Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/6420
AuthorsLombardi, A. M.* 
Marzocchi, W.* 
TitleThe Assumption of Poisson Seismic-Rate Variability in CSEP/RELM Experiments
Issue Date2010
Series/Report no.5A/100 (2010)
DOI10.1785/0120100012
URIhttp://hdl.handle.net/2122/6420
Keywordsstatistical tests
forecasting models
Subject Classification04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability 
AbstractEvaluating the performances of earthquake forecasting/prediction models is the main rationale behind some recent international efforts like the Regional Earthquake Likelihood Model (RELM) and the Collaboratory for the Study of Earthquake Predictability (CSEP). Basically, the evaluation process consists of two steps: 1) to run simultaneously all codes to forecast future seismicity in well-defined testing regions; 2) to compare the forecasts through a suite of statistical tests. The tests are based on the likelihood score and they check both the time and space performances. All these tests rely on some basic assumptions that have never been deeply discussed and analyzed. In particular, models are required to specify a rate in space-time-magnitude bins, and it is assumed that these rates are independent and characterized by Poisson uncertainty. In this work we have explored in detail these assumptions and their impact on CSEP testing procedures when applied to a widely used class of models, i.e., the Epidemic-Type Aftershock Sequence (ETAS) models. Our results show that, if an ETAS model is an accurate representation of seismicity, the same "right" model is rejected by the current CSEP testing procedures a number of times significantly higher than expected. We show that this deficiency is due to the fact that the ETAS models produce forecasts with a variability significantly higher than that of a Poisson process, invalidating one of the main assumption that stands behind the CSEP/RELM evaluation process. Certainly, this shortcoming does not negate the paramount importance of the CSEP experiments as a whole, but it does call for a specific revision of the testing procedures to allow a better understanding of the results of such experiments.
Appears in Collections:Papers Published / Papers in press

Files in This Item:
File Description SizeFormat 
lombardi_marzocchi_revised.doc.pdfMain article2.27 MBAdobe PDFView/Open
Show full item record

Page view(s)

233
Last Week
0
Last month
checked on Jun 24, 2017

Download(s)

324
checked on Jun 24, 2017

Google ScholarTM

Check

Altmetric