Publication Date:
2020-12-21
Description:
This article has been accepted for publication in Geophysical Journal International. Published by Oxford University Press on behalf of the Royal Astronomical Society.
Description:
The classical procedure of the Probabilistic Seismic Hazard Analysis (PSHA) requires a
Poissonian distribution of earthquakes. Seismic catalogs follow a Poisson distribution just after
the application of a declustering algorithm that leaves only one earthquake for each seismic
sequence (usually the stronger, i.e. the main shock). Removing earthquakes from the seismic
catalogs leads to underestimation of the annual rates of the events and consequently associate
with low seismic hazard as indicated by several studies. In this study, we aim investigating the
performance of two declustering methods on the Italian instrumental catalog and the impact of
declustering on estimation of the b-value and on the seismic hazard analysis. To this end, first the
spatial variation in the seismicity rate was estimated from the declustered catalogs using the
adaptive smoothed seismicity approach, considering small earthquakes (Mw≥3.0). We then
corrected the seismicity rates using new approach that allows for counting all events in the
complete seismic catalog by simply changing the magnitude frequency distribution. The impact
of declustering on seismic hazard analysis is illustrated using PSHA maps in terms of peak
ground acceleration (PGA) and spectral acceleration (SA) in 2 s, with 10% and 2% probability of
exceedance in 50 years, for Italy. We observed that the hazard calculated from the declustered
catalogs was always lower than the hazard computed using the complete catalog. These results
are in agreement with previous results obtained in different parts of the world.
Description:
Published
Description:
1174–1187
Description:
6T. Studi di pericolosità sismica e da maremoto
Description:
JCR Journal
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
