Recent paleoseismic investigations in Northern and Western Thailand

oleh: S. C. Wood, P. Charusiri, C. H. Fenton

Format: Article
Diterbitkan: Istituto Nazionale di Geofisica e Vulcanologia (INGV) 2003-06-01

Deskripsi

Recent paleoseismic investigations have identified a number of active faults in Northern and Western Thailand.
 Northern Thailand is an intraplate basin and range province, comprised of north-south-trending Cenozoic intermontane
 grabens and half grabens, bounded by north- to northwest-striking normal to normal-oblique faults and
 northeast-striking left-lateral strike-slip faults. The basin-bounding normal faults are marked by steep, linear
 range fronts with triangular facets and wineglass canyons and have slip rates of 0.1 to 0.8 mm/yr. Based on limited
 data, the average vertical displacement-per-event is about 1.0 to 1.5 m. These faults are characterized by
 recurrence intervals of thousands to tens of thousands of years and are capable of generating earthquakes up to
 moment magnitude (M) 7, and larger. The northeast-striking strike-slip faults are marked by shutter ridges, and
 deflected drainages. Slip rates are 3 mm/yr or less. Western Thailand is dissected by a number of northwest- and
 north-northwest-striking, right-lateral strike-slip faults related to the Sagaing Fault in Myanmar. Although showing
 much less activity than the faults in neighboring Myanmar, these faults display abundant evidence for late
 Quaternary movement, including shutter ridges, sag ponds, and laterally offset streams. The slip rate on these
 faults is estimated to be 0.5 to 2.0 mm/yr. These faults are considered capable of generating maximum earthquakes
 of up to M 71/2.