Retrospective on the Accelerating Seismic Release (ASR) hypothesis: Controversy and new horizons

The hypothesis that large earthquakes may be preceded by a period of accelerating seismicity, or Accelerating Seismic Release (ASR), was proposed about twenty years ago. A compilation of almost one hundred peer-reviewed publications on this topic since the late 1980s to the present day shows that the rate of ASR studies increased gradually until 2004 but decreased afterwards. This negative trend is amplified by a recent increase in the number of negative results and criticisms of the ASR hypothesis. The author suggests that much of the recent negativity regarding this topic is due to the formulation of this hypothesis as a power-law fit to cumulative seismicity series. This approach is intrinsically linked to the consensus for criticality, evident from an overview of the ASR literature, to explain the emergence of power-laws in earthquake populations. The holistic view of the earth's crust as a complex system restricts seismicity pattern analyses to the study of main features such as power-laws, while a reductionist view would allow for more refined ones. Such a paradigm shift, or 'sea change', might be under way in the ASR literature where in 2007 a new approach was proposed to explain the ASR power-law from combined concepts of elastic rebound and geometry. Reductionism versus holism is a fundamental problem that not only applies to the study of ASR but also to the broader field of earthquake physics and earthquake predictability science. (C) 2011 Elsevier B.V. All rights reserved.