重庆及邻区地震精定位研究   总被引：1，自引：1，他引：0  

魏红梅  王同军 《地震地磁观测与研究》2015,(1)

采用双差地震定位法,对2008年1月—2013年11月重庆及邻区的荣昌、綦江、石柱、巫山—湖北巴东、巫溪地区地震进行精定位。结果表明,重新定位后地震震源位置比常规地震定位法得到的结果更加精确。荣昌、綦江、石柱地区地震震中呈条带状分布较明显,与断裂构造一致性较好;巫山—巴东、巫溪地区地震震中成团现象明显,地震成因较复杂。  相似文献   

Improved seismic risk estimation for Bucharest,based on multiple hazard scenarios and analytical methods     

《Soil Dynamics and Earthquake Engineering》2015

Bucharest, capital of Romania, is one of the most exposed big cities in Europe to seismic damage, due to the intermediate-depth earthquakes in the Vrancea region, to the vulnerable building stock and local soil conditions.This paper tries to answer very important questions related to the seismic risk at city scale that were not yet adequately answered. First, we analyze and highlight the bottlenecks of previous risk-related studies. Based on new researches in the hazard of Bucharest (recent microzonation map and ground-motion prediction equations, reprocessed real recorded data) and in vulnerability assessment (analytical methods, earthquake loss estimation software like SELENA and ELER, the recently implemented Near Real-Time System for Estimating the Seismic Damage in Romania) we provide an improved estimation of the number of buildings and population that could be affected, for different earthquake scenarios. A new method for enhancing the spatial resolution of the building stock data is used successfully.  相似文献   

大地震前体应变临震异常现象     

吴利军  陈正位  李函谷  徐磊  安巴雅尔  徐顺强 《中国地震研究》2015,29(3):373-385

本文对2011年1月至2014年4月间全球发生的80次MS≥7.0级地震前,二张营台和天堂河台Sacks体应变临震异常现象进行了研究,针对复杂震例提出了异常识别的前提条件。统计结果显示,体应变观测对震中距为8000km范围内的MS≥7.0级地震映震和前兆异常反映较好。同时,对异常现象进行了分类和描述,划分了三种异常类型：即固体潮畸变型、突变型和慢地震型,并对各种类型作了统计分析,进行了力学性质初步探讨。从研究结果来看,体应变异常信息对未来全球强震的发生具有一定的预示意义。  相似文献   

Patterns of significant seismic quiescence on the Mexican Pacific coast     

《Physics and Chemistry of the Earth》2015

Many authors have proposed that the study of seismicity rates is an appropriate technique for evaluating how close a seismic gap may be to rupture. We designed an algorithm for identification of patterns of significant seismic quiescence by using the definition of seismic quiescence proposed by Schreider (1990). This algorithm shows the area of quiescence where an earthquake of great magnitude may probably occur. We have applied our algorithm to the earthquake catalog on the Mexican Pacific coast located between 14 and 21 degrees of North latitude and 94 and 106 degrees West longitude; with depths less than or equal to 60 km and magnitude greater than or equal to 4.3, which occurred from January, 1965 until December, 2014. We have found significant patterns of seismic quietude before the earthquakes of Oaxaca (November 1978, M_w = 7.8), Petatlán (March 1979, M_w = 7.6), Michoacán (September 1985, M_w = 8.0, and M_w = 7.6) and Colima (October 1995, M_w = 8.0). Fortunately, in this century earthquakes of great magnitude have not occurred in Mexico. However, we have identified well-defined seismic quiescences in the Guerrero seismic-gap, which are apparently correlated with the occurrence of silent earthquakes in 2002, 2006 and 2010 recently discovered by GPS technology.  相似文献   

云南澜沧老厂多金属矿床矿石类型及其成因探讨     

王磊  李高权  李洪江  陈品鸿  蔡昌厚  杨大省 《地质与资源》2019,28(6):535-542

云南澜沧老厂是三江成矿带南段最重要的铅锌铜钼多金属矿床之一.根据不同的赋矿特征、含矿岩性、矿石构造及成矿元素将澜沧老厂多金属矿床矿石类型系统地划分为铅锌硫化矿石、铅锌氧化矿石、颗粒状含铜黄铁矿石、块状含铜黄铁矿石、夕卡岩型矿石及斑岩型钼矿石6种类型.矿体产状、微量元素地球化学、年代学证据均表明铅锌硫化矿石、颗粒状含铜黄铁矿石及块状含铜黄铁矿石为火山喷流沉积型成因（VMS型）,而铅锌氧化矿石、夕卡岩型矿石及斑岩型钼矿石为斑岩热液型成因.其中,铅锌硫化矿石、颗粒状含铜黄铁矿石及块状含铜黄铁矿石的主控矿因素为地层;铅锌氧化矿石为构造;夕卡岩型矿石为岩性;斑岩型钼矿石为岩体.  相似文献   

