共查询到20条相似文献，搜索用时 31 毫秒
1.
2.
2018年9月4日新疆伽师发生MS5.5地震，震中处于塔里木地块西北缘，位于1997~1998年伽师强震群震区内。此次伽师地震前发生了MS4.7前震，截至9月30日最大余震震级为MS4.6（ML5.0），初步判定为前-主-余型地震序列。序列精定位结果显示，余震沿近NE向展布，主震震源深度与1997~1998年伽师强震主震基本一致，发震断层陡立。本文从区域的构造环境、地震震源机制解和余震分布特征等方面分析认为，地震发生在伽师隐伏断裂东南端部，为1997~1998年伽师强震群震区的一次新的构造活动。序列参数、视应力等计算结果显示，伽师MS5.5地震的预测最大余震震级与最大余震震级MS4.6接近，表明序列最大余震已经发生。 相似文献
3.
The 2018,Songyuan,Jilin M_S5. 7 earthquake occurred at the intersection of the FuyuZhaodong fault and the Second Songhua River fault. The moment magnitude of this earthquake is M_W5. 3,the centroid depth by the waveform fitting is 12 km,and it is a strike-slip type event. In this paper,with the seismic phase data provided by the China Earthquake Network, the double-difference location method is used to relocate the earthquake sequence,finally the relocation results of 60 earthquakes are obtained. The results show that the aftershock zone is about 4. 3km long and 3. 1km wide,which is distributed in the NE direction. The depth distribution of the seismic sequence is 9km-10 km. 1-2 days after the main shock,the aftershocks were scattered throughout the aftershock zone,and the largest aftershock occurred in the northeastern part of the aftershock zone. After 3-8 days,the aftershocks mainly occurred in the southwestern part of the aftershock zone. The profile distribution of the earthquake sequence shows that the fault plane dips to the southeast with the dip angle of about 75°. Combined with the regional tectonic setting,focal mechanism solution and intensity distribution,we conclude that the concealed fault of the Fuyu-Zhaodong fault is the seismogenic fault of the Songyuan M_S5. 7 earthquake. This paper also relocates the earthquake sequence of the previous magnitude 5. 0 earthquake in 2017. Combined with the results of the focal mechanism solution,we believe that the two earthquakes have the same seismogenic structure,and the earthquake sequence generally develops to the southwest. The historical seismic activity since 2009 shows that after the magnitude 5. 0 earthquake in 2017,the frequency and intensity of earthquakes in the earthquake zone are obviously enhanced,and attention should be paid to the development of seismic activity in the southwest direction of the earthquake zone. 相似文献
4.
In this study,data from the Xinjiang regional network and IRIS shared global stations are used to relocate the Akto M_S6. 7 earthquake sequence on November 25,2016 by using double difference location method. Three earthquakes of M_S4. 8,M_S6. 7 and M_S5. 0 are inverted by using the g CAP method,and the focal mechanism solutions are obtained.According to the results of relocating,the location of the main shock is 39. 22°N,73. 98°E,the distribution of the earthquake sequence is about 70 km in length,and the focal depth is mainly within the range of 5-20 km. The plane and depth profiles of the earthquake sequence show that aftershocks extended in SEE direction after the main shock and the dip angle of fault plane is steep. Focal mechanism results show that the three earthquakes are characterized by strike-slip movement. Based on the results of field geological investigation,it is inferred that the seismogenic fault of the Akto earthquake is Muji fault,which is located at the northernmost end of the Kongur extensional system.The possible cause of this earthquake is that the Indian Plate continues to push northward,and during this compression process,the Indian Plate is affected by the clockwise rotation of the Tarim basin,which causes the accumulation of right-lateral action of the Muji fault,resulting in this earthquake. 相似文献
5.
主要研究2009年7月24日西藏尼玛西南MS5.6地震的基本参数、地震序列特征、震源参数、发震构造等;利用震中附近600km范围内台站测定参数研究地震的震源机制解,与哈佛大学给出的震源机制解较一致,且与通过现场考察的发震断层走向具有一致性。研究认为本次地震发生在冈底斯山—拉萨块体内部,断裂为NNW向,主要受张应力作用产生左旋走滑正断层活动。此外还分析了震前地震学条带异常特征,结束表明,震前1年出现NW向条带非常显著,研究结论为该地区今后地震预测提供科学依据。 相似文献
6.
