The estimate of damage after an earthquake using spaceborne remote sensing data is one of the main application of the change detection methodologies widely discussed in literature. APhoRISM - Advanced PRocedures for volcanIc and Seismic Monitoring is a collaborative European Commission project (FP7-SP ACE- 2013-1) addressing the development of innovative methods, using space and ground sensors to support the management and mitigation of the seismic and the volcanic risk. In this paper a novel approach aimed at damage assessment based on the use of a priori information derived by different sources in a preparedness phase is described and a preliminary validation is shown.