After the great Sumatra earthquakes in 2004, the Thailand Metrological
Department (TMD) installed several broadband (Trillium120P, Trillium
40 and Geotech KS2000M) and short period (Geotech S13)
seismometers around the country (Fig. 1). One of the seismometers of
the TMD network station (CMMT) is located within the same borehole
as the seismometer of the IRIS station (CHTO) in Chiang Mai province
in the north of Thailand. Since 2009, Mahidol University also deployed
three broadband seismometers (Trillium 120P) around Kanchanaburi
province in the western part of Thailand where two major faults cut
across the region. There are 33 stations in total: 29 from the TMD network,
1 IRIS and 3 Mahidol stations. In each station of the TMD and
Mahidol networks, earthquakes with a magnitude Mb greater than 5.5
and epicentral distances in the range of 30–95° fromthe stations recorded
from 2011 to April of 2013 were selected for use in this analysis.
There were a total of 771 such earthquake events originating mostly
from either Japan or Papua New Guinea and fewer events from Europe
(Fig. 3). However, in practice, the instability of the instrument leads to
a large reduction in the number of events at each station with a maximum
of 171 at the LAMP station, and a minimum of 17 at the LOEI station
and 51 events on average. However, for the IRIS station (CHTO), the
data was acquired at different times from2010 to 2011 withmore than
200 earthquakes