We introduce a disaster simulation system that supports collaborative planning of disaster measures. While several simulation tools are available for examination and evaluation of disaster prevention plans, they are limited to use on traditional computers and displays, and rarely used in collaborative planning sessions. To address this issue, we have designed and prototyped a tabletop tangible user interface for disaster simulation. This paper describes the design and implementation of our prototype and reports our preliminary user observations and their feedback. The results show that our system can effectively support collaborative emergency planning tasks by a group of users and that users can easily learn how to use our system. Keywords Disaster simulation, tangible user interfaces, Geographic Information Systems (GIS), collaborative design ACM Classification Keywords H.5.2 [Information Interfaces and Presentation]: User Interfaces.