Geothermal and seismic evidence for a southeastern continuation of the three pagodas fault zone into the Gulf of Thailand
Prinya Putthapiban, Wanida Chantong, Phumee Srisuwon, Charongporn Praipiban, and Passakorn Pananont
pp. 445 - 452
Abstract
Aerial photographic maps and landsat image interpretations suggest the major fault segments of the Three Pagoda
Fault (TPF) Zone and Sri Swat Fault (SSF) Zone are oriented parallel or sub-parallel in the same NW-SE directions. The Kwae
Noi River is running along the TPF in the south whereas the Kwae Yai River is running along the SSF in the north. The
southeastern continuation of both faults is obscured by thick Cenozoic sediments. Hence, surface lineaments cannot be
traced with confidence. However, based on some interpretations of the airborne magnetic survey data, the trace of such faults
are designated to run through the western part of Bangkok and the northern end of the Gulf of Thailand. Paleo-earthquakes
and the presence of hot springs along the fault zones indicate that they are tectonically active. The changes of both physical
and chemical properties of the water from Hin Dart Hot Spring and those of the surface water from a shallow well at Ban Khao
Lao during the Great Sumatra–Andaman Earthquake on 26th of December 2004 clearly indicated that the southeastern continuation of the TPF is at least as far south as Pak Tho District, Ratburi. Our new evidence of the alignment of the high heat
flow in the upper part of the Gulf of Thailand verified that the TPF also extend into the Gulf via Samut Songkhram Province.
Studies of the seismic data from two survey lines along the Western part of the upper Gulf of Thailand acquired by Britoil
Plc. in 1986, namely Line A which is approximately 60 km long, starting from Bang Khen passing through Bang Khae and
ending in Samut Songkhram and Line B is approximately 30 km long starting from Samut Sakon ending in Samut Song Khram
suggest that all the faults or fractures along these seismic profiles are covered by sediments of approximately 230 m thick
which explain that the fault underneath these seismic lines is quite old and may not be active. The absent of sign or trace of
the TPF Path to the west suggested that there is no segment of such fault along these seismic lines.
