves that acted on the four stations was about 0.001 MPa, which is a little lower than the threshold value of dynamic triggering, therefore, we may conclude that the Datong volcanic region is more sensitive to the Coulomb stress change. To verify, if the similar phenomena are widespread, we used the same filtering to observecontrastively continuous waveform data before, and 5 h after, the Ms7.0 Lushan earthquake and Ms9.0 Tohoku earthquake in 2011. The results show that the similar phenomena occur before the earthquakes, but the seis- micity rates after the earthquakes are remarkably increased. Since these weak earthquakes are quite small, it is hard to get clear phase arrival time from three or more stations to locate them. In addition, the travel time differences between P waves and S waves （S-P） are all less than 4 s, that means the events should occur in 34 km around the stations in the volcanic region. The stress of initial dynamic triggering of the Ms9.0 Tohoku earthquake was about 0.09 MPa, which is much higher than the threshold value of dynamic triggering stress. The earthquakes after the Ms9.0 Tohoku earthquake are related to dynamic triggering stress, but the events before the earthquake cannot be linked to seismic events, but may be related to the back- ground seismicity or from other kinds of local sources, such as anthropogenic sources （i.e., explosions）. Using two teleseismic filtering, the small background earthquakes in the Datong volcanic region occur frequently, thus we postulate that previous catalog does not apply bandpass filter to pick out the weak earthquakes, and some of the observed weak events were not triggered by changes in the dynamic stress field. 相似文献
4.
In this paper, we focused on earthquakes with Ms ≥ 7.0 in the Chinese mainland from 1900 to 2012, calculated the lunisolar tidal Coulomb failure stress on the seismic fault plane and got the tidal phase through Schuster＇s test, then quantitatively analyzed the correlation between strong earthquakes in the Chinese mainland and tidal Coulomb failure stress. Research shows that among 57 strong earthquakes with focal mechanism solutions, over 71.9% took place within the tidal loading phase, with the p-value of 3.83%, indicating that strong earthquakes with Ms ≥ 7. 0 in Chinese mainland have a certain correlation with lunisolar tidal Coulomb failure stress. In the active period, the p-value is 4. 56%, 75.5% of earthquakes occurred in the tidal loading phase zone, and 50% of earthquakes occurred in the quiescence period, indicating that strong earthquakes in the active period were obviously triggered with the tidal Coulomb failure stress loading. 相似文献
5.
The coseismic Coulomb stress change caused by fault interaction and its influences on the triggering and delaying of earthquake are briefly discussed.The Xianshuihe fault belt consists of Luhuo,Daofu,Kangding,Qianning and Ganzi fault.Luohuo(Ms=7.6,1973)-Kangding(Ms=6.2,1975)-Daofu(Ms=6.9,1981)-Ms=6.0,1982)earthquake is a seismic sequence continuous on the time axis with magnitude greater than6.0.They occurred on the Luhuo.Kangding,Daofu and Ganzi fault,respectively.The coseismic Coulomb stress changes caused by each earthquake on its surrounding major faults and microcracks are calculated,and their effects on the triggering and delaying of the next earthquake and aftershocks are analyzed.It is shown that each earthquake of the sequence occurred on the fault segment with coseismic Coulomb stress increases caused by its predecessors,and most after-shocks are distributed along the microcracks with relatively larger coseismic Coulomb stress increases resulted from the main shock.With the fault interaction considered,the seismic potential of each segment along Xianshuihe fault belt is reassessed,and contrasted with those predicted results ignoring coseismic Coulomb stress change,the significance of fault interaction and its effect on triggering and delaying of earthquake are emphasized.It is con-cluded that fault interaction plays a very important role on seismic potential of Xianshuihe fault belt,and the maximal change of future earthquake probability on fault segment is up to 30.5%. 相似文献
6.
Long Sisheng 《中国地震研究》2004,18(3):212-224
The Yajiang earthquake sequence in 2001, with the major events of Ms5.1 on Feb. 14 and of Ms6.0 on Feb.23, are significant events in the Sichuan region during the last 13 years. Eighty-eight earthquakes in the sequence with at least 5 distinct onset parameters for each recorded by the Sichuan Seismic Network in the period of Jan. 1 through June 30,2001 were chosen for this study. The events are relocated and the focal mechanism is derived from P-wave onsets for 13 events with relatively larger magnitudes. The focal depth of all earthquakes fall between a range of 2km to 16km, with dominant distribution between 9km to 11km. Theforeshocks, the Ms5.1 earthquake and the Ms6.0 earthquake and their aftershocks are all located close to the Zihe fault and the dominant epicentral distribution is in NW direction, identical to that of the fault. The fracture surface of the focal mechanism is determined in accordance to the mass transfer orientation in the recent earth deformation field in the Yajiang region. The P axes of the principal compressive stress in focal mechanism solutions of the 13 events show bigger vertical components, and the horizontal projection trending SE. The earthquakes are of left-lateral, strike-slip normal, and normal strike-slip types. The rupture surface of most earthquakes strike NW-SE, dipping SW. Based on the above information, we conclude that the Zihe fault that crosses the earthquake area, striking NW and dipping SW, is the seismogenic fault for the Yajiang earthquake sequence. 相似文献
7.
