Radar remote sensing for damage assessment: case study on L'Aquila, Italy, 6th April 2009 earthquake

Destructive earthquakes, as much as other natural disasters, represent a challenge for Earth Observation (EO) systems to demonstrate their usefulness in supporting intervention and relief actions. The use of EO data in a disaster context has been widely investigated by many actors, but only recently the developed methods seem to have reached near to the operational use. In this paper a case study on the 6th April 2009 earthquake event, which stroke L'Aquila, Italy, is considered. In particular, the use of new-generation satellite Very High Resolution (VHR) radar data such as those provided by the COSMO/SkyMed constellation opens new opportunities. Such data may be profitably used for damage assessment and for detection of relevant objects on the disaster site. Satisfying results may be achieved if the damage is assessed at a block level, somehow averaging the unreliable -due to speckle noise- results of pixel-wise comparing pre-and post-event images. Though, pre-post event pairs have to be available, which may not be always the case for new generation, very high resolution systems like COSMO/SkyMed, especially when operated in spotlight mode. In this paper a preliminary study is described which investigates possible damage signatures in the post-event image alone, starting from texture measures and possibly integrating ancillary information like urban block partition and seismic vulnerability. In addition to such investigation, a detector of anomalous scatterers is also presented as a tool to support inspection of potentially dangerous structures in the observed area. The paper will illustrate and discuss the results and provide some clues for an operational use of the developed methods.