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  • 1
    Publication Date: 2022-02-16
    Description: Abstract
    Description: This dataset includes particle image correlation data from 26 experiments performed with Foamquake, a novel analog seismotectonic model reproducing the megathrust seismic cycle. The seismotectonic model has been monitored by the means of a high-resolution top-view monitoring camera. The dataset presented here represents the particle image velocimetry surface velocity field extracted during the experimental model through the cross-correlation between consecutive images. This dataset is supplementary to Mastella et al. (2021) where detailed descriptions of models and experimental results can be found.
    Description: Methods
    Description: Foamquake is a scaled seismotectonic model that reproduces the key features of a generic natural megathrust. The experimental setup is composed of a Plexiglass box where a flat-topped elastic foam rubber wedge with a dimension of 145x90x20 cm^3 (the overriding plate analog) overlaying a planar, 10° dipping rigid plate (the subducting plate analog). The model is free to move laterally for 5 cm within the Plexiglass box. Thus, it is not affected by friction acting at the two sides of the foam wedge. Instead, the rear (i.e., the thickest side) of the vertical wedge is confined by a rigid vertical backstop. The interface between the foam and the lower plate mimics the megathrust interface. Along the rigid subducting plate, a plastic conveyor belt moves downward at the constant velocity of 0.01 cm/s reproducing a steady trench-orthogonal subduction. Along the plate interface a 1 cm layer of granular material (i.e., rice) mimics a seismic asperity surrounded by sand reproducing the heterogeneous frictional configuration of the analog fault zone. Due to the physical properties of granular materials placed along the analog megathrust, Foamquake experiences stick-slip behavior. This behavior, can be described in the rate and state framework, results in the quasi-periodic spontaneous nucleation of frictional instabilities within the rice layer, named foamquakes. The rice is characterized by a velocity weakening frictional behavior while the sand is characterized by velocity neutral behavior. As a consequence, analog earthquakes nucleate within the granular seismic asperity, while the sand tends to inhibit the rupture propagation. Given the 3D nature of the setup, models with more than one asperity can be performed with Foamquake. This dataset includes data from 22 models with a single-asperity configuration. Those models differ from each other by a variation of the normal load applied above the asperity and of the along trench asperity length. This repository also includes data derived from 4 models characterized by the presence of two asperities divided by a barrier.
    Keywords: subduction megathrust earthquakes ; asperities ; multi-scale laboratories ; EPOS ; Analog modelling results ; deformation ; geologic process ; tectonic process ; subduction ; Particle Image Velocimetry (PIV) ; analogue models of geological processes ; MatPIV ; Earthquake simulator ; earthquake ; seismic activity ; geological process ; seismic activity ; thrust fault ; subduction zones ; plate margin setting ; Wedge simulator ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 EARTHQUAKES ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 PLATE TECTONICS 〉 PLATE BOUNDARIES ; EARTH SCIENCE SERVICES 〉 MODELS 〉 GEOLOGIC/TECTONIC/PALEOCLIMATE MODELS ; EARTH SCIENCE SERVICES 〉 MODELS 〉 PHYSICAL/LABORATORY MODELS ; geological process 〉 seismic activity 〉 earthquake ; lithosphere 〉 earth's crust 〉 fault
    Type: Dataset , Dataset
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  • 2
    Publication Date: 2023-02-18
    Description: Abstract
    Description: This dataset provides friction and elasticity data from ring shear and axial tests, respectively, on rock analogue materials used at the University Roma Tre (Rome, IT) in “Foamquake”, a novel seismotectonic analog model mimicking the megathrust seismic cycle (Mastella et al., under review). Two granular materials (quartz sand and Jasmine rice) have been characterized by means of internal friction coefficients µ and cohesions C. An elastic material (foam rubber) have been characterized by means of Young’s modulus E and Poisson’s ratio v. According to our analysis the granular materials show Mohr-Coulomb behaviour characterized by linear failure envelopes in the shear stress vs. normal load Mohr space. Peak, dynamic and reactivation friction coefficients of the quartz sand are µP = 0.69, µD = 0.56 and µR = 0.64, respectively. Cohesion ranges between 50 and 100 Pa. Rate-dependency of friction in quartz sand seems insignificant. Peak, dynamic and reactivation friction coefficients of the Jasmine rice are µP = 0.70, µD = 0.59 and µR = 0.61, respectively. Cohesion ranges between 30 and 50 Pa. Rate-weakening of Jasmine rice is c. 6% per tenfold change in shear velocity v. The Young’s modulus of the foam rubber has been constrained to 30 kPa, its Poisson’s ratio is v=0.1.
    Keywords: multiscale laboratories ; analogue models of geologic processes ; property data of analogue modelling materials ; analogue ; EPOS ; Cohesion ; Density ; Digital Image Correlation (DIC) / Particle Image Velocimetry (PIV) 〉 StrainMaster (La Vision GmbH) ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 EARTHQUAKES ; EARTH SCIENCE 〉 SOLID EARTH 〉 TECTONICS 〉 PLATE TECTONICS 〉 PLATE BOUNDARIES ; Earthquake simulator ; Flour 〉 Rice ; Foam rubber ; Force sensor ; Friction coefficient ; geolocical hydrogeological 〉 earthquake ; megathrust ; Poisson ratio ; Python ; Ring-shear tester ; Sand 〉 Quartz Sand ; Subduction box ; tectonic and structural features ; tectonic process 〉 subduction ; tectonic setting 〉 plate margin setting 〉 forearc setting ; tectonic setting 〉 plate margin setting 〉 subduction zone setting ; Time lapse camera ; Triaxal tester ; Uniaxial tester ; Young modulus
    Type: Dataset , Dataset
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  • 3
    Publication Date: 2024-01-12
    Description: Accurate assessment of the rate and state friction parameters of rocks is essential for producing realistic earthquake rupture scenarios and, in turn, for seismic hazard analysis. Those parameters can be directly measured on samples, or indirectly based on inversion of coseismic or postseismic slip evolution. However, both direct and indirect approaches require assumptions that might bias the results. Aiming to reduce the potential sources of bias, we take advantage of a downscaled analog model reproducing megathrust earthquakes. We couple the simulated annealing algorithm with quasi-dynamic numerical models to retrieve rate and state parameters reproducing the recurrence time, rupture duration and slip of the analog model, in the ensemble. Then, we focus on how the asperity size and the neighboring segments’ properties control the seismic cycle characteristics and the corresponding variability of rate and state parameters. We identify a tradeoff between (a-b) of the asperity and (a-b) of neighboring creeping segments, with multiple parameter combinations that allow mimicking the analog model behavior. Tuning of rate and state parameters is required to fit laboratory experiments with different asperity lengths. Poorly constrained frictional properties of neighboring segments are responsible for uncertainties of (a-b) of the asperity in the order of per mille. Roughly one order of magnitude larger uncertainties derive from asperity size. Those results provide a glimpse of the variability that rate and state friction estimates might have when used as a constraint to model fault slip behavior in nature.
    Description: Published
    Description: e2023JB026594
    Description: OST4 Descrizione in tempo reale del terremoto, del maremoto, loro predicibilità e impatto
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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