Combination of coseismic displacement fields, a geodetic perspective

Abstract

This work provides the mathematical framework for the rigorous combination of coseismic offsets observed by a GPS network and investigates the results obtained in occasion of the recent Emilia earthquake (Italy). The seismic sequence that affected northern Italy on 20th May 2012, allowed us to compute two offset fields, one referred to the mainshock (M=5.9, followed by two other M=5.1 events on the same day) and a second one referred to the replicas occurred on the 29th May (M=5.8, M=5.3 and M=5.2, ISIDe data archive http://iside.rm.ingv.it). The final displacement field is basically the result of a comparison and validation process with repeated feedbacks between different analysis groups at INGV (Istituto Nazionale di Geofisica e Vulcanologia) that was established in order to obtain a prompt coseismic displacement solution, as precise as possible in the first days after the event.