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利用新技术、新方法,研究历史强震的发震构造及震害,是修订历史强震震源参数的重要内容.本文以1718年通渭M7.5地震滑坡为研究对象,采用地质学"将今论古"原理,基于历史文献分析、遥感解译、野外验证等方法获得通渭地震滑坡数据库.研究发现,(1)总解译滑坡数量5019处,总面积635 km2,滑坡密集沿通渭断裂分布,与X度等震线吻合,但范围均向西、向北各扩展约20 km;(2)与2008年汶川M8地震滑坡相比,面积<103 m2的滑坡大量缺失,面积103~104 m2的滑坡部分缺失,面积>104 m2的滑坡数量相当;(3)尽管通渭地震滑坡数据库并不完整,但是能够反映极震区中大型滑坡的总体特征,可据此确定极震区范围;(4)通渭地震极震区至少有27处以"泄山"等记录地震滑坡的地名,这些受滑坡影响的居民点集中在通渭断裂两侧,占比超过50%,是致7万人死亡的重要致灾因素.研究认为,在黄土高原地区,确认密集的中大型滑坡体可能由单次历史强震触发,且排除其他远场强震影响之后,可以利用现今多时相的高分辨率卫星影像解译获得"相对完整"的历史地震滑坡数据库,为历史强震震源参数的修订提供基础资料.  相似文献
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Analyzing the spatial distribution characteristics of earthquake-induced secondary disasters based on advanced techniques is significantly important, especially in understanding the process of strong earthquakes in the Loess Pateau. Using ArcGIS, this study interprets multi-temporal high-resolution satellite images, field investigation data, and historical seismic records. Major conclusions are obtained as follows:① Landslides induced by the Haiyuan earthquake are mainly distributed in the intersection area of the end of the Haiyuan fault and Liupanshan fault, as indicated by multiple dense distribution centers; ② The landslide distribution of the Haiyuan Earthquake is determined by the distance to the fault, topographic relief, slope, lithology, and other factors. In detail, the closer the distance to the fault, the greater the density of the landslide. The greater the slope and relief of the terrain, the greater the density and the smaller the average area of a landslide. Compared with tertiary strata, Quaternary strata has a larger average area, and the density of the landslides is smaller; ③ The density curve of the death toll in the Haiyuan earthquake can be used as a reference for the distribution of co-seismic landslides. Several Haiyuan co-seismic landslides are distributed in the Tongwei landslide area; however, the major landslides here are induced by the 1718 Tongwei earthquake rather than the 1920 Haiyuan earthquake; ④ The co-seismic landslides of the Haiyuan earthquake exhibits the "slope effect" in the south-west plate of Haiyuan fault, presenting the dominant sliding direction towards the fault and epicenter; however, the "slope effect" is not evident in the northeast plate of the fault.  相似文献
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A complete landslide inventory and attribute database is the importantly fundamental for the study of the earthquake-induced landslide. Substantial landslides were triggered by the MW7.9 Wenchuan earthquake on May 12th, 2008. Google Earth images of pre- and post-earthquakes show that 52 194 co-seismic landslides were recognized and mapped, with a total landslides area of 1 021 km2.Based on the statistics,we assigned all landslide parameters and established the co-seismic landslides database, which includes area, length, and width of landslides, elevation of the scarp top and foot edge, and the top and bottom elevations of each located slope. Finally, the spatial distribution and the above attribute parameters of landslides were analyzed. The results show that the spatial distribution of the co-seismic landslides is extremely uneven. The landslides that mainly occur in a rectangular area (a width of 30 km of the hanging wall of the Yingxiu-Beichuan fault and a length of 120 km between Yingxiu and Beichuan) are obviously controlled by surface rupture, terrain, and peak ground acceleration. Meanwhile, a large number of small landslides (individual landslide area less than 10 000 m2)contribute less to the total landslides area. The number of landslides larger than 10 000 m2 accounts for 38.7% of the total number of co-seismic landslides, while the area of those landslides account for 88% of the total landslides area. The 52 194 co-seismic landslides are caused by bedrock collapse that usually consists of three parts:source area, transport area, and accumulation area. However, based on the area-volume power-law relationship, the resulting regional landslide volume may be much larger than the true landslide volume if the landslide volume is calculated using the influenced area from each landslide.  相似文献
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