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

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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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.

10.31223/osf.io/ufc4v ◽

2018 ◽

Author(s):

Zoë Mildon ◽

Gerald Roberts ◽

Joanna Walker ◽

Francesco Iezzi

Keyword(s):

Central Italy ◽

Stress Transfer ◽

Normal Faults ◽

Coulomb Stress ◽

Seismic Sequence ◽

Fault Interaction

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The delayed aftershocks of the Illapel Earthquake Mw 8.3, 2015, Chile

10.5194/egusphere-egu21-6978 ◽

2021 ◽

Author(s):

Franco Lema ◽

Mahesh Shrivastava

Keyword(s):

Tide Gauge ◽

Stress Transfer ◽

Large Earthquake ◽

Seismic Source ◽

Coulomb Stress ◽

Coulomb Stress Changes ◽

Finite Fault ◽

Stress Changes ◽

2015 Illapel Earthquake ◽

Illapel Earthquake

The delayed aftershocks 2018 Mw 6.2 on April 10 and Mw 5.8 on Sept 1 and 2019 Mw 6.7 on January 20, Mw 6.4 on June 14, and Mw 6.2 on November 4, associated with the Mw 8.3 2015 Illapel Earthquake occurred in the &#8203;&#8203;central Chile. The seismic source of this earthquake has been studied with the GPS, InSAR and tide gauge network. Although there are several studies performed to characterize the robust aftershocks and the variations in the field of deformation induced by the megathrust, but there are still aspects to be elucidated of the relationship between the transfer of stresses from the interface between plates towards delayed aftershocks with the crustal structures with seismogenic potential. Therefore, the principal objective of this study is to understand how the stress transfer induced by the 2015 Illapel earthquake of the heterogeneous rupture mechanism to intermediate-deep or crustal earthquakes. For this, coulomb stress changes from &#160;finite fault model of the Illapel earthquake and with the biggest aftershocks in year 2015 are used. These cumulative stress pattern provides substantial evidences for the delayed aftershocks in this region. The subducting Challenger Fault Zone and Juan Fernandez Ridge heterogeneity are existing feature, which releases the accumulated coulomb stress changes and provide delayed aftershocks.&#160; Therefore along with stress induced by a large earthquake such as Mw 8.3 from Illapel 2015 along with biggest aftershocks, have a direct mechanism that may activate the&#160; delayed aftershocks. Our study suggests &#160;the activation of crustal faults in this research as a risk assessment factor for the evaluating in the seismic context of the region and useful for another subduction zone.

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Miocene structural inversion of the Adjara-Trialeti back-arc basin as a far-field effect of the Arabia-Eurasia collision

10.5194/egusphere-egu21-179 ◽

2021 ◽

Author(s):

Thomas Gusmeo ◽

William Cavazza ◽

Victor Alania ◽

Onise Enukidze ◽

Massimiliano Zattin ◽

...

Keyword(s):

Late Miocene ◽

Field Effect ◽

Stress Transfer ◽

Normal Faults ◽

Far Field ◽

Magmatic Arc ◽

Late Middle Miocene ◽

Structural Inversion ◽

Lesser Caucasus ◽

Back Arc

Young back-arc rift basins, because of the not yet dissipated extensional thermal signature, can be easily inverted following changes in the geodynamic regime and/or far-field stress transmission. Structural inversion of such basins mainly develops through reactivation of normal faults, particularly if the latter are favourably oriented with respect to the direction of stress transfer. The Adjara-Trialeti fold-and-thrust belt of SW Georgia is an example of this mechanism, resulting from the structural inversion of a continental back-arc rift basin developed on the upper plate of the northern Neotethys slab in Paleogene times, behind the Pontides-Lesser Caucasus magmatic arc. New low-temperature thermochronological data [apatite fission-track (AFT) and (U-Th)/He (AHe) analyses] were obtained from a number of samples, collected across the Adjara-Trialeti belt from the former sedimentary fill of the basin and from syn-rift plutons. AFT central ages range between 46 and 15 Ma, while AHe ages cluster mainly between 10 and 3 Ma. Thermal modelling, integrating AFT and AHe data with independent geological constraints (e.g. depositional/intrusion age, other geochronological data, thermal maturity indicators and stratigraphic relationships), clearly indicates that the Adjara-Trialeti back-arc basin was inverted starting from the late Middle Miocene, at 14-10 Ma. This result is corroborated by many independent geological evidences, found for example in the adjacent Rioni, Kartli and Kura foreland basins and in the eastern Black Sea offshore, which all suggest a Middle-Late Miocene phase of deformation linked with the Adjara-Trialeti FTB building. Adjara-Trialeti structural inversion can be associated with the widespread Middle-to-Late Miocene phase of shortening and exhumation that is recognised from the eastern Pontides to the Lesser Caucasus, the Talysh and the Alborz ranges. This tectonic phase can in turn be interpreted as a far-field effect of the Arabia-Eurasia collision, developed along the Bitlis suture hundreds of kilometres to the south.

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Coulomb Stress Transfer Influences Fault Reactivation in Areas of Wastewater Injection

Geophysical Research Letters ◽

10.1029/2018gl079713 ◽

2018 ◽

Vol 45 (20) ◽

Cited By ~ 3

Author(s):

Yan Qin ◽

Xiaowei Chen ◽

Brett M. Carpenter ◽

Folarin Kolawole

Keyword(s):

Stress Transfer ◽

Fault Reactivation ◽

Coulomb Stress

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Coulomb Stress Transfer and Tectonic Loading Preceding the 2002 Denali Fault Earthquake

Bulletin of the Seismological Society of America ◽

10.1785/0120050007 ◽

2006 ◽

Vol 96 (5) ◽

pp. 1662-1674 ◽

Cited By ~ 7

Author(s):

C. G. Bufe

Keyword(s):

Stress Transfer ◽

Coulomb Stress ◽

Denali Fault ◽

Tectonic Loading

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Static stress transfer from the May 20, 2012, M 6.1 Emilia-Romagna (northern Italy) earthquake using a co-seismic slip distribution model

Annals of Geophysics ◽

10.4401/ag-6176 ◽

2012 ◽

Vol 55 (4) ◽

Author(s):

Athanassios Ganas ◽

Zafeiria Roumelioti ◽

Konstantinos Chousianitis

Keyword(s):

Stress Transfer ◽

Northern Italy ◽

Static Stress ◽

Distribution Model ◽

Coulomb Stress ◽

Coulomb Stress Changes ◽

Seismic Slip ◽

Seismological Data ◽

Stress Changes ◽

Fixed Orientation

We model the static stress transfer for the May 2012 northern Italy earthquakes, assuming that failure of the crust occurs by shear. This allows the mechanics of the process to be approximated by the Okada (1992) expressions for displacement and strain fields due to a finite rectangular source in an elastic, homogeneous and isotropic half-space. The slip model of the May 20, 2012, earthquake was derived using empirical Green’s functions and a least-squares inversion scheme of source time functions computed from regional broadband seismological data. The derived model is then incorporated into the computation of Coulomb stress change (ΔCFF) to investigate the possibility that the May 20, 2012, M 6.1 event triggered the second earthquake that occurred on May 29, 2012 (M 5.9). We calculate the Coulomb stress changes for both: (a) optimally oriented planes to regional compression; and (b) planes of fixed orientation assuming that E-W striking, south-dipping thrust faults of the May 29, 2012, type of rupture was a candidate for failure. In both cases, we find that the triggering is promoted as the ΔCFF values in the hypocentral area of the May 29, 2012, earthquake are positive (between 0.61-0.74 bar).

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