Power-law fault size (throw) distributions spanning ca seven orders of
magnitude are analysed using sample lines from seismic, coal-mine pla
n 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 rela
tionship does exist, then probably it cannot be accounted for by sampl
ing 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, b
ut at smaller scales show a greater range of exponent values due to sp
atial clustering.