以地震应变场作为地震活动的变量，通过自然正交函数展开方法，计算2017年8月8日四川九寨沟7.0级地震前的地震应变场，提取出震前时间因子的异常变化。计算结果发现应变场前4个时间因子在震前1~3年的中短期异常并不显著，只有第2个和第4个时间因子震前有小幅度的异常变化，分析其原因，时间因子可能受到2008年汶川8.0级地震和2013年岷县漳县6.6级地震前大幅度异常的影响。与时间因子对应的空间等值线形成局部应变高值异常危险区，可能是2013年岷县漳县6.6级地震和2017年九寨沟7.0级地震空间异常的中短期特征。再对比九寨沟7.0级地震前后与松潘-平武7.2级双震的空间异常随时间演变，分析异常发展变化模式的差异，最后应用地震资料的累积频次从物理角度解释异常形成的机制。 相似文献
7.
Liu Pu-xiong Zheng Da-lin Che Shi Pan Huai-wen Liu Gui-ping Yang Li-ming 《地震学报(英文版)》2003,16(2):219-225
A great earthquake of M
S=8.1 took place in the west of Kunlun Pass on November 14, 2001. The epicenter is located at 36.2°N and 90.9°E. The analysis
shows that some main precursory seismic patterns appear before the great earthquake, e.g., seismic gap, seismic band, increased activity, seismicity quiet and swarm activity. The evolution of the seismic patterns
before the earthquake of M
S=8.1 exhibits a course very similar to that found for earthquake cases with M
S≥7. The difference is that anomalous seismicity before the earthquake of M
S=8.1 involves in the larger area coverage and higher seismic magnitude. This provides an evidence for recognizing precursor
and forecasting of very large earthquake. Finally, we review the rough prediction of the great earthquake and discuss some
problems related to the prediction of great earthquakes. 相似文献
8.
地震地下流体在地震预测研究与震情跟踪方面发挥着重要作用,本文对2021年5月22日青海玛多MS7.4地震前震中附近地下流体观测资料及异常特征进行系统分析,并结合震前预测过程进行了回顾性总结。结果表明,玛多MS7.4地震震中距500km范围内存在5项异常,其中4项为短期异常,主要出现在震前2～3个月。异常在空间上分布不均匀,主要位于玛多MS7.4地震震中的东北部和西南部,整体呈现出由外围向震中收缩的迁移特征,且玛多MS7.4地震和2010年青海玉树MS7.1地震在异常特征和应力加载作用方面具有较好的相似性。研究结果为地震监测能力较低地区积累了震例资料,对于提升强震地下流体前兆异常认识及未来震情趋势判定水平具有一定的参考意义。 相似文献
9.
The characteristics of spatio-temporal seismicity evolution before the Wenchuan earthquake are studied. The results mainly involve in the trend abnormal features and its relation to the Wenchuan earthquake. The western Chinese mainland and its adjacent area has been in the seismically active period since 2001, while the seismic activity shows the obvious quiescence of M≥?7.0, M≥?6.0 and M?≥5.0 earthquakes in Chinese mainland. A quiescence area with M?≥7.0 has been formed in the middle of the North-South seismic zone since 1988, and the Wenchuan earthquake occurred just within this area. There are a background seismicity gap of M?≥5.0 earthquakes and a seismogenic gap of ML?≥4.0 earthquakes in the area of Longmenshan fault zone and its vicinity prior to the Wenchuan earthquake. The seismic activity obviously strengthened and a doughnut-shape pattern of M?≥4.6 earthquakes is formed in the middle and southern part of the North-South seismic zone after the 2003 Dayao, Yunnan, earthquake. Sichuan and its vicinity in the middle of the doughnut-shape pattern show abnormal quiescence. At the same time, the seismicity of earthquake swarms is significant and shows heterogeneity in the temporal and spatial process. A swarm gap appears in the M4.6 seismically quiet area, and the Wenchuan earthquake occurred just on the margin of the gap. In addition, in the short term before the Wenchuan earthquake, the quiescence of earthquake with ML≥?4.0 appears in Qinghai-Tibet block and a seismic belt of ML?≥3.0 earthquakes, with NW striking and oblique with Longmenshan fault zone, is formed. 相似文献
10.
