Expertise in disaster management (DM) is scarce and often unavailable in a timely manner. Moreover, it is not timely shared as it is often perceived as too tied to kinds of events (floods, bushfires, tsunamis, pandemic or earthquake), leading to catastrophic consequences. In this paper, we lay out a framework to create a decision support system to unify, facilitate and expedite access to DM expertise. We observe that many DM activities are actually common even when the events vary. We provide ontology as a metamodel to describe the various DM activities and desired outcomes. This ontology will serve as a representational layer of DM expertise leading to a DM decision support system based on combining and matching different DM activities according to the disaster on hand.