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The 2016 central Italy seismic sequence; a first look at the mainshocks, aftershocks, and source models

Lauro Chiaraluce, R. Di Stefano, E. Tinti, L. Scognamiglio, M. Michele, E. Casarotti, M. Cattaneo, P. De Gori, Claudio Chiarabba, G. Monachesi, A. Lombardi, L. Valoroso, D. Latorre and S. Marzorati
The 2016 central Italy seismic sequence; a first look at the mainshocks, aftershocks, and source models
Seismological Research Letters (March 2017) 88 (3): 757-771

Abstract

The 2016 central Italy seismic sequence consists so far of a series of moderate-to-large earthquakes activating within a few months along a 60-km-long and Apenninic-trending normal-fault system. Regrettably, the high vulnerability of the local infrastructure and the shallowness of the largest events (depth around 8 km) resulted in 299 casualties and more than 20,000 homeless, with great difficulties in the disaster management. The sequence evolved around its largest event (M (sub w) 6.5, 30 October) that occurred right in the middle of a fault system already activated two months before with a first M (sub w) 6.0 mainshock (on 24 August) located to the south near the town of Amatrice. Then, another M (sub w) 5.9 mainshock occurred just four days before the largest mainshock (26 October) at the northernmost extent of the sequence, near the town of Visso. We analyze the space-time evolution of the first four months of seismic activity through the relocation of approximately 26,000 earthquakes and the kinematic source models of the three mainshocks. All the main events nucleated at the base of a southwest-dipping normal-fault system segmented by the presence of crosscutting compressional structures. The presence of these inherited faults, separating diverse geological domains, appears to modulate evolution of the sequence interfering with coseismic slip distribution and fault segments interaction. Several secondary antithetic and synthetic faults are located at a shallow depth (<4 km), both in the hanging wall and footwall. The whole normal fault system, confined within the first 8 km of the upper crust, is bounded below by a shallow east-dipping and 2-3-km-thick layer in which small events plus a series of large extensional aftershocks ( nearly equal M (sub w) 4) occur, possibly decoupling the upper and lower crusts.


ISSN: 0895-0695
EISSN: 1938-2057
Serial Title: Seismological Research Letters
Serial Volume: 88
Serial Issue: 3
Title: The 2016 central Italy seismic sequence; a first look at the mainshocks, aftershocks, and source models
Affiliation: Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
Pages: 757-771
Published: 20170329
Text Language: English
Publisher: Seismological Society of America, El Cerrito, CA, United States
References: 43
Accession Number: 2017-037597
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N42°00'00" - N43°00'00", E12°30'00" - E14°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201721
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