2022年1月8日青海省海北州门源县发生MS6.9地震,震中距离2016年1月21日门源MS6.4地震震中约33km,两次门源地震均发生在冷龙岭断裂附近,但在震源机制、主发震断层破裂过程及地震序列余震活动等方面显著不同。针对两次门源地震序列的比较分析,对研究冷龙岭断裂及其附近区域强震序列和余震衰减特征等具有重要研究意义。通过对比分析2022年门源MS6.9地震和2016年门源MS6.4地震余震的时空演化特征,发现二者在震源过程和断层破裂尺度上存在明显差异,前者发震断层破裂充分,震后能量释放充分,余震丰富且震级偏高;而后者发震断层未破裂至地表,余震震级水平偏低。综合分析两次门源地震序列表现出来的差异性,认为其可能与地震发震断层的破裂过程密切相关,且同时受到区域构造环境的影响。 相似文献
11.
2017年8月8日青藏高原东缘四川九寨沟地区发生7.0级强震,依据前人研究结果分析九寨沟7.0级地震发震构造,并计算震前应力状态。结果显示:本次地震受到构造和历史强震的影响,是发生在历史强震引起的应力加载区域。另外,采用中国地震台网1990年以来的地震目录,在评估目录完整性的基础上,利用最大似然法计算得到2017年8月8日九寨沟7.0级地震前震源区及邻区地震b值空间图像。结果显示,九寨沟7.0级地震发生在四川北部地区显著低b值高应力异常区域内部(0.82b0.75)。所以,研究区域内外历史强震可能促进了九寨沟7.0级地震的发生。 相似文献
12.
内蒙古和林格尔地处鄂尔多斯块体北缘阴山地震带内,历史上6级以上强震频发。2020年3月30日和林格尔发生M_L4.5地震,打破了自2005年以来阴山地震带M_L4.0以上地震的长期平静。研究此次地震序列的发震构造对区域应力状态和地震危险性分析有重要作用,然而内蒙古地震台网台站较为稀疏,相对于华北其他地区地震监测能力较低,对和林格尔地震序列的分析造成不利影响。本文采用匹配定位检测方法(ML)检测区域台网目录遗漏的微震,并对检测到的地震事件进行精定位。匹配定位方法共检测到序列中可定位的地震事件61个,约为台网目录的1.3倍,可定位地震约为台网目录的2.9倍。地震序列重定位结果中余震整体呈现NE向的分布,与使用CAP方法得到主震震源机制NE向节面走向基本一致,破裂为正断走滑型,显示和林格尔M_L4.5地震序列发震构造为NE走向、NW倾向的拉张性断层。结合计算结果和区域地震地质构造特征,认为M_L4.5地震序列发震构造为NE走向的岱海-黄旗海盆地南缘断裂。 相似文献
13.
利用乌什台数字化前兆形变观测资料，分析乌什MS 4.5级地震前乌什台水管倾斜仪、洞体应变仪数据变化情况。通过对比分析发现:地震前，洞体应变仪北南分量数据曲线正常，东西分量数据曲线加速拉张，05:14-20:32拉张幅度达到7.40×10-7，7月19日5时至20日16时乌什洞体应变仪东西分量快速拉张了9.20×10-7；7月19日5-19时，水管倾斜仪北南分量数据曲线正常，东西分量数据曲线反向西倾7.13ms，且05:59-06:06、07:36-07:46、18:42-18:56数据掉格，水管倾斜仪异常结束后1小时，在洞体应变仪异常过程中发生了乌什MS 4.5级地震。水管仪东西分量震前反向西倾，洞体应变仪东西分量震前拉张加速，短临异常明显，且2套形变观测震前异常时间同步性较好。 相似文献
14.
We obtained the displacement and deformation caused by the 2015 Nepal MS8.1 earthquake adopting the finite element method, and analyzed the displacement and deformation characteristics and effect of three large earthquakes on seismic activity in the Qinghai-Tibetan block. Our primary results suggest southward movement of the Qinghai-Tibetan block is caused by a large earthquake occurring on thrust fault in the Himalayan zone, the displacement direction is reverse to the background displacement. The occurrence of these large earthquakes will result in stress unloading and earthquake activity will be weakened in stress unloading areas. Through the simulation results, we can detect the distribution area of stress loading and unloading caused by large earthquakes. Simultaneously, it provides a fundamental evidence for determination of earthquake activity trend. 相似文献
15.
