PSHA after a strong earthquake: hints for the recovery

<p>We perform aftershock probabilistic seismic hazard analysis (APSHA) of the ongoing aftershock sequence following the Amatrice August 24th, 2016 Central Italy earthquake. APSHA is a time-dependent PSHA calculation where earthquake occurrence rates decrease after the occurrence of a mainshock following an Omori-type decay. In this paper we propose a fault source model based on preliminary evidence of the complex fault geometry associated with the mainshock. We then explore the possibility that the aftershock seismicity is distributed either uniformly or non-uniformly across the fault source. The hazard results are then computed for short-intermediate exposure periods (1-3 months, 1 year). They are compared to the background hazard and intended to be useful for post-earthquake safety evaluation.</p>

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Imaging the tectonic framework of the 24 August 2016, Amatrice (central Italy) earthquake sequence: new roles for old players?

Annals of Geophysics ◽

10.4401/ag-7229 ◽

2016 ◽

Vol 59 ◽

Author(s):

Lorenzo Bonini ◽

Francesco Emanuele Maesano ◽

Roberto Basili ◽

Pierfrancesco Burrato ◽

Michele Matteo Cosimo Carafa ◽

...

Keyword(s):

Central Italy ◽

Active Role ◽

Thrust Fault ◽

Aftershock Sequence ◽

Central Italy Earthquake ◽

Tectonic Reconstruction ◽

Seismogenic Faults ◽

Tectonic Framework ◽

2016 Amatrice Earthquake

We reconstruct the tectonic framework of the 24 August 2016, Amatrice earthquake. At least three main faults, including an older thrust fault (Sibillini Thrust), played an active role in the sequence. The mainshock nucleated and propagated along an extensional fault located in the footwall of the Sibillini Thrust, but due to the preliminary nature of the data the role of this thrust is still unclear. We illustrate two competing solutions: 1) the coseismic rupture started along an extensional fault and then partially used the thrust plane in extensional motion; 2) the thrust fault acted as an upper barrier to the propagation of the mainshock rupture, but was partially reactivated during the aftershock sequence. In both cases our tectonic reconstruction suggests an active role of the thrust fault, providing yet another example of how structures inherited from older tectonic phases may control the mainshock ruptures and the long-term evolution of younger seismogenic faults.

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Exploring probabilistic seismic risk assessment accounting for seismicity clustering and damage accumulation: Part I. Hazard analysis

Earthquake Spectra ◽

10.1177/8755293020957338 ◽

2020 ◽

pp. 875529302095733

Author(s):

Athanasios N Papadopoulos ◽

Paolo Bazzurro ◽

Warner Marzocchi

Keyword(s):

Seismic Risk ◽

Hazard Analysis ◽

Central Italy ◽

Building Design ◽

Companion Paper ◽

Aftershock Sequence ◽

Risk Models ◽

Epidemic Type Aftershock Sequence ◽

One Year ◽

Compare And Contrast

Probabilistic seismic hazard analysis (PSHA), as a tool to assess the probability that ground motion of a given intensity or larger is experienced at a given site and time span, has historically comprised the basis of both building design codes in earthquake-prone regions and seismic risk models. The PSHA traditionally refers solely to mainshock events and typically employs a homogeneous Poisson process to model their occurrence. Nevertheless, recent disasters, such as the 2010–2011 Christchurch sequence or the 2016 Central Italy earthquakes, to name a few, have highlighted the potential pitfalls of neglecting the occurrence of foreshocks, aftershocks, and other triggered events, and pinpointed the need to revisit the current practice. Herein, we employ the epidemic-type aftershock sequence (ETAS) model to describe seismicity in Central Italy, investigate the model’s capability to reproduce salient features of observed seismicity, and compare ETAS-derived one-year hazard estimates with ones obtained with a standard mainshock-only Poisson-based hazard model. A companion paper uses the hazard models derived herein to compare and contrast loss estimates for the residential exposure of Umbria in Central Italy.

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Complex Fault Geometry and Rupture Dynamics of the M W 6.5, 30 October 2016, Central Italy Earthquake

Journal of Geophysical Research Solid Earth ◽

10.1002/2018jb015603 ◽

2018 ◽

Vol 123 (4) ◽

pp. 2943-2964 ◽

Cited By ~ 41

Author(s):

L. Scognamiglio ◽

E. Tinti ◽

E. Casarotti ◽

S. Pucci ◽

F. Villani ◽

...

Keyword(s):

Central Italy ◽

Fault Geometry ◽

Rupture Dynamics ◽

Central Italy Earthquake ◽

Complex Fault

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Kinematic finite fault and 3D seismic wave propagation of the 24 August, 2016, Mw 6.0 central Italy earthquake

Annals of Geophysics ◽

10.4401/ag-7265 ◽

2016 ◽

Vol 59 ◽

Author(s):

Federica Magnoni ◽

Emanuele Casarotti

Keyword(s):

Wave Propagation ◽

Seismic Wave ◽

Structural Model ◽

Central Italy ◽

Seismic Wave Propagation ◽

Source Model ◽

Geological Structure ◽

Fault System ◽

Central Italy Earthquake ◽

Finite Fault

The magnitude Mw 6.0 earthquake of 24th August 2016 caused severe damages and nearly 300 fatalities in the central Italy region. Initial reports revealed an asymmetrical distribution of damage and coseismic effects, suggesting a major role of heterogeneities, both in the rupture history and in the geological structure of the region. Near realtime availability of seismological data afforded a timely determination of a finite fault model (Tinti et al., 2016). Here we test this source model by performing a 3D simulation of seismic wave propagation within a 3D structural model containing the major geological features of the region. Agreement between modeled seismograms and observed seismograms suggests that some complexities in the waveforms, such as high amplification in the region of the Mt. Vettore fault system, can be accounted for by complexities in the fault rupture and 3D structural models. Finally, the consistency of the hypothesis of two distinct events has been analyzed.

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