Temporal variation in crustal shear wave splitting associated with a moderate earthquake around Nias Island, Indonesia Syuhada Syuhada, Titi Anggono, Febty Febriani, Jauhari Arifin, Cinantya Nirmala Dewi, Aditya Dwi Prasetio, Mohammad Hasib
Research Centre for Physics - National Research and Innovation Agency Republic of Indonesia (BRIN)
Abstract
We investigate temporal variation in shear wave splitting parameters of local earthquakes around Nias Island, northern part of Sumatran forearc. We analyse a total of 79 high-quality splitting measurements recorded at a GEOFON seismic station (GSI) from 2009-2015. We observe that there is no clear time variation in fast polarization of the splitting waves. On the other hand, an increase in delay time of the splitting waves is found prior to a medium earthquake that occurred around the island on August, 2010. Therefore, we suggest that this temporal change may be related to the change in crack geometry of rocks following the accumulation of the stress in the crust before the earthquake occurred.
Keywords: Temporal variation- shear wave splitting- Nias Island
