Friday, 26 August 2016 15:17

Satellite sensing helps to identify the faults of the Amatrice earthquake of 24/08/2016

By exploiting the data of the Japanese satellite ALOS 2, obtained through scientific projects, a team of CNR and INGV researchers (coordinated by Riccardo Lanari, director of CNR-IREA, and by Stefano Salvi, technologist manager of INGV), measured with high precision the permanent ground displacements occurred during the earthquake, using the Differential Interferometry techniqueThis technique allows detecting deformations of the ground surface with centimeter accuracy by comparing radar images acquired before the event with those after the earthquake.

In particular, a ground subsidence with the shape of a "spoon" has been pointed out, which extends for about 20 km northwards and has a maximum value of about 20 centimeters at the Accumoli area. 

 

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Deformation map obtained by elaborating, with the differential interferometry technique, the radar images of the satellite ALOS 2 acquired on 09/09/2015 (pre-event) and 24/08/2016 (post-event); the red area highlights the area affected by subsidence due to the seismic events, which reaches approximately 20 centimeters at Accumoli.

 

The ground displacement map was then used to develop the physical-mathematical models of the fault that originated the earthquake. Faults can be visualized as fracture planes along which two blocks of the Earth's crust are sliding: when the movement is very rapid an earthquake is generated. The fault that originated the Amatrice earthquake lies a few miles deep in the area between Amatrice and Norcia, under Accumuli. It is a 25 km long fracture plan that drifts southwest (towards Rieti) with a tilt of 50°. This plan corresponds to a fault already known by surface geological studies. A detailed knowledge of the location and characteristics of seismic sources is a key element for emergency management and is also important for the development of more reliable seismic hazard maps.

It is worth noting that obtaining in a short time a synoptic picture of ground deformations and displacements caused by an earthquake in the epicenter area is one of the objectives of the Civil Protection Department during a seismic emergency. In this specific case, the obtained outcomes are the result of the long and consolidated collaboration promoted by the Department among its Competence Centers - in this case, CNR-IREA and INGV. Based on their expertise, these centers support the DPC in the use of satellite data and information and their integration with in situ data. This activity has enabled the development of products, methods, and procedures that have improved the capabilities of the national alert and emergency response system. The results of this first interferometric monitoring are available for the entire National Civil Protection System through the Civil Protection Department, which is involved in the coordination of emergency management.

Download the file to see the deformation map in Google Earth

 


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