How can processes occurring at depth during the preparation of large earthquakes be reproduced in the laboratory?
To answer this question, a group of researchers from the Njord Centre and the Departments of Geosciences and Physics at the University of Oslo are developing novel experimental techniques to image rock samples approaching failure.
The work is performed within the project "Break-Through Rocks," funded by the European Research Council (ERC Break) and led by Professor François Renard.
Laboratory Earthquakes at the European Synchrotron Radiation Facility
The experiments take place at a large international facility, the European Synchrotron Radiation Facility (ESRF), located in Grenoble, France. This world-leading facility delivers the most powerful source of X-rays among all synchrotrons worldwide. The experiments involve installing rock samples into a rock deformation apparatus that reproduces the conditions of temperature, pressure, and depth where earthquakes occur in the Earth's crust. The pressure is then slowly increased on the sample, and 3D X-ray scans are acquired at different time intervals. The result is a time series of 3D scans acquired in operando, allowing quantification of the preparation process of laboratory earthquakes in 4D.
Results
Before a laboratory earthquake, small precursory activity can be detected in the form of small microfractures, also called damage, that nucleate, grow, and then coalesce into the rock volume. When approaching system-size failure, the number and volume occupied by these microfractures increase, and their spatial organization evolves. The characteristics of this damage are then used in physical models of rupture in rocks to predict when system-size failure will occur.
FAIR Data for Laboratory Experiments
Experiments produce a large amount of data that is transferred to the NIRD storage infrastructure operated by Sigma2. After two years of the project, 160 Terabytes of data have already been acquired and processed directly from NIRD or high-end graphic stations at the University of Oslo. Each series of experiments is made available to the community with a specific Digital Object Identifier (DOI) number as soon as a publication is released.
