Earthquake Activities Along the Strike-Slip Fault System on the Thailand-Myanmar Border

This study investigates the present-day seismicity along the strike-slip fault system on the Thailand-Myanmar border. Using the earthquake catalogue the earthquake parameters representing seismic activities were evaluated in terms of the possible maximum magnitude, return period and earthquake occurrence probabilities. Three different hazardous areas could be distinguished from the obtained results. The most seismic-prone area was located along the northern segment of the fault system and can generate earthquakes of magnitude 5.0, 5.8, and 6.8 mb in the next 5, 10, and 50 years, respectively. The second most-prone area was the southern segment where earthquakes of magnitude 5.0, 6.0, and 7.0 mb might be generated every 18, 60, and 300 years, respectively. For the central segment, there was less than 30 and 10% probability that 6.0- and 7.0-mb earthquakes will be generated in the next 50 years. With regards to the significant infrastructures (dams) in the vicinity, the operational Wachiralongkorn dam is situated in a low seismic hazard area with a return period of around 30 - 3000 years for a 5.0 - 7.0 mb earthquake. In contrast, the Hut Gyi, Srinakarin and Tha Thung Na dams are seismically at risk for earthquakes of mb 6.4 - 6.5 being generated in the next 50 years. Plans for a seismic-retrofit should therefore be completed and implemented while seismic monitoring in this region is indispensable

Archaeoseismology of the AD 1545 earthquake in Chiang Mai, Northern Thailand

The A.D. 1545 Chiang Mai earthquake in northern Thailand was studied by historical and archaeological sources.The temple Wat Chedi Luang has lost about half of the original 80-metres height due to southward-directed collapse. Twenty-one temple sites – out of 74 visited – has tilted pagodas, up to 5° in various directions, dominated by a SE trend. All damaged temples were built before the 1545 earthquake. We suggest that a city-wide liquefaction event caused tilting. The responsible earthquake possibly occurred along the Doi Suthep Fault within city limits. Possible activity of distant faults is assessed

Earthquake Activities in the Thailand-Laos-Myanmar Border Region: A Statistical Approach

A large number of earthquakes have been recorded by instrument in the past along the Thailand-Laos-Myanmar border region. However, the locations of most of these earthquakes do not coincide with the location of morphological features which indicate seismogenic faults. Thus, a statistical evaluation of the earthquake record is focused upon in this earthquake hazard study. The spatial distributions of the a- and b-values from the frequency-magnitude distribution relationship were investigated from the complete earthquake catalogue

Evidence of coastal landforms and age determination related to the sealevel change at Nakhon Si Thammarat province in southern Thailand

We present evidence of sea-level changes over the past 15,000 years from dating sandy beach sediments in Nakhon Si Thammarat province. First, we classified various types of coastal landforms from satellite images. The orientations of beach ridges and old lagoons are very important to understanding the evolution of sea-level rise and fall. In this area, there were two groups of old sandy beaches: (i) the inner beach, and (ii) the outer beach, which were separated by old lagoons. Then, nine quartz-rich samples were analyzed using Optically Stimulated Luminescence analysis to estimate the ages of deposition. The results supported the concept that the inner series of old sandy beach deposits indicated the onset of sea-level regression occurring approximately 15,000 years ago (YA). Sea level still stands, derived from the erosion of the beach ridge and deposition of old tidal flats, were estimated to be between 10,000 and 4,000 YA. The old lagoon showed a period of being covered from approximately 4,000 to 2,000 YA before outer beach ridge deposition some 2,000 to 400 YA during sea-level regression. Considering these measured ages, the sandy beach sediments yield the oldest range of depositional ages among all the Holocene beach deposits in southern Thailand

Probabilities of Earthquake Occurrences along the Sumatra-Andaman Subduction Zone

Earthquake activities along the Sumatra-Andaman Subduction Zone (SASZ) were clarified using the derived frequency-magnitude distribution in terms of the (i) most probable maximum magnitudes, (ii) return periods and (iii) probabilities of earthquake occurrences. The northern segment of SASZ, along the western coast of Myanmar to southern Nicobar, was found to be capable of generating an earthquake of magnitude 6.1–6.4 Mw in the next 30–50 years, whilst the southern segment of offshore of the northwestern and western parts of Sumatra (defined as a high hazard region) had a short recurrence interval of 6-12 and 10-30 years for a 6.0 and 7.0 Mw magnitude earthquake, respectively, compared to the other regions. Throughout the area along the SASZ, there are 70– almost 100% probabilities of the earthquake with Mw up to 6.0 might be generated in the next 50 years whilst the northern segment had less than 50% chance of occurrence of a 7.0 Mw earthquake in the next 50 year. Although Rangoon was defined as the lowest hazard among the major city in the vicinity of SASZ, there is 90% chance of a 6.0 Mw earthquake in the next 50 years. Therefore, the effective mitigation plan of seismic hazard should be contributed

Probabilities of Earthquake Occurrences along the Sumatra-Andaman Subduction Zone

Earthquake activities along the Sumatra-Andaman Subduction Zone (SASZ) were clarified using the derived frequency-magnitude distribution in terms of the (i) most probable maximum magnitudes, (ii) return periods and (iii) probabilities of earthquake occurrences. The northern segment of SASZ, along the western coast of Myanmar to southern Nicobar, was found to be capable of generating an earthquake of magnitude 6.1–6.4 Mw in the next 30–50 years, whilst the southern segment of offshore of the northwestern and western parts of Sumatra (defined as a high hazard region) had a short recurrence interval of 6-12 and 10-30 years for a 6.0 and 7.0 Mw magnitude earthquake, respectively, compared to the other regions. Throughout the area along the SASZ, there are 70– almost 100% probabilities of the earthquake with Mw up to 6.0 might be generated in the next 50 years whilst the northern segment had less than 50% chance of occurrence of a 7.0 Mw earthquake in the next 50 year. Although Rangoon was defined as the lowest hazard among the major city in the vicinity of SASZ, there is 90% chance of a 6.0 Mw earthquake in the next 50 years. Therefore, the effective mitigation plan of seismic hazard should be contributed

Analyses of seismic activities and hazards in Laos: A seismicity approach

The seismic activities and hazards in People’s Democratic Republic Laos were analyzed using the most up-to-date seismicity data. Both the a- and b-values of the frequency-magnitude distribution model, including the return period of earthquake magnitude in the range of 5.0 - 6.0 Mw, were evaluated spatially in a region that ex­tends 300 km from Laos. Six seismic source zones with different seismic activities were found. Based on these seismic source zones and a suitable attenuation model, seismic hazards were then analyzed in both deterministic and probabilistic scenarios. The deterministic map showed a possible maximum ground shaking up to 0.4 g in Northern Laos, whereas the ground shaking calculated from the probabilistic ap­proach was 90, 70 - 90, and 20 - 40%, respectively, and was higher in the northern part. From these seismic activities and hazard analyses, Laos can be clearly separated into the three hazard zones of north­western, northeastern and southern Laos with a high, medium and low earthquake hazard, respectively. Therefore, effective mitigation plans to reduce the impact of seismic hazards should be formulated and in particular for a number of major prov­inces located in the northern part of Laos

MOESM1 of Seismic hazards in Thailand: a compilation and updated probabilistic analysis

Additional file 1: 1.txt-75.txt. Earthquake source files containing longitude (degree), latitude (degree), and depth (km), respectively. EQ-parameters.txt. 6 columns of earthquake source parameters used for this PSHA