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Paleoearthquakes along Xaignabouli Fault Zone in Western Lao PDR |
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| รหัสดีโอไอ | |
| Creator | Patchawee Nualkhao |
| Title | Paleoearthquakes along Xaignabouli Fault Zone in Western Lao PDR |
| Contributor | Punya Charusiri, Chinda Sutiwanich, Santi Pailoplee |
| Publisher | Department of Geology, Chulalongkorn University |
| Publication Year | 2559 |
| Journal Title | Bulletin of Earth Sciences of Thailand (BEST) |
| Journal Vol. | 8 |
| Journal No. | 1 |
| Page no. | 25-32 |
| Keyword | Active fault, Lao, OSL dating, Paleoearthquake, Paleoseismicity, Xaignabouri |
| URL Website | https://www.bestjournal.org/ |
| Website title | Bulletin of Earth Sciences of Thailand |
| ISSN | 1906-280X |
| Abstract | A paleoseismic investigation has been carried out to identify the faults at the Xaignabouli (XYB) area in western Lao PDR to determine if they are seismologically and geologically active. There have been earthquakes of intermediate magnitudes reported recently (5.4 and 3.9 ML in February and March 2011, respectively) suggesting that the area is seismologically active. Our remotesensing data show that these two earthquakes may have been related to the northeast-southwest trending fault. Regionally, the fault commenced in the north from Dien Bien Phu (DBP) in Vietnam. Lineaments analysis using SRTM DEM image data together with epicentral distribution suggest that there are not only northeast-southwest trending lineaments but also those of the northwest-southeast and north-south strikes. Our interpretation and synthesis using geological, present-day seismicity, seismotectonic, and paleoseismological data reveal that there are at least two active strike-slip fault zones with sinistral movement and these faults are branches of the DBP fault. The first fault zone passes the western part of the XYB and is oriented in the NE-SW direction and comprised of about 20 segments ranging from 10 km up to 110 km with a total length of about 450 km. The second is almost subparallel to first and has a total length of 350 km also consisting of shorter segments. Results of morphotectonic features and Quaternary age dating imply horizontal slip rate at ca. 0.8 mm/yr. The main northeast-southwest trending fault is estimated at about 16.8 km east of the XYB area. Our study reveals that the area has been subject to multiple tectonic phases of deformation, with the most essential episode occurring during late Cenozoic time. OSL dating result indicates that three earthquake faulting events ca. 3,000, 2,000, and 1,000 years ago support a recurrence interval of approximately 1,000 years. Surface rupture length indicates maximum credible earthquake magnitudes between 5.6 and 7.3 Richter. |
