دانلود رایگان مقاله انگلیسی تجزیه و تحلیل کمی زلزله نپال در 25 آوریل سال 2015 برای دیدگاه خطر زلزله آینده - الزویر 2017

abstract

The earthquake that occurred in Nepal on 25 April, 2015 was followed by about 256 aftershocks which continued for another 20e25 days. The Coulomb stress change due to the main shock has been estimated at depths 10 km, 15 km and 22 km which justify the occurrence of about 218 aftershocks of magnitudes 4 to 5 mostly at 10 km depth and the rest of magnitudes 5 to 7.3 mostly at 15e30 km depth. The western, southern and northern fringes of the fault plane that slipped on 25 April, 2015 show a high value of positive Coulomb stress change estimated at the above mentioned depths and yet these parts of the fault remained devoid of any aftershock epicentre and therefore must be treated as seats for possible future events. Co-seismic displacement of 5 GPS stations located in Nepal after the devastating earthquake of Mw7.8 on 25 April, 2015 and its largest aftershock of Mw7.3 on 12 May, 2015 have been separately estimated and analysed.

5. Conclusions

On 25 April, 2015 a southward slip on about 160 km  115 km portion of MBT resulted in the devastating earthquake of Mw7.8 (E1) in Nepal and the largest aftershock of Mw7.3 (E2) on 12 May, 2015 and killed thousands of human lives and left many injured and homeless. GPS stations DNGD, GRHI and RMTE situated south of MBT have moved in the northeast direction and among these three stations RMTE has experienced the maximum offset of 12.3 ± 2.0 mm towards ENE. while station CHLM located in the higher Himalayas north of MBT has been offset by 1.41 ± 0.4 m southward due to E1. The co-seismic offset of GPS stations due to E2 alone are not remarkable.

The main shock of 25 April was followed by about 256 aftershocks resulting from the failure to sustain the positive Coulomb stress change imparted at various depths due to the main event. The locations of greater number of aftershocks at 10 km depth are consistent with the Coulomb stress change imparted at depth of 10 km on a fault plane with strike ¼ 295, dip ¼ 10 and rake ¼ 108. The locations of aftershocks of magnitude >5 including the largest event of Mw7.3 on 12 May, 2015 (E2) are consistent with Coulomb stress change imparted on a fault plane with strike ¼ 305, dip ¼ 9 and rake ¼ 90 at depth of 15 km. The aftershock of Mw6.7 at depth 22 km which occurred on 26, April, 2015 agrees well with the CSC estimated at that depth. But the stress increase that resulted from the E1 event has not been released totally through aftershocks. The main shock E1 has resulted in generating positive CSC at depths 10 km, 15 km and 22 km in the bordering parts of the fault plane without any aftershock occurring there. The accumulating stress will probably be released in the coming decades. Therefore these regions of enhanced CSC should be treated as future threats for the people of Nepal.