When’s the Next Earthquake?

Unlike the situation for hurricanes, it is not clear whether the recurrence of large earthquakes is better described as time‐independent or time‐dependent. The simplest approach is to assume time‐independence, and to try to estimate earthquake recurrence from the statistics of earthquakes. The starting point is that the number of earthquakes that occur in a given area depends on magnitude, with successively smaller earthquakes being more common. This variation is described approximately by the earthquake frequency‐magnitude, or Gutenberg–Richter relation. As a result, lots of effort has gone into trying to estimate time‐dependent probabilities to describe earthquake recurrence. The idea comes from the earthquake cycle model, in which strain on faults accumulates slowly over time and is released eventually in large earthquakes.