Earthquakes in the Lab

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Science  05 Oct 2012:
Vol. 338, Issue 6103, pp. 54-55
DOI: 10.1126/science.1227085

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Understanding how earthquakes of different sizes occur is one of the most challenging questions in fault and earthquake mechanics. On page 101 of this issue, Chang et al. (1) report the results of a carefully conducted experiment using a spinning flywheel attached to a high-velocity frictional testing machine to produce what they term an earthquake-like slip event. By changing the rate of revolution of the flywheel, the amount of kinetic energy transferred to the simulated fault in Sierra White granite or Kasota dolomite could be varied by about six orders of magnitude and could produce a series of frictional slips ranging from 0.003 to 4.6 m, corresponding to a moment magnitude range of Mw = 4 to 8 with respect to the range of fault displacements. The power relationship between energy input and displacement is similar to that found for natural earthquakes. Also, the slip produced by the flywheel is characterized by very rapid initial acceleration followed by gradual deceleration, somewhat similar to slip history recognized for natural earthquakes (2). Such experiments will arouse discussions about whether they are realistic proxies of natural earthquakes.