Publication Date:
2017-04-04
Description:
The site-corrected source scaling pattern is estimated for local earthquakes
(0:9 ≤MD ≤ 3:6) at Mt. Vesuvius. The dataset comprises 35 low-to-moderate
local earthquakes recorded by 14 three-component seismic stations during 1993,
1996, and 1999.
Site-transfer functions in the frequency range 1 Hz–25 Hz are estimated from the
spectra of S waves and coda waves and from the horizontal-to-vertical (H=V) spectral
ratios. We applied the direct spectral ratios method to S waves, considering as a reference
the average spectrum and the inversion method to S waves and coda waves.
The site amplification on the coda waves was also compared with that evaluated using
the wavelet transform. The standard deviation associated with the experimental results
is computed for all of the used methods.
Results indicate a general agreement among the methods, and the site-transfer
functions show interesting features. The highest amplifications are found for frequencies
lower than 12 Hz for sites located at lower altitude. The methods based on coda
waves show highest amplification with respect to the methods based on S waves for
most of the sites located in the summit part of the volcano. This can be a phenomenon
of coda localization, which consists in the trapping inside the upper part of the volcano
of scattered waves. The H=V spectral ratios do not show total agreement with the other
methods, mostly for the sites located in the summit part of the volcano. The discrepancies
among the results obtained in this work are also due to the different normalization
applied in the methods of analysis.
Generalized inversion method allowed us to estimate the source scaling of the
site-corrected source seismic spectrum for the investigated area. The source scaling
obtained in terms of seismic moment and source radii shows that the seismicity of
Mt. Vesuvius is characterized by stress drop as low as a few bars (10 bars) except
for the event of MD 3:6 (Δσ 100 bars). The scaling pattern shows an apparent
linear relationship between source size and seismic moment (for MD ≤ 3:3) but the
statistical test shows that the linear trend has low reliability.
Description:
Published
Description:
1705-1719
Description:
1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
Description:
3.1. Fisica dei terremoti
Description:
JCR Journal
Description:
reserved
Keywords:
Source Scaling
;
Site Effects
;
Mt. Vesuvius
;
04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
;
04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology
;
04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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