Coseismic and postseismic creep in the Andaman Islands associated with the 2004 Sumatra‐Andaman earthquake

Abstract

for measurements of biological indicators and eyewitness accounts confirm that large coseismic and postseismic surface deformation occurred over the Andaman Islands in association with the 2004 Sumatra-Andaman earthquake. Amount of uplift was as large as 1.3 m in the islands off NW coast, and decreased to ESE with a zone of subsidence in the SE Andaman. The coseismic deformation did not generate large seismic waves or tsunamis, indicating that slip was much slower than that off Sumatra. The coseismic uplift was followed by postseismic subsidence, which was evidenced by local residents to have occurred within two months after the earthquake. A simple dislocation model explains the deformation pattern by a coseismic rupture (50 km wide with its down-dip limit 130 km east of the trench axis) followed by an up-dip propagation of the rupture front for about 10 km. Citation:

Revealing the coastal event-history of the Andaman Islands (Bay of Bengal) during the Holocene using radiocarbon and OSL dating

“…Due to the stabilized surface no strong storm in the past occurred. A tectonic uplift of North Cinque Island as described in Kayanne et al (2007) and Shishikura et al (2005) is also possible but cannot be shown here.…”

“…Especially in the southern part of the Andamans the movement occurs in a NE-SW oriented direction, like a syncline. The central part of this synclinal structure lies in the area of Port Blair (Kayanne et al 2007). After the 2004 earthquake the co-and post-seismic movements resulted in a subsidence of nearly 1 m. In the outer parts of this subsiding synclinal-like structure the resulting movement was zero.…”

“…It is not clear which of these two events about 1,000 and 3,000 years before present reported by Rajendran et al (2007) is reflected here. Kayanne et al (2007) show that there is a coseismic subsidence and a postseismic uplift of the South Andaman Islands. This movement follows a complex pattern.…”

Advances in earthquake and tsunami sciences and disaster risk reduction since the 2004 Indian ocean tsunami

“…The analysis of tsunami waveforms recorded on tide gauge stations [4] showed a shorter, up to 900 km, source of the tsunami. Satellite image analyses and ground-truth field investigations [5][6][7] indicated that the coseismic coastal sea level change extended from Sumatra through North Andaman Island with a total length of 1600 km. Some of the northern slip is attributed to afterslip on the fault plane which occurred up to 40 days [8].…”

Local inundation distances and regional tsunami recurrence in the Indian Ocean inferred from luminescence dating of sandy deposits in Thailand

“…In contrast, changes in the coastal geomorphology by erosion, deposition, uplift and subsidence, caused by the Indian Ocean Tsunami (IOT) and its triggering earthquake, demonstrate that tsunami impact may leave its signature in the geological record (e.g. Szczucinski et al, 2006;Choowong et al, 2007;Kelletat et al, 2007;Kayanne et al, 2007;Sibuet et al, 2007;Srinivasalu et al, 2007;Fagherazzi and Du, 2008;Morton et al, 2008;Paris et al, 2009;Switzer et al, 2012). While co-seismic movement at near-field sites along the rupture area is used to detect palaeoearthquakes that might have generated past tsunamis (e.g.…”