1区域地震地质背景 Regional Seismogeological Backgrounds 青藏高原晚新生代以来的强烈隆升,对周边地区气候与环境产生了深刻影响。在 青藏高原向东挤出过程中,在高原东部形成了显著的地貌、地质构造分异带,成为强 烈构造活动区（曾融生、孙为国,1992；张培震等,2003；徐锡伟等,2007）。据不 完全统计,1900年至2013年间,中国大陆共发生Ms7.0级以上大震64次,其中37次发生 在青藏高原东部（南北地震带）。青藏高原东部复杂的地质演化历史和新构造活动, 导致地层岩性和岩体结构完整性差、地形陡峻、河流深切,为地震地质灾害的发生创 造了有利条件。 The strong uplift of the Tibetan Plateau in Late Cenozoic has had a profound climate and environment impact. During the eastward squeezing-out process of the Tibetan Plateau, a distinct landform and geotectonic differentiation zone formed on the eastern margin of the plateau, and thus has become an intense tectonic active zone Zeng and Sun, 1992; Zhang et al., 2003; Xu et al., 2007. According to incomplete statistics, from 1900 to 2013, there were 64 earthquakes bigger than Ms7.0, among which 37 occurred in the eastern marginal region of the Tibetan Plateau South-North Earthquake Belt. The complex geological evolution history and neotectonic activity have resulted in integrity of strata and rock mass structure, high and precipitous landform, and deeply incised rivers in the region, which have provided favorable conditions to the occurrence of earthquake geohazards. 2014-060龙门山1－16.indd 1 14-10-31 上午9:21 青藏高原东部在新构造运动和水系 深切作用下,形成复杂的地形地貌 青藏高原东部地形地貌及主要水系分布图 Topographic map of the eastern marginal region of the Tibetan Plateau 格局。一般将四川盆地西缘的龙门山及其南延的锦屏山、玉龙雪山看作是中国东西部一级地貌边界带。 以阿尼玛卿山、大雪山、贡嘎山、锦屏山、玉龙雪山一线为界,西部高原地势相对平坦,东部地区侵蚀地貌发育。青藏高原东部大江大河发育,以金沙江、怒江、澜沧江最为著名。 It is the neotectonic movement and the river-incision that would make the eastern margin of the Tibetan Plateau appear as a complex geomorphological framework. Generally, Mt. Longmenshan and its southern extension, i.e. Mt. Jinping and Mt. Yulong, are regarded as a first-level geomorphological boundary between the west and the east of China. This region can be further divided into two parts by taking Mt. Anyemaqen, Mt. Daxueshan, Mt. Gongga, Mt. Jinping and Mt. Yulong as the boundary: the western part is relatively even, the eastern part is occupied with high mountains and deep valleys. And there are such famous rivers as the Jinsha River, the Nu River, and the Lancang River to flow through here. 青藏高原东部地形起伏度图 Relief degree of the eastern marginal region of the Tibetan Plateau 青藏高原东部崇山峻岭、峡谷纵横,在地貌上从海拔不到500m的成都平原,向西上升到海拔4000m以上,形成一个巨大的地形陡变带。区内地形起伏度大多在1000mkm2以上,地形起伏最大的地区位于若尔盖盆地以东和以南的岷山、邛崃山、龙门山和大雪山,发及南部贡境山和锦屏山一带,最大的地形起伏超过3000km2. The eastern marginal region of the Tibetan Plateau is occupied with lofty mountains and high ridges, as well as crisscross gorges and valleys. A huge geomorphologic sharp-change zone occurs from the Chengdu Plain with elevations of lower than 500 m to the west side of Mt. Longmenshan with elevations of higher than 4000 m. The relief degree is commonly more than 1000 mkm2. The areas covered by Mt. Minshan, Mt. Qionglai, Mt. Longmenshan, Mt. Daxueshan, Mt. Gongga, and Mt. Jinping, are the most distinct in relief degrees, more than 3000 mkm2. 青藏高原东部地层岩性分布略图 青藏高原东部涉及地域广,跨越多个地层单元。地层从上太古界到第四系均有出露,其中侏罗系、三叠系分布最广泛,占全区的30%以上。不同时代地层或岩浆岩的空间分布明显受到地质构造的控制。 The eastern marginal region of the Tibetan Plateau covers a wide area where there are multiple stratigraphic units from the Upper Archean to the Quaternary to be exposed. Among them, the strata of Jurassic and Triassic are most widely distributed, accounting for more than 30% of the total area. The spatial distribution of them and magmatic rocks is ignificantly controlled by geological structures. 青藏高原东部工程地质岩组分布略图 Engineering geological rock groups in the eastern marginal region of the Tibetan Plateau 龙门山及邻区布格重力异常图（据方慧等,2013） Bouguer gravity anomaly in Mt. Longmenshan and its adjacent areas after Fang et al., 2013 龙门山及邻区布格重力异常值全部为负值,以龙门山-锦屏山为明显过渡带,由东南向西北逐渐降低。从东到西可划分为明显不同的三个区带：川中重力低负异常区带、九寨沟-石棉-攀西裂谷重力渐变带和松潘-甘孜重力高负异常区带。“两区夹-带”的布格重力异常特征及明显的南宽北窄异常带,显示该区深部构造格局形成于复杂的构造挤压作用背景。 ouguer gravity anomalies in Mt. Longmenshan and its adjacent areas all are negative, and by Mt. Longmenshan and Mt. Jinping as an obvious transitive zone, gradually decrease from southeast to northwest. Thus three distinct zones can be divided into from east to west: the central Sichuan lower negative gravity anomaly zone, the Jiuzhaigou-Shimian-Panxi gravity anomaly transition zone, and the Songpan-Garzi higher negative gravity anomaly zone, suggesting that the deep tectonic framework here would form under complicated tectonic compression.龙门山及邻区航磁异常图（据方慧等,2013） Aeromagnetic anomaly in Mt. Longmenshan and its adjacent areas after Fang et al., 2013 龙门山及邻区航磁异常强弱层次分明,可划分为以龙门山-锦屏山为界的华南地块磁异常区带和松潘甘孜地块磁异常区带。前者的磁场以高值正异常为主,展布方向主要是北东向和南北向,并偶有北西向和东西向；后者的磁场以低值负异常为主,局部有低值正异常,多呈北西向、南北向展布。上述特征反映了不同地质构造单元的区别。 Aeromagnetic anomalies in Mt. Longmenshan and its adjacent areas are distinct in gradient, and by Mt. Longmenshan and Mt. Jinping as a boundary, can be divided into the South China block aeromagnetic anomaly zone and the Songpan-Garzi aeromagnetic anomaly zone. The former is dominated by higher positive anomalies, mainly showing t
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