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Acoustic emission source parameters of laboratory triaxial stick-slip experiments on two Westerly granite samples

These data are supplementary to the GJI research article of Blanke et al. 2020, in which static stress drop estimates of laboratory acoustic emission (AE) waveform records were analyzed. Stick-slip experiments were conducted on two triaxial loaded Westerly Granite samples of different roughness: 1) a smooth saw-cut fault (sample S12) and 2) a rough fault (sample W5). Both experiments resulted in six stick-slip failures of which five were analyzed for each fault. A variant of the spectral ratio technique was applied to find the best fitting source parameters. Laboratory Experiments: Acoustic emission waveform data of two triaxial stick-slip experiments was recorded at room temperature on cylindrical oven-dried Westerly Granite samples of 105-107 mm height and 40-50 mm diameter. The experiments were conducted on a smooth saw-cut (sample S12) and a rough fault (sample W5). Both experiments were performed in a servo-controlled MTS loading frame equipped with a pressure vessel. The acoustic emission activity was monitored by 16 piezoceramic transducers with a resonance frequency of about 2 MHz. A transient recording system (DAX-Box, Prökel, Germany) recorded full waveform data in triggered mode at a sampling frequency of 10 MHz and an amplitude resolution of 16 bits. The rough fault W5 was first prepared with Teflon-filled saw-cut notches at 30° inclination to the vertical axis and then fractured at 75 MPa. Then, each sample, S12 and W5, was subjected to constant confining pressure of 133 MPa and 150 MPa and then loaded in axial compression using a strain rate of 3*10-4 mm/s and 3*10-6 mm/s, respectively. Data description: The tables 2020-008_Blanke-et-al_S1_S12.txt and 2020-008_Blanke-et-al_S2_W5.txt contain AE locations and occurrence, and source parameter estimates of the smooth fault S12 and the rough fault W5, respectively. Both column headers show coordinates of AE locations (X, Y, Z [mm]), temporal occurrence (t [sec]), seismic moment (M0 [Nm]), corner frequency (f0 [Hz]), source radius (r [mm]), static stress drop (stress drop [MPa]), and moment magnitude (MW). M0 and f0 were estimated from the amplitude spectra, using the spectral ratio technique. The source radii were calculated for S-waves using the dynamic circular source model of Madariaga (1976). Static stress drops were estimated following Eshelby (1957). Both tables are used and displayed in Blanke et al. (2020).

Effect of sieving height on density and friction of brittle analogue material: Ring-shear test data of corundum sand used for analogue experiments in the Tectonic Modelling Lab of the University of Bern (CH)

This dataset provides friction data from ring-shear tests (RST) for a corundum sand (“NKF120”). This material is used in various types of analogue experiments in Tectonic Modelling Lab of the University of Bern as an analogue for brittle layers in the crust or lithosphere. The material has been characterized by means of internal friction coefficients μ and cohesions C. Three sub-datasets represent a systematic increase of the sieving height from 10 cm to 20 cm to 30 cm into a shear cell of type No. 1, following the same protocol. This dataset shows that packing density of corundum sand is dependent on the chosen sieving height. However, the effect of the sieving height on internal friction coefficients μ as well as cohesion C is minor and thus negligible in sandbox experiments. According to our analysis the material shows for a sieving height of 10 cm a Mohr-Coulomb behaviour characterized by a linear failure envelope and peak, dynamic and reactivation friction coefficients of μP = 0.75, μD = 0.64 and μR = 0.68, respectively. Cohesions C are in the order of 70 – 105 Pa.

Experimental data of analogue landscape evolution models

This dataset includes raw data used in the paper by Reitano et al. (2020), focused on the effect of different analogue materials on the mechanical and erosional properties of some defined samples. The samples are mixes of three different analogue materials in various proportions. The experiments have been carried out at Laboratory of Experimental Tectonics (LET), University “Roma Tre” (Rome). Detailed descriptions of the experimental apparatus and experimental procedures implemented can be found in the paper to which this dataset refers. We used the MATLAB toolbox “TopoToolbox” (Schwanghart and Scherler, 2014). Here we present: - Pictures recording the evolution of the models. - Laser scans used for further analysis. - Scripts created ad hoc by the authors and used for analyzing and plotting the data. A detailed methodological description can be found in the associated "2020-021_Reitano-et-al_Dataset decription" pdf file.

