MULTI-SCENARIOS TSUNAMI HAZARD AND EVACUATION ROUTES USING SEISMIC DATA IN PACITAN BAY, INDONESIA

Abstract

On the southern coast of Java Island, Pacitan Bay is densely populated and faces Java Trench, making it susceptible to trapping tsunami waves. This geographical setting, characterized by a dense population, bay morphology, and proximity to the trench, increases the risk of a tsunami. Despite the increase in such risk, comprehensive mitigation measures are lacking in the region. Addressing this gap requires the development of effective strategies, advanced modeling, and robust evacuation plans to enhance community resilience. Therefore, this study aimed to model tsunami scenarios using seismic data and assess evacuation routes to identify potential bottlenecks. Numerical modeling was adopted to generate tsunami propagation and inundation. The Delft3D software, based on the Shallow-water Equations, was used for tsunami propagation modeling, while Hloss calculations were adopted for inundation. Subsequently, evacuation routes were generated using network analysis from hazard zones to designated shelters. Approximately 1500 random locations were generated across the hazard zone, and line-to-line overlay analysis was conducted to determine the frequency of route segment usage, thereby enabling the identification of bottlenecks. This study examined three tsunami scenarios based on fault parameters, with Scenario 1 having significant threats characterized by a 6.28-meter run-up, short evacuation times, and extensive inundation. Furthermore, the results showed varying levels of impact across sub-districts. The analysis of evacuation routes indicated varied travel times, signifying potential bottlenecks at Jendral Gatot Subroto Road, Sinoboyo-Plumbungan Road, and roads leading to Shelters 3 and 5. The Tsunami model predicted scenarios of varying severity, assisting in the identification of bottlenecks in evacuation routes.