Seismic noise at Solfatara Volcano (Campi Flegrei, Italy): acquisition techniques and first results

In the period 2-6 April 2007 a seismic survey
was carried out at Solfatara Volcano, with the
aim of inferring the shallow structure and evaluating
local site effects. Seismic noise was recorded
by five circular seismic arrays deployed in different
areas of the crater. The geometry was
designed in order to obtain also a sub-configuration
consisting of two profiles oriented in the NS
and E-W directions. An other seismic station
was installed on the eastern rim of the crater, for
a hardrock reference. A preliminary spectral
analysis was performed on some samples of seismic
noise recorded during the experiment.
As future development, surface wave dispersion
will be obtained by using array techniques,
such as the Spatial Autocorrelation
method (SPAC) of Aki (1957) and its recent modifications
(MSPAC, Bettig et al, 2001; CCA, Cho
et al., 2004). The shear-wave velocity models
will be inferred for each array from the inversion
of the dispersion curves. Moreover experimental
site transfer functions will be evaluated for each
station, using both Nakamura’s technique and the
reference-site spectral ratio method.
The high density of the deployment and
the large number of the sampled sites will allow
to obtain a detailed shallow velocity structure
and to map resonance frequencies and amplification
values in different areas of the crater.