We consider the sequence of earthquakes on the Parkfield segment of the San Andreas fault to be representative “characteristic” earthquakes.We consider the recurrence interval statistics of these earthquakes and the frequency-magnitude statistics of smaller earthquakes prior to the 2004 Parkfield earthquake.We give results for a “stiff” slider-block model and show strong similarities between the model and the Parkfield results. In both cases a power-lawdistribution of smaller events were observed. In both cases theWeibull fit to the distribution of interval timeswas quite good with similar values of the power-lawexponent.We have also drawn an analogy between an earthquake rupture and a first-order phase change (nucleation). We consider this analogy both with and without damage. With damage the rupture is equivalent to an equilibrium phase change, without damage the rupture is equivalent to a spinodal phase change.We argue that the absence of a systematic precursory acceleration of seismicity prior to earthquakes is evidence that precursory damage does nor occur. Thus fault rupture can be associated with a spinodal phase change.
|Title of host publication||Acoustic Emission and Critical Phenomena|
|Subtitle of host publication||From Structural Mechanics to Geophysics|
|Number of pages||17|
|Publication status||Published - 1 Jan 2008|