The APE procedure has been now defined with a significant detail, which includes specification of input data and processes. The novelty with respect to already existing risk assessment tools is the joint use of remote sensing observations collected after an earthquake together with risk indicators in order to minimize the errors which may affect the change detection product alone, and thus maximize the quality of the final damage map. The pre-event information integrated in the procedure includes urban maps and structural vulnerability of each individual building. We have also investigated further and novel possible indicators derivable from remote sensing, like for example soil instability from SAR interferometry multi pass data processing. After the event the change detection algorithm can take advantage from concurrent data, like for instance shake maps or deformation maps produced by SAR interferometry.
During the preparedness phase, the APE procedure will exploit a long sequence of pre-crisis SAR images in order to derive an InSAR velocity map by means of Persistent Scatterers Interferometry (PSI). In particular, the IPTA - Interferometric Point Target Analysis - method will be adopted. The InSAR velocity map allows us measuring possible slow surface deformation related to natural and/or anthropogenic activities. The outcomes of IPTA coupled with geological information and data concerning the stratigraphy of the studied area, are used to obtain the soil vulnerability of this area and to take in account any site effect locally amplifying the seismic waves. In addition to soil vulnerability, the APE method will take into account the building vulnerability, in order to finalise the Vulnerability Scenario. This latter will contribute to the preparation of the a-priori information layers.
The a-priori information will be completed as soon as an earthquake occurs and the seismological Institutes, in charge of the seismic accelerometer networks, generate the shake-maps that provide information about the soil velocity and acceleration in the epicentral region. At this step the a-priori information layers are ready and constitute the first input to the data fusion algorithm.
Furthermore, as soon as SAR data are available, a coseismic interferogram is also generated to measure the displacements and restrict the damage evaluation analysis to the regions affected by surface deformation.
During the crises phase, the APE will generate the change detection maps using optical or SAR or both kinds of images. The changes will highlight building damages, at a scale of groups of buildings or single buildings, depending on the spatial resolution of the available satellite data.
The a-priori information will be integrated with the change detection products using a data fusion algorithm that will be defined during project development.
The APE method, by integrating a-priori information and change detection images, will provide a Likelihood Index Damage Map (LIDaM), which represents a map of groups of buildings or single buildings and infrastructures that are likely collapsed or strongly damaged.
Logical scheme of APE procedure.