Graviquakes in Italy

Petricca, Patrizio; Barba, Salvatore; Carminati, Eugenio; Doglioni, Carlo; Riguzzi, Federica

doi:10.1016/j.tecto.2015.07.001

Cited by 39 publications

(41 citation statements)

References 73 publications

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“…Moreover, on 30 October, a third large event of magnitude M w 6.5 nucleated below the town of Norcia, striking the area between the two preceding events and filling the gap between the previous ruptures. Fault plane solutions for the main events exhibit normal faulting (http://cnt.rm.ingv.tdmt) consistent with the direction of active extension of~3-4 mm/yr in this sector of the Apennines [Petricca et al, 2015;Devoti et al, 2017]. Previous geological studies [Boncio et al, 2004;Galli et al, 2008;Pizzi and Galadini, 2009] have identified several NW-SE trending normal fault systems, which are active in this area, and are often segmented by preexisting tectonic structures inherited from the pre-Quaternary compressional tectonic phases [Pizzi and Galadini, 2009].…”

Section: Introductionmentioning

confidence: 65%

Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data

Cheloni

Novellis

Albano

et al. 2017

Geophysical Research Letters

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We investigate a large geodetic data set of interferometric synthetic aperture radar (InSAR) and GPS measurements to determine the source parameters for the three main shocks of the 2016 Central Italy earthquake sequence on 24 August and 26 and 30 October (Mw 6.1, 5.9, and 6.5, respectively). Our preferred model is consistent with the activation of four main coseismic asperities belonging to the SW dipping normal fault system associated with the Mount Gorzano‐Mount Vettore‐Mount Bove alignment. Additional slip, equivalent to a Mw ~ 6.1–6.2 earthquake, on a secondary (1) NE dipping antithetic fault and/or (2) on a WNW dipping low‐angle fault in the hanging wall of the main system is required to better reproduce the complex deformation pattern associated with the greatest seismic event (the Mw 6.5 earthquake). The recognition of ancillary faults involved in the sequence suggests a complex interaction in the activated crustal volume between the main normal faults and the secondary structures and a partitioning of strain release.

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Section: Introductionmentioning

confidence: 65%

Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data

Cheloni

Novellis

Albano

et al. 2017

Geophysical Research Letters

Self Cite

176

257

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“…7a) stored during the interseismic phase, within a hangingwall volume confined by the main normal fault and an antithetic fractured dilated zone. When the stresses related to this gravitational energy exceed the strength of the dilated zone and of the main normal fault, the rock volume collapses slipping along the main fault, generating the earthquake 60 (Fig. 7a).…”

Section: Discussionmentioning

confidence: 99%

Longer aftershocks duration in extensional tectonic settings

Valerio

Tizzani

Carminati

et al. 2017

Sci Rep

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Aftershocks number decay through time, depending on several parameters peculiar to each seismogenic regions, including mainshock magnitude, crustal rheology, and stress changes along the fault. However, the exact role of these parameters in controlling the duration of the aftershock sequence is still unknown. Here, using two methodologies, we show that the tectonic setting primarily controls the duration of aftershocks. On average and for a given mainshock magnitude (1) aftershock sequences are longer and (2) the number of earthquakes is greater in extensional tectonic settings than in contractional ones. We interpret this difference as related to the different type of energy dissipated during earthquakes. In detail, (1) a joint effect of gravitational forces and pure elastic stress release governs extensional earthquakes, whereas (2) pure elastic stress release controls contractional earthquakes. Accordingly, normal faults operate in favour of gravity, preserving inertia for a longer period and seismicity lasts until gravitational equilibrium is reached. Vice versa, thrusts act against gravity, exhaust their inertia faster and the elastic energy dissipation is buffered by the gravitational force. Hence, for seismic sequences of comparable magnitude and rheological parameters, aftershocks last longer in extensional settings because gravity favours the collapse of the hangingwall volumes.

