福建及沿海地区地震活动力源探讨

综合地震震源机制解和地壳形变观测资料的研究, 求得福建及其沿海地区现代震源应力场, 认为这与台湾地区、 台湾海峡应力场相互衔接, 主压应力轴优势方位为NW-SE向, 力轴仰角较小, 应力场近于水平挤压, 形变场反映近期福建沿海亦受北西方向, 接近与海岸垂直的挤压力。 进一步分析该区域内的断裂构造特征和地震活动强度由东至西逐渐减弱的规律, 认为菲律宾海板块与欧亚板块的相互作用力不仅是台湾强震力源所在, 而且其影响向西扩展, 福建及其沿海地区地震活动主要力源仍然是来自这两大板块的相互作用力。     

中国后地台活动区动力特征及浅源强震发震模式

本文根据中国后地台活动区的特征,讨论了活动区型深大断裂的复活过程,穿过莫霍界面引起上地幔顶部的变化及由此衍生出的垂直作用力。文中提出这种地区的浅源地震,除受区域水平作用力外,亦兼受到震源底部上地慢隆起产生的垂直作用力的作用。并初步讨论了这种浅源地震的发震模式。     

小震震源机制与应力场反演方法及其应用研究

正众所周知,构造应力场的分析与研究在地球科学研究以及生产实践应用中都具有相当重要的地位。同样,我们也知道,天然地震的震源机制在构造应力场的分析和研究中也具有相当重要的地位。地震矩张量的引入使地震产生的远场位移与描述震源机制的地震矩张量之间成为线性关系。如果地震产生的位移与描述地震波传播路径效应的格林函数已知,则很容易通过波形反演得到地震矩张量,即震源机制。然而,波形反演技术只适用于远场记录或较大     

腾冲火山区地震构造应力场研究

通过对腾冲火山区强震和中小地震震源机制制解分析,对火山区构造应力场方向空间分布,以及震源类型和破裂特征作了研究。利用腾冲火山区中小地震地震波资料,计算得到的地震震源处剪应力强度值,对火山区应力场强度或初始应力状态进行了研究。腾冲火山区构造庆力场主要为北北东－北东－北东东向,接近水平的压应力场。腾冲火山区凛环境剪应力场高值区所包围的低剪应力值分布区。腾冲火山区地震震源具有多种类型,震源破裂具有多种形     

利用小震震源机制解研究宁夏北部及邻区构造应力场

利用垂直向和波振幅比方法计算了2003年1月至2009年10月间宁夏北部及邻区的31个中小地震震源机制解,然后对计算所得的31个地震震源机制解进行系统聚类及应力场分析,并利用格点尝试法研究阿拉善区域（I区）和银川盆地及以北地区（II区）的平均震源机制解。结果表明：31个中小地震中走滑型地震占了近77％,显示出宁夏北部及邻近地区地震错动方式以近走滑为主;I区域地震产生的震源区构造变形是近南北向发生压缩,近东西向发生相对扩张;II区域构造应力场主压应力方向以水平作用为主,地震产生的震源区构造变形是北东向发生压缩,北西向发生相对扩张。     

震源应力场与构造应力场

每个地震按照双力偶模型所得到的震源应力场,有的反映构造应力场,有的反映转换应力场。凡是在已存在的活动断裂上由粘滑发震的震源机制解而得出的P、B和T轴与构造应力场的最大、中等、最小的压力主轴是对应的,只是略有偏离。分析了岩块相对滑动产生的转换应力场,证明由转换应力场所产生的脆性剪切破裂而发震的震源机制解得出的P、B、T轴则与构造应力场三个主轴方向可以完全不符。通过对具体震例分析表明,当考虑了转换应力场之后可对几个地震区的应力场得到统一的解释。因此,在一个地区根据震源机制解来恢复构造应力场时必须先判明:是构造应力的直接作用下的粘滑或剪切破裂,还是转换应力场所形成的、共轭剪切破裂,前者可直接恢复构造应力场,后者则应经过转换寸能恢复构造应力场。     

冷底辟与热底辟地震信息

冷底辟是指盐、膏、泥岩等塑性地层向上侵入或刺穿所产生的构造样式;热底辟主要指岩浆侵入或喷发所产生的底辟构造样式。不论哪种底辟构造,在人工地震剖面上反映均非常明显,其底辟内部呈杂乱反射,而围岩反射界面在此突然中断。在岩浆底辟处常出现磁力高异常,并有较高的层速度,冷底辟具有较低的层速度,盐膏底辟也具有较高的层速度。构造与火山地震关系密切,而冷底辟也可以形成破坏性地震,是今后值得注意的研究课题     

