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Constant stress drop from small to great earthquakes in magnitude-area scaling

Bruce E. Shaw

Published 2009, SCEC Contribution #1389

Earthquakes span a tremendous range of scales, more than 5 orders of magnitude in length. Are earthquakes fundamentally the same across this huge range of scales, or are the great earthquakes somehow different from the small ones? We show that a robust scaling law seen in small earthquakes, with stress drops being independent of earthquake size, indeed holds for great earthquakes as well. The simplest hypothesis, that earthquake stress drops are constant from the smallest to the largest events, combined with a more thorough treatment of the geometrical effects of the finite seismogenic layer depth gives a new magnitude-area scaling that matches the data well and matches the data better over the whole magnitude range than the currently used scaling laws, which have nonconstant stress-drop scaling. This has significant implications for earthquake physics and for seismic hazard estimates.

Shaw, B. E. (2009). Constant stress drop from small to great earthquakes in magnitude-area scaling. Bulletin of the Seismological Society of America, 98, 871. doi: 10.1785/0120080006.