Options
Near-Source Attenuation and Spatial Variability of the Spectral Decay Parameter Kappa in Central Italy
Author(s)
Language
English
Obiettivo Specifico
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
4/93 (2022)
ISSN
0895-0695
Publisher
Seismological Society of America
Pages (printed)
2299–2310
Issued date
2022
Abstract
We study the spectral decay parameter κ using S-wave recordings from the central Italy dense regional array. The data set used consists of 266 earthquakes, 353 stations, and 13,952 observations of κ with a mean value of 0.0412 ± 0.0177 within the distance range of 7.1–168.8 km. We model the variation of κ with hypocenter distance r as κ r κ0 κs ̃κ r , in which κ0 and κs represent the near-site and the near-source decay parameters, respectively, and ̃κ r the average κ along the S-wave source-station paths. We first determine ̃κ r with a nonparametric inversion approach and then we solved for κ0 and κs with a second inversion. We found that ̃κ r increases with distance within the whole distance range analyzed (9.2–80.6 km). The near-source decay parameter takes values in the range 0:0 < κs ≤ 0:026 with a mean value of 0.003 ± 0.006, which represents 7.52% of the mean value of the observed κ. The values of the near-site decay parameter vary in the range 0:0035 ≤ κ0 ≤ 0:0823 with a mean value of 0.0298 ± 0.0133, that is, 72.28% of the mean value of the κ observed. We conclude that most of the high- frequency attenuation takes place near the site, because ̃κ r contributes with only 20.2% of the spectral decay. We also investigate the spatial variability of κ by determining ̃κ r within four quadrants that divide the studied region taking as a reference axis the Apennines chain orientation. We found higher values of ̃κ r in the southern quad- rants, where seismicity and faulting are more active, and less attenuation in the more stable northeast quadrant.
Type
article
File(s)
Loading...
Name
SRL-D-21-00276_R2.pdf
Size
5.79 MB
Format
Adobe PDF
Checksum (MD5)
8f67ec5b944fbe6bb8a8fcb4a0417d42
No Thumbnail Available
Name
Castro et al. 2022 SRL.pdf
Description
Restricted Paper
Size
6.96 MB
Format
Adobe PDF
Checksum (MD5)
a550c4c9c86ee187541b0bbd83371175