Activation of the SIGRIS monitoring system for ground deformation mapping during the Emilia 2012 seismic sequence, using COSMO-SkyMed InSAR data
Salvi, Stefano ; Tolomei, Cristiano ; Boncori, John Peter Merryman ; ...Zoffoli, Simona ; ...Coletta, Alessandro
Oct - 2012
DOI: 10.4401/ag-6181
ISSN : 2037-416X ;
journal : Annals of Geophysics

Issue : 4
type: Article Journal

Abstract
On May 20, 2012, at 02:03 UTC, a moderate earthquake of local magnitude, Ml 5.9 started a seismic sequence in the central Po Plain of northern Italy The mainshock occurred in an area where seismicity of comparable magnitude has neither been recorded nor reported in the historical record over the last 1,000 years. The aftershock sequence evolved rapidly near the epicenter, with diminishing magnitudes until May 29, 2012, when at 07:00 UTC a large earthquake of Ml 5.8 occurred 12 km WSW of the mainshock, starting a new seismic sequence in the western area; a total of seven earthquakes with Ml \>5 occurred in the area between May 20 and June 3, 2012. Immediately after the mainshock, the Italian Department of Civil Protection requested the Italian Space Agency to activate the Constellation of Small Satellites for Mediterranean Basin Observation (COSMO-SkyMed) to provide Interferometric Synthetic Aperture Radar (InSAR) coverage of the area. COSMO-SkyMed consists of four satellites in a 16-day repeat-pass cycle, with each carrying the same SAR payload. In the current orbital configuration, within each 16-day cycle, image pairs with temporal baselines of 1, 3, 4 and 8 days can be formed from the images acquired by the four different sensors. Combined with the availability of a wide range of electronically steered antenna beams with incidence angles ranging from about 16˚ to 50˚ at near-range, this capability allows trade-offs between temporal and spatial coverage to be exploited during acquisition planning. A joint team involving the Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Istituto per il Rilevamento Elettromagnetico dellAmbiente (IREA-CNR) was activated to generate InSAR-based scientific products to support the emergency management. In this framework, the ASI and DPC requested that INGV activated the Space-based Monitoring System for Seismic Risk Management (SIGRIS). SIGRIS consists of a hardware/software infrastructure that is designed to provide the DPC with value-added information products in the different phases of the seismic cycle. During earthquake emergencies, its goal is to rapidly provide decision-support products, such as validated ground-displacement maps and seismic source models. This study reports the details of the activation of the SIGRIS system in the case of the Emilia sequence. It provides a description of the COSMO-SkyMed datasets and processing procedures, as well as selected interferometric results for the coseismic and post-seismic ground deformation. []

keywords : Co-seismic displacement,Earthquakes,Italy,SAR interferometry,SIGRIS system