[S10-1] Development, testing and application of earthquake forecasting models

[S10-1-03] Seismological and geodetic tools can jointly contribute to the understanding and prediction of earthquakes

Giuliano F. Panza^{1, 2, 3}, Antonella Peresan⁴, Fernando Sanso'^2,5, ^○Mattia Crespi⁶, Augusto Mazzoni⁶, Andrea Nascetti⁶ (1.Institute of Geophysics, China Earthquake Administration, Beijing, China, 2.Accademia Nazionale dei Lincei, Rome, Italy, 3.International Seismic Safety Organization (ISSO) - www.issoquake.org, 4.CRS – Istituto Nazionale di Oceanografia e Geofisica Sperimentale, Trieste, Italy, 5.DICA - Politecnico di Milano, Milan, Italy, 6.Geodesy and Geomatics Division – DICEA – University of Rome La Sapienza, Rome, Italy)

Earthquakes cannot be predicted with precision but, based on seismicity patterns, algorithms exist for intermediate-term middle range prediction of strong main shocks. A first attempt was made in the framework of project SISMA funded by Italian Space Agency to jointly use seismological tools, like CN algorithm and scenario earthquakes, and geodetic methods and techniques, like GPS and SAR, to constrain priority areas where to concentrate prevention and seismic risk mitigation.

Here the seismic crisis, started in Central Italy in August 2016 with the Amatrice earthquake is considered in a retrospective analysis of both SAR and GPS data, including stability tests.

Differently from the common approach, GPS data are not used to estimate the standard 2D velocity and strain field in the area, but to reconstruct the velocity and strain pattern along transects, properly oriented according to the known tectonic setting. SAR data related to the Amatrice earthquake coseismic displacement are used as independent check of the GPS results.

This further development of integration of seismological and geodetic information, clearly shows the contribution of geodesy to the understanding and prediction of earthquakes. In fact, it turns out possible to highlight the velocity variation and the related strain accumulation in the area of Amatrice event, within the area alarmed by CN since November 1st, 2012. Some counter examples, across CN alarmed and not-alarmed areas, do not show any spatial acceleration localized trend, comparable to the one well defined along the Amatrice transect.

The combined analysis of the results of intermediate term middle range earthquake prediction algorithms, like CN, with those from the processing of adequately dense and permanent GNSS network data, possibly complemented by a continuous InSAR tracking, may allow the routine highlight in advance of the strain accumulation. Thus it is possible to significantly reduce the size of the CN alarmed areas.