共查询到13条相似文献,搜索用时 93 毫秒
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2.1地壳和上地幔形成地球膨胀的“炽热模型”假设富有物理依据,现已为最新地球物理资料所证实。根据这种模型,内核物质是在重力压缩条件下地球形成过程中得到过热、过压、坚实、高密度的气态物质。地球演化过程中,压缩和过热物质可逆转换成凝聚态,地球消耗积累的能量,这个过程地球密度减少——地球膨胀(图略)。地球形成于4.5×109年前,其半径小于0.55R3(R3为现代地球半径),地球物质平均温度为5×104K,平均密度约为3.5g/cm3,主要成分为氢、氧、硅。重力能为2×1039erg。地球模型是多圈层:G地核(过热汽)、F层(汽液相变区)、E层(液熔态物质)… 相似文献
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A. V. Solomatin 《Seismic Instruments》2012,48(4):351-357
Relationships between the average seismic energy of strong and weak earthquakes in confined ranges are considered. These relationships are related to the earthquake recurrence (Gutenberg-Richter) law parameters. The theoretical foundation of the study is based on the results obtained by M.A. Sadovsky and V.F. Pisarenko in 1999, who described the indicated law as a ratio of the total seismic energy and maximum expected earthquake. Some empirical relationships obtained by the author on the basis of the Kamchatka and Sakhalin regional earthquake catalogs are reported. The determination of the recurrence law parameters on the basis of these relationships is shown to be efficient. 相似文献
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The Qian-Gorlos earthquake, which occurred in the Songliao basin in Jilin Province in 1119 AD, was the largest earthquake to occur in NE China before the 1975 Haicheng earthquake. Based on historical records and surface geological investigations, it has been suggested previously that the earthquake epicenter was in the Longkeng area. However, other workers have considered the epicenter to be in the Halamaodu area based on the landslides and faults found in this region. No seismogenic structure has yet been found in either of these two regions. We tried to detect active faults in the urban areas of Songyuan City, where the historical earthquake was probably located. One of the aims of this work was to clarify the seismogenic structure so that the seismic risk in the city could be more accurately evaluated. The area was investigated and analyzed using information from remote sensing and topographic surveys, seismic data from petroleum exploration, shallow seismic profiles, exploratory geological trenches on fault outcrops, and borehole data. The geophysical data did not reveal any evidence of faults cutting through Cretaceous or later strata under the Longkeng scarp, which has been suggested to be structural evidence of the Qian-Gorlos earthquake. The continuous fault surfaces on the back edge of terraces in the Halamaodu area stretch for >3.5 km and were probably formed by tectonic activity. However, results from shallow seismic profiles showed that the faults did not extend downward, with the corresponding deep structure being identified as a gentle kink band. A new reverse fault was found to the west of the two suggested epicenters, which presented as a curvilinear fault extending to the west, and was formed by two groups of NE- and NW-trending faults intersecting the Gudian fault. Three-dimensional seismic and shallow seismic data from petroleum exploration revealed its distinct spatial distribution and showed that the fault may cut through Late Quaternary strata. Exploration boreholes and later geomorphological studies provided further proof of this. Based on these results and analysis, the Gudian fault was confirmed as having been an active fault since the Late Quaternary, with the possibility of earthquakes of magnitude >7 in the future. The Qian-Gorlos earthquake was most probably the result of breakage on one or two sections of this 66-km-long fault. 相似文献