Geophysical investigation of the karst geosites in Satun UNESCO Global Geopark, Thailand: implication for sinkhole hazard assessment

摘要

Satun Geopark is the first UNESCO Global Geopark of Thailand, locating in Satun province, southern peninsular. Regarding geotourism, this area is unique and of international interest, where abundance of outstanding karst-related geosites exist. However, endowed with such geosites in the region poses high potential sinkhole vulnerability. This study aims in evaluating the sinkhole hazard in this area by means of geophysical investigation and susceptibility hazard assessment. Extensive subsurface studies include the determination of sediment covers, bedrock topography, where cavities, fractures and trigger conditions were extracted from electrical resistivity tomography (ERT), seismic tomography and multichannel analysis of surface wave (MASW) data. Based on the geophysical results, the four selected karst geosites were found to be capable of voids and fractures development. Evidences of water drainage pathway and bedrock dissolution can be seen by the highly weathered rock layer and irregular bedrock topography. The susceptibility hazard assessment based on analytical hierarchy process (AHP) approach and sinkhole susceptibility index (SSI) revealed low to slightly high level of sinkhole risk for the studied geosites. The results from this research provide the local risk management with necessary information to develop a strategic plan in the geopark.