Studi Variasi Spasial Parameter Seismotektonik Untuk Mengetahui Kondisi Stress Lokal Tektonik dan Tingkat Keaktifan Kegempaan Di Wilayah Sumatera Barat dan Sekitarnya

Abstract

Spatial variations of seismotectonic parameters. a and b values ??can describe tectonic stress conditions and the level of seismic activity in an area. a and b values ??are the level of seismic activity and seismotectonic characteristics in an area. A low a value reflects a low level of seismic activity and vice versa for a high a value, while a low b value can reflect high local tectonic stress conditions and vice versa for a high b value. In this study, using catalogs from the BMKG and NEIC/USGS, the observation period was 1 January 1973 – 31 December 2010 with coordinate boundaries of 2 North Latitude – 4 South Latitude and 94 East Longitude – 104 East Longitude covering the area of ??West Sumatra and its surroundings. To determine spatial variations in seismotectonic parameters using ZMAP software (Wiemer and Wyss, 2002). From the analysis, it was found that the spatial variation of b-value ranged from 0.6 – 2.0 and the a-value ranged from 4 – 11. High local stress conditions (low b-value) were observed around the Mentawai Islands, the southern part of Nias Island and along the hills of West Sumatra and Low local stress conditions (high b-value) were observed in the west-northwest of Nias Island and along the northern Sumatran hill range. Meanwhile, low levels of seismic activity occur in the Mentawai Islands and high levels of seismic activity occur in the west-northwest of Nias Island and along the hills of the northern part of Sumatra.