Instrumental seismicity of the Amatrice earthquake epicentral area: a review

Abstract

This study presents a review of the instrumental seismicity of the Norcia-Amatrice area (central Italy) where a still on-going seismic sequence started on August 24th 2016 with a Mw6.0 earthquake. The review is based on the analysis of the seismic catalogs 1981-2016, the CMT (Centroid Moment Tensor) solutions and the TDMT (Time Domain Moment Tensor) solutions, dividing the area into three regions based on the main seismic sequences preceding the Amatrice 2016 mainshock. The seismicity of this region is characterized by different types of activity: single events, minor sequences and swarms with hypocenters within the upper 15 km of the crust. Small-magnitude seismic sequences on March 2007 with maximum Mw3.9, and one earthquake on March 2012, Mw37, not followed by significant seismicity, affected the area east of the Norcia, close to the Mw 5.4 aftershock of the Amatrice 2016 sequence. In the central area, near Accumoli, and in the southern sector close to Amatrice, minor seismic sequences occurred on February 2014 Ml3.5 and on November 2013 Mw3.7 respectively. We integrated hypocentral locations and fault plane solutions to give a first look at the main features of the instrumental seismicity compared to the present seismic sequence in order to relate the seismicity patterns to seismogenic structures of this area of the central Italy.

Keywords

• Seismic sequence
• Swarm
• Central Apennines