The Role of Viscoelastic Stress Transfer in Long‐Term Earthquake Cascades: Insights After the Central Italy 2016–2017 Seismic Sequence

Verdecchia, Alessandro; Martinelli, F.; Visini, Francesco; Scotti, Oona; Peruzza, Laura; Benedetti, Lucilla

doi:10.1029/2018tc005110

Cited by 38 publications

(34 citation statements)

References 77 publications

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“…On the contrary, we estimate that the cumulated moment released the Mount Gorzano fault (April 2009, 24 August 2016, and 18 January 2017), corresponding to a cumulated M w of ~6.1, is still far from the maximum magnitude expected in the literature on the fault (6.6–6.7; Galadini & Galli, ; Pace et al, ). Verdecchia et al () recently suggested a contribution of the coseismic and postseismic viscoelastic stress transfer in controlling the seismic sequence evolution, including the participation of the two major faults.…”

Section: Seismotectonic Modelmentioning

confidence: 99%

Definition of Seismic Input From Fault‐Based PSHA: Remarks After the 2016 Central Italy Earthquake Sequence

et al. 2019

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This work focuses on how the progress in earthquake science that follows a large, deeply studied earthquake might be promptly combined with updated approaches of seismic hazard analysis to guide applicative choices for seismic risk reduction, such as postevent seismic microzoning and building design. Both seismic microzoning and seismic design of structures require strong motion records to perform numerical site response analyses. These records have to be related to the seismotectonic context and historical seismicity of the investigation area. We first performed a fault-based probabilistic seismic hazard analysis in the area struck by the 2016 central Italy seismic sequence to individuate reference uniform hazard spectra at rock conditions. We used two different seismic hazard models, one considering 27 individual seismogenic sources (ISSs), and the second one involving grid point seismicity, using a fixed-radius smoothing approach. The geological and seismotectonic data of the 2016 seismic sequence were used to update the model of ISSs. We performed a deaggregation analysis to evaluate the contribution of the ISS in the hazard of four representative sites and to select the magnitude-distance pairs useful in the selection of the real accelerograms. The deaggregation analysis has been performed to identify which source and magnitude most contribute to the hazard for each site, and for different periods of spectral accelerations. Finally, we select, for each site, a set of natural accelerograms, from both nonimpulsive and pulse-like records, based on the magnitude-distance pairs that are compatible on average with target uniform hazard spectra.

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Section: Seismotectonic Modelmentioning

confidence: 99%

Definition of Seismic Input From Fault‐Based PSHA: Remarks After the 2016 Central Italy Earthquake Sequence

et al. 2019

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“…It is unclear because on the 30 October 2016, before field surveys of the 26 October earthquakes, a M w 6.5 earthquake ruptured the total length of the Mt. Vettore fault, rerupturing locations that slipped in the 24 August 2016 earthquake and perhaps those on the 26 October (see Figures , , and ; Calderoni et al, ; Cheloni et al, ; Chiaraluce et al, ; Civico et al, ; Falcucci et al, ; Ferrario & Livio, ; Lavecchia et al, ; Mildon et al, ; Pavlides et al, ; Perouse et al, ; Pizzi et al, ; Porreca et al, ; Scognamiglio et al, ; Verdecchia et al, ; Villani, Civico, et al, ; Villani, Pucci, et al, ; Walters et al, ). Meter‐scale offset across surface ruptures was measured with near‐field 1‐Hz global navigation satellite system for the 30 October ruptures, revealing that the ruptures formed within 2–4 s and, before peak ground acceleration, supporting the primary tectonic origin of the ruptures (Wilkinson et al, ; Figure ).…”

Section: Geologic Backgroundmentioning

confidence: 99%

Coseismic Throw Variation Across Along‐Strike Bends on Active Normal Faults: Implications for Displacement Versus Length Scaling of Earthquake Ruptures

