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Abstract The 2016–2017 central Italy seismic sequence occurred on an 80 km long normal-fault system. The sequence initiated with the Mw 6.0 Amatrice event on 24 August 2016, followed by the Mw 5.9 Visso event on 26 October and the Mw 6.5 Norcia event on 30 October. We analyze continuous data from a dense network of 139 seismic stations to build a high-precision catalog of ∼900,000 earthquakes spanning a 1 yr period, based on arrival times derived using a deep-neural-network-based picker. Our catalog contains an order of magnitude more events than the catalog routinely produced by the local earthquake monitoring agency. Aftershock activity reveals the geometry of complex fault structures activated during the earthquake sequence and provides additional insights into the potential factors controlling the development of the largest events. Activated fault structures in the northern and southern regions appear complementary to faults activated during the 1997 Colfiorito and 2009 L’Aquila sequences, suggesting that earthquake triggering primarily occurs on critically stressed faults. Delineated major fault zones are relatively thick compared to estimated earthquake location uncertainties, and a large number of kilometer-long faults and diffuse seismicity were activated during the sequence. These properties might be related to fault age, roughness, and the complexity of inherited structures. The rich details resolvable in this catalog will facilitate continued investigation of this energetic and well-recorded earthquake sequence.
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High-precision Aftershock Locations and Fault Planes of the 2016-2017 Central Italy Sequence
The earthquake catalog includes high-precision hypocenter relocations for 390,334 earthquakes recorded during the 2016-2017 Amatrice (Central Italy) earthquake sequence. The relative locations were computed by double-difference inversion of a combination of INGV phase picks and cross-correlation differential times measured from correlated seismograms with correlation coefficients > 0.7. Planes of normal faults (idx=1-5) are derived from PCA analysis of 2 months of aftershock locations in the CAT4 catalog following large events. Surfaces of detachment faults (idx=7-10) are derived from mapping out the location of correlated earthquakes. Citation: Waldhauser, F., Michele, M., Chiaraluce, L., Di Stefano, R., & Schaff, D. P. (2021). Fault planes, fault zone structure and detachment fragmentation resolved with highprecision aftershock locations of the 2016-2017 central Italy sequence. Geophysical Research Letters, 48, e2021GL092918. https://doi.org/10.1029/2021GL092918
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- Award ID(s):
- 1759782
- PAR ID:
- 10501593
- Publisher / Repository:
- Zenodo
- Date Published:
- Subject(s) / Keyword(s):
- High-precision earthquake catalog, fault planes, central Italy
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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