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Digital image correlation data from laboratory subduction megathrust models

This data set includes digital image correlation data from analog earthquakes experiments. The data consists of grids of surface strain and time series of surface displacement (horizontal and vertical) and strain. The data have been derived using a stereo camera setup and processed with LaVision Davis 10 software. Detailed descriptions of the experiments and results regarding the surface pattern of the strain can be found in Kosari et al. (2022), to which this data set is supplementary. We use an analog seismotectonic scale model approach (Rosenau et al., 2019 and 2017) to generate a catalog of analog megathrust earthquakes (Table 1). The presented experimental setup is modified from the 3D setup used in Rosenau et al. (2019) and Kosari et al. ( 2020). The subduction forearc model wedge is set up in a glass-sided box (1000 mm across strike, 800mm along strike, and 300 mm deep) with a dipping, elastic basal conveyor belt and a rigid backwall. An elastoplastic sand-rubber mixture (50 vol.% quartz sandG12: 50 vol.% EPDM rubber) is sieved into the setup representing a 240 km long forearc segment from the trench to the volcanic arc. The shallow part of the wedge includes a basal layer of sticky rice grains characterized by unstable stick-slip sliding representing the seismogenic zone. Stick-slip sliding in rice is governed by a rate-and-state dependent friction law similar to natural rocks. According to Coulomb wedge theory (Dahlen et al., 1984), two types of wedge configurations have been designed: a “compressional” configuration represents an interseismically compressional and coseismically stable wedge (compressional configuration), and a “critical” configuration, which is interseismically stable (close to critically compressional) and may reach a critical extensional state coseismically (critical configuration). In the compressional configuration, a flat-top (surface slope α=0) wedge overlies a single large rectangular in map view stick-slip patch (Width*Length=200*800 mm) over a 15-degree dipping basal thrust. In the critical configuration, the surface angle of the elastoplastic wedge varies from the coastal segment onshore (α=10) to the inner-wedge offshore (α=15) segments over a 5-degree dipping basal thrust. Slow continuous compression of the wedge by moving the basal conveyor belt at a speed velocity of 0.05 mm/s simulates plate convergence and results in the quasi-periodic nucleation of quasi-periodic stick-slip events (analog earthquakes) within the rice layer. The wedge responds elastically to these basal slip events, similar to crustal rebound during natural subduction megathrust earthquakes.

High-speed digital image correlation data from laboratory subduction megathrust models

This data set includes data derived from high-speed surface displacement observations from analog earthquake experiments. The data consists of surface displacement of the experiment upper plate and slab, slip distribution, and grids of Coulomb Failure Stress (CFS). The surface displacement observations have been captured using a highspeed CMOS (Complementary Metal Oxide Semiconductor) camera (Phantom VEO 640L camera, 12 bit) and processed with LaVision Davis 10 software. Description of the experiments and results regarding the surface displacement observation, Slip distribution, and CFS can be found in Kosari et al. (2022), to which this data set is supplementary. We use an analog seismotectonic scale model approach (Rosenau et al., 2019 and 2017) to generate a catalog of analog megathrust earthquakes. The presented experimental setup is modified from the 3D setup used in Rosenau et al. (2019) and Kosari et al. ( 2020 and 2022). The subduction forearc model wedge is set up in a glass-sided box (1000 mm across strike, 800mm along strike, and 300 mm deep) with a dipping, elastic basal conveyor belt, and a rigid backwall. An elastoplastic sand-rubber mixture (50 vol.% quartz sandG12: 50 vol.% EPDM rubber) is sieved into the setup representing a 240 km long forearc segment from the trench to the volcanic arc. The shallow part of the wedge includes a basal layer of sticky rice grains characterized by unstable stick-slip sliding representing the seismogenic zone. The Stick-slip sliding in rice is governed by a rate-and-state dependent friction law similar to natural rocks. A flat-top (surface slope α=0) wedge overlies rectangular stick-slip patch/es over a 15-degree dipping basal thrust. Two different seismic configurations of the shallow part of the wedge base (the megathrust) represent the depth extent of the seismogenic zone in nature. In the first configuration (homogeneous configuration), a single large rectangular stick-slip patch (Width*Length=200*800 mm) is implemented as the main slip patch (MSP). In the second case (heterogeneous configuration), two square-shaped MSPs (200*200mm) have been emplaced, acting as two medium-size seismogenic asperities surrounded by a salt matrix hosting frequent small events. Slow continuous compression of the wedge by moving the basal conveyor belt at a speed velocity of 0.05 mm/s simulates plate convergence and results in the quasi-periodic nucleation of quasi-periodic stick-slip events (analog earthquakes) within the sticky-rice layer. The wedge responds elastically to these basal slip events, similar to crustal rebound during natural subduction megathrust earthquakes.

