What is the impact of the August 24, 2016 Amatrice earthquake on the seismic hazard assessment in central Italy?

Maura Murru Maura Murru,Aybige Akinci Aybige Akinci,Giuseppe Falcone Giuseppe Falcone,Matteo Taroni Matteo Taroni

doi:10.4401/ag-7209

Maura Murru Maura Murru, Aybige Akinci Aybige Akinci + Show 2 more

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https://doi.org/10.4401/ag-7209

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Abstract

The recent Amatrice strong event (Mw6.0) occurred on August 24, 2016 in Central Apennines (Italy) in a seismic gap zone, motivated us to study and provide better understanding of the seismic hazard assessment in the macro area defined as “Central Italy”. The area affected by the sequence is placed between the Mw6.0 1997 Colfiorito sequence to the north (Umbria-Marche region) the Campotosto area hit by the 2009 L’Aquila sequence Mw6.3 (Abruzzo region) to the south. The Amatrice earthquake occurred while there was an ongoing effort to update the 2004 seismic hazard map (MPS04) for the Italian territory, requested in 2015 by the Italian Civil Protection Agency to the Center for Seismic Hazard (CPS) of the Istituto Nazionale di Geofisica e Vulcanologia INGV. Therefore, in this study we brought to our attention new earthquake source data and recently developed ground-motion prediction equations (GMPEs). Our aim was to validate whether the seismic hazard assessment in this area has changed with respect to 2004, year in which the MPS04 map was released. In order to understand the impact of the recent earthquakes on the seismic hazard assessment in central Italy we compared the annual seismic rates calculated using a smoothed seismicity approach over two different periods; the Parametric Catalog of the Historical Italian earthquakes (CPTI15) from 1871 to 2003 and the historical and instrumental catalogs from 1871 up to 31 August 2016. Results are presented also in terms of peak ground acceleration (PGA), using the recent ground-motion prediction equations (GMPEs) at Amatrice, interested by the 2016 sequence.

Highlights

Central Apennines are one of the most seismically active areas in Italy, where a long history of earthquakes has strongly influenced the development of earthquake-resistant structural design
The Amatrice earthquake occurred while there was an ongoing effort to update the 2004 seismic hazard map (MPS04) for the Italian territory, requested in 2015 by the Italian Civil Protection Agency to the Center for Seismic Hazard (CPS) of the Istituto Nazionale di Geofisica e Vulcanologia INGV
To compute the Probabilistic Seismic Hazard Analysis (PSHA) in Central Italy we used the classical Cornell approach [Cornell, 1968], which provides an estimate of ground shaking at a given site for each earthquake magnitude and distance, through an earthquake rate model and a ground motion prediction equation (GMPE)

Summary

Introduction

Central Apennines are one of the most seismically active areas in Italy, where a long history of earthquakes has strongly influenced the development of earthquake-resistant structural design. Seismicity is mostly characterized by the occurrence of earthquakes which are distributed within a 50-60 km wide mountain belt extending, in NNW-SSE Apennines direction, from Tuscany to Abruzzi. The region has frequently experienced strong shaking caused by earthquakes. The updated historical/parametric catalog [CPTI15, Rovida et al, 2016] contains in the macro area of Central Italy 69 events with magnitude 5.0 or greater, and 7 with magnitude exceeding 6.0, considering a depth 30km. The most relevant of them are those of the 1703 Val Nerina seismic sequence (Mw6.92, I0XI MCS) that struck the whole central Italy killing roughly ten thousand people, and the 1915 Marsica earthquake (Mw7.08, I0XI MCS) about 60 km south of the latest site that killed around 32000 people.

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