Feasibility of Remote Sensing for Multihazard Analysis of Landslides in Padang Pariaman during the 2009 Padang Earthquake

Abstract

Obtaining accurate spatial details of the parameters involved in landslides has been a major challenge in determining the risk of landslide following an extreme event of rainfall, earthquake, or a combination of both. In recent decades, advances in remote sensing with high resolution satellite imagery and digital elevation models have permitted very detailed mapping and analysis of landslide hazards; however, there has been little work verifying the reliability and precision of these techniques as compared to traditional field surveys. This paper seeks to improve this situation by assessing the feasibility of using remote sensing to determine landslide vulnerability. This has been carried out in two parts. Firstly, global positioning system (GPS) coordinates collected in the field after the September 30, 2009, Padang earthquake in Sumatra, Indonesia were compared to advanced spaceborne thermal emission and reflection radiometer (ASTER) and Google Earth digital elevation model (DEMs) and Satellite Pour L’ Observation de la Terre (SPOT-5) satellite imagery. They showed reasonable spatial and elevation differences, which demonstrates the suitability of remote sensing for landslide hazard assessments. Secondly, results from a geographic information system (GIS) analysis carried out with these data showed that remote sensing is capable of producing practical landslide hazard maps that reflect an accurate measure of landslide risk during the 2009 Padang Earthquake. Inclusion of a water saturation contribution map in the conventional slope stability has proven able to better identify areas susceptible to landslides. Prior to the disaster, many of these landslide locations were demarcated as moderate risk regions in the local hazard map. Considering the high lethality of these events, this underestimate of the risk is a strong argument for a review of landslide risks using remote sensing to aid in assessing the combined effects of earthquake and rainfall on such landslides in this region.