关于昌马7.5级地震的成因探讨

本文从三维空间的角度,从昌马地震发生的区域构造背景和构造应力场,震源断裂和震源应力场,地震的动力来源,震源介质条件、震源闭锁形式和地震发震机制等方面探讨了昌马地震的成因,提出了“三维空间四方受压的震源闭锁模式和“倒楔型”劈裂的发震机制。     

大震前显示的地震震源机制趋于一致的变化

在构造应力场的制约下强震孕育过程中特定阶段, 震源区中小地震震源机制与构造应力场的方向大体一致, 根据这一特点, 定义各个震源机制解的P轴, B轴, T轴和构造应力场的3个应力主轴在3维空间的夹角之和为一致性参数a, 研究强震前应力场变化特征。 对2006年11月15日千岛岛弧M_W8.3地震和2001年6月23日秘鲁M_W8.4地震研究表明, 大震发生前孕震区一致性参数a比较低, 震源机制与构造应力场的差异较小, 说明这些前震受到了震源区应力场的统一作用, 而主震发生之后震源机制解的一致性参数比较高, 说明后续发生的地震的震源机制散乱, 表明背景应力场的控制作用开始减弱。     

苏鲁皖地区晚新生代构造应力场的初步探讨

据考察区的晚新生代断裂活动性质和结合地震断层、地震应变带、震源机制、地形变、地壳测深等资料的综合分析,认为本区与华北北部的晚新生代应力场既有一致性,又有本身特点。推论是近邻诸板块相向挤压作用和伴随的深部物质运动而导致地壳上部侧向运动等不同级次作用力复杂叠加的结果。指出它与中生代区域应力场不同     

唐山地震的孕育与强震的增震作用

唐山地震的孕震构造是唐山菱形块体,在NEE向的区域应力场的作用下,最大剪应力集中在它的对角线上,正好与唐山断裂带相一致,因此成了唐山地震大破裂的始发点.唐山地震前兆演化过程中,有两个显著特点:在空间上有“震中→外围→震中+外围”的转移过程;在时间上有明显的阶段性,前兆异常频次的每一次加速都发生在外围强震发生之后,本文用强震的增、减震理论,推测外围强震的发生对唐山地震的孕育有强化作用,在一个大的区域,强地震的增、减震效应可以形成多个高应力集中区,这些高应力集中区多数都是未来发生强震的地区.     

南天山东段地震活动特征

分析研究了南天山地震带构造环境、中强地震活动震源机制解、中强地震时空分布以及拜城周围小震群活动与中强地震的关系。结果表明：南天山东段中强震震源断错以倾滑逆断为主,主压应力P轴由西到东呈扇形分布;相距较近的库车与拜城地区地震活动存在较大差异,但均存在明显的成丛性分布特点;拜城地区中强地震分布呈北西向可能预示着该区存在隐伏断裂,小震群活动则可能反映了局部中强震对周围次级小构造的影响。     

THE STATIC STRESS TRIGGERING INFLUENCES OF THE 2015 MW6.4 PISHAN,XINJIANG EARTHQUAKE ON THE NEIGHBORING AREAS

Based on the rupture models of the 2015 Pishan M_W6.4 earthquake and half space homogeneous elastic model, the Coulomb stress changes generated by the earthquake are calculated on the active faults near the earthquake region. The horizontal stress changes and the displacement field are estimated on the area around the epicenter. Results show that:(1)The Coulomb stress is decreased in the west of the western Kunlun frontal thrust fault(9.5×10³Pa), and increased in the east of the western Kunlun frontal thrust fault and the middle of the Kangxiwa faults. More attention should be taken to the seismic rick of the east of the western Kunlun frontal thrust fault; (2)Based on the analysis on the location of the aftershocks, it is found that most of the aftershocks are triggered by the earthquake. In the region of increased Coulomb attraction, the aftershock distribution is more intensive, and in the area of the Coulomb stress reduction, the distribution of aftershocks is relatively sparse; (3)The horizontal area stress increases in the north and south of the earthquake(most part of the Qaidam Basin and the northwest of the Qinghai-Tibet plateau), and decreases in the east and west of the earthquake(northern part of the Qinghai-Tibet plateau and eastern part of the Pamir Mountains). In the epicenter area, the principal compressive stress presents nearly NS direction and the principal extensional stress presents nearly EW direction. The principal compressive stress shows an outward radiation pattern centered on the epicenter with the principal extensional stress along the direction of concentric circles. The principal compressive stress presents NW direction to the west of the epicenter, and NE to the east of the epicenter. With the increase of radius, the stress level gradually decays with 10⁷Pa in the epicenter and hundreds Pa in the Maidan Fault which is in the north of the Qaidam Basin.     

