Geophysics under stressed: a case study of Tham Luang Nang Non Cave

Abstract

          In the middle of June, 2018, the members of Wild Boar Academy football team consisted of 12 boys and their coach were trapped in a flooded cave complex of Tham Luang Nang Non, Mae Sai District, Chiang Rai Province, Thailand. The plight of the boys and their coach had drawn international attention, with divers, engineers and medics among others flying in from around the world to assist the rescue mission. Initially, there were three maps provided by different sources but none of them were accurate. Therefore, an application of geophysical exploration technique was considered as the alternative method for the determination accurate cave route and geological structure that allowed water flowing through the cave. In addition, electrical resistivity imaging survey and seismic survey were also applied. The results of the resistivity survey indicated that the geological structure of the mountain was useful for drilling operation at D01 and D88. The resistivity survey results at North and South of the mountain indicated the possibility of underground water that flew to the cave. Moreover, the seismic technique used for the earthquake measurement was applied to determine accurate cave route and the position of seismic source along the cave route. The seismic source for this test was from the cooperation with the Royal Thai Navy diving team by hitting their own empty air tank on the ground floor. Unfortunately, the application of the seismic technique was not a success due to the interference of high ambient noise from electrical water pumps, groundwater drilling, and the rescue activities. Later on, the test results revealed that the seismic technique was the effective method for homogeneous strata with sledgehammer source. The larger and stronger seismic source was required for the non-homogeneous strata.