Earthquake Catalogue of the Thailand Meteorological Department — A Commentary

Abstract

In this study, I investigated qualitatively the earthquake catalogue of the Thai Meteorological Department (TMD), Thailand, with respect to the seismicity patterns of Thailand. The readymade relationships between the different magnitude scales were derived to allow their convenient interconversion. Earthquake declustering was performed in order to screen the main shocks from the foreshocks and aftershocks, reducing the 1998–2009 records from ~48,900 to 2,620 main events. Man-made changes in the seismicity rate were carefully checked for, but only some minor changes were found and these were not related to any network improvements. In order to assess the limit of the earthquake detection in the catalogue the criterion of the magnitude of completeness (Mc) was employed, revealing a high efficiency of earthquake detection at a low Mc (3.0–3.5 Mw), especially for the inland active fault zone that dominates in Southeast Asia. Thus, the TMD's catalogue is one of the alternative catalogues for seismicity investigation of inland earthquakes. Meanwhile for the area surrounding the Sumatra Island and Northern Myanmar, the TMD's network is sufficient only for earthquakes with a Mw> 5.4–6.0 Mw. Thus, some additional seismic recording stations are needed in the Southern and Northern parts of Thailand.