Update of the single-station sigma analysis for the Italian strong-motion stations

Abstract

This paper is a reappraisal of the study on the single-station sigma for Italian strong-motion stations carried out by Luzi et al. (Bull Seismol Soc Am 104:467–483, 2014). A residual analysis considering the time interval 1972–2015 is carried out on two datasets, using 4.0 and 3.5 as magnitude thresholds, and the ground motion prediction equations by Bindi et al. (Bull Earthq Eng 9:1899–1920, 2011) as reference model for the calculations of the expected median intensity measures. The magnitude threshold of 3.5 is selected with the aim of obtain the largest number of records for each station and evaluate the influence of low magnitude events on the standard deviation of the residual compo- nents. The dataset contains about 8400 waveforms, relative to 522 events, recorded by 600 strong-motion stations, about five times the stations considered in Luzi et al. (2014). We also discuss elements that can influence the variability at individual station, as the number of records, the presence of analog waveforms and records from multiple source-to-site paths. For each station, the event-corrected single-station standard deviation for an indi- vidual site, /ss,s, and the site-term, dS2Ss, have been provided. The results of this study can be used as input for the site-specific probabilistic seismic hazard assessment in Italy, removing the ergodic assumption.