Fault size distributions — are they really power-law?

Power-law fault size (throw) distributions spanning ca seven orders of magnitude are analysed using sample lines from seismic, coal-mine plan and outcrop data sets. Outcrop data sets generally have lower power-law exponent values than seismic data sets, consistent with a general decrease in exponent value with decrease in fault size. If such a relationship does exist, then probably it cannot be accounted for by sampling bias alone. We suggest that either: (i) fault size populations are not power-law over a large scale range; or (ii) they are power-law, but at smaller scales show a greater range of exponent values due to spatial clustering.