eprintid: 1367 rev_number: 17 eprint_status: archive userid: 2 dir: disk0/00/00/13/67 datestamp: 2015-02-10 13:22:24 lastmod: 2017-02-08 13:01:13 status_changed: 2015-04-27 12:10:46 type: article metadata_visibility: show creators_name: Lombardi, Anna Maria creators_name: Marzocchi, Warner corp_creators: Instituto Nazionale di Geofisica e Vulcanologia, Rome, Italy corp_creators: Instituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy title: Evidence of clustering and nonstationarity in the time distribution of large worldwide earthquakes ispublished: pub subjects: MP2_1 subjects: MP2_3 divisions: EPOS-P full_text_status: none abstract: The purpose of this paper is to characterize the statistical distribution of worldwide largest earthquakes. We analyze the distribution of worldwide shallow events with M s 7.0+ since 1900, by following the Occam’s razor philosophy; we start from the simplest possible model (stationary Poisson process), and we inspect more complicated models only if the data show significant departures from the simplest one. The results show two important characteristics; first, worldwide M s 7.0+ earthquakes tend to cluster in time and space, with features similar to smaller events. Second, for some seismic regions there is evidence in favor of long-term fluctuations of the earthquake rate. These results support the hypothesis of universality, suggesting that an ETAS model with a background varying with time can be considered reliable to describe the seismicity distribution over a wide space-time-magnitude window. From a practical point of view, our findings suggest that the paradigm that seismic zones are stationary systems, implicitly assumed in seismic hazard assessment, should be regarded with caution. date: 2007-02-15 date_type: published publication: Journal of Geophysical Research volume: 112 number: B2 publisher: American Geophysical Union pagerange: 313-320 id_number: doi:10.1029/2006JB004568 refereed: TRUE issn: 0148-0227 official_url: http://dx.doi.org/10.1029/2006JB004568 access_IS-EPOS: limited owner: Publisher citation: Lombardi, Anna Maria and Marzocchi, Warner (2007) Evidence of clustering and nonstationarity in the time distribution of large worldwide earthquakes. Journal of Geophysical Research, 112 (B2). pp. 313-320. DOI: https://doi.org/10.1029/2006JB004568