NUMERICAL SIMULATION OF UJONG SEUDEUN LAND SEPARATION CAUSED BY THE 2004 INDIAN OCEAN TSUNAMI, ACEH-INDONESIA

The Aceh province in Indonesia, located around the Sumatra subduction area, was one of the worst hit areas with respect to damage from the impact of the 2004 Indian Ocean tsunami. A 9.15 Mw earthquake triggered the tsunami. One of the impacts was the disconnection of several areas from their mainland, thus creating new small islands. This happened around Ujong Seudeun village in Aceh Jaya District. Prior to the tsunami, the village had approximately 500 residents. However, after the tsunami, the area was severely eroded and a small strait had been inserted between the village and the Sumatra Island mainland. This study investigates the magnitude of the tsunami wave forces that separated the area to yield a newly deserted small island. This study was conducted by numerical simulations and by coupling the COMCOT (Cornell Multi-grid Coupled Tsunami Model) and Delft3D models. These tools have specific advantages, namely, COMCOT’s linear modeling is based on a series of earthquake mechanisms and Delft3D uses non-linear morphological dynamic modeling. Their software includes the explicit leapfrog finite difference scheme (COMCOT) and the non-linear shallow water equation (Delft3D). Bathymetry data fromnewly formed coastline and the small island’s shape were digitized using 2005 Quickbird Images. Results from this research reveal the estimated tsunami wave heights and forces that disconnected the small island of Ujong Seuden from the Sumatra Island mainland. These results can be used to further develop the COMCOT model to incorporate sediment modules