澜沧—耿马地区中小地震精确定位研究

概述了双差定位方法及其基本原理,并运用该方法对1979～2009年澜沧—耿马地区发生的4279个中小地震进行精确定位,获得了4124个地震基本参数,走时残差均方根的平均值由定位前的0.502s降到了0.086s.定位结果显示震中沿北北西向的构造呈明显的条带状分布,且更加集中于断层附近,在深度上改变了定位前的层状分布现象...     

青海地区各地震带强震活动基本状态探讨

利用青海地区1900年以来5级以上强震目录探讨了省内各地震带地震活动的基本状态,结合累积应变能释放现象讨论了各地震带现今地震活动所处的状态。结果显示,青海地区4个地震带强震活动存在明显的平静与活跃的交替特征,这是普遍的宏观规律,但平静与活跃的特点具有差异性。伴随各地震带地震活动状态的不同,其累积应变能释放呈现加速或减速的特征。     

双地震带的影响因素探讨

讨论了全球39个俯冲带内的双地震带层间距、应力类型与俯冲参数的相互关系,这些俯冲参数包括动力学参数(板块年龄、热参数、板片拉力)、运动学参数(俯冲板块速度、上覆板块运动速度、海沟迁移速度、弧后形变特征)、几何形态参数(浅俯冲角、深俯冲角、俯冲深度、长度)及上覆板块性质等.结果表明:(1)I型双地震带易形成于年龄较古老(...     

南北地震带强震迁移特征及其预测意义

在分析南北构造带构造体系的基础上，研究了该带强震的时空动态图象演化，结果表明，南北带的地震活动有如下特征：（１）经向迁移，其空间演化有步进型和步进折返型两种形态；（２）远程的快速响应；（３）诱发地震的链锁分布，该特征反映了强震间的相互耦合，对未来强震具有示踪意义，（４）时空可公度性，该结果对分析判定本带的地震趋势从而实现正确的预测具有实际意义。     

新疆南天山地震带部分地区强震前小震活动异常现象的讨论

新疆是一个地震多发区,中强地震活动频繁,小地震资料亦十分丰富,这为研究中强地震发生之前,震源及邻近地区小震活动的变化与强震之间的关系提供了有利的基础。南天山地震带是新疆境内中强地震活动强烈的地震带之一。无论是中强地震的活动频次,还是释放的能量都居全疆之首。“新疆地震目录(公元1600年—1987年M_S≥4.7)”表明,仅1890年以来,     

南北地震带的瑞利波群速度与地壳结构

本文用长周期面波资料研究了南北地震带及其西侧的地壳结构。结果表明:南北地震带的地壳厚度具有南薄北厚,西厚东薄的特征,南北带和其西侧区域地壳内都存在有低速层;地壳横波平均速度很低,约为3.37公里/秒;上地幔顶部的横波速度只有4.40公里/秒;南北带北段可能存在上地幔物质上隆,岩石圈厚度只有60多公里,该区域地壳底部存在有低速层。     

Seismogram Analysis and Fitting of Three Earthquakes,West Papua,Recorded at Stations ENH and KMI,China

The S wave velocity structure of the earth below Eastern Southeast Asia has been investigated by analyzing the seismogram from surface wave to multiple depth waves in the time domain and three Cartesian components simultaneously. The wave passes across the front area of subduction zone between the Philippine plate and the Asian plate. The main data are waveform comparisons, instead of the arrival times. The synthetic seismogram is calculated using the GEMINI method. The synthetic seismogram constructed by PREMAN global earth model deviates greatly from the measured one. To solve this problem, corrections are needed for the β speed structure. Corrections cover the gradient change of βh, which turns from negative to positive in upper mantle layers as in the PREMAN, change of earth crust depth and change of zero order coefficients of β velocity function in all earth mantle layers. So, the fitting is obtained, as well as the arrival time or the waveform of Love and Rayleigh surface waves, the S wave and the repetitive depth waves ScS2 and ScS3. This result reveals that the Southeast Asia, being stretched due to tectonic release, has a mantle in some parts with negative anomaly of S wave velocity and vertical anisotropy in all earth mantle layers.     

A Preliminary Study on the Datong Fault Belt

The Datong fault belt is a NE trending fault in the northern Qinghai-Xizang （Tibet） Plateau and controls the boundary of the Xining Basin and Datong Basin. It consists of the Maziying- Miaogou （F1） fault and the Laoye Mountain-Nanmenxia fault （F2）. There is obvious displacement in vertical direction along the belt. The field investigation results show that this belt has long-term activity. There are several meters long crushed zones and veins along the fault side in the basement rock. On the fault section, the Cambria system thrusts over the red- brick-colored Quaternary Period gravel, and there is a fault gouge of several centimeters thick developed on the fault plane. The fault gouge date （ESR） on the fault plane is 610 ± 61ka. The covering deluvial loess is not dislocated, and the OSL result is 14.6 ± 1.5ka. So it can be concluded that the fault belt was active in the middle Pleistocene, but inactive in the late Pleistocene according to the age data and geomorphologic features. Interior formations of the Datong basin features fold with the major axis orienting northwest. According to the relation of fault and fold deformation, Datong fault is a trausversal tear, which is due to uneven compression of the folds in different parts and NNE trending regional compressive stress. It is common among the NE trending faults in the northeast of Qinghai-Xizang （Tibet） Plateau. These NE trending faults aren＇t large, and most are located in the active plate. They are all nearly vertical to the axis of the folds and compressive basins.     

汶川8.0级地震与断层活动性初探

汶川8.0级特大地震震中位于我国南北地震带中段龙门山断裂.在南北地震带上(含渭河断块)目前共布设跨断层水准测量场地116处,监控区域为:23.6°～40.0°N,97.2°～110.4°E;所跨行政区域包括宁夏,内蒙古,甘肃,陕西,青海,四川,云南.控制的主要活动断裂有:①龙门山断裂;     

2008年3月21日于田7.4级地震的发震构造初探

2008年3月21日06时33分,新疆和田地区发生MS7.4地震,震中位于35.77°N,81.43°E,震源深度19km,距于田县城约110km,距和田市约215km.地震发生在西昆仑地震带和阿尔金地震带交汇区,塔里木盆地南部,靠近西昆仑山区边缘部分;震中位于西昆仑山中的阿什库勒盆地,附近存在新近纪火山活动,平均海拔高度5000m,属人烟稀少地区.