1997-1998年伽师强震群震源区应力场特征          下载免费PDF全文

龙海英  高国英  聂晓红 《地震工程学报》2007,29(2):145-149

利用1997-1998年伽师强震群中强地震震源机制系统聚类及震源区应力场反演,得到以下主要结果:(1)伽师强震群中强地震主要以走滑和正断层为主,伽师震源区主压应力方向为NNE或近NS向,与相邻的柯坪块体区域构造应力场方向不一致;伽师强震群的破裂面沿NEE方向,属左旋破裂;(2)4~5级中强地震应力场反演得到最大主压应力轴为NNE向,最小主压应力轴为NWW向,中等主应力轴倾角为65°,比较直立;(3)伽师强震群震源区应力场在强震前后经历了一系列变化。最后对所得结果进行了一定的讨论。  相似文献   

由多个震源机制解分析民乐Ms6.1级地震前后应力场演化     

张辉  刘小凤  赵凌云 《高原地震》2007,19(3):《高原地震》-6-9,20

2003年10月25日在甘肃省民乐县和山丹县境内发生了Ms6．1与Ms5．8级地震，对震区200km范围、震前2年内发生的地震，及对震后部分余震矩张量反演得到它们的震源机制解，并对其进行统计分析得到该区的背景应力场及应力轴的整体特征，根据发震区地质构造背景和对平均应力场变化分析，寻求民乐地震的发震机制。  相似文献   

压实粉土非线性应力-应变关系的试验研究     

彭丽云  刘建坤  肖军华  陈立宏  朱瑞龙 《工程地质学报》2007,15(1):50-55

对京九线路基粉土用GDS三轴仪进行固结不排水剪试验,研究不同围压、含水量、压实度下压实粉土样的应力-应变关系。结果表明:压实粉土在低围压下为应变软化,高围压下为应变硬化,存在一个屈服应力;含水量和压实度对粉土强度和应力-应变关系影响显著,随着含水量的减小、压实度的增大,压实粉土样强度增大,应力-应变曲线上升。对围压小于屈服应力的应变软化曲线,用常规的土的软化关系式进行拟和;对围压大于屈服应力的应变硬化曲线,用邓肯-张模型进行拟和;这二者的结合能描述压实粉土的应力-应变关系曲线,效果良好。  相似文献   

Source parameters of intermediate-depth Vrancea (Romania) earthquakes from empirical Green's functions modeling     

Adrien Oth  Friedemann Wenzel  Mircea Radulian 《Tectonophysics》2007,438(1-4):33-56

Several source parameters (source dimensions, slip, particle velocity, static and dynamic stress drop) are determined for the moderate-size October 27th, 2004 (M_W = 5.8), and the large August 30th, 1986 (M_W = 7.1) and March 4th, 1977 (M_W = 7.4) Vrancea (Romania) intermediate-depth earthquakes. For this purpose, the empirical Green's functions method of Irikura [e.g. Irikura, K. (1983). Semi-Empirical Estimation of Strong Ground Motions during Large Earthquakes. Bull. Dis. Prev. Res. Inst., Kyoto Univ., 33, Part 2, No. 298, 63–104., Irikura, K. (1986). Prediction of strong acceleration motions using empirical Green's function, in Proceedings of the 7th Japan earthquake engineering symposium, 151–156., Irikura, K. (1999). Techniques for the simulation of strong ground motion and deterministic seismic hazard analysis, in Proceedings of the advanced study course seismotectonic and microzonation techniques in earthquake engineering: integrated training in earthquake risk reduction practices, Kefallinia, 453–554.] is used to generate synthetic time series from recordings of smaller events (with 4 ≤ M_W ≤ 5) in order to estimate several parameters characterizing the so-called strong motion generation area, which is defined as an extended area with homogeneous slip and rise time and, for crustal earthquakes, corresponds to an asperity of about 100 bar stress release [Miyake, H., T. Iwata and K. Irikura (2003). Source characterization for broadband ground-motion simulation: Kinematic heterogeneous source model and strong motion generation area. Bull. Seism. Soc. Am., 93, 2531–2545.] The parameters are obtained by acceleration envelope and displacement waveform inversion for the 2004 and 1986 events and MSK intensity pattern inversion for the 1977 event using a genetic algorithm. The strong motion recordings of the analyzed Vrancea earthquakes as well as the MSK intensity pattern of the 1977 earthquake can be well reproduced using relatively small strong motion generation areas, which corresponds to small asperities with high stress drops (300–1200 bar) and high particle velocities (3–5 m/s). These results imply a very efficient high-frequency radiation, which has to be taken into account for strong ground motion prediction, and indicate that the intermediate-depth Vrancea earthquakes are inherently different from crustal events.  相似文献   

