龙门山断层破裂的频率非平稳特性     

李启成  郭雷  何书耕  齐庆杰 《吉林大学学报(地球科学版)》2019,49(3):865-871

为研究地震过程中的频率非平稳特性,对近年来龙门山断层发生的两次大地震:汶川大地震和芦山大地震的近断层地震记录进行频谱分析。结果表明:相对于芦山地震有较大走向滑动分量的汶川地震,大多数位于汶川地震断层滑动前方的台站接收到更高的频率成分,位于断层滑动后方的台站接收到的地震波频率较低;尽管芦山地震断层相对汶川地震有较小的走向滑动分量,但仍然可以得出与汶川地震相同的结论,不同的是虽然芦山地震沿断层面向上方向分量大,但是其同一台站东西、南北、竖直三方向分量记录幅值相当。把芦山地震三分量记录变换到走向和沿断层面向上方向,证实了沿断层面向上方向高频成分更丰富。在断层滑动前方接收到的地震波频率较高,在断层滑动后方接收到的频率较低,这正是多普勒效应影响的结果。由于多普勒效应的客观存在,其对频率非平稳特性的影响与震源、传播路径和场地效应一样具有普遍性;所以,工程场地接收到的地震波的频率不仅取决于震源、传播路径、场地效应,还取决于断层滑动速度(多普勒效应)。  相似文献   

太阳活动与华北强震关系的分析   总被引：10，自引：2，他引：8  

张素欣  解用明  乔子云  陈立强  赵振增 《华北地震科学》2004,22(2):59-63

统计了太阳黑子活动11年周期和22年周期与华北地区(E108°～124°,N34°～42°)1815年～2002年187年6级以上强震的关系。结果显示,它们之间存在着较好的对应关系,华北地区的强震自1815年第4高潮以来,有84.6%的强震集中在太阳黑子11年变化周期的峰年段(±1年)和谷年段(±1年)内发生;其中尤以双周峰年段、单周谷年段较为集中;而单周下降时段却从未有过强震发生。目前正处于太阳黑子活动第23周单周峰年之后的下降时段,该统计区内强震发生的概率极低。  相似文献   

菲律宾棉兰老岛2019年4次M_W>6.0地震断层运动模型及库仑应力传输研究     

吴少杰  杨莹辉  王泽根  熊凌艳  陈强  陈静  杨超 《大地测量与地球动力学》2022,42(3):240-246

基于雷达干涉测量技术,利用ALOS-2、Sentinel-1卫星升降轨雷达影像,获得2019-10~12发生在菲律宾棉兰老岛的4次M_W>6.0地震的同震形变场,并以此形变结果为约束,反演得到4次地震的断层运动模型。综合分析发现,此次地震序列由3条断裂的破裂引起,其中2019-10-16和2019-10-31的2次地震为同一发震断裂,2019-10-31地震断层破裂区域位于2019-10-16地震断层破裂的东北延伸段,最大滑动量约为1.1 m,约为2019-10-16地震最大滑动量的2倍。2019-10-29地震由一条独立断层破裂引起,断层最大滑动量约为2.0 m。2019-12-15地震由一条东北向倾斜断层破裂引起,断层最大滑动量约为3.0 m。此外,2019-10-16地震引起2019-10-29地震显著滑动区明显的正向库仑应力传输;而2019-10-29地震显著增加了2019-10-31地震震源区域的库仑应力;前3次地震对2019-12-15地震孕震断层的库仑应力传输总和为负值,说明静态库仑应力传输可能不是此次地震触发的主要诱因。  相似文献   

Possible Cause-Effect Relationships Between Vrancea (Romania) Earthquakes and Some Global Geophysical Phenomena     

D. Enescu  B. D. Enescu 《Natural Hazards》1999,19(2-3):233-245

The possibility that the Earth's tides are a triggering factor of Vrancea subcrustal earthquakes is investigated in the first part of this paper. A possible correlation between Vrancea subcrustal earthquakes and geomagnetic jerks is demonstrated in the second part. The last part of the paper presents a number of results concerning a possible relationship between the regularities of strong Vrancea subcrustal seismicity and the Chandler nutation parameters. An attempt is made to integrate all of these phenomena in a more general framework that takes into account physical processes in the Earth mantle and core. A long-term prediction of the next strong Vrancea earthquake is finally attempted.  相似文献   

Discontinuous Nature of the Lower Part of the South American Wadati-Benioff Zone in The Arica Elbow Region     

