HR: 0800h
AN: U11B-0837    [Abstracts]
TI: Coseismic Ground level Changes Associated with the Great Andaman-Sumatra Earthquake: A Tour from Nicobar to North Andaman
AU: * Rajendran, K
EM: kusala@seires.net
AF: Centre for Earth Science Studies, Akkulam, Trivandrum, 695031 India
AU: Rajendran, C
EM: cp_r@vsnl.com
AF: Centre for Earth Science Studies, Akkulam, Trivandrum, 695031 India
AU: Earnest, A
EM: anil@seires.net
AF: Centre for Earth Science Studies, Akkulam, Trivandrum, 695031 India
AU: Freymueller, J
EM: jeff@gisies.alaska.edu
AF: Geophysical Institute, University of Alaska, Fairbanks, 99775 United States
AB: The 26 December 2004 in the Andaman-Sumatra subduction zone led to significant ground level changes, uplift as well as subsidence of land, along the Andaman and Nicobar Islands. Falling nearly 400 km north of the epicenter of the main shock, and extending northwards, the second phase of the rupture observed in these islands account for more about two thirds of the total rupture. Ground level changes were observed along both the eastern and western margins of the islands. The western margins were generally characterized by uplift of about 1m, while the eastern margins subsided by nearly 1 m, permanently submerging many parts of these islands. Elevated beaches, uplifted coral colonies and biological markers such as mangroves, lines of barnacles on rock exposures and man-made structures provide spectacular visual effects of ground uplift. Along the western margin of the Interview Island, in the middle Andamans, we observed at least two older terraces, probably formed by the predecessors of the 2004 earthquake. In the Diglipur region, north Andaman, we observed elevation change of about 1 m, and in this part of the arc, both the western and eastern margins are characterized by uplift. Coseismic vertical offset observed from GPS data suggest a change of +0.6m at Diglipur, a region that also marks the termination of rupture in the north. Field observations conform to nearly +1m change in this region. Maximum subsidence of nearly 1.5 m was documented in Campbell Bay, Great Nicobar, and a GPS site there shows a change in elevation of -1.05m. This paper gives a short tour of the sites of ground level changes from Car Nicobar in the south to Diglipur in the North Andaman.
DE: 1734 Seismology
DE: 7200 SEISMOLOGY
DE: 7209 Earthquake dynamics (1242)
DE: 7299 General or miscellaneous
SC: Union [U]
MN: Fall Meeting 2005