GEOLOGICAL SURFACE EFFECTS INDUCED BY THE MAY 2012 EARTHQUAKES IN THE
EMILIA REGION (NORTH ITALY), DETECTED BY COSMO-SKYMED X-BAND SAR.
Marco Chini1, Christian Bignami1, Emanuela Falcucci1, Stefano Gori1, Marco Moro1, Nazzareno
Pierdicca2, Luca Pulvirenti2, Michele Saroli3, Salvatore Stramondo1
1
2
3
Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143, Rome, Italy
Sapienza University of Rome, Department of Informatics, Electronic and Telecommunication, Via
Eudossiana 18, 00184, Rome, Italy
University of Cassino and Southern Lazio, Department of Civil and Mechanical, Via G. di Biasio 43,
03043, Cassino, Italy.
ABSTRACT
The Emilia region (North Italy) has been hit by a Magnitude 5.9 earthquake on May 20, 2012, at 02:03
GMT. The seism occurred in the northern boundary of the Apennine chain compressive area, interested
by a moderate seismicity and where few historical earthquakes below Magnitude 6 occurred. The
earthquake caused some major damage and collapses of ancient and historical buildings in the small
villages within the epicentral region. Several minor quakes followed the main one, and on May 29, at 7:00
GMT, a second main shock (Magnitude 5.8) occurred some km Westward respect the first event, along
another seimogenic source roughly parallel to the May 20 fault.
The dataset used, for investigating the surface effects caused by the two earthquakes, is composed by
X-band SAR data from the COSMO-SkyMed constellation, which imaged the region before, during, and
after the seismic sequence.
In particular, we take the advantage of the very high spatial resolution of COSMO-SkyMed images for
detecting wide area of subsidence, uplift and surface cracks, which are reasonably related to pervasive
liquefaction phenomenon. To this purpose, the information derived from SAR interferometric coherence
and image intensity have been exploited highlighting well-defined areas of loss of coherence in
Sant’Agostino and San Carlo towns. We observed that in urban area the loss of coherence is related to
differential subsidence of buildings caused by liquefaction phenomena, while in rural area the loss of
SAR coherence corresponds to the subsidences of paleo-channels. Moreover, the coseismic deformation
fields measured by mean of Differential SAR interferometry (DInSAR), highlighted some local induced
geological effects, such as uplifting areas related to liquefaction as well, where the outflow of water and
sands did not occurred.