Analisis Kerentanan Bangunan Terhadap Bencana Tsunami Pada Zona Patahan Bengkulu Berdasarkan Probabilistik Tsunami Hazard Assessment (PTHA). Studi Kasus : Pandeglang, Banten

Abstract

Tsunami is a natural disaster with significant destructive impacts on the areas it passes through. Indonesia is situated at the convergence of three major active tectonic plates in the world: the Eurasian Plate, Indo-Australian Plate, and Pacific Plate. Tsunamis occurring in Indonesia are caused by underwater earthquakes to the extent of 90.5%, volcanic eruptions account for 8.6%, and 1% results from underwater landslides. The Sunda and Bengkulu Subduction Zones make Kabupaten Pandeglang one of the regions prone to tsunamis. Currently, information about disaster potential is limited, including data on building vulnerability. After conducting surveys, the Labuan Subdistrict is found to be significantly affected by the 2018 tsunami. It's necessary to assess building vulnerability to tsunami waves using the Building Tsunami Vulnerability (BTV) formulation method. In this research, the BTV method is applied to the Labuan Subdistrict as the study area. Probabilistic Tsunami Hazard Assessment (PTHA) is a method developed to predict tsunami hazards with return periods ranging from hundreds to thousands of years. Based on stochastic slip, simulations conducted for moment magnitudes 8.6 Mw – 9.0 Mw with 20 scenarios per magnitude yield varying outcomes from the initial conditions in each scenario. PTHA calculations result in hazard curves using tsunami wave heights calculated based on the wave heights at each building location. This also affects the annual rate of exceedance for each tsunami wave height level. Based on the BTV analysis performed, over a 500-year period, in the event of a tsunami hitting the coastal areas of the Labuan Subdistrict in Pandeglang, there are 7 buildings with vulnerability level 4 (highest), followed by 36 buildings at level 4 (high), 2 buildings at level 2 (medium), 1 building at level 1 (low), and finally 13,225 buildings at the lowest vulnerability level 0, signifying safety from tsunami impact in the Labuan Subdistrict. In a 1000-year period, there are 27 buildings at vulnerability level 4 (highest), 16 buildings at level 4 (high), 2 buildings at level 2 (medium), 1 building at level 1 (low), and 13,225 buildings at the lowest vulnerability level 0.