et al. 2018

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Fault bends, and associated changes in fault dip, play a key role in explaining the scatter in maximum offset versus surface rupture length fault scaling relationships. Detailed field measurements of the fault geometry and magnitude of slip in the 2016–2017 Central Italy earthquake sequence, alongside three examples from large historical normal‐faulting earthquakes in different tectonic settings, provide multiple examples in which coseismic throw increases across bends in fault strike where dip also increases beyond what is necessary to accommodate a uniform slip vector. Coseismic surface ruptures produced by two mainshocks of the 2016–2017 Central Italy earthquake sequence (24 August 2016 Mw 6.0 and 30 October 2016 Mw 6.5) cross a ~0.83‐km amplitude along‐strike bend, and the coseismic throws for both earthquakes increase by a factor of 2–3, where the strike of the fault changes by ~28o and the dip increases by 20–25o. We present similar examples from historical normal faulting earthquakes (1887, Sonora earthquake, Mw 7.5; 1981, Corinth earthquakes, Mw 6.7–6.4; and 1983, Borah Peak earthquake, Mw 7.3). We demonstrate that it is possible to estimate the expected change in throw across a bend by applying equations that relate strike, dip, and slip vector to horizontal strain conservation along a nonplanar fault for a single earthquake rupture. The calculated slip enhancement in bends can explain much of the scatter in maximum displacement (Dmax) versus surface rupture length scaling relationships. If fault bends are unrecognized, they can introduce variation in Dmax that may lead to erroneous inferences of stress drop variability for earthquakes, and exaggerate maximum earthquake magnitudes derived from vertical offsets in paleoseismic data sets.

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“…A series of four additional moderate magnitude earthquakes, all with extensional kinematics, hits the southern termination of the system with moment magnitudes ranging between 5.0 and 5.5 in the Campotosto area (Figure 1). The cascade type evolution of the sequence typically observed along this sector of the Apenninic chain (Chiaraluce et al, 2004; Papadopoulos et al, 2017; Verdecchia et al, 2018; Xu et al, 2017) prevented additional human losses after the AM earthquake, because many people had already abandoned their habitations.…”

Section: Introductionmentioning

confidence: 99%

“…These sequences belong to a unique 150 km long normal fault system composed by individual contiguous and/or sub parallel, 10–30 km long, SW‐dipping fault segments. Their static and dynamic interaction (Cocco et al, 2000; De Natale et al, 2011; Hernandez et al, 2004; Lavecchia et al, 2012; Mildon et al, 2017; Nostro et al, 2005; Pace et al, 2014; Papadopoulos et al, 2017; Pino et al, 1999; Verdecchia et al, 2018) as well as their interference with compressional structures formed during the previous tectonic phase is still debated (Chiaraluce et al, 2005, Chiaraluce et al, 2011; Chiaraluce, Di Stefano, et al, 2017 Scognamiglio et al, 2018; Buttinelli et al, 2018; Bonini et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Fine‐Scale Structure of the 2016–2017 Central Italy Seismic Sequence From Data Recorded at the Italian National Network

et al. 2020

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We explore the three-dimensional structure of the 2016-2017 Central Italy sequence using 34,000 M L ≥ 1.5 earthquakes that occurred between August 2016 and January 2018. We applied cross-correlation and double-difference location methods to waveform and parametric data routinely produced at the Italian National Institute of Geophysics and Volcanology. The sequence activated an 80 km long system of normal faults and near-horizontal detachment faults through the M W 6.0 Amatrice, the M W 5.9 Visso, and the M W 6.5 Norcia mainshocks and aftershocks. The system has an average strike of N155°E and dips 38°-55°southwestward and is segmented into 15-30 km long faults individually activated by the cascade of M W ≥ 5.0 shocks. The two main normal fault segments, Mt. Vettore-Mt. Bove to the North and Mt. della Laga to the South, are separated by an NNE-SSW-trending lateral ramp of the Sibillini thrust, a regional structure inherited from the previous compressional tectonic phase putting into contact diverse lithologies with different seismicity patterns. Space-time reconstruction of the fault system supports a composite rupture scenario previously proposed for the M W 6.5 Norcia earthquake, where the rupture possibly propagated also along an oblique portion of the Sibillini thrust. This dissected set of normal fault segments is bounded at 8-10 km depth by a continuous 2 km thick seismicity layer of extensional nature slightly dipping eastward and interpreted as a shear zone. All three mainshocks in the sequence nucleated along the high-angle planes at significant distance from the shear zone, thus complicating the interpretation of the mechanisms driving strain partitioning between these structures.

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The Role of Viscoelastic Stress Transfer in Long‐Term Earthquake Cascades: Insights After the Central Italy 2016–2017 Seismic Sequence

Cited by 38 publications

References 77 publications

Definition of Seismic Input From Fault‐Based PSHA: Remarks After the 2016 Central Italy Earthquake Sequence

Definition of Seismic Input From Fault‐Based PSHA: Remarks After the 2016 Central Italy Earthquake Sequence

Coseismic Throw Variation Across Along‐Strike Bends on Active Normal Faults: Implications for Displacement Versus Length Scaling of Earthquake Ruptures

Fine‐Scale Structure of the 2016–2017 Central Italy Seismic Sequence From Data Recorded at the Italian National Network

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