Visualization of laboratory earthquakes using the digital image correlation technique

Vito Rubino, Ares J. Rosakis, & Nadia Lapusta

In Preparation 2017, SCEC Contribution #7263

We report on dynamic full-field measurements of spontaneously evolving shear ruptures in a unique laboratory earthquake setup. These measurements are enabled by the development of a new technique, which combines ultra-high-speed photography with the digital image correlation method, enhanced to capture displacement discontinuities. Earthquakes are mimicked in the laboratory by dynamic rupture propagating along the inclined frictional interface of an analog material, Homalite, prestressed in compression and shear. This experimental setup has been successfully used in the past to study key rupture features but the previous diagnostics was not capable of quantifying the full-field rupture behavior. In this paper, we discuss our experimental measurements that capture the evolution of full-field displacements, velocities, strains, strain rates and stresses. Images of the dynamic shear rupture are taken at 1-2 million frames/sec over several sizes of field of view and are analyzed with the digital image correlation method to produce a sequence of evolving full-field maps. The imaging area size is selected to either capture the rupture features extending into the far field or to focus on near-field structures. Simultaneous velocimeter measurements on selected experiments verify the accuracy of our DIC measurements. Our measurements are capable of resolving the characteristic field structures of the shear ruptures shown in this study.

Rubino, V., Rosakis, A. J., & Lapusta, N. (2017). Visualization of laboratory earthquakes using the digital image correlation technique. Experimental Mechanics, (in preparation).