1994年9月16日台湾海峡7.3级地震震源过程的研究

采用数字化台网Ｐ波波形资料及台湾台网Ｐ波初动方向资料,研究了１９９４年９月１６日台湾海峡７３级地震及邻近地区（北纬２１～２６°,东经１１５～１２０°）ＭＬ≥５８级共５次地震的矩张量解及震源参数。结果表明,这次７３级地震的矩张量解以双力偶成分为主,是断层面接近ＮＷ走向的正断层。断层面的走向与大震前地震的条带分布走向及余震分布显示的破裂图象较相象,震源机制的张应力轴接近水平,近ＮＥ走向;压应力轴几乎垂直,近ＮＷＷ走向,似乎表明这次地震是受菲律海板块向欧亚板块北西向挤压的力源控制。从Ｐ轴接近竖直而Ｔ轴接近水平来看,发震断层为强烈拉张性正断层,可能还同时存在垂直向上的应力作用。其它４个强震的震源机制解与７３级大震的差别较大。这些地震震源机制解的复杂性,表明台湾海峡地震序列的发展过程比较复杂。     

扬子地块西南缘下震旦系火成岩系研究

研究区的天宝山组和苏雄组、开建桥组酸性、中酸性火山岩、火山碎屑岩同属下震旦系。它们及同期形成的花岗岩形成于后造山构造环境中,并非与裂谷活动有关。它们皆为S型,其源岩为太古界。     

新疆阿图什市近场区地震构造评价

在新疆阿图什市近场 2 5km范围内鉴别出全新世活断裂 1条 ,全新世活褶皱 5个。托特拱拜孜—阿尔帕雷克断裂在全新世时期曾有两次显示断错活动 ,累积铅直断距 170 cm,最新断错活动的 TL时间在 ( 8.6± 0 .0 3) Ka BP以内。该断裂历史上曾发生过 190 2年 8月 2 3日阿图什 8.2 5级地震 ,近期又发生了 1996年 3月 19日阿图什 6.9级地震 ,是一条地震断裂构造。由托特拱拜孜—阿尔帕雷克断裂与塔什皮萨克—阔诺勒果背斜褶皱构成的地震构造带所形成的潜在震源区距阿图什市工程场地以北 13km,其发生最大潜在地震的能力按 8.5级考虑 ,由全新世活褶皱构成的喀什—阿图什地震构造带所形成的潜在震源区的震级上限按 6.0级考虑     

被动源激发极化法的野外试验结果

对被动源激发极化法场源的基本性质、激发极化效应的提取方法进行了讨论,以野外试验结果为例研究了矿体与异常的对应规律,对该方法的有效性和可行性进行了说明。     

Silicon Isotope Geochemistry of Micro—Fine Disseminated Gold Deposits in SW Guizhou and NW Guangxi,China

Quartz was studied with respect to its silicon isotopic composition and cathodoluminescence in micro-fine disseminated gold deposits in SW Guizhou and NW Guangxi.The results showed that quartz in wall rocks.ores and that in association with hydrothermal silicification are distinctive in silicon isotopes and cathodoluminescence characters.Quartz in association with primary silicification is non-luminescent while that in wall rocks and associated with secondary silicification exhibits striking luminescence.Based on the dynamic fractionation of silicon isotopes,it is suggested that the mineralization was accompanied by rapid transport of aprimary siliceous fluid along the major deep fault system into subordinate faults before ore components deposited in favorable strata via penetration and metasomatism.Therefore,a deep origin is implicit for gold deposits of this type.     

湘西新元古界—寒武系中锑砷存在相态研究

应用部分提取技术研究湘西地区新元古界－寒中武系锑和砷元素的存在相态表明,岩石中以可交换离子,与碳酸盐有关,与硫化物有关和赋存于硅酸直放物晶格的４种形式存在的锑元素分别占岩石中锑总量的１８．６５％,０．８５％,３１．４１％和４３．８１％,砷则分别为７．０５％,４．２９％和５６．１１％和２９．１８％,呈易迁移相态存在锑和砷分别为５５．９１％和６７．４５％,在含硫开放体系中,岩石中元素的淋滤率与其中易迁     

Thermoelastic stress due to a rectangular heat source in a semi-infinite medium. Presentation of an analytical solution

The thermoelastic response due to a time-dependent rectangular heat source in a semi-infinite medium is analyzed. The problem originates from studies of nuclear waste repositories in rock. Canisters containing heat-emitting nuclear waste are deposited over a large rectangular area deep below the ground surface. The solution for a time-dependent heat source is obtained from the corresponding instantaneous heat source by superposition. The thermoelastic problem for the instantaneous rectangular heat source in a infinite surrounding is solved exactly. An important step is the introduction of so-called quadrantal heat sources. The solution for the rectangle is obtained from four quadrantal solutions. The solution for the quadrantal heat source depends on the three dimelasionless coordinates only. Time occurs in the scale factors only. The condition of zero normal and shear stresses at the ground surface is fulfilled by using a mirror heat source and a boundary solution. The boundary solution accounts for the residual normal stress at the ground surface. Using a Hertzian potential, a surprisingly simple solution is obtained. The final analytical solution is quite tractable considering the complexity of the initial problem. The solution may be used to test numerical models for coupled thermoelastic processes. It may also be used in more detailed numerical simulations of the process near the heat sources as boundary conditions to account for the three-dimensional global process.     

根据含超压气体裂隙震源模式讨论P波初动符号的分布

利用含超压气体裂隙震源模式［１］分析研究了Ｐ波初动符号的分布．根据理论推导,不同倾角含超压气体裂隙可分别形成Ｐ波初动符号的四象限分布图象和圆、椭圆、抛物线、双曲线等圆锥曲线形Ｐ波节线．按节线形状和失稳方式进行了地震分类．所推论的初动Ｐ波、Ｓ波振幅分布规律和地形变特征都与实际相符     

地震前兆复杂性成因机理研究的讨论（一）：地震前兆复杂性的表现形式

通过国内外成功与失败的震例分析,介绍了地震前兆共性的一面,如在台网具有一定监测能力的地区,如果发生６级以上地震,震前总能或多或少地观测到异常现象。地震越大震前异常越多,分布越广,持续时间越长,异常幅度也较大,同时章着重对前兆复杂性的表现形式进行了较系统的归纳,整理,主要从以下几方面进行了分析,异常与地震关系的不确定性,主要表现在除了“有异常有地震”和“无异常无地震”的理论情况外,还存在“有异常无     

Delineation of Potential Seismic Source Regions of Moderately Strong Earthquakes Without Seismogenic Tectonics

In this paper,approaches are developed to delineate the potential seismic source regions of moderately strong earthquakes that do not have clear seismotectonic settings.Based on comprehensive analysis of regional tectonic backgrounds and seismicity,the data,such as isoseisrnals,spatial distribution of after shocks,regional tectonic stress field,and focal mechanisms,are employed for the delineation of the potential seismic source regions.The reliability of such potential seismic source regions is also discussed.