Rheology of glucose syrup from the Tectonic Modelling Lab (TecLab) of the University of Bern (CH)

This dataset provides results from rheological tests of glucose syrup from two suppliers tested within the EPOS Multi-scale Laboratories (MSL) trans-national access (TNA) program 2019 at the Laboratory of Experimental Tectonics (LET), Univ. Roma TRE, Italy. Syrups Glucowheat 45/81 (GW45) and Glucowheat 60/79 (GW60) are produced by Blattmann Schweiz AG, Switzerland (2019 batch). Syrups GlucoSweet 44 (GS44) and GlucoSweet 62 (GS62) are produced by ADEA (Amidi Destrini ed Affini), Italy (2019 batch) . The four tested glucose syrups are labeled according to their DE value (dextrose equivalent value). For tested products from Blattmann Schweiz AG, the second number refers to the weight percentage of dry substance. Glucose syrup GS44 is used in full lithospheric scale analogue experiments at the Tectonic Modelling Lab (TecLab) at the University of Bern, Switzerland as a low-viscosity material simulating the asthenospheric mantle lithosphere to provide isostatic equilibration. The materials have been analyzed using a MCR301 Rheometer (Anton Paar) equipped with parallel plates geometry and rotational regime . To prevent the evaporation of the samples during the measurements, an external water-lock device has been used.

Analysis of analogue models testing the influence of rheologically weak layers and basal fault kinematics on deformation in the overburden

This data set includes overviews depicting the surface evolution (time-lapse photography, topography analysis, digital image correlation [DIC] analysis), as well as and progressive physical cross-section analysis of 18 laboratory experiments (analogue models) testing the influence of rheologically weak layers (i.e. layers with [a component of] viscous behaviour) and basal fault kinematics on deformation in the weak layer’s overburden. This model set-up was inspired by the geological situation in the Swiss Alpine Foreland. All experiments were performed at the Tectonic Modelling Laboratory of the University of Bern (UB). Detailed descriptions of the model set-up preparation and results, as well as the monitoring techniques can be found in Zwaan et al. (in review).

Ring Shear and Slide-Hold-Slide Test Measurements for Soda-Lime Glassbeads of 300-400µm diameter used at the Helmholtz Laboratory for Tectonic Modelling, Potsdam, Germany

This data set provides two series of experiments from ring-shear tests (RST) on glass beads that are in use at the Helmholtz Laboratory for Tectonic Modelling (HelTec) at the GFZ German Research Centre for Geosciences in Potsdam. The main experimental series contains shear experiments to analyse the slip behaviour of the granular material under analogue experiment conditions. Additionally, a series of slide-hold-slide (SHS) tests was used to determine the rate and state friction properties. A basic characterisation and average friction coefficients of the glass beads are found in Pohlenz et al. (2020). The glass beads show a slip behaviour that is depending on loading rate, normal stress and apparatus stiffness which were varied systematically for this study. The apparatus was modified with springs resulting in 4 different stiffnesses. For each stiffness a set of 4 experiments with different normal stresses (5, 10, 15 and 20 kPa) were performed. During each experiment loading rate was decreased from 0.02 to 0.0008 mm/s resulting in 9 subsets of constant velocity for each experiment. We observe a large variety of slip modes that ranges from pure stick-slip to steady state creep. The main characteristics of these slip modes are the slip velocity and the ratio of slip event duration compared to no slip phases. We find that high loading rates promote stable slip, while low loading rates lead to stick-slip cycles. Lowering the normal stress leads to a larger amount of creep which changes the overall shape of a stick-slip curve and extends the time between slip events. Changing stiffness leads to an overall change in slip behaviour switching from simple stick-slip to more complex patterns of slip modes including oscillations and bimodal slip events with large and small events. The SHS tests were done at maximum stiffness and higher loading rates (>0.05 mm/s) but at the same normal stress intervals as the main series. Using various techniques, we estimate the rate-and-state constitutive parameters. The peak stress after a certain amount of holding increases with a healing rate of b=0.0057±0.0005. From the increase in peak stress compared to the loading rate in slide-hold-slide tests we compute a direct effect a=-0.0076±0.0005 which leads to (a-b)=-0.0130±0.0006. Using a specific subset of the SHS tests, which have an equal ratio of hold time to reloading rate, we estimate (a-b)=-0.0087±0.0029. Both approaches show that the material is velocity weakening with a reduction in friction of 1.30 to 0.87 % per e-fold increase in loading rate. Additionally, the critical slip distance Dc is estimated to be in the range of 200 µm. With these parameters the theoretical critical stiffness kc is estimated and applied to the slip modes found in the main series. We find that the changes in slip mode are in good agreement with the estimated critical stiffness and thus confirm the findings from the SHS tests.

