Publication Date:
2017-04-04
Description:
The Campi Flegrei (southern Italy) is one of the most active calderas in
the world. This caldera is characterized by episodes of slow vertical ground movement,
called bradyseism. With several hundred thousand people living within its borders,
this area is in a high-risk category should there be an eruption. The seismological
monitoring system in the Campi Flegrei is based on nine seismic stations, eight of
which are equipped with short-period seismometers (1 Hz), and one with a broadband
seismometer (60 sec–50 Hz). While all of the seismic stations are located on land, part
of the seismic activity occurs in the undersea area of the Pozzuoli Gulf (Campi Flegrei),
where there are no seismic stations. This gap in the data coverage produces a
biased and incomplete image of the volcanic area.We carried out an experiment in the
Pozzuoli Gulf with the installation of two broadband seismic stations on the seafloor
with remote and continuous data acquisition for a duration of 31 days between January
and March 2005. Using the data acquired, we have computed the power spectral density
(PSD) to characterize the background seismic noise, and to evaluate the true noise
variation, we have generated the seismic noise probability density functions from the
computed PSD curves. The results of our analysis show that the broadband seismic
noise is high when compared with the Peterson noise model (land model), but for
periods less than 0.3 sec, the seismic noise on the seafloor is lower than the recordings
on land over the same period range. The last bradyseismic crisis (1982–1984) highlights
the importance of this frequency range, where most of the spectral content of
the recorded earthquakes was observed. Finally, we evaluate the detection threshold
of a new seismic station located on the seafloor of the Campi Flegrei caldera considering
the characteristics of the local seismicity. This analysis shows that the detection
threshold for the sea-floor stations (Mw ∼ 0:2) is less than that for land stations
(Mw ∼ 0:8).
Description:
Published
Description:
2962–2974
Description:
1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
Description:
JCR Journal
Description:
reserved
Keywords:
Campi Flegrei Caldera
;
Sea-Floor and On-Land Seismic
;
04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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