UHH-Tec - Experimental tectonics laboratory
Scaled analogue modelling has become a fundamental experimental approach for testing tectonic and geodynamic hypotheses. This is achieved by scaling down the geometry, kinematics and dynamics of geological processes such that they can be studied in the laboratory over hours to days, rather than the millions of years over which they may occur in nature. The deformational behavior (shape change) of rock analogue materials under known kinematic boundary conditions is monitored in respective experiments. The validation of experimental results with field observations is a most powerful approach to elucidate the physics behind a given geodynamic process.
In order to simulate any deformation regime of continental crust, we designed the Multifunctional analogue modelling Box (MultiBox). The MultiBox is made of transparent acrylic glass and consists of two halves, a fixed one and a mobile one, each of which is equipped with a piston. Horizontal shear can be imposed by moving the mobile box half relative to the fixed one parallel to the box midline. Convergence and divergence is achieved by motion of the pistons. Therefore, the MultiBox allows us to simulate any deformation regime including pure shear, simple shear and any chosen components of transpression and transtension. The large size of the box (1 m x 1 m x 40 cm) guarantees high accuracy of length scaling. Computer-controlled stepper motors driving all mobile parts of the MultiBox ensure precise reproducibility of kinematic boundary conditions of an experiment series. Fluids can be injected through a feeder valve in the base plate near the box midline during an ongoing experiment. The system can be easily upgraded by instruments, such as force sensors.
The Monitoring System
The experiments are recorded with a 3-D Stereo Digital Image Correlation (DIC) StrainMaster system manufactured by LaVision GmbH (Germany). Two monochrome Imager M-lite 12M CMOS cameras with a 12-bit sensor (12-megapixel, 4112 x 3008 pixels, 4096 values of grey) are mounted above the model surface. The images are recorded and synchronized with a Device Control Unit X (DCU X) running DaVis 10.1 by LaVision GmbH. Stereo DIC permits the computation of 3-D surface displacements by cross-correlation of sequentially recorded stereo image pairs. Simultaneous application of stereo image reconstruction generates a high-resolution 3-D model of surface topography. This allows us to quantify the shape change of monitored surfaces, often composed of granular materials. Dark particles in such materials serve as markers for DIC cross correlation. Calibration of the cameras prior to each experiment ensures high-precision vector field calculation. The software DaVis 10.1 is used to calculate the displacement vector field evolution at a resolution of a few grain size diameters by calculating the incremental and cumulative vector fields for each experiment. Based on the computed vector fields, the software furnished important kinematic derivatives of surface deformation, such as surface displacements in X-, Y- and Z-directions, vertical-axis rotation and shear strain.
- Modelling boxes for static experiments
- 2D and 3D Digital image correlation by LaVision GmbH
- High-frequency GPR by proceq SA
- Fluid injection system
- Granular material processing
- 3D Printing
- Video equipment
- UAV (DJI Mavic 2 Pro)
- Differential GPS
- Photogrammetry (Pix4D)
- Remote sensing (ArcGIS, Envi, Matlab)
- High-performance computing
- Volcano-tectonics under intra-arc transpression
- RELAX – Crustal relaxation below large impact craters
- Laboratory modelling of plate boundary transpression zones