Analysis of sequence earthquake of Lombok Island, Indonesia

On August 5, 2018, Lombok Island, an island off the eastern part of Bali Island, Indonesia experienced a 6.9 magnitude earthquake. To provide a reliable measure to estimate the intensity of earthquake impact, this study observes land deformation after the event using Differential SAR (DinSAR) Interferometry algorithm that is applied to Sentinel-1 satellite imageries. The semi-automatic classification method is developed to produce infrastructure-damage-level estimation map in the study area. For accuracy assessment, multi-sensor dataset of PlanetScope and Google Earth images, as well as data from field survey is utilised. The results reveal consistent locations of damaged area caused by the earthquake, both from the SAR and optical datasets. Accuracy of infrastructure damage classification is relatively low for small-sized destruction (<3 m), which is due to the limited spatial resolution of the satellite imagery. Yet for large-sized destruction, the method provides high accuracy. In longer-term, the method to identify and classify infrastructure damage that is developed in this study can help to build a historical database of earthquake impact in a vulnerable area, and support the organization of a robust mitigation system.