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Localizing ground motion models in volcanic terranes: Shallow events at Mt. Etna, Italy, revisited.
Author(s)
Language
English
Obiettivo Specifico
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
6/110 (2020)
ISSN
0037-1106
Publisher
SSA
Pages (printed)
2843–2861
Issued date
December 2020
Abstract
We present a set of revised ground motion models (GMMs) for shallow events at Mt.
Etna volcano. The recent occurrence of damaging events, in particular two of the
strongest earthquakes ever instrumentally recorded in the area, has required revising
previous GMMs as these failed to match the observations made for events with local
magnitude ML >4.3, above all for sites situated close to the epicenter. The dataset
now includes 49 seismic events, with a total of 1600 time histories recorded at
distances of up to 100 km, and ML ranging from 3.0 and 4.8. The model gives
estimates of peak ground acceleration (PGA, both horizontal and vertical), peak
ground velocity (PGV, both horizontal and vertical) and 5%-damped horizontal pseudoacceleration
response spectral ordinates (PSA) up to a period of 4 s.
GMMs were developed by using the functional form proposed by Boore and Atkinson
(2008). Furthermore, with a slightly modified approach, we also considered a
regression model using a pseudo-depth (h) depending on magnitude according to the
scaling law by Azzaro et al . (2017). Both models were applied to hypocentral
distance ranges of up to 60 km, and up to 100 km, respectively. From the statistical
analysis, we found that reducing the maximum distance from the event up to 60 km
and introducing a magnitude-dependent pseudo-depth, improved the model in terms of
total error. We compared our results to those derived with the GMMs for shallow
events at Mt. Etna found by Tusa and Langer (2016) and for volcanic areas by
Lanzano and Luzi (2019). The main differences are observed at short epicentral
distances and for higher magnitude events. The use of variable pseudo-depth avoids
sharp peaks of predicted ground motion parameters around the epicenter, preventing
instabilities when using a GMM in probabilistic seismic hazard analysis.
Etna volcano. The recent occurrence of damaging events, in particular two of the
strongest earthquakes ever instrumentally recorded in the area, has required revising
previous GMMs as these failed to match the observations made for events with local
magnitude ML >4.3, above all for sites situated close to the epicenter. The dataset
now includes 49 seismic events, with a total of 1600 time histories recorded at
distances of up to 100 km, and ML ranging from 3.0 and 4.8. The model gives
estimates of peak ground acceleration (PGA, both horizontal and vertical), peak
ground velocity (PGV, both horizontal and vertical) and 5%-damped horizontal pseudoacceleration
response spectral ordinates (PSA) up to a period of 4 s.
GMMs were developed by using the functional form proposed by Boore and Atkinson
(2008). Furthermore, with a slightly modified approach, we also considered a
regression model using a pseudo-depth (h) depending on magnitude according to the
scaling law by Azzaro et al . (2017). Both models were applied to hypocentral
distance ranges of up to 60 km, and up to 100 km, respectively. From the statistical
analysis, we found that reducing the maximum distance from the event up to 60 km
and introducing a magnitude-dependent pseudo-depth, improved the model in terms of
total error. We compared our results to those derived with the GMMs for shallow
events at Mt. Etna found by Tusa and Langer (2016) and for volcanic areas by
Lanzano and Luzi (2019). The main differences are observed at short epicentral
distances and for higher magnitude events. The use of variable pseudo-depth avoids
sharp peaks of predicted ground motion parameters around the epicenter, preventing
instabilities when using a GMM in probabilistic seismic hazard analysis.
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article
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