Sumatra is one of the Indonesian regions categorized as active tectonics. The majority of past earthquakes in Sumatra and its surrounding areas have originated from the accumulated stress in the subduction zone, namely the submergence of the Indo-Australian plate against the Eurasian plate. This research was conducted to identify the level of accumulated stress and earthquake-prone areas in the subduction zone of Sumatra Island based on the spatial variation of the b-value, using the least square method. The data used in this study are earthquake parameter data from the International Seismological Center the United States Geological Survey and Meteorological, Climatological, and Geophysical Agency catalogs from 2005-2019 with a magnitude ≥ 1 and a depth of 0-200 km located 90° to 106°E and -6° to 5.8°S. The results showed that the spatial variation of the b-value in the subduction zone of Sumatra Island in 2005-2009 ranged from 0.31-0.77, the b-value for 2010-2014 ranged from 0.18-1.29. In 2015-2019, the spatial variation of b-values ranged from 0.28-1.2. Earthquake-prone areas are located around Breuh Island, Banyak Islands, and Sipura and Pagai Islands, as evidenced by a low b-value, correlating with a high level of unreleased accumulated stress from the past 15 years, leading to an immense earthquake potential in the next period within the area. This analysis shows very significantly found that high b-value matches with earthquake spots. Detailed spatial and temporal b-value characteristics and its interpretation can advance our comprehension of earthquake occurrence and ideally lead to improved forecasting agility.
Spatial variation of subduction zone fluids during progressive subduction: Insights from Serpentinite Mud Volcanoes
