Imaging of Seismogenic Asperities of the 2016 ML 6.0 Amatrice, Central Italy, Earthquake Through Dynamic Rupture Simulations

Aochi, Hideo; Twardzik, Cédric

doi:10.1007/s00024-019-02199-z

Cited by 18 publications

(44 citation statements)

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“…Our inferred set of models of the 2016 Amatrice earthquake (including the best‐fitting model) agrees with published kinematic and dynamic models in a general sense. They exhibit bilateral rupture propagation and have two slip maxima away from the rupture nucleation (Aochi & Twardzik, ; Cirella et al, ; Pizzi et al, ). The latter feature has been also revealed in geodetic inversion by Huang et al ().…”

Section: Discussionmentioning

confidence: 99%

Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 M_w 6.2 Amatrice, Italy, Earthquake

et al. 2019

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In 2016 Central Italy was struck by a sequence of three normal-faulting earthquakes with moment magnitude (M w ) larger than 6. The M w 6.2 Amatrice event (24 August) was the first one, causing building collapse and about 300 casualties. The event was recorded by a uniquely dense network of seismic stations. Here we perform its dynamic source inversion to infer the fault friction parameters and stress conditions that controlled the earthquake rupture. We consider a linear slip-weakening friction law with spatially variable parameters along the fault. The inversion uses a novel Bayesian framework developed in our companion paper, which combines efficient finite-difference dynamic rupture simulations and the Parallel Tempering Monte Carlo algorithm to sample the posterior probability density function. The main advantage of such formulation is that by subsequent analysis of the posterior samples we can infer stable features of the result and their uncertainty. The inversion results in a million of visited models. The preferred model ensemble reveals intriguing dynamic features. The rupture exhibits a slow and irregular nucleation followed by bilateral rupture propagation through two asperities, accelerating toward the heavily damaged city of Amatrice. The stress drop reaches locally 10-15 MPa, with slip-weighted mean of 4-4.5 MPa. The friction drop ranges from 0.1 to 0.4. The characteristic slip-weakening distance is the most heterogeneously distributed dynamic parameter, with values of 0.2-0.8 m. The radiation efficiency was rather low, 0.2, suggesting that approximately 80% of the total available energy was spent in the fracture process, while just 20% was radiated by seismic waves.

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Section: Discussionmentioning

confidence: 99%

Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 M_w 6.2 Amatrice, Italy, Earthquake

et al. 2019

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“…Few dynamic rupture models have been proposed of moderate size normal faulting events (Gallovič et al, 2019;Aochi and Twardzik, 2020). Surface breaching reverse and normal faulting dynamic models are challenged by free-surface induced normal stress, strength, loss of ground motion symmetry, trapped waves in the hanging wall, and other dynamic and quasi-static e↵ects (e.g., Oglesby et al, 1998;Aochi, 2018).…”

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confidence: 99%

“…The largest event, which occurred on October 30th, struck the region close to Norcia village with magnitude M w 6.5 and was preceded only four days earlier, on October 26th, by the Mw 5.9 Visso earthquake. For the Mw 6.0 Amatrice event, simplified dynamic rupture inferences from strong ground motion data (Gallovič et al, 2019;Aochi and Twardzik, 2020) reveal complex dynamics (e.g., two asperities and a slow nucleation phase) and imply that rupture arrested south of the secondary fault activated during the Norcia earthquake.…”

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confidence: 99%

Constraining families of dynamic models using geological, geodetic and strong ground motion data: the Mw 6.5, October 30th, 2016, Norcia earthquake, Italy

Tinti¹,

Casarotti²,

Ulrich³

et al. 2022

Preprint

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The 2016 Central Italy earthquake sequence is characterized by remarkable rupture complexity, including highly heterogeneous slip across multiple faults in an extensional tectonic regime. The dense coverage and high quality of geodetic and seismic data allow to image intriguing details of the rupture kinematics of the largest earthquake of the sequence, the Mw 6.5 October 30th, 2016 Norcia earthquake, such as an energetically weak nucleation phase. Several kinematic models suggest multiple fault planes rupturing simultaneously, however, the mechanical viability of such models is not guaranteed.Using 3D dynamic rupture and seismic wave propagation simulations accounting for two fault planes, we constrain 'families' of spontaneous dynamic models informed by a high-resolution kinematic rupture model of the earthquake. These families differ in their parameterization of initial heterogeneous shear stress and strength in the framework of linear slip weakening friction.First, we dynamically validate the kinematically inferred two-fault geometry and rake inferences with models based on only depth-dependent stress and constant friction coefficients. Then, more complex models with spatially heterogeneous dynamic parameters allow us to retrieve slip distributions similar to the target kinematic model and yield good agreement with seismic and geodetic observations. We discuss the consistency of the assumed constant or heterogeneous static and dynamic friction coefficients with mechanical properties of rocks at 3-10 km depth characterizing the Italian Central Apennines and their local geological and lithological implications. We suggest that suites of well-fitting dynamic rupture models belonging to the same family generally exist and can be derived by exploiting the trade-offs between dynamic parameters.Our approach will be applicable to validate the viability of kinematic models and classify spontaneous dynamic rupture scenarios that match seismic and geodetic observations at the same time as geological constraints.

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“…The Global CMT solution (Dziewonski et al., 1981; Ekström et al., 2012) is obtained via https://www.globalcmt.org/. The forward modeling codes of BIEM (Aochi et al., 2000) and FDM (Aochi & Madariaga, 2003) are available at http://doi.org/10.5281/zenodo.1472238 and http://doi.org/10.5281/zenodo.3763864. GAUL is an open source programming library, accessible at http://gaul.sourceforge.net/index.php.…”

Section: Data Availability Statementmentioning

confidence: 99%

Early Stage and Main Ruptures of the 2015 Mw8.3 Illapel, Chile, Megathrust Earthquake: Kinematic Elliptical Inversions and Dynamic Rupture Simulations

Aochi

Ruiz

2021

JGR Solid Earth

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Imaging of Seismogenic Asperities of the 2016 ML 6.0 Amatrice, Central Italy, Earthquake Through Dynamic Rupture Simulations

Cited by 18 publications

References 50 publications

Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 M_w 6.2 Amatrice, Italy, Earthquake

Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 M_w 6.2 Amatrice, Italy, Earthquake

Constraining families of dynamic models using geological, geodetic and strong ground motion data: the Mw 6.5, October 30th, 2016, Norcia earthquake, Italy

Early Stage and Main Ruptures of the 2015 Mw8.3 Illapel, Chile, Megathrust Earthquake: Kinematic Elliptical Inversions and Dynamic Rupture Simulations

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Imaging of Seismogenic Asperities of the 2016 ML 6.0 Amatrice, Central Italy, Earthquake Through Dynamic Rupture Simulations

Cited by 18 publications

References 50 publications

Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 Mw 6.2 Amatrice, Italy, Earthquake

Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 Mw 6.2 Amatrice, Italy, Earthquake

Constraining families of dynamic models using geological, geodetic and strong ground motion data: the Mw 6.5, October 30th, 2016, Norcia earthquake, Italy

Early Stage and Main Ruptures of the 2015 Mw8.3 Illapel, Chile, Megathrust Earthquake: Kinematic Elliptical Inversions and Dynamic Rupture Simulations

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Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 M_w 6.2 Amatrice, Italy, Earthquake

Bayesian Dynamic Finite‐Fault Inversion: 2. Application to the 2016 M_w 6.2 Amatrice, Italy, Earthquake