Stress Transfer and Aftershock Distribution of The Strong Earthquakes in The Thailand‑Laos‑Myanmar Border

Abstract

This study analyzed the stress transfer and the aftershock distribution in the Thailand-Laos-Myanmar border. The fault parameters of the three strong earthquakes with M ≥ 6.0 that occurred during 2010-2022 in the Thailand-Laos-Myanmar border were used to calculate the Coulomb stress change with the numerical modeling techniques resolved on the receiver fault with i) focal mechanism similar to the mainshock, ii) strike-slip, iii) thrust, and iv) normal faulting, respectively. The earthquake events were declustered spatially and temporally to identify the aftershocks in the area. Then, the stress transfer and aftershock distribution were analyzed to investigate the relationship. The results indicated that the type of receiver fault was the important factor that influenced the pattern of stress transfer on the Thailand-Laos-Myanmar border. The M6.1 earthquake in 2014 in Thailand generated most aftershocks in the areas of increased stress with stress change levels of more than 0.8 bar. The M6.9 earthquake in 2011 in Myanmar caused the stress to transfer into Thailand with increased stress levels smaller than 0.3 bar, and there was no aftershock generated in this area of Thailand. Meanwhile, the M6.2 earthquake in 2019 in Laos induced stress transferred into Thailand with levels of increased stress up to 0.8 bar, and there was one aftershock generated around this area of Thailand. The results are likely to be the characteristic of stress transfer and aftershock distribution, especially with increased stress levels above 0.8 bar, which can be used to identify the areas of aftershocks after the strong earthquake occurred in the Thailand-Laos-Myanmar border.