The analysis of tsunami vertical shelter in Padang city

Padang is a coastal city, which is located opposite to the Indian Ocean. Just across Padang city there are areas of subduction, which can trigger a powerful earthquake and generate tsunami. Geologists have to say that the city of Padang is the area that is highly vulnerable to tsunamis in the near future. Several studies have been conducted to prepare Padang city for tsunamis. Through the research, maps of tsunami inundation area has been successfully designed. So that the tsunami-prone areas, and tsunami safe area can be clearly identified. According to Singh (2008), the time interval between the first powerful earthquake and tsunami to hit the coast of Padang is about 20-30 minutes. While residents have to walk 3-5 km to the safe area. It can be said that the time for tsunami evacuation in Padang city is very short. Therefore the choice of conducting vertical evacuation is urgent for the majority of the population rather than walking along the horizontal evacuation. Padang city government with the aid of the international donors has built buildings for the shelter. Some of them are schools that have a strong structure, three storeys in which the roof are served as a tsunami evacuation. Data from the BPBDs office (Disaster Management Agency), stated that there are 13 tsunami evacuation buildings at this time with a total capacity of 30.550 people and the capacity for each building is varied between 1,000 -3,000 people (BPBDs, 2013). This amount is very far from enough when compared to the potential loss of life as many as 400,000 people or more, or as only 7.64% of the total amount. And the location of the shelter buildings are not evenly distributed in tsunamis prone areas Places for vertical tsunami evacuation in Padang are called TES (Temporary Evacuation Shelter). There have been 13 shelters established by the Government of Padang and BPBDs, and there is only one TES found in the study area. It really is not enough as it is seen in the range of services. Therefore the existing buildings and multi-storey structure is another alternate places to rescue in which they are expected to withstand earthquakes and tsunamis. This alternative building called Potential TES (PTES) and there are 14 shelters for the study area. By using GIS analysis as well as buffer analysis method, a measurement against a range of services from 1 TES and 14 P-TES is conducted. Buffer radius service area in this analysis, are 450m, 900m, and 1350m. It means that the community who are in the circle will be able to reach shelter in time. As it is seen, the 15 shelters can accommodate refugees within a radius of 450m and 900m, and only few refuges can be accommodated within a radius of 1350m. (C) 2014 The Authors. Published by Elsevier B.V.