Challenges in increasing community preparedness against tsunami hazards in tsunami-prone small islands around Sumatra, Indonesia

Fifteen years since the 2004 Indian Ocean tsunami, which caused massive destruction around the Andaman Sea, people have participated in efforts to reduce tsunami risks in Indonesia. However, the most important question continues to be on whether such efforts are sufficient in dealing with tsunami risks. Among the most striking challenges here is bridging the gap in tsunami risk reduction between the Sumatra mainland and among communities in several small islands. Thus, this research aims to investigate the recent conditions of selected towns/cities in tsunami-prone small islands and identify the impediments to their tsunami hazard preparedness. It focuses on comparing efforts in terms of available facilities for tsunami evacuation plans and the tsunami estimated time of arrival (ETA), which is computed based on deterministic tsunami propagation models. In this regard, five of the observed locations are classified as being in a critical tsunami preparedness condition, namely Balai island, Lahewa of Nias Island, Sabeugunggung of North pagai Island, Surat Aban of South Pagai island, and Enggano Island. Most of them have limited space for tsunami evacuation and a short tsunami ETA, which constitutes an extreme condition requiring immediate tsunami mitigation measures. One possible approach is to construct a vertical tsunami evacuation building or modify existing buildings that can be used for tsunami evacuation on the islands. This article also highlights societal aspects related to tsunami preparedness.