以2017年3月27日漾濞5.1级地震为例，根据区域特性和信噪比要求，选取数据较为完整的6个台站记录的2017年1月1日～6月6日期间的宾川地震信号发射台气枪震源波形资料，采用互相关检测技术提取6个台站各自稳定震相的走时数据，并对漾濞5.1级地震前后走时数据的变化情况进行分析。结果表明，漾濞5.1级地震前后6个台站各自稳定震相存在较为明显的走时变化，且短期内走时变化具有较好的同步性，相关台站异常幅度大小和异常出现时间存在细小差异。地震发生前，6个台站走时低值异常过程明显，以YUL台最为显著。地震发生前后走时变化形态特征为双“V”型，漾濞5.1级地震发生在第1个“V”型末端。地震发生后，不同方位相关台站受地震的影响程度不同，走时波动大小存在差异。 相似文献
16.
The Stone Canyon earthquake sequence started during August 1982 and lasted for about four months. It contained four mainshocks withM
L
4, each with an aftershock zone about 4 km long. These mainshocks, progressing from southeast to northwest, ruptured a segment of the fault approximately 20 km long leaving two gaps, which were later filled by theM
L
=4.6 mainshocks of January 14, and May 31, 1986. The equivalent magnitude of the sequence isM
L
=5.0.Precursory seismic quiescence could be identified in: (1) the northernmost 10 km of the aftershock zone which contained three of the mainshocks; and (2) the southern gap in the aftershock zone. The fault segment containing the first mainshock and its aftershocks did not show quiescence. This pattern of precursory quiescence is very similar to two cases in Hawaii where the rupture initiation points of the mainshocks (M
S
=7.2 and 6.6, respectively) were located in volumes of constant seismicity rate, surrounded by volumes with pronounced precursory quiescence.The precursory quiescence before the August 1982 Stone Canyon earthquakes lasted for 76 weeks, amounted to a reduction in rate of about 60%, and could be recognized without any false alarms. That is, the anomaly was unique within the 60 km study segment of the fault and in the years 1975 through August 1982. Eighteen foreshocks occurred between July 27 and August 7, 1982. We conclude that the August 1982 mainshocks could have been predicted, based on seismic quiescence and foreshocks. 相似文献
17.
The July 3, 2015 Pishan MS6.5 earthquake occurred in the intersection area of the Tarim block and West Kunlun block where the moderate-strong earthquakes have become active in recent years. This paper has studied the seismicity parameters of the earthquake sequences such as the b-value in the Pishan region and its vicinity. In addition, we also relocated the aftershocks of the Pishan MS6.5 earthquake using the seismic phase report by the double-difference method. The temporal and spatial variation characteristics of the Pishan earthquake sequence in the rupture zone are analyzed. The study is of great significance in the seismic hazard assessment in this region. 相似文献
18.
本文基于匹配滤波技术，通过SEPD（Seismic Events and Phase Detection）对2018年11月25日新疆博乐MS4.9地震序列进行检测，检测出遗漏地震32条，84.4%地震为ML0.0—1.0，9.4%地震小于ML0.0，较地震目录中原有15条地震多213%，检测出的遗漏地震事件使地震目录更加完整。检测后的最小完整性震级由检测前的ML1.6减至ML0.8，地震目录最小完整性震级的减小有利于地震工作者对区域地震活动性作出更准确全面的结论，并使地震危险性分析更可靠。 相似文献
19.
通过对2014年4月20日安徽霍山MS4.3地震前地下流体异常进行回溯性分析，总结了流体异常特征。结果显示，在时间上，流体异常具有配套性、阶段性特征，震前11个月异常月频次逐渐增加；震前3个月异常月频次加速上升，进入临震阶段，震前1.5个月，部分异常结束，异常月频次转折下降；在空间上，流体异常主要集中在震中200km范围内，且外围流体异常主要表现为趋势上升或低值，震中附近流体异常表现为突升。震前流体异常还与测项有关，水温、水化测项映震效果较好，水氡、氢气突升异常短临意义明显。 相似文献
20.
利用匹配定位方法对2020年5月18日云南巧家M_S5.0地震震后24h震源附近台站记录的连续波形进行遗漏地震扫描和定位,共识别出327个地震事件,约为台网目录的2.4倍,最小完整震级由最初的M_L1.9降至M_L1.1。随后,依据最新目录计算了震后震源区的b值,并结合余震展布形态,初步分析此次地震发震构造。研究结果显示,余震序列在平面上显示出NNW-SSE优势展布方向,长度约14km,震源优势深度集中在3～15km;深度剖面展示出主震的发震断层面较陡,并且具有向西倾的趋势。综合主震震源机制解、余震展布形态和周边地质构造背景,认为巧家M_S5.0地震发震断层可能为NNW-SSE向走滑性质的断裂,与2014年鲁甸MS6.5地震的发震构造密切相关。 相似文献