Video
Video 1 (3.0 MB, MPEG4 format)
Video 2 (3.2 MB, MPEG4 format)
Video 3 (2.2 MB, MPEG4 format)

The Seismological Laboratory of the University of Nevada, Reno is carrying out studies of precariously balanced rocks near active faults to estimate ground shaking from past earthquakes. As part of this project, we are carrying out theoretical and experimental tests of the toppling of rocks of various shapes to various types of earthquake ground motions. One experiment tests the response of rocks with varying shapes and other objects to specific ground motions using the University of Nevada School of Engineering shake table. A given shape of ground motion is progressively increased in amplitude until the objects topple. The results are then compared with theory. The video shows one of these toppling experiments in which objects are exposed to shake table ground motions corresponding to a particular earthquake. Some of the objects topple and others do not. The results help in interpreting the precariously balanced rocks observed in the field near the San Andreas fault in Southern California and near active faults in Nevada.

PLEASE: If you find an apparently precariously balanced rock, please do not disturb it. Valuable information could otherwise be lost. But, please report them to us. For detail, check the link below "To be part of this research."

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