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Recent seismic sequences and activation of normal fault systems in the Mugello Basin and surrounding areas (Northern Apennines, Italy)

Recent seismic sequences and activation of normal fault systems in the Mugello Basin and surrounding areas (Northern Apennines, Italy)
Recent seismic sequences and activation of normal fault systems in the Mugello Basin and surrounding areas (Northern Apennines, Italy)
The Mugello Basin (North-Eastern Tuscany) is an intermontane basin of the Northern Apennines (Italy) with a well-documented record of seismicity; the two major historical earthquakes occurred in 1542 (Mw = 6.0) and in 1919 (Mw = 6.4). In this study, we integrate different seismic catalogs spanning the 2005–2019 time interval, and complement these data with phase arrival times from a temporary network that specifically operated in the area throughout the 2019–2021 time interval. The subsequent relocation of this data set with a double-difference algorithm allows for accurate analyses of the most relevant seismic sequences which affected the study area in 2008, 2009, 2015–2017, and 2019. These sequences are associated with the activation of adjacent segments of larger NW-striking fault systems, one of which bounds the NE margin of the Mugello Basin (Ronta Fault System). For each seismic sequence, best-fit fault surfaces are derived from orthonormal regression of relocated hypocenters, yielding consistent results with that derived from fault plane solutions. The four sequences mark a significant increase in the seismicity rate with respect to what was recorded in the previous decades. This suggests that, following the 2008 renewal of seismicity, static or dynamic stress changes, or both depending on the case, played a role in advancing the time of failure of the fault segments activated subsequently.
earthquake triggering, fault segmentation, northern apennines, seismic sequence, stress transfer
Saccorotti, Gilberto
504abd4e-409e-473b-97c5-e1182e5a0905
Bruni, Rebecca
cf20752b-abdc-4794-97d0-af30f8544a6f
Bonini, Marco
26149ec2-8c04-450a-8475-6ed45d70f304
Corti, Giacomo
dce88b12-5b7a-43b1-8a58-5bd1bc13634c
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Sani, Federico
6c59b4c4-ecca-4ecc-ba2c-66efa5e5e3df
Saccorotti, Gilberto
504abd4e-409e-473b-97c5-e1182e5a0905
Bruni, Rebecca
cf20752b-abdc-4794-97d0-af30f8544a6f
Bonini, Marco
26149ec2-8c04-450a-8475-6ed45d70f304
Corti, Giacomo
dce88b12-5b7a-43b1-8a58-5bd1bc13634c
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Sani, Federico
6c59b4c4-ecca-4ecc-ba2c-66efa5e5e3df

Saccorotti, Gilberto, Bruni, Rebecca, Bonini, Marco, Corti, Giacomo, Keir, Derek and Sani, Federico (2022) Recent seismic sequences and activation of normal fault systems in the Mugello Basin and surrounding areas (Northern Apennines, Italy). Frontiers in Earth Science, 10, [879160]. (doi:10.3389/feart.2022.879160).

Record type: Article

Abstract

The Mugello Basin (North-Eastern Tuscany) is an intermontane basin of the Northern Apennines (Italy) with a well-documented record of seismicity; the two major historical earthquakes occurred in 1542 (Mw = 6.0) and in 1919 (Mw = 6.4). In this study, we integrate different seismic catalogs spanning the 2005–2019 time interval, and complement these data with phase arrival times from a temporary network that specifically operated in the area throughout the 2019–2021 time interval. The subsequent relocation of this data set with a double-difference algorithm allows for accurate analyses of the most relevant seismic sequences which affected the study area in 2008, 2009, 2015–2017, and 2019. These sequences are associated with the activation of adjacent segments of larger NW-striking fault systems, one of which bounds the NE margin of the Mugello Basin (Ronta Fault System). For each seismic sequence, best-fit fault surfaces are derived from orthonormal regression of relocated hypocenters, yielding consistent results with that derived from fault plane solutions. The four sequences mark a significant increase in the seismicity rate with respect to what was recorded in the previous decades. This suggests that, following the 2008 renewal of seismicity, static or dynamic stress changes, or both depending on the case, played a role in advancing the time of failure of the fault segments activated subsequently.

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e-pub ahead of print date: 9 May 2022
Published date: 9 May 2022
Additional Information: Funding Information: The facilities of SEISUK are supported by the Natural Environment Research Council (NERC) under agreement R8/H10/64. DK acknowledges support from NERC grant NE/L013932/1 and from the University of Florence funds ATEN 2019, 2020, and 2021. PhD scholarship to RB was funded by the Pegaso fellowship scheme awarded by Regione Toscana. Publisher Copyright: Copyright © 2022 Saccorotti, Bruni, Bonini, Corti, Keir and Sani.
Keywords: earthquake triggering, fault segmentation, northern apennines, seismic sequence, stress transfer

Identifiers

Local EPrints ID: 457074
URI: http://eprints.soton.ac.uk/id/eprint/457074
PURE UUID: e6754328-cc1f-4917-8cc4-c75126f8f77a
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 23 May 2022 16:47
Last modified: 04 Oct 2022 01:44

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Contributors

Author: Gilberto Saccorotti
Author: Rebecca Bruni
Author: Marco Bonini
Author: Giacomo Corti
Author: Derek Keir ORCID iD
Author: Federico Sani

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