Probabilistic Seismic Hazard Assessment of Southern Offshore East Java Using Poisson and Gutenberg–Richter Models
Abstract
The southern region of East Java is part of the Sunda Subduction Zone, which has high seismic activity due to the convergence of the Indo-Australian and Eurasian Plates. This study aims to analyze the probability of earthquake occurrences in the southern offshore of East Java using the Poisson distribution and the Gutenberg–Richter law. Earthquake catalog data from the International Seismological Centre (ISC) for the period 1996–2025 were used. After declustering using the Gardner and Knopoff method, 1,348 mainshock events were obtained. The initial Magnitude of Completeness ( ) was determined to be 4.0 using the Maximum Curvature (MAXC) method, then corrected to 4.2, resulting in 888 events with a mean magnitude of . The seismic parameters obtained were and . The Kolmogorov–Smirnov test showed that the annual earthquake data follow a Poisson distribution (Dcalculated (0.204086)≤ DTable (0.297595)), confirming the validity of the Poisson model. Extrapolation using the Gutenberg–Richter law yielded earthquake probabilities for of 92.78% within 50 years, of 15.42%, and of 1.06%. This study is expected to serve as a reference for seismic hazard assessment and disaster risk mitigation in the southern coastal area of East Java.
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References
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