مقاله انگلیسی رایگان در مورد آنالیز کمی زلزله نپال برای دیدگاه خطر زلزله آینده – الزویر 2017

On 25 April, 2015 an earthquake of Mw7.8 occurred about 77 km northwest of Kathmandu in Nepal at a focal depth of 8.2 km (http:// earthquake.usgs.gov/earthquakes). The fatal earthquake that caused huge loss of human lives occurred in the Himalayan thrust wedge near the basal decollement which defines the lower boundary of the thrust wedge and is referred to as the Main Himalayan Thrust Fault (MHT) [1]. The three main thrust systems in the Himalayas, branching off as ramps from MHT are the Main Central thrust (MCT), Main Boundary thrust (MBT) and the Main Frontal thrust (MFT) which respectively separate the Greater Himalayan, the Lesser Himalayan, the Sub-Himalayan Zones and the Indo-Gangetic Plains from one another [2,3]. The convergence rate of Indian plate under Tibet varies from west to east along the length of the Himalayas [4]. The convergence rate across Nepal is about 20 mm/yr [5]. As a result of the fast convergence across Nepal, a portion of Himalayan thrust wedge moved southward over the Indian Plate along the MHT and resulted in the devastating earthquake on 25 April, 2015. According to the slip distribution model proposed by the “finite fault” analysis of USGS (http://earthquake. usgs.gov), a maximum slip of 3.5 m occurred. According to Zhang et al. [6], however, the slip distribution resulted in a maximum slip of 4.5 m. The main shock of 25 April was followed by more than 250 aftershocks (Fig. 1), one aftershock of Mw6.7 occurred at depth of 22 km on 26 April, 2015 and the largest one (Mw7.3) occurred on 12 May, 2015 with its epicentre located about 30 km east of the 25 April earthquake. The variation of earthquake magnitude with their depth of occurrence is plotted in Fig. 2. In this paper, we have estimated and analysed the Coulomb stress change at 10 km and 15 km and 22 km depths imparted due to the earthquake based on the slip distribution model and the fault plane geometry proposed by USGS. Abundance of aftershock locations in the areas showing positive Coulomb stress change have been shown and areas experiencing positive Coulomb stress change and yet remaining devoid of any aftershock have been demarcated as probable locations for future events. The co-seismic displacement of 5 GPS stations located in Nepal after the main shock on 25 April, 2015 and the aftershock on 12 May, 2015 separately have also been estimated and analysed.