Surface ruptures and off-fault deformation of the October 2016 central Italy earthquakes from DInSAR data

Abstract

Large magnitude earthquakes produce complex surface deformations, which are typically mapped by field geologists within the months following the mainshock. We present detailed maps of the surface deformation pattern produced by the M. Vettore Fault System during the October 2016 earthquakes in central Italy, 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, we identify a large number of surface ruptures, in agreement with those observed in the field. At a larger scale, the inferred coseismic deformation shows a typical long-wavelength convex curvature of the subsiding block, not directly recognizable in the field. The detection of deformation patterns from DInSAR technique can furnish important constraints on the activated fault segments, their spatial distribution and interaction soon after the seismic events. Thanks to the large availability of satellite SAR acquisitions, the proposed methodological approach can be potentially applied to worldwide earthquakes (according to the environmental characteristics of the sensed scene) to provide a wider and faster picture of surface ruptures. Thus, the derived information can be crucial for emergency management by civil protection and helpful to drive and support the geological field surveys during an ongoing seismic crisis.

Reaction of the carbonate Sibillini Mountains Basal aquifer (Central Italy) to the extensional 2016–2017 seismic sequence

“…1 b,c) shows that shocks propagated up to the range of depths where groundwater is hosted, determining an increase of fracturing and hydraulic conductivity. Such increase is also consistent with DInSAR measurements 45 , 46 showing that, after the 2016–2017 seismic sequence, major subsidence and extension, coherent with a significant permeability increase and a process of fractures cleaning, occurred at hanging-wall of VBFS, in the area corresponding to Central Basin (Fig. 1 b).…”

“…We compared hydrogeological sections 40 with earthquake locations 35 , and DInSAR data 45 , 46 to build up an integrated geological model of the study area (Fig. 1 ).…”

“…DInSAR data 45 , 46 were sampled along section A–A′ in Fig. 1 b and show that, in response to the seismic sequence, major co-seismic extension in the order of 20–25 cm and subsidence in the range of 90 cm was concentrated within the Central Basin and close to the VBFS.…”

“…( b ) Hydrogeological cross section with projection of earthquakes 35 from a 4 km wide stripe. The green dashed line represents the vertical deformation (VD) recorded by DInSAR data 45 , 46 (Open access Creative Commons CC BY license, 10.3390/rs10121901; 10.1038/s41598-022-07068-9). The bar above the cross section indicates the amount of horizontal deformation (HD) recorded by DInSAR data 45 , 46 .…”

“…The green dashed line represents the vertical deformation (VD) recorded by DInSAR data 45 , 46 (Open access Creative Commons CC BY license, 10.3390/rs10121901; 10.1038/s41598-022-07068-9). The bar above the cross section indicates the amount of horizontal deformation (HD) recorded by DInSAR data 45 , 46 . ( c ) Longitudinal hydrogeological section along the central basin with projection of earthquakes 35 from a 7 km wide stripe showing that apart from surface co-seismic ruptures, earthquakes propagated up to shallow depths, where groundwater is hosted, in a widespread area.…”