细胞自动机地震波模拟的并行化算法

采用区域分解的办法对格子气自动机地震波传播模拟的并行化算法进行了研究,提出了两种区域分解算法,并在SGIPowerChallenge并行计算机上进行了实际地质模型中平面波反射地震响应的计算,获得了较高的并行计算效率．     

水饱和裂纹对地壳岩样中地震波速及各向异性的影响

选择４种地壳岩石样品,经干燥或水饱和处理后在不同围压条件下测量了在其中传播的纵、横波的速度及其各向异性．在大气压条件下低孔隙度(＜１％岩样中,水饱和样品中的纵波速度明显地比干燥样品中的高,但横波速度的差别不大．因为在低孔隙度岩样中纵波速度对孔隙流体的反应比横波速度敏感,可以用泊松比的变化来反映随着围压的增加晶粒间流体对弹性波传播特性的影响．根据实验数据,按Ｏ’Ｃｏｎｎｅｌｌ模型分别计算了干燥和水饱和岩样中的裂纹密度,与通过实测体应变曲线得到的裂纹孔隙度十分吻合．利用横波的速度和偏振特性可以推断岩样中定向排列微裂纹的空间取向情况．研究表明,同时测量在岩样中传播的纵、横波的速度,通过Ｖｐ／Ｖｓ比值可以给出有关颗粒边界流体的证据,也可以估计岩样中的裂纹密度．     

地震层析成像反演中3种广义解的误差分析与评价

在地震波速度和地震波　值层析成像中,对于非线性反演问题解的可靠性研究非常重要．为了讨论ＡＲＴ（ＡｌｇｅｂｒａｉｃＲｅｃｏｎｓｔｒｕｃｔｉｏｎ　Ｔｅｃｈｎｉｑｕｅ）、ＳＶＤ（Ｓｉｎｇｕｌａｒ　ＶａｌｕｅＤｅｃｏｍｐｏｓｉｔｉｏｎ）、ＬＳＱＷ（ＬｅａｓｔＳｕａｒｅ）３种方法的算法稳定性以及反演效果,本研究将这３种算法用于求解非常病态问题和一般稳定问题,根据数值计算结果,分别给出了在非常病态问题和一般稳定问题中３种算法的相对误差及其算法稳定性评价．进而针对３种算法在同一地质模型上的速度成像结果进行了比较,为地震层析成像反演效果分析提供了定量参数．     

用不完整的地震资料估计地震矩年变化率

在充分考虑现有地震资料的不完备性和震级服从两端截去泊松分布的条件下,建立了用历史地震资料和现代地震资料及考古地震资料计算地震矩年变化率的方法。计算了西南地区几个地震带的地震矩年变化率,并与地质资料得到的结果进行了比较,结果表明该方法是切实可行的     

Evolution of the seismic activity from the 1982 eruption of El Chichon Volcano, Chiapas, Mexico

 We analyzed more than 1700 earthquakes related to the 1982 eruption of El Chichon volcano in southern Mexico. The data were recorded at specific periods throughout the whole eruptive interval of March to April 1982, by three different networks. The seismic activity began several months before the first eruption on 28 March. During this period the seismicity consisted of hybrid and long-period shallow earthquakes most likely related to processes of faulting, fracturing, and fluid movement underneath the volcano. The foci of events occurring before the eruption circumscribe an aseismic zone from approximately 7 to 13 km below the volcano. After the eruption, the seismic activity consisted of tectonic-type earthquakes that peaked at 1200 events/h. This later activity occurred over a wide range of depths, mostly between 5 and 20 km, that includes the former aseismic zone and is roughly limited by the major tectonic faults in the area. Received: 19 May 1998 / Accepted: 13 June 1999     

Seismic Wave Propagation and Excitation in Multi-layered Media with Irregular Interfaces Part (Ⅰ): SH Case

Study of seismic wave excitation and propagation in laterally heterogeneous media was an active and important subject in seismology in the past two decades, numerous analytical and numerical efforts have been made in this research field. In this article, I have, first, made a brief review on those developments and then introduced and summarized a unified and efficient method, global generalized reflection-transmission (abbreviated to R/T thereafter) matrices method, for synthetic seismograms in multi-layered media with irregular interfaces developed by the author [24~26]. As demonstrated in this article, this method could be regarded as an extension of the generalized R/T coefficients method for the horizontally layered case [2,5] to the layered media with irregularly shaped interfaces by incorporating the T matrices technique [27,28]. Because of the use of a recursive scheme in computing the global generalized R/T matrices, this method is efficient, particularly for the case with a large number of irre     

Crustal structure of the Alpine–Pannonian transition zone: a combined seismic and gravity study

 The crustal structure of the transition zone between the Eastern Alps and the western part of the Pannonian depression (Danube basin) is traditionally interpreted in terms of subvertical Tertiary strike-slip and normal faults separating different Alpine tectonic units. Reevaluation of approximately 4000-km-long hydrocarbon exploration reflection seismic sections and a few deep seismic profiles, together with data from approximately 300 wells, suggests a different structural model. It implies that extensional collapse of the Alpine orogene in the Middle Miocene was controlled by listric normal faults, which usually crosscut Alpine nappes at shallow levels, but at depth merge with overthrust planes separating the different Alpine units. The alternative structural model was tested along a transect across the Danube basin by gravity model calculations, and the results show that the model of low-angle extensional faulting is indeed viable. Regarding the whole lithosphere of the western Pannonian basin, gravity modelling indicates a remarkable asymmetry in the thickness minima of the attenuated crust and upper mantle. The approximately 160 km lateral offset between the two minima suggests that during the Miocene extension of the Pannonian basin detachment of the upper crust from the mantle lithosphere took place along a rheologically weak lower crust. Received: 13 July 1998 / Accepted: 18 March 1999     

涵江地电站外线路改造效果评价

涵江地电站经过彻底改造,已可以记录到区域内的地电阻率和自然电位的变化情况,为东南沿海地区的地震预报提供一定的台北信息和连续可靠的观测资料,是一个必要的地震台北信息的观测手段。     

数字地球及其对地震科学的影响

本文综述和探讨了数字地球概念的起源、内涵及其相关的关键技术,以及数字地球对地震科学发展的作用和影响。     

提高763长周期地震仪的抗干扰能力

我台以《提高763地震仪的抗干扰能力》为课题,在基建完成后,对763仪器重新进行安装调试,对仪器的连续线及耦合系统进行了全面的改进处理。投入运行工作两年来,记录效果较好,仪器的抗干扰能力有了较大程度的提高。