Toward Nanoseismology

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Raymond JeanlozEAR-0126217The occurrence of deep-focus earthquakes remains one of the great mysteries of geophysics because laboratory experiments demonstrate that materials become ductile at the pressures of the Earth's deep interior. How then can rock undergo brittle rupture at the pressures of the deepest earthquakes, some 0.25 million atmospheres? The proposal requests support for a 3-year effort intended to develop and then begin applying a new experimental method for characterizing acoustic emissions generated from samples at high pressures. An array of GHz-frequency sensors is to be attached to a diamond-anvil cell in order to characterize the elastic-energy released by high-pressure phase transitions in mantle minerals and their analogs. The work combines proven technologies (acoustic-emission recording and GHz ultrasonics with the diamond cell), and shows considerable promise for future development of a large variety of complementary methods (optical, spectroscopic, diffraction) for characterizing brittle failure in detail and under a wide range of conditions.