Stress Inversion and Fault Instability Analysis of Seram-Buru Region

Abstract

The Eastern Indonesia is situated at the convergence of the Alpine-Himalayan orogenic belt and the Circum-Pacific belt, where the convergence of three tectonic plates generates an area of significant geological complexity and neotectonic activity. This research aims to ascertain the stress regime influencing the Seram-Buru area and its implications on fault instability within the region. The study area encompasses the islands of Seram and Buru, Maluku, utilizing earthquake catalogs and focal mechanism data obtained from the International Seismological Center (ISC) and the Global Centroid Moment Tensor (GCMT), spanning the recording period from January 1st, 1964, to March 31st, 2024, comprising a total of 5198 earthquake catalog entries and 449 focal mechanism data points. Processing involves seismicity analysis of the area, followed by spatial data clustering utilizing a density-based spatial clustering algorithm. Subsequently, stress regime inversion is performed for each clustered area, culminating in an analysis of tectonic instability within the region. The clustering analysis categorizes the data into 5 clusters deemed to correlate well with the neotectonic conditions of the research area, namely shallow subduction earthquakes, intra-subduction earthquakes, and shallow fault-related earthquakes. The results of stress inversion reveal variable shape ratios ranging from 0.5051 to 0.7506, with friction coefficients ranging from 0.3 to 0.85. Sigma 1 exhibits a compressive NE-SW stress regime with a predominantly horizontal plunge, whereas Sigma 3 displays a NW-SE trending stress regime with a predominantly vertical plunge, aligning with the focal mechanism tendencies indicative of uplift faults.