V. Hanuš  A. Slancová  A. Špiccaron;ák  J. Vaněk 《Studia Geophysica et Geodaetica》1999,43(2):163-184

The Arica Elbow region represents that part of Andean South America where the azimuth of the strike of the Peru-Chile trench changes from 150° to 190°. The area under study is roughly bounded by latitudes 17 °S and 23 °S, The shape of the Wadati-Benioff zone was studied in terms of the distribution of ISC hypocentres dated between 1964 and 1993. A system of 22 vertical cross-sections, perpendicular to the trench axis, and a map of epicentres was used to derive the detailed shape of the Wadati-Benioff zone of the presently descending slab. The distribution of earthquake foci indicates a fingerlike shape of the lower part of the Wadati-Benioff zone beneath the aseismic gap. The slab length shows small changes around 350 km in the northern sections, pronounced length oscillations between 350 and 750 km in the neighbouring central sections and a constant value of 650 km in the southern sections. The dip and thickness of the Wadati-Benioff zone are practically constant in all sections. Fault plane solutions, separated spatially into three zones, were used to estimate the state of stress in the slab.  相似文献   

Stress Field Estimations for Colima Volcano, Mexico, Based on Seismic Data     

Francisco J. Núñez-Cornú  Claudia Sánchez-Mora 《Bulletin of Volcanology》1999,60(7):568-580

 For first time, during 1991, seismic activity was recorded during an eruption at Colima volcano. We analyze these data to obtain a stress pattern using a composite focal mechanism technique. From the analysis of regional seismicity, the Tamazula Fault and the Armeria River appear as active features and the dip of the slab east of the Jalisco Block is approximately 12°. Southwest of Colima volcano a vertical alignment of seismic events was observed. We estimate five different composite focal mechanism solutions from our data set, which indicate a change of the stress field at the volcano after the 1991 eruption. These solutions suggest that the stress field in the volcanic edifice was controlled by stresses related to the emplacement of magma superimposed on the regional stress field. No evidence of active local faults in the volcanic edifice was found. We propose a model for the eruptive process that involves tilting of the volcanic edifice. Received: 15 October 1995 / Accepted: 26 October 1998  相似文献   

Dynamic variation of ambient shear stress field before and after three strong earthquakes in Yunnan     

王绍晋  龙晓帆 《地震学报(英文版)》1999,12(2):165-174

IntroductionThecrustaltectonicmovementisacomplicatedevolutionprocesswithtimeandspace.Spatially,themovementofcrustaltectoniciscloselyrelatedtotheinter-movementandinteractionofmulti-leveledcrustalblocksinacertainregionandtheirborderfaults.Temporally,themovementiscloselyrelatedtothatofmulti-leveledcrustalblocksandtimesequencedevelopmentofinteraction.Anearthquakeoccurrenceistheresultofsuddenruptureofcrustmediaundertheactionoftectonicstressfield,isalsoacomplicatedprocessinnercrust.Duetotheobviousi…  相似文献   

The seismic history of Catania     

R. Azzaro  M.S. Barbano  A. Moroni  M. Mucciarelli  M. Stucchi 《Journal of Seismology》1999,3(3):235-252

A detailed study of the most significant seismic effects that took place in the city of Catania has been performed in order to build up a site catalogue, to assess seismic hazard directly from it and to provide the picture of damage scenarios which happened in the past. In the last 1000 years Catania was destroyed twice (1169 and 1693) and more or less severely damaged twelve times (e.g., 1542, 1818, 1848, etc.). Destruction or severe damage are mainly related to earthquakes occurring in the coastal sector of the Hyblean foreland, while slighter, moderate effects are usually due to earthquakes taking place in the seismogenic sources of the Messina Straits and in the inner Hyblean region. The analysis of the historical reports allowed to delineate the damage scenarios of the most relevant events. In particular, for the 1693 case-history it has also been possible to map the damage distribution with reference to the existing urban settlement of the city. The site catalogue was used for assessing seismic hazard; the obtained estimates show that the probability of occurrence for intensity 7 and 10 exceeds 99.9% for 150 and 500 years, respectively. These values, associated with the high vulnerability caused by the city growth which occurred mainly before the introduction of the seismic code (1981) and without ad-hoc planning policies, implies that the urban system is exposed to high seismic risk.  相似文献   

Probabilities of occurrence of great earthquakes in the Himalaya     

K. N. Khattri 《Journal of Earth System Science》1999,108(2):87-92

Long-term conditional probabilities of occurrence of great earthquakes along the Himalaya plate boundary seismic zone have been estimated. The chance of occurrence of at least one great earthquake along this seismic zone over a period of 100 years (beginning the year 1999) is estimated to be about 0.89. The 100-year probability of such an earthquake occurring in the Kashmir seismic gap is about 0.27, in the central seismic gap about 0.52 and in the Assam gap about 0.21. The 25-year probabilities of their occurrence in these gaps are 0.07, 0.17, and 0.05 respectively. These probability estimates may be used profitably to assess the seismic hazard in the Himalaya and the adjoining Ganga plains.  相似文献   

Is the September 5, 2022, Luding MS6.8 earthquake an ‘unexpected’ event?          下载免费PDF全文

Shengfeng Zhang  Zhongliang Wu  Yongxian Zhang 《地震科学（英文版）》2023,36(1):76-80

Whether the September 5, 2022, Luding M_S6.8 earthquake is an ‘expected’ event in the context of earthquake forecast? This commentary discusses this issue mainly using the recently proposed ‘earthquake nowcasting’ approach.  相似文献