Abstract: Maps, showing the tactical or the administrative situation at any particular time, play a central role in disaster management. They can be realized as interactive map mashups. In addition to classical information (weather, water levels, energy network, forces), they can also be used to present a view on citizen-generated content, e.g. from social media. In this paper we offer insights into how mobile map mashups can assist citizens during infrastructure failures that often occur in large-scale emergencies. Based on a review of approaches and mobile applications from literature and especially from practice, we present SOMAP (social offline map), a mobile app we developed in Android. It offers offline map functionality in terms of (A) pro-active loading and storing of potentially needed maps of the respective area as well as (B) the possibility of exchanging information from social media using Bluetooth. The application was evaluated qualitatively, to gain insights into the potential of such applications.