Characteristic Earthquake Model, 1884-2011, R.I.P.

Abstract

A precept of science is that theories unsupported by observations and experiments must be corrected or rejected, however intuitively appealing they might be. Unfortunately, working scientists sometimes reflexively continue to use buzz phrases grounded in once‐prevalent paradigms that have been subsequently refuted. This can impede both earthquake research and hazard mitigation. > All of us in earthquake science must wake up to the problems caused by relying on selected data. Arbitrarily chosen data sets are fine for formulating hypotheses, but not for validating them. Well‐worn seismological buzz phrases include “earthquake cycle” (66 instances recorded in the ISI Web of Science database for the period 2009–2012), “seismic gap” (84), and “characteristic earthquake” (22). And the grand prize goes to…“seismic cycle,” with 88 hits. Each phrase carries heavy baggage of implicit assumptions. The primary assumption loading these phrases is that there are sequences of earthquakes that are nearly identical except for the times of their occurrence. If so, the complex process of earthquake occurrence could be reduced to a description of one characteristic earthquake plus the times of the others in the sequence. Often, such a characteristic earthquake sequence is assumed to dominate the displacement on fault or plate boundary segments. This view holds that characteristic earthquakes should be the largest on a given segment and exhibit quasi‐periodic recurrence; it thus has characteristic earthquakes occurring at a rate higher than that implied by the classic Gutenberg–Richter distribution. The problem is that the surmised properties of characteristic earthquakes were inferred by selecting examples from the past and have proven too imprecise to apply to future earthquakes. Perhaps the best‐known example of a characteristic sequence is that near Parkfield, California, which was the basis for a 1985 prediction that there was a 95% probability of a repeat before 1993 (see Bakun et al. , 2005 …