Ares J. Rosakis Ares J. Rosakis
Theodore von Kármán Professor of Aeronautics and Mechanical Engineering

Research Interests

Laboratory Earthquakes
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Collaborators: H. Kanamori and N. Lapusta, Caltech; J. Rice, Harvard; M. Bouchon, U.S. Fourier, France; Students: K. Xia and X. Liu.

imageThe goal of the this work is to create model laboratory experiments mimicking the dynamic shear rupture process. Such experiments are used to observe new physical phenomena and to also create benchmark comparisons with existing analysis and numerics and field observations. The experiments use high-speed photography, photoelasticity, and infrared thermography as diagnostics. The fault systems are simulated using two photoelastic plates (Homalite) held together by friction. The far field tectonic loading is simulated by pre-compression and the triggering of dynamic rupture (spontaneous nucleation) is achieved by an exploding wire technique. The fault forms an acute angle with the compression axis to provide the shear driving force necessary for continued rupturing. We investigate the dependence the characteristics of rupturing, such as rupture speed, rupture mode on experimental conditions such as far-field biaxial compression, tilt angle and interface roughnes. Both homogeneous and bimaterial interfaces are investigated. For bimaterial interfaces, various combination of dissimilar materials, including Homalite/polycarbonate pairs, are chosen to mimic wave speed mismatch conditions that are reported to exist across mature, crustal faults. Here we investigate the issue of directionality of earthquakes in relation to well studied historic sequences of ruptures occurring along the North Anatolian fault in Turkey.

So far we have concentrated on the experimental observation of the phenomenon of spontaneously nucleated, supershear rupture and on the visualization of the mechanics of the Sub-Rayleigh to supershear rupture transition in such frictionally held interfaces. The results suggest that under certain conditions supershear rupture propagation can be facilitated during large earthquakes (e.g. the 2001 central Kunlunshan earthquake in Tibet or the 2002 Denali earthquake in Alaska). Future plans include the study of inhomogeneous tectonic loads and non-uniform fault structures.

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Division of Engineering & Applied Science
California Institute of Technology

Caltech    last update: 05/31/2016