Publication Date:
2020-05-25
Description:
We explore the three‐dimensional structure of the 2016–2017 Central Italy sequence using
~34,000 ML ≥ 1.5 earthquakes that occurred between August 2016 and January 2018. We applied
cross‐correlation and double‐difference location methods to waveform and parametric data routinely
produced at the Italian National Institute of Geophysics and Volcanology. The sequence activated an 80 km
long system of normal faults and near‐horizontal detachment faults through the MW 6.0 Amatrice, the
MW 5.9 Visso, and the MW 6.5 Norcia mainshocks and aftershocks. The system has an average strike of
N155°E and dips 38°–55° southwestward and is segmented into 15–30 km long faults individually activated
by the cascade of MW ≥ 5.0 shocks. The two main normal fault segments, Mt. Vettore‐Mt. Bove to the
North and Mt. della Laga to the South, are separated by an NNE‐SSW‐trending lateral ramp of the Sibillini
thrust, a regional structure inherited from the previous compressional tectonic phase putting into contact
diverse lithologies with different seismicity patterns. Space‐time reconstruction of the fault system
supports a composite rupture scenario previously proposed for the MW 6.5 Norcia earthquake, where the
rupture possibly propagated also along an oblique portion of the Sibillini thrust. This dissected set of normal
fault segments is bounded at 8–10 km depth by a continuous 2 km thick seismicity layer of extensional
nature slightly dipping eastward and interpreted as a shear zone. All three mainshocks in the sequence
nucleated along the high‐angle planes at significant distance from the shear zone, thus complicating the
interpretation of the mechanisms driving strain partitioning between these structures.
Description:
Published
Description:
e2019JB018440
Description:
3T. Sorgente sismica
Description:
JCR Journal
Keywords:
normal fault
;
shear zone
;
fault segmentation
;
apennines
;
04.06. Seismology
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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