Rapid investigation of co and post-seismic deformation resulting from the 24th August 2016 Amatrice Earthquake (M 6.2)

At 3:36 AM on the 24th of August a magnitude 6.2 earthquake struck the Amatrice region. The shaking in this event caused nearly 300 deaths and significant damage to the villages distributed across the region. The earthquake ruptured across two faults, the Laga-Amatrice and Vettore faults, which were previously thought to be separate structures that could not rupture in a single event. Our team visited the region days after the event to begin scientific study of this earthquake, investigating the surface expression of the earthquake and installing GNSS equipment that will measure high-resolution motion of the ground continuously for weeks and months following the earthquake. Our team comprises UK and Italian scientists from the University of Leeds, University of Durham, Univeristy of London, Birkbeck University of London, University of Insurbia, the Italian Geological Survey (ISPRA), and Geospatial Research Ltd (Durham). Members of our team who are experts in using satellite data to investigate ground deformation (Durham) processed data in real-time to direct the initial field campaign.

This project will aim to fully characterise the nature of the Amatrice earthquake in terms of what happened during and what is continuing to occur after the seismic event. We will use a variety of techniques including satellite radar measurements and modelling of co and post -seismic deformation, GNSS (Global Navigation Satellite System) measurements of ground deformation, photogrammetry and laser scanning to make high resolution measurements of the surface rupture, detailed field work in the region of the earthquake, and modelling techniques to determine how this earthquake affected stress on the surrounding faults. The work is urgent due to the need to document post-seismic deformation in the weeks and months following the earthquake, and the degrading nature of the surface rupture. This research will allow us to investigate fault connectivity and how linkage develops. We will test hypotheses regarding the role of postseismic deformation after an earthquake that links previously independent structures. Fault linkage typically happens over long geological timescales and has never before been captured before with such a high quality dataset. Our results will be important for incorporating multi-fault rupturing earthquakes into future hazard assessments made in central Italy and globally.

Direct and short term benefits

A direct impact of this project will be to further develop commercially viable GNSS equipment used for monitoring surface deformation, in collaboration with GRL. GRL has developed continually operating GNSS receivers that are low-cost and quick to deploy. The short-baseline receivers are capable of measuring surface deformation continuously at very high resolution. This is the first time the receivers have been installed immediately after an earthquake, and our project will test and lead to improvements in the rapid deployment of equipment following an event. The GNSS equipment has a broad range of applications, specifically position surveying to provide control for datasets acquired using other geospatial technologies (such as TLS, ground- and UAV-based structure from motion SfM), and the installation of continually operating stations to monitor a variety processes, both geological and anthropogenic.

Our collaborators at ISPRA will directly benefit from the additional datasets we can provide on the characteristics of the rupture based on terrestrial geophysical surveys and satellite data, both measuring the evolving post-seismic slip. Significant post-seismic deformation has the potential to cause further disruption to the ground surface, particularly in the Pescara del Tronto valley where shaking on the steep soft-rock slopes caused landslips and disruption to the road network. Our work mapping the distribution of surface deformation with combined InSAR and GNSS measurements will help to quantify these surface disruptions. These datasets will be incorporated into ISPRA reports on the environmental effects of the earthquake and taken into account when managing repairs in the region.

Indirect and long term benefits

The long term benefit of this project will be to develop a better understanding of the process of fault linkage. This process leads to earthquakes that are much larger than would be expected if the individual strands ruptured independently. Fault linkage is poorly understood, but results from this project will give insight into how links develop. If this process is more likely to occur on Abruzzo faults than previously thought, it will be crucial to incorporate into hazard models for the region, which comprises multiple presumed short fault strands. There is potential for global impact in this study as incorporating multi-fault ruptures into hazard models has been highlighted as one of the key challenges and updates to the recent Uniform California Earthquake Rupture Forecast (UCERF3), which includes a higher likelihood for large events due to the inclusion of multifault ruptures. There are few physical constraints on this process, particularly for normal faults, and therefore our study will be a key dataset for future study of this process and how to integrate it into earthquake hazard models.