Gkarlaouni Ch Papadimitriou E E Karakostas V G 闻学泽 金学申 Kilias A 潘华 杨家亮 《地震学报(英文版)》2008,21(2):181-201
Coulomb stress changes associated with the strong earthquakes that occurred since 1904 in Sichuan and Yunnan provinces of China are investigated. The study area comprises the most active seismic fault zones in the Chinese mainland and suffers from both strong and frequent events. The tectonic regime of this rhombic-shaped area is affected by the eastern extrusion of the Tibetan highland due to the collision of Eurasian Plate against the Indian lithospheric block along the Himalayan convergent zone. This movement is accommodated on major strike-slip intraplate fault zones that strike in an E-W direction. The gradual 90° clockwise rotation of the faults in the study area contributes to the complexity of the stress field. The seismic hazard assessment in this region is attempted by calculating the change of the Coulomb Failure Function (?CFF) arising from both the coseismic slip of strong events (MS≥6.5) and the stress built-up by continuous tectonic loading on major regional faults. At every step of the stress evolutionary model an examination of possible triggering of each next strong event is made and the model finally puts in evidence the fault segments that apt to fail in an impending strong event, thus providing fu-ture seismic hazard evaluation. 相似文献
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The relation between the gravity variation features and Ms=8.1 earthquake in Qinghai-Xizang monitoring area is analyzed preliminarily,by using spatial dynamic variation results of regional gravity field from absolute gravity and relative gravity observation in 1998 and 2000.The results show that:1)Ms\8.1 earthquake in Kulun mountain pass westem occurred in the gravity variation high gradient near gravity‘s high negative variation;2)The Main tectonic deformation and emnergy accumulation before MS=8.1 earthquake are distributed at south side of the epicenter;3)The range of gravity‘s high negative variation at east of the MS=8.1 earthquake epicenter relatively coincides with that rupture region according to field geology investigation;4)Gravity variation distribution in high negative value region is just consistent with the second shear strain‘s high value region of strain field obtained from GPS observation. 相似文献
9.
On October 27, 2001, a large earthquake with Ms6.0, named the Yongsheng earthquake, occurred along the Jinshajiang segment of Chenghai fault in Yongsheng County, Yuunan Province. It is the largest event to occur along the Chenghai fault in the last 200 years. The seismo-geological survey shows that the seismogenic fault, which is the Jinshajiang segment of Chenghal fault, takes left-lateral strike-slip as its dominant movement pattern. According to differences in vertical motion, motion time, landforms and scales, the Chenhai fault can be divided into eight segments. The Jinshajiang segment has a vertical dislocation rate of 0.4mm/a, far lower than the mean rate of the Chenghai fault, about 2.0 mm/a. It‘ s deduced that the two sides of Jinshajiang segment “stuck“ tightly and hindered the strike-slip of the Chenghai fault. The strong earthquake distribution before this event shows that the Jinshajiang segment was in the seismic gap. The Chenghai fault, as a boundary of tectonic sub-blocks, makes the Northwest Yunnan block and the Middle Yunnan block move clockwise, and their margins move oppositely along the Chenghai fault. In the motion process of the Chenghai fault, structural hindrance and the seismic gap of strong earthquakes are propitious to the concentration and accumulation of structure stress. As a result, the Yongsheng Ms6.0 earthquake occurred. The Sujiazhuang-Shangangfu segment is similar to the Jinshajiang segment with a low vertical motion rate of 0.3 mm/a and in the seismic gap. So it‘s postulated that the segment may become a new structure hindrance, and the Yongsheng Ms6.0 earthquake may trigger the occurrence of future large earthquakes along this segment. 相似文献
10.
This paper calculates the static stress changes generated by the Yushu M_S 7. 1 earthquake in Qinghai Province. On the basis of regional stress,we take account of the static stress change triggered by the Yushu M_S 7. 1 earthquake to find the optimally oriented fault planes,then calculate the Coulomb stress change on the optimally oriented fault plane. The results indicate that most of the aftershocks are triggered by the mainshock. The image of Coulomb stress changes is also in accord with regional earthquakes ( M_L ≥3. 0 ) distribution,but the value is lower than 0. 01MPa. In addition,this paper calculates the Coulomb stress changes in the case that the aftershock fault plane is the same as the main shock. Through comparison,we find that the image of Coulomb stress changes obtained using the "optimally oriented fault"approach is more consistent with the distribution of Yushu aftershocks and regional earthquakes. 相似文献
11.
