Coulomb stress transfer and fault interaction over millennia on non-planar active normal faults: the Mw 6.5-5.0 seismic sequence of 2016-2017, central Italy.

Abstract In order to investigate the importance of including strike-variable geometry and the knowledge of historical and palaeoseismic earthquakes when modelling static Coulomb stress transfer and rupture propagation, we have examined the August–October 2016 A.D. and January 2017 A.D. central Apennines seismic sequence (Mw 6.0, 5.9, 6.5 in 2016 A.D. (INGV) and Mw 5.1, 5.5, 5.4, 5.0 in 2017 A.D. (INGV)). We model both the coseismic loading (from historical and palaeoseismic earthquakes) and interseismic loading (derived from Holocene fault slip-rates) using strike-variable fault geometries constrained by fieldwork. The inclusion of the elapsed times from available historical and palaeoseismological earthquakes and on faults enables us to calculate the stress on the faults prior to the beginning of the seismic sequence. We take account the 1316–4155 yr elapsed time on the Mt. Vettore fault (that ruptured during the 2016 A.D. seismic sequence) implied by palaeoseismology, and the 377 and 313 yr elapsed times on the neighbouring Laga and Norcia faults respectively, indicated by the historical record. The stress changes through time are summed to show the state of stress on the Mt. Vettore, Laga and surrounding faults prior to and during the 2016–2017 A.D. sequence. We show that the build up of stress prior to 2016 A.D. on strike-variable fault geometries generated stress heterogeneities that correlate with the limits of the main-shock ruptures. Hence, we suggest that stress barriers appear to have control on the propagation and therefore the magnitudes of the main-shock ruptures.

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Multiple Lines of Evidence for a Potentially Seismogenic Fault Along the Central-Apennine (Italy) Active Extensional Belt–An Unexpected Outcome of the MW6.5 Norcia 2016 Earthquake

Frontiers in Earth Science ◽

10.3389/feart.2021.642243 ◽

2021 ◽

Vol 9 ◽

Author(s):

Federica Ferrarini ◽

Rita de Nardis ◽

Francesco Brozzetti ◽

Daniele Cirillo ◽

J Ramón Arrowsmith ◽

...

Keyword(s):

Late Quaternary ◽

Tectonic Setting ◽

Central Italy ◽

Stress Transfer ◽

Normal Fault ◽

Normal Faults ◽

Coulomb Stress ◽

Seismic Sequence ◽

Seismogenic Fault ◽

Seismogenic Source

The Apenninic chain, in central Italy, has been recently struck by the Norcia 2016 seismic sequence. Three mainshocks, in 2016, occurred on August 24 (MW6.0), October 26 (MW 5.9) and October 30 (MW6.5) along well-known late Quaternary active WSW-dipping normal faults. Coseismic fractures and hypocentral seismicity distribution are mostly associated with failure along the Mt Vettore-Mt Bove (VBF) fault. Nevertheless, following the October 26 shock, the aftershock spatial distribution suggests the activation of a source not previously mapped beyond the northern tip of the VBF system. In this area, a remarkable seismicity rate was observed also during 2017 and 2018, the most energetic event being the April 10, 2018 (MW4.6) normal fault earthquake. In this paper, we advance the hypothesis that the Norcia seismic sequence activated a previously unknown seismogenic source. We constrain its geometry and seismogenic behavior by exploiting: 1) morphometric analysis of high-resolution topographic data; 2) field geologic- and morphotectonic evidence within the context of long-term deformation constraints; 3) 3D seismological validation of fault activity, and 4) Coulomb stress transfer modeling. Our results support the existence of distributed and subtle deformation along normal fault segments related to an immature structure, the Pievebovigliana fault (PBF). The fault strikes in NNW-SSE direction, dips to SW and is in right-lateral en echelon setting with the VBF system. Its activation has been highlighted by most of the seismicity observed in the sector. The geometry and location are compatible with volumes of enhanced stress identified by Coulomb stress-transfer computations. Its reconstructed length (at least 13 km) is compatible with the occurrence of MW≥6.0 earthquakes in a sector heretofore characterized by low seismic activity. The evidence for PBF is a new observation associated with the Norcia 2016 seismic sequence and is consistent with the overall tectonic setting of the area. Its existence implies a northward extent of the intra-Apennine extensional domain and should be considered to address seismic hazard assessments in central Italy.

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The November 2019 Seismic Sequence in Albania: Geodetic Constraints and Fault Interaction

Remote Sensing ◽

10.3390/rs12050846 ◽

2020 ◽

Vol 12 (5) ◽

pp. 846 ◽

Cited By ~ 3

Author(s):

Alessandro Caporali ◽

Mario Floris ◽

Xue Chen ◽

Bilbil Nurce ◽

Mauro Bertocco ◽

...

