Risk assessment to low frequency - high impact coastal hazard in Indonesia: Integrating tsunami hazard and vulnerability assessment in the context of Early Warning

Abstract

The development of a risk assessment methodology reflects the different stages of the disaster management cycle (warning chain and response phase). Consequently the risk components hazard, exposure (e.g. how many people are exposed?), susceptibility (e.g. are the people able to receive a warning?), coping capacity (are the people able to evacuate?) and recovery (are the people able to restore their livelihoods?) are addressed and quantified. Thereby, the risk assessment encompasses three steps: (i) identifying the nature, location, intensity and probability of a threat (hazard assessment); (ii) determining the existence and degree of vulnerabilities and exposure to those threats (e.g. the physical and socio-economic spheres) and (iii) identifying the coping capacities and resources available to address or manage threats. The assessment methodology presented follows a people-centered assessment approach to deliver relevant risk and vulnerability information for the purposes of early warning and disaster management considering the entire coastal areas of Sumatra, Java and Bali facing the Sunda trench. Thereby it is demonstrated how to characterise and quantify risk and vulnerability components as hazard intensity, people and critical infrastructure exposed, their susceptibility and coping capacity. Additionally, dedicated products like maps, guidelines and other information products are developed according to end user needs. The currently established risk assessment results cover the entire coast of Sumatra, Java and Bali facing the Sunda trench. This information on the location of high, moderate and low tsunami risk areas is available on different scales (down to 1 : 100 000 map scale) and aggregation levels (e.g. desa / warning segments). Furthermore the assessed risk information and products are integrated in the database of the Early Warning Center to be used for decision support. To link national scale decision making whether to warn or not in case of a tsunami occurence, the risk products can also be provided to local level decision makers to react adequately concerning their local risks