Satellite data analysis has allowed us to measure the ground motion generated by the four seismic events with magnitudes ranging from 5 to 5.5 that occurred on January 18th in the Montereale area, and to identify the fault that caused the earthquakes. This activity is coordinated by the Department of Civil Protection (DPC) and is being carried out by a team of researchers from theIstituto Nazionale di Geofisica e Vulcanologia (INGV) and the Institute for Electromagnetic Sensing of the Environment of the National Research Council (CNR-IREA in Naples), centers of expertise in the fields of seismology and satellite radar data processing, with the support of the Italian Space Agency (ASI). Thanks to the use of radar data acquired by the Sentinel-1 constellation of the European Copernicus Program and the ALOS-2 constellation of the Japanese Aerospace Exploration Agency (JAXA) under an agreement with ASI, the CNR-IREA research team was able to measure the ground motions caused by the January 18 earthquakes. The INGV used the ground motion maps developed by IREA-CNR to generate a model of the fault along which the four January 18 earthquakes occurred within a few hours, at depths ranging from 8 to 10 km. The maximum displacement of the Earth's crust along the fault was approximately 90 cm and did not reach the surface but stopped at a depth of approximately 3 km (Figure 1). The reconstructed model is still preliminary but clearly indicates that these earthquakes occurred on the Monte Gorzano regional fault plane, the same one where the sequence began on August 24, 2016, with the Amatrice event, and where smaller events occurred in the Campotosto area in 2009 (Figures 2 and 3).
Figure 1 - South-west view of the Monte Gorzano fault with the segments activated from 2009 to 18 January 2017.
Figure 2 - Plan view of the fault segments that have been activated since 2009 with seismic events of different magnitudes. The source of the Montereale earthquakes is indicated.
Figure 3 - Perspective view from the west of the source patterns of the main earthquakes in the area from 6 April 2009 to today. See Figure 3 for geographical references.