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“…In crustal settings, the maximum volume that can be activated during the seismic cycle is constrained by the depth of the brittle‐ductile transition (BDT) or the depth of the decollement layer, which can be slightly shallower. Moreover, the volume is a function of the tectonic style and the hypocentre depth/fault length (Lf/z max ) ratio (Doglioni et al, ; Doglioni, Carminati, et al, ; Petricca et al, ). In addition, in nature, the potential seismogenic volume, hence the released magnitude, is often reduced by regional factors, such as lithological, fluids pressure and thermal variations modifying the frictional behavior of rocks determining creeping versus locked portions of the faults (Ahrens, ; Albaric et al, ; Doglioni, Barba, et al, ; Keefner et al, ; Scholz, ; Sibson, ), along‐strike discontinuity of faults limiting the potential dimension of single coseismic ruptures (Bonini et al, ; Butler et al, ; Calamita, ; Carrera et al, ; Goldsworthy et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, in nature, the potential seismogenic volume, hence the released magnitude, is often reduced by regional factors, such as lithological, fluids pressure and thermal variations modifying the frictional behavior of rocks determining creeping versus locked portions of the faults (Ahrens, 1995;Albaric et al, 2009;Doglioni, Barba, et al, 2015;Keefner et al, 2011;Scholz, 1988;Sibson, 1983), along-strike discontinuity of faults limiting the potential dimension of single coseismic ruptures (Bonini et al, 2010;Butler et al, 2006;Calamita, 1990;Carrera et al, 2006;Goldsworthy et al, 2002). It is also observed that, while the steeper (40°-70°) normal fault rupture tends to propagate cutting the entire brittle crust (Chiarabba & De Gori, 2016;Marone & Scholz, 1988;Petricca et al, 2015;Sibson, 1986), thrust faults are less inclined (0-45°) and do not necessarily reach the BDT (Hyndman et al, 1997). For given convergence and subduction rates, the depth of the decollement in an accretionary prism determines the volume of the accreted rocks: The deeper the decollement, the largest the volume.…”

Section: Introductionmentioning

confidence: 99%

The Decollement Depth of Active Thrust Faults in Italy: Implications on Potential Earthquake Magnitude

2019

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Thrust fault ruptures during earthquakes do not often propagate down to the brittle‐ductile transition. Lithological variations control the behavior and depth of regional basal thrusts and decollement planes. Thrust fronts may be discontinuous along strike, limiting the dimension of single coseismic ruptures. These factors control the maximum expected magnitude in one region. This is the case of Italy where the convergence of few millimeter per year in the Apennines accretionary prism and along the retrobelt of the Alps generates compressional earthquakes with moderate to strong magnitudes. Here, using geological and geophysical data, we first compile a map of the undulated active basal thrust decollement for Italy that occurs from 1 to 17‐km depth. Then, we verify the relationship between the length of seismogenic ruptures in thrust faults (Lf) and the maximum depth of thrust faulting (zmax) of related earthquakes and find that their ratio (Lf/zmax) ranges between 2 and 4. Finally, we compute the potential seismogenic volume and estimate the maximum magnitude using an empirical relationship that multiplies the decollement depth and the Lf/zmax ratio. Maximum calculated magnitude is 6.7 ± 0.37 (depending on Lf/zmax and fault dip angle), consistent with the largest magnitude of thrust‐related earthquakes recorded in Italy (6.5–7.0). Lower magnitudes are predicted in the Ionian Seas at the external front of the Apennines where smaller crustal volumes are involved, whereas higher magnitudes are expected in the southern Po Basin, the western Adriatic Sea, Sicily offshore, and the Southern Alps where the decollement is deeper and the brittle volumes are far greater.

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Graviquakes in Italy

Cited by 39 publications

References 73 publications

Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data

Geodetic model of the 2016 Central Italy earthquake sequence inferred from InSAR and GPS data

Longer aftershocks duration in extensional tectonic settings

The Decollement Depth of Active Thrust Faults in Italy: Implications on Potential Earthquake Magnitude

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