Scattering of seismic waves by cracks in multi-layered geological regions: II. Numerical results

The mechanical model for plane strain, time-harmonic seismic wave propagation problems in cracked, multi-layered geological regions with surface topography and non-parallel interfaces was described in the first part of this work. Here, this model is used to investigate the response of such a region to the presence of traveling elastic waves generated by a seismic source. The computational methodology that was developed in the first part is based on a combination of both the regular (displacement-based) and the hypersingular (traction-based) Boundary Integral Equation Method (BIEM). First, the accuracy and convergence characteristics of this hybrid BIEM are studied. Then, a series of problems involving four different configurations of a reference geological deposit with both interface and internal cracks are solved, for a loading that is due to a seismically-induced pressure wave propagating upwards from the underlying rigid half-plane. The purpose of the numerical study is to investigate the influence of various key parameters of the problem, such as frequency and incidence angle of the incoming wave, size of the surface relief, location and size of the buried cracks, interaction effects between cracks and finally the presence of layers, on both the scattered displacement field and the stress concentration field.     

Investigation of a landslide in the new site of Badong County by integrated geophysical survey

An integrated geophysical survey which combines vertical seismic profile method, shallow reflection seismic method, electric sounding, soil temperature measurement and radioactive gas measurement was used to investigate Zhaoshuling landslide in the new site of Badong County and to assess the stability of the landslide. By rational use of these methods together with borehole geological profile and other geological information, the spatial distribution of the landslide body, the formations and structures within and without the landslide body were determined and the stability of the landslide was also assessed, thus making great contribution to the successful and rational investigation and assessment of the landslide.     

北祁连石居里地区Cu(Zn)-S矿床地质特征及综合成矿模式

文章主要论述了北祁连山西段石居里矿田内Ⅵ号沟、Ⅷ号沟、九个泉等矿床的基本地质特征，并与北祁连山东段老虎山地区银硐沟、猪嘴哑吧等矿床对比。结合其早古生代构造演化历史、古洋脊或弧间、弧后拉张环境确定矿床类型，将上述3个矿床归属为蛇绿岩Cu(Zn）－S型矿床（类塞浦路斯型）。建立综合成矿模式的基本要求：（1）矿床具有一定的时控性，有一定的含矿层位；（2）生长性断裂的积极参与；（3）海底火山喷发、喷气中心与次级盆地双向控制；（4）多元热流体成矿系统。     

陆相红层盆地1:5万区调中的遥感应用研究

本文采用遥感地质方法,对陆相红层盆地的沉积岩相、沉积体系界面、盆地充填序列、岩相变化以及地层格架影像特征进行了识别研究,取得了较好效果,为遥感在红层盆地1:5万区调中的应用,开辟了新思路。     

视距测量方法的改进

在视距测量中．本文应用上、下视距丝与中丝所夹视角均为17′11″这一原理，证得：上、中、下三丝读数与坚盘读数之间存在着一个多余观测；去除中丝读数同样能求得测站点与碎部点间的平距及高差，且不影响结果的精确性。碎部测量时，对每个碎部点就从根本上减少了一个观测要素。实践证实：此法可节省约15％的碎部测量时间.     

Modeling,ray tracing,and block nonlinear travel-time inversion in 3D

We describe an integrated forward and inverse three-dimensional modeling system that can deal with complex geological structures. The system has been designed to handle large-scale problems by using a distributed approach. It uses seismic ray tracing for forward simulation, time-to-depth mapping, and nonlinear travel-time inversion.A novel decomposition method is our tool to attack large-scale problems in a parallel approach. The system is fully implemented and we demonstrate its performance with synthetic examples.This research was partially supported by the National Science Foundation under SBIR Grant III-9300992.     

和硕5.0级地震气体地球化学异常特征

１９９５年３月１９日，新疆和硕县那音克乡发生Ｍｓ５．０级地震。震前，乌鲁木齐地区地下水中溶解气体Ａｒ、ＣＨ４、ＣＯ２、Ｈ２Ｓ等和库尔勒地区的断层气Ｒｎ相继出现明显的异常。异常具有短期临震性质，主要表现为短期趋势升高，临震突跳。     

关于宁夏近代地震烈度考察结果的讨论

对宁夏１９次近代地震烈度考察结果进行分析表明，地震烈度明显受震中区地质条件、民房抗震性能、人为因素、地震类型等因素的影响。据此提出了今后在地震烈度考察中应注意的问题，及合理使用地震烈度考察结果的建议。     

工程VSP技术在三峡坝区中的应用

通过对长江三峡枢纽工程坝区白岩尖１井的工程ＶＳＰ测试，在采用四分量采集、双子波监控和复杂波场的波形识别等技术的基础上，提出反映岩石特性的多种动弹模量，综合解释井口周围复杂的花岗岩岩体内部风化带分布和裂隙及岩脉充填分布．     

华北震后趋势判断的前兆综合指标与方法

在对华北邢台、渤海、海城、唐山、大同五大震例的各前兆学科震后变化进行分析的基础上,本文归纳出综合判断后续地震异常的3项定量指标与4项定性指标,还给出了模糊综合评判的方法并计算出符合实际的结果,当评判有震时又给出预报后续地震三要素的经验性判据.