Properties of rock analogue materials used for Foamquake: a novel seismotectonic analog model mimicking the megathrust seismic cycle at RomaTre University (Italy)

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.

Digital image correlation data from analogue subduction megathrust earthquakes addressing the control of geodetic coverage on coseismic slip inversion

This data set includes digital image correlation data from thirteen analogue earthquakes generated by means of an analogue seismotectonic scale model approach. The data consists of grids of 3D static coseismic surface displacements. The data have been derived using a stereo camera setup and processed with LaVision Davis 8 software. Detailed descriptions of the experiments and results regarding the control of geodetic coverage on the slip inversion problem can be found in Kosari et al. (2020) to which this data set is supplementary material. We use an analogue seismotectonic scale model approach (Rosenau et al., 2017) to generate a catalogue of analogue megathrust earthquakes (Table 1). The presented experimental setup is modified from the 3D setup used in Rosenau et al. (2019). To monitor surface deformation of the wedge analogue model a stereoscopic set of two CCD cameras (LaVision Imager pro X 11MPx, 14 bit) monitors images the wedge surface continuously at 2.5 Hz. To derive observational data similar to those from geodetic techniques, i.e. velocities at the location on the surface, we use digital image correlation (DIC, Adam et al., 2005) to derive the 3D incremental surface displacement (or velocity) at high spatial resolution (< 0.1 mm). The time series of incremental surface displacement data was calculated using LaVision Davis 8 software. The result is an evenly spaced grid of vectors per time step, oriented parallel with respect to the principal dimensions of the box.

Supplement to “Synchronization of great subduction megathrust earthquakes: Insights from scale model analysis”

This data set provides data from subduction zone earthquake experiments and analysis described in Rosenau et al. (2019). In the experiments analogue seismotectonic scale models of subduction zones characterized by two seismogenic asperities are used to study the interaction of asperities over multiple seismic cycles by means of static (Coulomb failure) stress transfer. Various asperity geometries (lateral/along-strike of the subduction zone distance and vertical/across-strike of the subduction zone offset) are tested on their effect on recurrence pattern of simulated great (M8+) earthquakes.The results demonstrate the role of stress coupling in the synchronization of asperities leading to multi-asperity M9+ events in nature. The data set contains time series of experimental surface velocities from which analogue earthquakes are detected and classified into synchronized events and solo events. The latter are subcategorized into main events and aftershocks and into normal and thrust events. An analogue earthquake catalogue lists all categorized events of the 12 experiments used for statistical analysis. Moreover, results from elastic dislocation modelling aimed ate quantifying the stress coupling between the asperities for the various geometries are summarized. Basic statistics of classified events (e.g. percentage of categorized events, coefficient of variation in size and recurrence time etc.) are documented. Matlab scripts are provided to visualize the data as in the paper.

Supplementary material to "Rough subducting seafloor reduces interseismic coupling and mega-earthquake occurrence: insights from analogue models"

This dataset contains digital image correlation (DIC) data of eight seismotectonic analogue experiments that were performed at the Laboratory of Experimental Tectonics (LET), Univ. Rome Tre, to investigate the effect of subduction interface roughness on the seismogenic behaviour of the megathrust. The study has been done in the framework of the Marie Sklodowska-Curie grant agreement 642029 – ITN CREEP. Together with DIC data we also provide analogue earthquake characteristics and Matlab scripts for visualization.Here we provide Digital Image Correlation data for eight experiments that last about 20 minutes (i.e., including tens of seismic cycles), of which four experiments include a smooth subduction interface and four a rough subduction interface. The DIC analysis provides a velocity field between two consecutive frames, measured at the surface of the model. Details about the nature and geometry of this interface, as well as the experimental procedure, model set-up and materials can be found in van Rijsingen et al. (2019), paragraph 2 and supporting information.A more detailed description of the data that we provide, the methods and the matlab scripts used for visualisation can be found in the data description file. An overview of the dataset can be found in the list of files.