DInSAR analysis to detect local and regional coseismic ground deformation: insights from the 2016 central Italy earthquake

Over the past three decades, remote sensing techniques, particularly Differential Synthetic Aperture Radar Interferometry (DInSAR), have been used to investigate ground deformation phenomena accurately. The DInSAR method is extensively adopted for reconstructing the deformation pattern induced by earthquakes and for discerning the seismogenic fault, particularly in cases where field evidence are not comprehensive.

This study focuses on the application of DInSAR method to the 2016 Mw 6.5 mainshock occurred in the Apennines, central Italy. The earthquake produced a complex surface rupture distribution in a wide area which was meticulously examined by field geologists for a long time after the seismic sequence.

Here, we present detailed maps of the surface deformation pattern produced by the M. Vettore Fault System (VFS) during the October 2016 earthquakes, derived from ALOS-2 SAR data via DInSAR technique. On these maps, we trace a set of cross-sections to analyse the coseismic vertical displacement, essential to identify both surface fault ruptures and off-fault deformations. At a local scale, several coseismic ruptures are identified in agreement with previous field observations. On a larger scale, the VFS hanging-wall displays a long-wavelength upward-convex curvature, less evident toward the south and interrupted by the presence of an antithetic NE-dipping fault. The quantitative comparison between DInSAR- and field-derived vertical displacement highlights the reliability of the approach for constraining ruptures with vertical displacement up to 50-60 cm. The rapid detection of deformation patterns using DInSAR provides crucial information on activated fault segments, their distribution, and interaction shortly after seismic events. The proposed workflow, applicable globally with satellite SAR data, can support geological field surveys during seismic crises and offer rapid insights into surface ruptures essential for emergency management in not easily accessible areas.