Keyword(s):

Moment Tensor ◽

Stress Transfer ◽

Elastic Half Space ◽

Dislocation Model ◽

Coulomb Stress ◽

Reverse Fault ◽

Seismic Sequence ◽

Fault Interaction ◽

Before And After ◽

Dextral Strike Slip Fault

The seismic sequence of November 2019 in Albania culminating with the Mw = 6.4 event of 26 November 2019 was examined from the geodetic (InSAR and GNSS), structural, and historical viewpoints, with some ideas on possible areas of greater hazard. We present accurate estimates of the coseismic displacements using permanent GNSS stations active before and after the sequence, as well as SAR interferograms with Sentinel-1 in ascending and descending mode. When compared with the displacements predicted by a dislocation model on an elastic half space using the moment tensor information of a reverse fault mechanism, the InSAR and GNSS data fit at the mm level provided the hypocentral depth is set to 8 ± 2 km. Next, we examined the elastic stress generated by the Mw = 7.2 Montenegro earthquake of 1979, with the Albania 2019 event as receiver fault, to conclude that the Coulomb stress transfer, at least for the elastic component, was too small to have influenced the 2019 Albania event. A somewhat different picture emerges from the combined elastic deformation resulting after the two (1979 and 2019) events: we investigated the fault geometries where the Coulomb stress is maximized and concluded that the geometry with highest induced Coulomb stress, of the order of ca. 2–3 bar (0.2–0.3 MPa), is that of a vertical, dextral strike slip fault, striking SW to NE. This optimal receiver fault is located between the faults activated in 1979 and 2019, and very closely resembles the Lezhe fault, which marks the transition between the Dinarides and the Albanides.

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The first month of the 2016 central Italy seismic sequence: fast determination of time domain moment tensors and finite fault model analysis of the ML 5.4 aftershock

Annals of Geophysics ◽

10.4401/ag-7246 ◽

2016 ◽

Vol 59 ◽

Author(s):

Laura Scognamiglio ◽

Elisa Tinti ◽

Matteo Quintiliani

Keyword(s):

Time Domain ◽

Moment Tensor ◽

Central Italy ◽

Model Analysis ◽

Fault Model ◽

Normal Faults ◽

Seismic Sequence ◽

Moment Tensors ◽

Finite Fault ◽

Finite Fault Model

<p>We present the revised Time Domain Moment Tensor (TDMT) catalogue for earthquakes with M_L larger than 3.6 of the first month of the ongoing Amatrice seismic sequence (August 24th - September 25th). Most of the retrieved focal mechanisms show NNW–SSE striking normal faults in agreement with the main NE-SW extensional deformation of Central Apennines. We also report a preliminary finite fault model analysis performed on the larger aftershock of this period of the sequence (M_w 5.4) and discuss the obtained results in the framework of aftershocks distribution.</p>

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A 667 year record of coseismic and interseismic Coulomb stress changes in central Italy reveals the role of fault interaction in controlling irregular earthquake recurrence intervals

Journal of Geophysical Research Solid Earth ◽

10.1002/2017jb014054 ◽

2017 ◽

Vol 122 (7) ◽

pp. 5691-5711 ◽

Cited By ~ 18

Author(s):

L. N. J. Wedmore ◽

J. P. Faure Walker ◽

G. P. Roberts ◽

P. R. Sammonds ◽

K. J. W. McCaffrey ◽

...

Keyword(s):

Central Italy ◽

Coulomb Stress ◽

Earthquake Recurrence ◽

Fault Interaction ◽

Coulomb Stress Changes ◽

Stress Changes ◽

Recurrence Intervals

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Coulomb stress transfer between parallel faults. The case of Norcia and Mt Vettore normal faults (Italy, 2016 Mw 6.6 earthquake).

Results in Geophysical Sciences ◽

10.1016/j.ringps.2020.100003 ◽

2020 ◽

Vol 1-4 ◽

pp. 100003

Author(s):

A. Galderisi ◽

P. Galli

Keyword(s):

Stress Transfer ◽

Normal Faults ◽

Coulomb Stress

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Groundwater-Surface Water Interaction in the Nera River Basin (Central Italy): New Insights after the 2016 Seismic Sequence

Hydrology ◽

10.3390/hydrology8030097 ◽

2021 ◽

Vol 8 (3) ◽

pp. 97

Author(s):

Lucio Di Di Matteo ◽

Alessandro Capoccioni ◽

Massimiliano Porreca ◽

Cristina Pauselli

Keyword(s):

River Basin ◽

River Discharge ◽

Central Italy ◽

Normal Faults ◽

Seismic Sequence ◽

Permeability Enhancement ◽

Recession Curves ◽

Straight Line ◽

Groundwater Surface Water Interaction ◽

Hydrogeological System

The highest part of the Nera River basin (Central Italy) hosts significant water resources for drinking, hydroelectric, and aquaculture purposes. The river is fed by fractured large carbonate aquifers interconnected by Jurassic and Quaternary normal faults in an area characterized by high seismicity. The October 30, 2016, seismic sequence in Central Italy produced an abrupt increase in river discharge, which lasted for several months. The analysis of the recession curves well documented the processes occurring within the basal aquifer feeding the Nera River. In detail, a straight line has described the river discharge during the two years after the 2016 seismic sequence, indicating that a turbulent flow characterized the emptying process of the hydrogeological system. A permeability enhancement of the aquifer feeding the Nera River—due to cleaning of fractures and the co-seismic fracturing in the recharge area—coupled with an increase in groundwater flow velocity can explain this process. The most recent recession curves (2019 and 2020 periods) fit very well with the pre-seismic ones, indicating that after two years from the mainshock, the recession process recovered to the same pre-earthquake conditions (laminar flow). This behavior makes the hydrogeological system less vulnerable to prolonged droughts, the frequency and length of which are increasingly affecting the Apennine area of Central Italy.

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