玛尼7.9级地震对昆仑山口西8.1级地震的触发作用及动力背景初探 总被引：6，自引：1，他引：6
根据库仑静应力变化的概念，对青藏块体中部地区1997年11月8日玛尼7．9级地震及2001年11月14日昆仑山口西8．1级地震的应力触发作用进行了初步研究。不同震源机制解计算结果表明，玛尼地震造成了昆仑地震断层面上10^-3MPa量级的库仑应力增量，该变化仅使得昆仑地震的发生提前了最长10年左右，表明当前地壳应变能水平可能并不很低。对照20世纪初以来全球7级以上强震频度和强度演化特征与地球自转变化的关系，认为地球自转幅度衰减、变化频率升高是近期强震活动的重要控制因素。昆仑山口西8．1级地震的发生，可能是地球自转持续加速阶段后期，青藏块体内部区域应力场逐渐强化，及玛尼地震应力触发的结果。 相似文献
12.
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
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本文用三维非连续变形与有限元相结合（DDA+FEM）的方法,在青藏川滇地区三维构造块体相互制约的大背景中,通过用GPS资料做位移速率边界约束和震源机制约束,计算得到研究区的初始位移场和应力场与该地区GPS测量结果和震源机制分布结果基本一致.在此基础上进一步数值模拟1997年玛尼7.9级大震的发生过程,研究大震引起研究区各块体边界断层应力状态变化的特征.（1）发震断层两侧发生左旋走滑错动,最大水平位错大约7 m;（2）深部位错面上位错分布与用地震波资料震源反演的结果类似;（3）最大差应力变化等值线图与由星载D\|INSAR技术获取的地表形变场图像相似;（4）地表垂直位移表明地震断层面略向北逆冲.计算模拟得到了玛尼地震发生引起青藏川滇地区构造块体系统各边界断层上库仑破裂应力变化的分布,表明玛尼大震的发生除了使其发震断层的两端库仑破裂应力增大,应力进一步集中外,位于上地壳层上东昆仑断裂中段的2001年昆仑山8.1大震（H=11 km）发震断层段的库仑破裂应力增加约2 MPa,位于中地壳层上喀拉昆仑断裂带中的2008年改则6.9级地震（H=30 km）发震断层段的库仑破裂应力也增加约0.7 MPa,可见这两个已接近破裂强度地段的失稳对发生大震起了一定促进作用.研究结果也表明：作者发展的三维DDA+FEM方法能有效地用于大震活动与各构造块体相互作用关系的研究. 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
15.
为分析2008年5月12日四川汶川MS8.0级地震对周边断层地震活动的影响,本文首先基于Burgers体黏滞松弛模型计算汶川MS8.0级地震引起的库仑应力动态演化,分析认为2008年汶川MS8.0级地震在周边断层上引起的库仑应力显著增加的主要有四个断层段,分别为鲜水河断裂道孚-康定段、东昆仑断裂东段玛曲段、青川断裂和龙门山断裂南段.而且震后4年内黏滞松弛引起的库仑应力变化量可能与同震变化相当,相当于再发生一次汶川地震所造成的影响,因此震后效应在分析强震影响时不应忽略.本文基于强震引起的库仑应力变化动态演化,结合背景地震发生率、由Dieterich(1994)模型给出地震发生概率,结合相关构造地质、历史地震、余震活动等方面资料的综合分析认为,上述4个断裂段地震危险性由高到低依次为鲜水河断裂道孚-康定段、龙门山断裂南段、东昆仑断裂东段玛曲段和青川断裂. 相似文献
16.
IntroductionItisshowedbyresearchesonearthquakestresstriggeringrecentlythatsmall'static'stresschangesduetopermanentfaultdisplacementcanalterthelikelihoodof,ortrigger,earthquakesonnearbyfaults(Harris,1998).Manystudiesoftriggeringinthenear-field,particularlyofaftershocks,showthesestaticchangesaretriggeringagent(Kilb,etal,2000).ReasenbergandSimpson(1992)studiedthere-sponseofregionalseismicitytothestaticstresschangeproducedbyLomaPrietaearthquake,andtheresultsshowedthataftershockratesincreasedinre… 相似文献
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The great Kunlun earthquake occurred on Nov. 14, 2001 in Qinghai Province, China. Five large aftershocks with magnitude larger than 5.0 occurred near the Kunlun fault after main shock. Calculations of the change in Coulomb failure stress reveal that 4 of 5 large aftershocks occurred in areas with Δσf>0 (10?2–10?1 MPa) and one aftershock occurred in an area with Δσf=?0.56 MPa. It is concluded that the permanent fault displacement due to the main shock is the main cause of activity of large aftershocks, but not the whole cause. 相似文献
20.
应用多种遥感影像处理方法提取玛尼7.5级地震中的热红外异常信息 总被引：2，自引：0，他引：2
以1997年11月8日发生在西藏玛尼的Ms7．5地震为例，应用多种红外遥感影像处理方法，提取地震发生前后的红外辐射的时空演变信息。结果发现，在震前4天震中所在的玛尔盖茶卡断层以及东昆仑断裂带，出现3—5℃的增温现象，该异常在地震后逐渐消失。 相似文献