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171.
172.
利用新近获得的子午面磁盔-电流片背景太阳风稳态解,对激波从盔底沿电流片方向往外传播时与磁盔间的相互作用进行了数值模拟研究,重要新结果是:1.磁盔的存在使受扰介质速度跃变中央出现下凹,随着激波传出磁盔区并沿电流片方向传播,速度下凹逐渐减弱以致消失;2.激波将磁盔拉长并把盔顶的环形(垂直赤道面)磁场带到行星际空间,成为行星际磁场南向分量的来源之一;3.5个太阳半径(R⊙)内的磁盔部分将出现精细结构,沿盔外边界形成两条高速带,以及马蹄形密度(亮)环形结构等.这些结果表明,太阳附近高速等离子体与磁盔间存在重要的动力学相互作用过程,对行星际空间的太阳风三维结构有重要影响. 相似文献
173.
This paper presents a numerical investigation on the effects of thermal shock as a pretreatment of rock prior to comminution. More specifically, the effect of heat shock-induced cracks on the uniaxial compressive strength of rock is numerically studied. The chosen constitutive model of rock employs a (strong) embedded discontinuity finite element formulation to describe cracks. The thermomechanical problem that governs the heat shock pretreatment of rocks is considered as an uncoupled problem because of a highly dominating role of the external heat influx. Two solution methods of the global problem are presented: an explicit-explicit dynamic scheme and an implicit-implicit quasi-static scheme. The model performance is tested in simulations on heterogeneous numerical rock samples subjected first to a heat shock pretreatment and then to a mechanical compression test. According to the results, the compressive strength of intact granite rock having the axial splitting failure mode can be substantially reduced by heat shock pretreatment. 相似文献
174.
Tjörnes fracture zone. New and old seismic evidences for the link between the North Iceland rift zone and the Mid-Atlantic ridge 总被引:1,自引:1,他引:0
The Tjörnes facture zone (TFZ) connects the EW extension of the Mid-Atlantic ridge north of Iceland to the extension of the North volcanic zone (NVZ) of Iceland. Earthquakes up to magnitude 7 (Ms) can occur in TFZ, volcanic eruptions have been observed and large crustal deformations are expected in similar way as have been observed in the NVZ. Most of the zone is below ocean, which limits the historical information and geological observations. For studying the dynamics of the zone we must rely on interpretation and modelling based on seismic observations, especially on microearthquake observations for the last 10 years. In this paper we demonstrate how microearthquakes can be applied to map the details of the plate boundary, and how this information can be applied to find epicenters and fault planes of large historical earthquakes, also how seismic information can be applied in dynamic modelling and to infer spatial and temporal interplay in activity, and to enhance hazard assessment. 相似文献
175.
176.
177.
给出了1994年1月25日在吉林省白山市三岔子区大安屯地震的基本参数,烈度分布与震害,分析发震的地质构造背景,总结发震前的地倾斜异常特征。 相似文献
178.
Dynamic stress variations due to shear faults in a plane-layered medium 总被引:11,自引:0,他引:11
A complete set of expressions is presented for the computation of elastic dynamic stress in plane-layered media. We use a discrete-wavenumber reflectivity method to compute the stress field radiated by arbitrary moment-tensor sources. The expressions derived here represent an interesting tool for both-the observational and theoretical analysis of dynamic stress changes associated with earthquake phenomena. Dynamic stress changes associated with a strike-slip fault having unilateral rupture are shown. This modelling, which is similar to the 1992 Landers California earthquake, illustrates the effects of distance, directivity and depth on transient stress changes. 相似文献
179.
The parameters of rocks in ultrahigh-presure state are very important to understanding the geodynamics and explosion engineering
of rocks. In these experiments the plane wave dynamite lenses were used to drive the flying plates. The flying plate hits
the target and produces the ultrahigh-pressure shock wave. The propagation velocity and the particle velocity of shock wave
in rock samples were measured by probes, and the relation between density of rocks and pressure was obtained by Rankine-Hugoniot
formulas. The maximum pressure in experiments was higher than 70 GPa. The ultrahigh-pressure state formulas obtained are:
Limestoneρ=3.22+0.016p; Graniteρ=3.20+0.024p. In which the unit for ρ is g/cm3, the unit forp is GPa.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 96–103, 1991. 相似文献
180.
本文将云南地区分为三个地震预报区,利用马尔科夫齐次模型,分别计算了其未来5年和10年时间内可能发生M≥6.0、M≥6.5和M≥7.0级地震的概率。 相似文献