Stress strain data of experimentally deformed Carrara marble in the semi-brittle field

The data set contains stress-strain data of Carrara marble experimentally deformed in triaxial compression at temperatures of 20 – 800°C, confining pressures of 30 – 300 MPa, and strain rates between 10-3 and 10-6 s-1. This range covers conditions, at witch marble deforms in the semi-brittle regime, i.e., strength depends on all parameters, but with different sensitivity. Semi-brittle deformation behavior is expected to be important in the mid continental crust. The experiments were conducted in the Experimental Rock Deformation Laboratory of the GFZ German Research Centre for Geosciences in Potsdam, Germany. The data are separated into 91 individual ASCII files, one for each sample. The corresponding temperature, pressure and strain rate conditions are listed in Tab. 1. of the data description and in the associated work by Rybacki et al. (submitted).

Digital image correlation data from analogue modelling experiments addressing extension of weakened crust

This data set includes the results of digital image correlation analysis applied to analogue modelling experiments (Table 1) on the effect of weakness during distributed crustal extension performed at the Helmholtz Laboratory for Tectonic Modelling (HelTec) of the GFZ German Research Centre for Geosciences in Potsdam. Ten generic analogue models made of a layer of Quartz sand (G12, Rosenau et al., 2018) including a weak silicone oil “seed” (PDMS G30M, Rudolf et al., 2016) to localize deformation have been extended on top of a basal foam block. A benchmark experiment (basal foam only) and a reference model (layer of sand without seed) are also reported. Detailed descriptions of the experiments can be found in Osagiede et al. (2021) to which this data set is supplement. The models have been monitored by means of digital image correlation (DIC) analysis (Adam et al., 2005). DIC analysis yields quantitative information about model surface deformation in 2D and 3D. The data presented here are visualized as finite strain and displacement maps as well as cumulative strain and displacement profiles.

CT data, PIV analysis results and surface view videos of analogue models of interacting crustal and mantle weak- nesses during rifting

This data set includes videos depicting the surface evolution (time laps photographs and Particle Image Velocimetry or PIV analsys) of 15 analogue models on rift tectonics, as well as 4D CT imagery (figures and videos) from four of these experiments. The experiments examined the influence of differently oriented mantle and crustal weaknesses on rift system development using a brittle-viscous set-up. All experiments were performed at the Tectonic Modelling Laboratory of the University of Bern (UB). Detailed descriptions of the experiments and monitoring techniques can be found in Zwaan et al. (2021).

Experimental data of analogue models of subduction investigating the interplays between mantle flow and slab pull

This dataset includes images depicting the evolution in map view and lateral view of 7 analogue experiments of subduction to better understand the interplays between slab pull and mantle flow at subduction zones. The experiments are performed under a natural gravity field and are designed to understand the influence of plate width and magnitude and direction of mantle flow on slab geometry, trench kinematics and shape, and superficial mantle deformation around the subduction zone. All experiments were performed at the Laboratory of Experimental Tectonics at the Università Roma Tre (Italy). The laboratory models consist of one viscous layer of silicone putty representing the subducting lithosphere resting on top of a tank filled with glucose syrup, representing the convective mantle. We impose a horizontal flow in the convective mantle by pushing at a constant velocity a piston in the glucose syrup below an intermediate horizontal plate representing the upper mantle-lower mantle discontinuity. The pictures show the time evolution of each experiment from the top (« top » folder) and lateral position (« lateral » folder) and were taken synchronously every 30 seconds, and downsampled to 5 minutes in this dataset. The entire set of pictures are available from the authors upon request. Model F14 is the reference model, without imposed mantle flow and with a slab width of 2000. Models F15 and F16 are models with 660 km and 4000 km, respectively. They allow us analyzing the effect of slab width in the absence of a background flow. Models F17 and F20 are models with slab width of 2000 km and a background flow coming from above the slab at velocities of 0.9 and 1.8 mm/min in the lab (corresponding to 0.9 and 2 cm/yr once scaled to nature), respectively. Models F24 and F26 are models with slab width of 2000 km and a background flow coming from below the slab at velocities of 0.9 and 1.8 mm/min in the lab (corresponding to 1.2 and 2.7 cm/yr once scaled to nature), respectively. For details on the experimental set-up, monitoring techniques and interpretation of the results, please refer to Guillaume et al. (2021) to which these data are supplementary material.

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