Publication Date:
2022-03-02
Description:
We studied the anatomy of the fault system where the 2009 L’Aquila earthquake
(MW 6.1) nucleated by means of ~64 k high-precision earthquake locations spanning
1 year. Data were analyzed by combining an automatic picking procedure for P and S
waves, together with cross-correlation and double-difference location methods reaching a
completeness magnitude for the catalogue equal to 0.7 including 425 clusters of similar
earthquakes. The fault system is composed by two major faults: the high-angle L’Aquila
fault and the listric Campotosto fault, both located in the first 10 km of the upper crust. We
detect an extraordinary degree of detail in the anatomy of the single fault segments
resembling the degree of complexity observed by field geologists on fault outcrops. We
observe multiple antithetic and synthetic fault segments tens of meters long in both the
hanging wall and footwall along with bends and cross fault intersections along the main
fault and fault splays. The width of the L’Aquila fault zone varies along strike from 0.3 km
where the fault exhibits the simplest geometry and experienced peaks in the slip
distribution, up to 1.5 km at the fault tips with an increase in the geometrical complexity.
These characteristics, similar to damage zone properties of natural faults, underline the key
role of aftershocks in fault growth and co-seismic rupture propagation processes.
Additionally, we interpret the persistent nucleation of similar events at the seismicity cutoff depth as the presence of a rheological (i.e., creeping) discontinuity explaining how normal faults detach at depth.
Description:
Published
Description:
1-21
Description:
4T. Fisica dei terremoti e scenari cosismici
Description:
JCR Journal
Description:
open
Keywords:
seismic sequences; normal faults; high-resolution earthquake catalogues
;
04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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