Particle image velocimetry data from seismotectonic analog models focusing on the role of seamount subduction on megathrust seismicity

This dataset provides the surface velocity fields derived with MatPIV (open-source Matlab toolbox for Particle Image Velocimetry; Sveen 2004) of three seismotectonic analog models (e.g., Rosenau et al., 2017) performed to investigate the role of geometry and friction of a single subducting seamount on the seismogenic behavior of the megathrust. Model 1 has a seamount covered by sandpaper (i.e., high friction) that is placed at 1/2 of the trench-parallel length of the seismogenic zone. Model 3 has the same geometry of model 1, but the seamount is in direct contact with the gelatin (i.e., not covered by sandpaper, hence low friction). Model 5 has a low friction patch (i.e., no geometry) that is placed again at 1/2 of the trench-parallel length of the seismogenic zone. Together with the surface velocity fields, we also provide Matlab scripts for visualization. A more detailed description of the experimental setup, configuration of the models and materials can be found in Menichelli et al. (submitted), to which this dataset is supplementary. Our seismotectonic models represent a downscaled subduction zone (1 cm in the model corresponds to 6.4 km in nature; Rosenau et al., 2017). The experimental setup consists of a 60 x 34 cm2 Plexiglass box with a 10°-dipping aluminum basal plate that moves downward with a constant velocity of 0.01 cm/s, analog of the subducting plate. The overriding plate is represented by an elastic wedge of 2.5 wt% pigskin gelatin at T = 10 °C (Di Giuseppe et al., 2009). The seismogenic zone of the megathrust is simulated using a rectangular sandpaper patch (Corbi et al., 2013), with a downdip width of 16 cm and located 31 and 47 cm from the backstop. This corresponds to a 100-km-wide seismogenic zone extending over a depth interval between 15 and 34 km. The updip and down dip aseismic regions of the megathrust are simulated by plastic sheets that are fixed on the setup frame and not subject to subduction (Corbi et al., 2013). A 3D-printed PLA seamount is placed on the seismogenic zone (e.g., Van Rijsingen et al., 2019). The seamount has a height of 6.28 mm and a diagonal length of 94 mm, corresponding to 4 km and 60 km in nature, respectively. These dimensions scale well-known seamounts, such as the Joban Seamount chain in the Japan Trench or the Louisville seamount chain in the Tonga-Kermadec Trench. Experiments were monitored with a CCD camera that acquired a sequence of high-resolution top-view images (1600 x 1200 pixels2, 8 bit, 256 gray levels) at 7.5 fps for the entire duration of the experiment (i.e., ca. 24 minutes). Images are processed with Particle Image Velocimetry (PIV; Adam et al., 2005) using the open-source Matlab toolbox MatPIV (Sveen, 2004). MatPIV provides the velocity field between two consecutive frames, measured at the surface of the model. The velocity field was then used as input to identify analog seismic events using the open-source Matlab function findpeak. The threshold used was 0.1 cm/s. Once earthquakes were identified, we derived their source parameters such as seismic slip, magnitude, and recurrence time following Corbi et al. (2017) and van Rijsingen et al. (2019).