EGU2020-14510, updated on 13 Feb 2021
EGU General Assembly 2020
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Does the seismic cycle slip toward randomness?

Zakaria Ghazoui1,2,3, Jean-Robert Grasso3, Arnaud Watlet4, Corentin Caudron3, Abror Karimov3, Sebastien Bertrand2, Yusuke Yokoyama5, and Peter van der Beek3
Zakaria Ghazoui et al.
  • 1GFZ German Research Centre for Geosciences, Potsdam, Germany (
  • 2Department of Geology, Ghent University, Ghent, Belgium
  • 3Université Grenoble Alpes, CNRS, ISTerre (Institut des Sciences de la Terre), Grenoble, France
  • 4British Geological Survey, Environmental Science Centre, Nottingham, United-Kingdom
  • 5Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan

Seismology and paleoseismology seem to be two distant sisters when we address earthquake time-interval distributions. One observation stands out; an apparent discrepancy in time-interval models, i.e. periodic to cluster, within similar tectonic context. As a departure point, we will use the Himalayan context where according to instrumental or paleoseismic catalogues, time-interval distributions are presented as Poisson to periodic. We report on a new 6000-year lake-sediment seismic record and perform statistical analyses to show that time intervals between large (M≥6.5) earthquakes are robustly described by a Poisson distribution, while second-order fluctuations imply event clustering. These patterns are calibrated against an instrumental catalogue for the entire Himalaya; we show that both catalogues are inconsistent with periodic models. Throughout this presentation, we will compare the Himalayan results with paleoseismic catalogues from three distinct tectonic settings (Indonesia, New-Zealand and Jordan). Each of them displays a close to Poisson distribution, in consonance with instrumental catalogues results. Our results imply that the occurrence of major seismic events is as uncertain as smaller events on any time scale, increasing drastically previous estimate of the seismic hazard.

How to cite: Ghazoui, Z., Grasso, J.-R., Watlet, A., Caudron, C., Karimov, A., Bertrand, S., Yokoyama, Y., and van der Beek, P.: Does the seismic cycle slip toward randomness?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14510,, 2020

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