© IREA-CNR
An Envisat Advanced Synthetic Aperture Radar (ASAR) interferogram over the L'Aquila area in central Italy showing the deformation pattern caused by the seismic events in early April 2009. This interferogram was generated by Italy's Istituto per il Rilevamento Elettromagnetico dell' Ambiente (IREA-CNR) in Naples, Italy just a few hours after Envisat's acquisition on 12 April 2009. It combines that acquisition with a pre-seismic acquisition on 1 February 2009, with an estimated baseline (separation between the two Envisat orbital positions) of about 154 m. The satellite's right-looking angle is 23 degrees. Each fringe of the interferogram, corresponding to a colour cycle, is equivalent to an Earth surface displacement of 2.8 cm along the satellite direction.
An Envisat Advanced Synthetic Aperture Radar (ASAR) interferogram over the L'Aquila area in central Italy showing the deformation pattern caused by the seismic events in early April 2009. This interferogram was generated by Italy's Istituto per il Rilevamento Elettromagnetico dell' Ambiente (IREA-CNR) in Naples, Italy just a few hours after Envisat's acquisition on 12 April 2009. It combines that acquisition with a pre-seismic acquisition on 1 February 2009, with an estimated baseline (separation between the two Envisat orbital positions) of about 154 m. The satellite's right-looking angle is 23 degrees. Each fringe of the interferogram, corresponding to a colour cycle, is equivalent to an Earth surface displacement of 2.8 cm along the satellite direction.
Scientists from Italy's Istituto per il Rilevamento Elettromagnetico dell' Ambiente (IREA-CNR) and the Istituto Nazionale di Geofisica e Vulcanologia (INGV) are studying Synthetic Aperture Radar (SAR) data from these satellites to map surface deformations after the earthquake and the numerous aftershocks that have followed.
The scientists are using a technique known as SAR Interferometry (InSAR), a sophisticated version of 'spot the difference'. InSAR involves combining two or more radar images of the same ground location in such a way that very precise measurements - down to a scale of a few millimetres - can be made of any ground motion taking place between image acquisitions.
