@article{BindiSpallarossaPicozzietal.2018,
  author    = {Bindi, Dino and Spallarossa, D. and Picozzi, M. and Scafidi, D. and Cotton, Fabrice},
  title     = {Impact of magnitude selection on aleatory variability associated with ground-motion prediction equations},
  series = {Bulletin of the Seismological Society of America},
  volume    = {108},
  journal   = {Bulletin of the Seismological Society of America},
  number    = {3A},
  publisher = {Seismological Society of America},
  address   = {Albany},
  issn      = {0037-1106},
  doi       = {10.1785/0120170356},
  pages     = {1427 -- 1442},
  year      = {2018},
  abstract  = {In this study, we analyzed 10 yrs of seismicity in central Italy from 2008 to 2017, a period witnessing more than 1400 earthquakes in the magnitude range 2.5≤Mw≤6.5⁠. The data set includes the main sequences that have occurred in the area, including those associated with the 2009 Mw 6.3 L'Aquila earthquake and the 2016-2017 sequence (⁠Mw 6.2 Amatrice, Mw 6.1 Visso, and Mw 6.5 Norcia earthquakes). We calibrated a local magnitude scale, investigating the impact of changing the reference distance at which the nonparametric attenuation is tied to the zero-magnitude attenuation function for southern California. We also developed an attenuation model to compute the radiated seismic energy (⁠Es⁠) from the time integral of the squared ground-motion velocity. Seismic moment (⁠M0⁠) and stress drop (⁠Δσ⁠) were estimated for each earthquake by fitting a ω-square model to the source spectra obtained by applying a nonparametric spectral inversion. The Δσ-values vary over three orders of magnitude from about 0.1 to 10 MPa, the larger values associated with the mainshocks. The Δσ-values describe a lognormal distribution with mean and standard deviation equal to log(Δσ)=(-0.25±0.45) (i.e., the mean Δσ is 0.57 MPa, with a 95\% confidence interval from 0.08 to 4.79 MPa). The Δσ variability introduces a spread in the distribution of seismic energy versus moment, with differences in energy up two orders of magnitudes for earthquakes with the same moment. The variability in the high-frequency spectral levels is captured by the local magnitude (⁠ML⁠), which scales with radiated energy as ML=(-1.59+0.52logEs) for logEs≤10.26 and ML=(-1.38+0.50logEs) otherwise. As the peak ground velocity increases with increasing Δσ⁠, local and energy magnitudes perform better than moment magnitude as predictors for the shaking potential. The availability of different magnitude scales and source parameters for a large earthquake population will help characterize the between-event ground-motion variability in central Italy.},
  language  = {en}
}