SGER: Coseismic Uplift and Submergence in Aceh, Sumatra

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The intent of this project is to complete mapping of emergence and submergence in the region near the southern end of the giant Aceh-Andaman earthquake. The work must be done as soon as possible, to minimize the conflation of coseismic and post-seismic signals and the degradation of the data by natural processes of erosion and burial. During the giant Aceh-Andaman earthquake, the northernmost Sumatran island (Simeulue) experienced an uplift of ~1.5 meters, with a pronounced eastward tilt. Preliminary modeling shows that this is consistent with many meters of slip on the underlying megathrust, to a depth of a few tens of km. The abundance of coral microatolls around this island and along the Acehnese mainland afford the opportunity to measure precisely the uplift and submergence associated with the earthquake rupture and thereby to constrain the nature of the southern 200 km of the Aceh-Andaman rupture. The PI will map in detail, with Total Station, the submergence along the mainland Sumatran coast in Aceh and to map uplift and submergence around Simeulue. Uplift can be measured easily as the elevation difference between old and new highest levels of living coral. Submergence can also be measured by determining the elevation of highest living coral relative to sea level at the time of measurement, and then using a tidal model to determine the relationship of that sea level to the lowest annual low-tide. Broader Impacts of the work include dissemination of information to students, the scientific community, and the general public both in the US and Indonesia through weblogs, scientific publications, posters and television and radio.