Relocation of aftershocks, focal mechanisms and stress inversion: Implications toward the seismo-tectonics of the causative fault zone of Mw7.6 2001 Bhuj earthquake (India)   总被引：2，自引：0，他引：2  

P. Mandal  S. Horton   《Tectonophysics》2007,429(1-2):61-78

The HYPODD relocation of 1172 aftershocks, recorded on 8–17 three-component digital seismographs, delineate a distinct south dipping E–W trending aftershock zone extending up to 35 km depth, which involves a crustal volume of 40 km × 60 km × 35 km. The relocated focal depths delineate the presence of three fault segments and variation in the brittle–ductile transition depths amongst the individual faults as the earthquake foci in the both western and eastern ends are confined up to 28 km depth whilst in the central aftershock zone they are limited up to 35 km depth. The FPFIT focal mechanism solutions of 444 aftershocks (using 8–12 first motions) suggest that the focal mechanisms ranged between pure reverse and pure strike slip except some pure dip slip solutions. Stress inversion performed using the P and T axes of the selected focal mechanisms reveals an N181°E oriented maximum principal stress with a very shallow dip (= 14°). The stress inversions of different depth bins of the P and T axes of selected aftershocks suggest a heterogeneous stress regime at 0–30 km depth range with a dominant consistent N–S orientation of the P-axes over the aftershock zone, which could be attributed to the existence of varied nature and orientation of fractures and faults as revealed by the relocated aftershocks.  相似文献   

浅析WAAS完好性算法   总被引：2，自引：0，他引：2  

何骞  王天应  施闯 《地理空间信息》2007,5(6):54-56

广域增强系统完好性是度量系统时空可用性的关键指标,它关系到用户所获得的改正信息是否真实可靠。在阐述广域增强系统完好性定义的基础上,对完好性算法流程、思路进行了分析。  相似文献   

利用地基土应力分布原理确定砂垫层厚度     

刘翔  姜秀萍 《国土资源》1998,(2)

软弱土层场地若采用天然地基不能满足建筑物所需强度与沉降要求,采用换土撼砂法就可以提高地基的承载力。运用应力分布原理合理确定撼砂层厚度不仅可保证工程稳固性,并可节约投资和缩短工期。  相似文献   

A hybrid discrete-continuum approach to model hydro-mechanical behaviour of jointed rocks     

Lingli Wei  John A. Hudson 《Engineering Geology》1998,49(3-4):317-325

A hybrid discrete-continuum approach has been presented in this paper to simulate water flow in the near and far fields of deformable fractured rocks. In the near field, the discrete model is used; while in the far field, the equivalent continuum model is employed. The discrete element method (with the static relaxation algorithm) is used in the near field and the boundary integral equation method in the far field. Along the interface of these two domains, both mechanical and hydraulic compatibility conditions are satisfied. Fully coupled hydro-mechanical analysis can be conducted in the combined near and far fields. Application to a dam foundation problem has demonstrated the capability of the developed approach.  相似文献   

浅谈数字化时代的电视产业     

卢兆辉 《福建地震》1998,(3)

本文闸述了数字化时代,对服务于电视的高清晰度设备数字化摄像机的功能作了简单介绍以及后期非线性编辑给从业人员带来的要求。  相似文献   

东北地区5 000 aB.P.～4 700 aB.P.左右的降温事件及对考古文化的影响   总被引：2，自引：0，他引：2  

李永化  尹怀宁  张小咏  赵军 《云南地理环境研究》2003,15(1):12-18

距今5000年左右世界各地普遍存在一次幅度较大的短期降温气候事件，通过对金川剖面泥炭地层14C测年，孢粉分析，认为东北地区此次降温事件结束的14C年龄在4700aB.P.左右，降温事件出现之前气候温暖湿润，降温事件过后温度持续下降，金川剖面的记录与东北地区其它类型沉积物所记录的降温事件出现的时间基本吻合，降温事件对燕辽地区古文化演变产生了深刻的影响。  相似文献