Activation of the SIGRIS monitoring system for ground deformation mapping during the Emilia 2012 seismic sequence, using COSMO-SkyMed InSAR data

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 (Figure 1) [Scognamiglio
et al. 2012, this volume]. 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 [Rovida et al. 2011].
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 (Figure 1); a total of seven earthquakes
with ML >5 occurred in the area between May 20 and
June 3, 2012 (Figure 1). The details of the seismic sequence
can be found in the report by Scognamiglio et al. [2012].
Immediately after the mainshock, the Italian Department
of Civil Protection (Dipartimento di Protezione
Civile; DPC) requested the Italian Space Agency (Agenzia
Spaziale Italiana; ASI) to activate the Constellation of Small
Satellites for Mediterranean Basin Observation (COSMOSkyMed)
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 [Italian Space Agency
2007]. 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
[E-geos 2012], 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; National Institute of Geophysics
and Volcanology) and the Istituto per il Rilevamento
Elettromagnetico dell'Ambiente (IREA-CNR; Institute for
the Electromagnetic Sensing of the Environment) 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 Spacebased
Monitoring System for Seismic Risk Management
(SIGRIS) [Salvi et al. 2010]. 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. Fault
modeling results for the seismic sources of the largest earthquakes,
and a more detailed discussion of the observed
ground deformations are reported in Pezzo et al. [2012].