A study on the active faults structures and geohazards triggered by the Ms 8.1 Earthquake in Nepal
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摘要: 2015年4月25日，尼泊尔境内发生Ms 8.1级地震，诱发了较大面积的崩塌、滑坡灾害。笔者通过遥感构造解析和野外实地调查取得以下主要认识：（1）中尼边境的喜马拉雅地区活动构造以NWW向挤压逆冲断裂最为显著，从南到北大致可分南、中、北三个带，中带由众多短小、密集的逆冲断裂构成一个网络状断裂带，是这次Ms 8 1级地震的发震断裂；（2）喜山中段NNE—SN向横张断裂将该地区分割成几个东西向块体，吉隆—樟木近南北向断裂带控制了这次强震的余震分布；（3）本次地震引发了至少445处地震崩塌、滑坡、堰塞湖以及融雪形成的泥石流灾害，这些灾害主要分布在NWW向发震断裂的北侧上盘，受发震断裂控制，其中面积超过2.4×104 m2的地震滑坡有30处；（4）中国境内的NNE—SN向深切河谷是滑坡、崩塌等地质灾害的主要发生带，而这些河谷多为公路沿线和村镇居住地，应成为重点防范区。Abstract: The Ms 8.1 Earthquake on April 25, 2015 occurred in Nepal in the southern Himalayas, triggered a large area of landslides and rock falls in the earthquake area. Based on the remote sensing interpretation of active faults and preliminary field investigations, the following conclusions are achieved: (1) There are some significant active compressive reverse thrust faults extending in the NWW direction in the border between China and Nepal of the Himalayas areas, which can be divided into three belts, the south, middle and north. The middle belt is the network cross belts consisting of a number of short, intensive compressive reverse thrust faults, which are the seismogenic faults of the Ms 8.1 Nepal Earthquake. (2) The regions are divided into several blocks from east to west by the NNE—SN faults in the middle Himalayan and the distribution of the aftershocks were controlled by the Jilong-Zhangmu NS-trending faults. (3) This earthquake triggered at least 445 rock falls, landslides, dammed lakes and debris flow induced by snowmelt in the high mountains, which are mainly located in the upfaulted blocks and extend in the NWW direction, and are strictly controlled by the seismogenic fault and the high and steep mountains, in which 30 landslides with an area of over 24,000 m2 occur, and the largest landslide has a volume of about 2.7×106 m3 (4) Rock falls and landslides mainly occurred in the deep valleys extending in the NNE—SN direction, where most roads and villages exist. Therefore, these areas should be prevented as the key areas in Tibet.
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Key words:
- Nepal /
- the Ms 8.1 Earthquake /
- active faults /
- geohazards
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