Coastal Geomorphological Dynamics and Tsunami Hazard Zones (5–12 m ASL) in Padang City, West Sumatra, Indonesia

Abstract

Padang City is one of the capital cities in the western part of the island of Sumatra, with a total coastline length of approximately 68,126 km and directly adjacent to the Indian Ocean. The last time the province of West Sumatra was hit by a tsunami was in 2009 and 2010, which caused tsunamis with heights of <1 metre to >12 metres caused by an earthquake with a magnitude of 7.9. Experts estimate the potential for earthquake disasters originating from megathrust plate faults along the Mentawai Islands. Early and optimal mitigation efforts can minimise the impact caused by tsunami disasters. This study aims to provide an overview of the influence of shoreline changes on the tsunami distribution zones of 5 and 12 metres above sea level. This research uses the coastline parameters of Padang city from 2005 to 2021, obtained from Google Earth, administration, slope and land cover, which will be processed by utilising the Geographic Information System in ArcGIS software. The method used in the research is Tsunami Inundation by dividing the height of tsunami inundation into three scales, including low, medium and high. Observations were made at 122 observation points spread along 18,520 metres of coastline of the study area. The results show that there are five to six sub-districts in Padang city that are affected by tsunami disasters of 5 and 12 metres above sea level, including the sub-districts of South Padang, East Padang, West Padang, North Padang, Nanggalo, and Koto Tangah. The difference in coastline from 2005 to 2021 shows a change in the area of the tsunami disaster distribution zone of around 78.69 to 91.51 hectares at each water level caused by accretion events that occur along the coastline of the observation area.