北部湾地震的震源机制及地震地质条件

对北部湾地震的震源机制解和地震地质条件进行了详细分析，认为靖西－崇左断裂带过震中的北北西向断层为发震断裂，四会－吴川断裂带过震中的北东东向断层为控震构造，震源构造应力场的主压应力方向为北西－南东向，发震断层的活动方式既有垂直差异运动又有走滑运动。     

考虑速度脉冲型地震动的实际高层隔震结构地震响应研究

针对昆明市某99.7 m高层剪力墙隔震建筑,使用90组非脉冲与速度脉冲型地震时程,按震中距及有效持时分别分为7类与6类后,对其结构进行中震及大震作用下的快速非线性分析。结果表明:(1)中震时,该结构非脉冲层间剪力与倾覆力矩均小于脉冲数值,且其比例随楼层增加而增大;(2)大震时,速度脉冲对支座应力及位移的平均放大效应可达1.23~2.44倍,同时时程震中距为(50 km,70km],或有效持时为(40 s,50 s]时支座受脉冲作用放大效应影响最大;(3)结构边缘的橡胶隔震支座拉应力、压应力、天然橡胶支座水平剪切力等受脉冲作用的影响更为明显。     

STUDY ON THE SEISMOGENIC FAULT AND DYNAMICS PARAME-TERS OF THE 2014 MS6.6 JINGGU EARTHQUAKE IN YUNNAN

On October 17, 2014, a M_S6.6 earthquake occurred in Jinggu, Yunnan. The epicenter was located in the western branch of Wuliang Mountain, the northwest extension line of Puwen Fault. There are 2 faults in the surrounding area, one is a sinistral strike-slip and the other is the dextral. Two faults have mutual intersection with conjugate joints property to form a checkerboard faulting structure. The structure of the area of the focal region is complex. The present-day tectonic movement is strong, and the aftershock distribution indicates the faulting surface trending NNW. There is no obvious surface rupture related to the known fault in the epicenter, and there is a certain distance from the surface of the Puwen fault zone. Regional seismic activity is strong. In 1941, there were two over magnitude 7.0 earthquakes in the south of the epicenter of Jinggu County and Mengzhe Town. In 1988, two mainshock-aftershock type earthquakes occurred in Canglan-Gengma Counties, the principal stress axes of the whole seismic area is in the direction of NNE. Geological method can be adopted to clarify the distribution of surficial fracture caused by active faults, and high-precision seismic positioning and spatial distribution characteristics of seismic sequences can contribute to understand deep seismogenic faults and geometric features. Thus, we can better analyze the three-dimensional spatial distribution characteristics of seismotectonics and the deep and shallow tectonic relationship. The focal mechanism reveals the property and faulting process to a certain extent, which can help us understand not only the active property of faults, but also the important basis for deep tectonic stress and seismogenic mechanism. In order to study the fault characteristic of the Jinggu earthquake, the stress field characteristics of the source area and the geometric parameters of the fault plane, this paper firstly uses the 15 days aftershock data of the Jingsuo M_S6.6 earthquake, to precisely locate the main shock and aftershock sequences using double-difference location method. The results show that the aftershock sequences have clustering characteristics along the NW direction, with a depth mainly of 5~15km. Based on the precise location, calculations are made to the focal mechanisms of a total of 46 earthquakes including the main shock and aftershocks with M_L ≥ 3.0 of the Jinggu earthquake. The double-couple(DC)component of the focal mechanism of the main shock shows that nodal plane Ⅰ:The strike is 239°, the dip 81°, and the rake -22°; nodal plane Ⅱ, the strike is 333°, the dip 68°, and the rake -170.31°. According to focal mechanism solutions, there are 42 earthquakes with a focal mechanism of strike-slip type, accounting for 91.3%. According to the distribution of the aftershock sequence, it can be inferred that the nodal plane Ⅱ is the seismogenic fault. The obtained focal mechanism is used to invert the stress field in the source region. The distribution of horizontal maximum principal stress orienation is concentrated. The main features of the regional tectonic stress field are under the NNE-SSW compression(P axis)and the NW-SE extension(T axis)and are also affected by NNW direction stress fields in the central region of Yunnan, which indicates that Jinggu earthquake fault, like Gengma earthquake, is a new NW-trending fault which is under domination of large-scale tectonic stress and effected by local tectonic stress environment. In order to define more accurately the occurrence of the fault plane of the Jinggu earthquake, with the precise location results and the stress field in the source region, the global optimal solution of the fault plane parameters and its error are obtained by using both global searching simulated annealing algorithm and local searching Gauss-Newton method. Since the parameters of the fault plane fitting process use the stress parameters obtained by the focal mechanism inversion, the data obtained by the fault plane fitting is more representative of the rupture plane, that is, the strike 332.75°, the dip 89.53°, and the rake -167.12°. The buried depth of the rupture plane is 2.746km, indicating that the source fault has not cut through the surface. Based on the stress field characteristics and the inversion results of the fault plane, it is preliminarily believed that the seismogenic structure of the Jinggu earthquake is a newly generated nearly vertical right-lateral strike-slip fault with normal component. The rupture plane length is about 17.2km, which does not extend to the Puwen fault zone. Jinggu earthquake occurred in Simao-Puer seismic region in the south of Sichuan-Yunnan plate. Its focal mechanism solution is similar to that of the three sub-events of the Gengma earthquake in November 1988. The seismogenic structure of both of them is NW-trending and the principal stress is NE-SW. The rupture plane of the Jinggu main shock(NW direction)is significantly different from the known near NS direction Lancang Fault and the near NE direction Jinggu Fault in the study area. It is preliminarily inferred that the seismogenic structure of this earthquake has a neogenetic feature.     