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   

地震岩问题   总被引：6，自引：6，他引：0       下载免费PDF全文

山穆玕著  冯增昭  刘敏译 《古地理学报》2017,19(1):19-46

在过去的82年(1931—2013)中,共出现了39个成因术语。在这39个术语中,只有10个是真正沉积成因的(例如浊积岩),其他29个术语都是比较草率地提出的(just jargons;例如地震岩、海啸岩等)。“地震岩”(seismites)这一成因术语是赛拉赫(Seilacher,1969)提出的,它指沉积记录中的古地震。这是一个误用的(misnomer)术语。赛拉赫仅仅根据美国加利福尼亚州的中新统蒙特雷组(Miocene Montery Formation)10,m厚的露头观察,就匆忙地提出这个术语。他并未对这个露头进行认真的科学研究。最根本的问题是,地震是一个触动因素^①,并不是一个沉积作用。在古代的沉积记录中,鉴别不出各种触动因素(trigger)^②,因为自然界不能保留触动因素曾经存在过的证据。“软沉积物变形构造”(soft-sediment deformation structures,可简称为SSDS),通常被人们用来作为地震岩的鉴别标志,其实它是“液化作用”(liquefacation)的结果。液化作用可以由21种触动因素中的任何一种引起,其中包括地震(earthquake)、陨石冲击(meteorite impact)、海啸(tsunami)、沉积负载(sediment loading)等。在死海盆地中的角砾碎屑,所谓典型的由地震引起的沉积,实际上是常见的同沉积作用的碎屑流的产物,与地震没有关系。其他类型的SSDS,例如 “双向叠层构造”(duplex-like structures)和碎屑注入体(clastic injections),也可以说是同沉积作用的产物,与地震没有关系。世界上广泛分布的砂岩储油层,包括墨西哥湾、北海、挪威海、尼日利亚、赤道几内亚、加逢、孟加拉湾,都表明这些地区的SSDS的第一起因(primary cause)是沉积负载,其证据是可以观察到的和令人信服的。海啸及陨石冲击,都可以形成大量的沉积,例如SSDS的侧向延伸(lateral extent of SSDS),但这些沉积都不能当作地震的鉴别标志。位于印度东部大陆边缘的Krishna-Godavari(KG)盆地中的SSDS,是多种触动因素^①引起的沉积物的失控和液化作用的结果,即多成因的SSDS。由于这些原因,“地震岩”这个成因术语确实没有什么科学价值,应当废弃。  相似文献   

Unknown large ancient earthquakes along the Kurai fault zone (Gorny Altai): new results of palaeoseismological and archaeoseismological studies     

E. V. Deev  I. V. Turova  A. P. Borodovskiy  I. D. Zolnikov  L. Oleszczak 《International Geology Review》2017,59(3):293-310

Palaeoseismological and archaeoseismological studies in the Kurai fault zone, along which the Kurai Range is thrust onto Cenozoic deposits of the Chuya intramontane basin, led to the identification of a long reverse fault scarp 8.0 m high. The scarp segments are primary seismic deformations of large ancient earthquakes. The scarp’s morphology, results of trenching investigations, and deformations of Neogene deposits indicate a thrusting of the piedmont plain onto the Kurai Range, which is unique for the Gorny Altai. Similarly for Northern Tien Shan, we explain this by the formation of both a thrust transporting the mountain range onto the depression and a branching thrust dislocation that forms the detected fault scarp. In a trench made in one of the scarp segments, we identified the parameters of the seismogenic fault – a thrust with a 30° dipping plane. The reconstructed displacement along the fault plane is 4.8 m and the vertical displacement is 2.4 m, which indicates a 7.2–7.6 magnitude of the ancient earthquake. The ¹⁴C age of the humus-rich loamy sand from the lower part of the colluvial wedge constrains the age of the earthquake at 3403–3059 years BP. Younger than 2500 years seismogenic displacements along the fault scarp are indicated by deformations of cairn structures of the Turalu–Dzhyurt-III burial mound, which was previously dated as iron age between the second half of I BC and I AD.  相似文献   

青藏高原东南缘地震活动与地壳运动所反映的块体特征及其动力来源   总被引：17，自引：6，他引：11       下载免费PDF全文

程佳  徐锡伟  甘卫军  马文涛  陈为涛  张勇 《地球物理学报》2012,55(4):1198-1212

通过分析青藏高原东南缘活动断裂带的活动特征和GPS资料显示的现今地壳形变场,辅以历史地震及地表破裂、震源机制解类型等资料,将青藏高原东南缘地区分成了11个次级块体.其中包括了西秦岭次级块体、阿坝次级块体、龙门山次级块体、藏东次级块体、雅江次级块体,香格里拉次级块体、滇中次级块体、保山次级块体、景谷次级块体、勐腊次级块体和西盟次级块体;并利用这些次级块体内的GPS站点速率计算出了这些块体现今运动情况及各块体之间断裂的滑动速率,分析认为各次级块体均受到了一种来自其相邻块体的主要应力作用而发生了旋转,其中保山次级块体、藏东次级块体、雅江次级块体、香格里拉次级块体、滇中次级块体的旋转尤为显著;同样,相邻块体之间的边界断裂带也呈现了相应的挤压或拉张活动特征,而藏东次级块体与雅江次级块体、雅江次级块体与滇中次级块体之间的挤压最为明显.利用上述结果,本文讨论了该地区的现今地壳形变特征,认为刚性块体的挤出作用与重力滑塌作用并存于该区域内,下地壳"管道流"的拖曳作用是该地区刚性块体挤出作用和重力滑塌的主要原因, 另外缅甸板块相对于自身的逆时针旋转作用在其北部引起的拉张作用也是重要因素之一.  相似文献   

云南地区中小地震静力学和动力学参数定标关系     

刘丽芳  杨晶琼  华卫  苏有锦  刘杰 《中国地震研究》2012,26(3):399-409

Source spectra for moderate and small earthquakes are obtained after removing the path effect, site effect, and instrument response, etc. in the observed S-wave spectra. Based on the Brune source model...  相似文献