A study on the active faults structures and geohazards triggered by the Ms 8.1 Earthquake in Nepal

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.