1989年大同—阳高地震的前兆过程及其场—源特征

本文对１９８９年山西大同－阳高６．１级地震的前兆过程及其场、源特征进行了综合研究，结果表明，大同－阳高地震震前较为丰富的前兆现象是震源应力场与区域应力场共同作用的结果，估计大同地震的震源区尺度为２０－３０ｋｍ，孕震区范围约２００ｋｍ。最早的异常（震前３－４年）表现为大同盆地沉降速率加大，且出现在震源区，然后扩展至孕震区边缘，在孕震区边缘（１５０－２００ｋｍ）存在中、短期异常的突出集中区，在孕震过程     

2013年西藏左贡与芒康交界6.1级地震的房屋震害特征

2013年8月12日在西藏自治区左贡与芒康交界发生6.1级地震,该地震宏观震中位于左贡县田妥镇嘎益村-仁果乡吞永村一带,最大烈度Ⅷ度,但不构成Ⅷ度区.根据现场工作队所收集的资料,分析了震区各类房屋建筑的震害特征及其破坏原因,并根据此次地震对该地区房屋所造成的破坏程度提出了防震减灾研究建议,并强调了此类民居需要加强抗震设计.     

1679年三河-平谷8级地震破裂带的大地切片实验研究

大地切片调查法,就是在不搅动的状态下从地下切出未固结的第四纪浅部地层的垂直断片,它是一种较新的活动断层探测技术。发生在1679年9月2日的三河-平谷8级地震(烈度Ⅺ),是北京及附近地区历史上记录到的最大地震。在该地震的宏观震中——潘各庄附近,运用大地切片调查法对该地震破裂带进行了实验性探测,获得了较好的效果。实验研究表明:大地切片保留了完好的沉积细结构特征;大地切片调查实施时,要选择合适的动力源,对于北京平原这种黏土含量较高的沉积层,挖掘机加振动锤的动力组合优于吊车加振动锤的动力组合;大地切片由于振动会造成一定地层厚度的压缩,但黏土含量较高的北京地区,压缩比例基本<5%。另外,结合探槽和大地切片的对比分析,揭示了最近2次古地震事件,分别是1679年事件和该地震之前的一次事件,两次地震的垂直同震位移分别是1·4m和1·2m     

塔里木盆地构造应力场的数值模拟及其对油气聚集的意义

据塔里木盆地结构和盆地地层资料建立了盆地三维地质模型,用三维有限单元方法计算模拟了塔里木盆地现代构造应力场。分析了在构造力和重力共同作用下,盆地由浅至深各构造层应力变化特征,并研究了盆地内油气藏聚集与地应力场的关系