Probability eruption, lahar flow and ashfall modeling of Semeru, East Java Province: Reference for mitigation
Idham Andri Kurniawan, Mirzam Abdurrachman, Qurrata^aini Aisyah, Salma Sakinah, Muhammad Bahrun Najjah, Asep Saepuloh, Eddy Ariyono Subroto, Very Susanto, Arif Susanto, I Gusti Bagus Eddy Sucipta, Nurcahyo Indro Basuki, Niniek Rina Herdianita, Andri Slamet Subandrio, Emmy Suparka, Muhammad Saung Penggalih, Uut Ihsan Firman Sauqi Nur Sabila, and Abdillah.

Petrology, Volcanology and Geochemistry Research group, Geological Engineering Program Study, Faculty of Earth Sciences and Technology, Bandung of Institute Technology.

Abstract

Semeru is one of the tallest volcanoes in Java and one of Indonesia^s most active volcanoes. Semeru eruption is dominated by the strombolian, with the flow of pyroclastic or lahar and ashfall being the primary source of the hazard. The aim of this study is to identify the potential hazards of the Semeru eruption. Based on eruption history data, this study used the probability of eruption with the event tree method, lahar flow modeling using LaharZ, and tephra fall modeling using TephraProb to evaluate the hazard. On the probability of eruption, this study used parameters such as restlessness, genesis, outcome, magnitude, phenomena, column eruption, sector, and distance. The source of secondary data is from the Global Volcanism Program website and the activity report of Semeru from The Center for Volcanology and Geological Hazard Mitigation (CVGHM) under the Geological Agency of the Indonesian Ministry of Energy and Mineral Resources. The eruption history data used focuses on eruptions from 2000 to 2022, a total of 24 eruptions. The geological conditions, magnitude and column eruption, and affected area are the main factors that determine the probability of hazard. Lahar flow modeling using LaharZ was performed on ArcGIS 10.8 with the input of Digital Elevation Model (DEM) data from DEM Nasional (DEMNAS). Lahar flow modeling focused on the December 4th, 2021 event. The results of this modeling are flow routes, volume of material, velocities, and travel times of lahar that can be used for rapid hazard assessment. The tephra fall modeling using TephraProb was performed on MATLAB with the input wind from NOAA, and thickness and other parameters from field observation. The ashfall modeling focused on the December 5th, 2020 event. The results of this modeling are isomass / isopach map and the value of hazard probability. Furthermore, this study can provide information to the government and the public regarding eruption products as a reference in mitigation activities.

Keywords: Event tree, Lahar, LaharZ, ashfall, TephraProb, Mitigation, Semeru

Topic: Solid Earth Sciences