HR: 17:15h
AN: S24A-06    [Abstracts]
TI: Paleoseismoloigcal evidence of the 1762 and earlier earthquakes off Myanmar
AU: Aung, T
AF: Geological Survey of Japan, AIST, Site C7, Tsukuba, 305-8567, Japan
AU: * Satake, K
EM: kenji.satake@aist.go.jp
AF: Geological Survey of Japan, AIST, Site C7, Tsukuba, 305-8567, Japan
AU: Okamura, Y
AF: Geological Survey of Japan, AIST, Site C7, Tsukuba, 305-8567, Japan
AU: Shishikura, M
AF: Geological Survey of Japan, AIST, Site C7, Tsukuba, 305-8567, Japan
AU: Swe, W
AF: Myanmar Geosciences Society, MES Office, Hlaing University Campus, Yangon, 11021, Myanmar
AU: Saw, H
AF: Dept. Meteorology and Hydrology, Kabaaye Pagoda Road, Mayangon Township, Yangon, 11081, Myanmar
AU: Swe, T
AF: Yangon Technological University, Insein Road, Yangon, 11011, Myanmar
AU: Tun, S
AF: Myanmar Earthquake Committee, MES Office, Hlaing University Campus, Yangon, 11021, Myanmar
AU: Aung, T
AF: Yangon University, University P.O., Yangon, 11041, Myanmar
AB: The potential for giant tsunamigenic earthquakes off the west coast of Myanmar, north of the 2004 Sumatra- Andaman earthquake has been debated. Tectonic environments (Cummins, 2007), recent GPS observations (Socquet, 2006) and historical descriptions of geomorphological changes and eyewitness accounts of the 1762 Bengal earthquake seem to support that the earthquake potential exists. As possible evidence of past earthquakes, marine terraces have developed along the Rakhine coast. Our field surveys at the four localities on west and middle Phayonkar islands identified at least three clear steps of marine terraces approximately 1-2 m, ~5 m and ~10 m above present sea level. These steps indicate that sudden sea level change, or coseismic uplift associated with the large earthquakes, occurred in the past. Radiocarbon dating of coral or shell fossils provide ages of the uplift events. Six samples from the lower terrace indicate the most recent uplift occurred between 1585 and 1860 AD. This range includes the 1762 Bengal earthquake. Dates of the middle step, based on four samples, range between 805 and 1220 AD. Four samples on the upper step indicate an uplift event between 1295 and 600 BC. The time interval between the lower and middle step is several hundred years, while that between the middle and upper step is more than 1000 years. The longer time span and the larger elevation difference of the earlier interval may indicate either missing event(s) or variability of earthquake size and recurrence interval.
DE: 4564 Tsunamis and storm surges
DE: 7221 Paleoseismology (8036)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 9320 Asia
SC: Seismology [S]
MN: 2007 Fall Meeting