FAULT RUPTURE PROCESSES DURING HIGH VELOCITY ROTARY SHEAR EXPERIMENTS

Abstract

High velocity shear experiments can provide information on fault rupture processes that seismological methods cannot. The present study focuses on two main aspects of fault rupture processes. One is developing a new, realistic, experimental loading method, power-density control, which can generate stick-slip motion, which is a laboratory model of earthquakes. This method uses energy-rate (power) loading instead of the classical velocity loading, and it generates multiple, spontaneous, high-velocity stick-slips. Our power-density experiments produced events that are comparable to natural earthquakes in terms of slip-velocity and slip displacement. The other aspect of the present research involves investigating acoustic emissions (AEs) recorded with 3D accelerometers during the shear experiments. With four accelerometers on the sample, I located the sources of AEs that are interpreted as asperity breakdown on the experimental fault surface. I conducted 66 velocity control experiments and 76 power-density control experiments on samples of granite, diorite, and limestone, at slip rates approaching seismic slip velocities (~ 1 m/s); 70 of the experiments with AE data. The combined results show that power-density control loading with AE recording has the potential to generate realistic simulations of fault rupture with rupture visualization.