Tsunami mitigation measures for tsunami prone small islands: Lessons learned from the 2010 tsunami around the Mentawai Islands of Indonesia

摘要

The challenge of protecting communities in tsunami-prone populated small islands is difficult to meet. Likewise, the islands are often found with a lack of disaster mitigation infrastructure. A tsunami that occurred around the Mentawai Islands of Indonesia on October 25, 2010, causing around 500 dead, is the inspiration for this paper. This study was aimed at elaborating practices in protecting communities of small islands from tsunamis by incorporating information about the estimated time of arrival of a tsunami into the islands mitigation measures. A field survey to obtain the impacts of the tsunami on the number of casualties and damages was conducted in February 2011 around the Mentawai Islands. In the survey, a set of questionnaires were distributed in the Mentawai Islands to investigate the small island residents' responses just after the shock from the tsunami waves. This study was also followed by numerical simulations to obtain tsunami wave Estimated Time of Arrival (ETA) for the Mentawai islands. Numerical simulations were conducted using Delft3D software coupled with Tsunami toolkit. This research found that the ETAs for the Mentawai Islands range between 9-20 min. With the existing tsunami early warning system in Indonesia, the ETAs are quite short. Comparing the Simulated ETAs to the findings from the Mentawai Islands tsunami survey led to the recommendation that the best way to increase the community's preparedness for a tsunami would be by managing village-based spatial planning. Such spatial planning may include relocating the residents far away from the coastal area. This would enable the community to have more time to evacuate should a tsunami threat occur.