Comparing land motion in Chiang Mai and Bangkok, Thailand, using Sentinel-1 InSAR time series

Abstract

Bangkok, Thailand's capital, and Chiang Mai in northern Thailand are both susceptible to land motion due to natural and human influences. They differ significantly in geological settings: Bangkok is characterized by Neogene clay deposits prone to compaction-induced land subsidence, while Chiang Mai's motion is driven by factors like geological structure and morphology, leading to slope instability and subsidence. Sustainable development in these cities necessitates precise monitoring of geological hazard-prone areas. Radar interferometry, particularly the persistent scatterer interferometry (PS-InSAR) technique, offers a high-resolution, cost-effective solution. This study utilizes Sentinel-1 data to monitor land deformation in both cities, combining geological, morphological, and ground measurements to create deformation maps. Analysis of 61 images for Bangkok and 62 images for Chiang Mai from January 2020 to May 2023 reveals Bangkok's subsidence driven by the early Miocene geological evolution of the Thon Buri Basin, exacerbated by construction and groundwater extraction. Chiang Mai experiences vertical and horizontal motion influenced by factors like depositional environment, morphology, and lithology. Both cities face land subsidence challenges due to rapid urbanization, leading to structural damage and heightened flood risk. This research highlights the potential of PS-InSAR techniques for geological hazard and land deformation monitoring, addressing city-specific challenges and advantages.