Publication Date:
2020-09-29
Description:
This chapter summarizes a comparative study of shear-wave velocity models and
seismic sources in the Campanian volcanic areas of Vesuvius and Phlegraean Fields.
These velocity models were obtained through the nonlinear inversion of surfacewave
tomography data, using as a priori constraints the relevant information
available in the literature. Local group velocity data were obtained by means of the
frequency–time analysis for the time period between 0.3 and 2 s and were combined
with the group velocity data for the time period between 10 and 35 s from the
regional events located in the Italian peninsula and bordering areas and two station
phase velocity data corresponding to the time period between 25 and 100 s. In order
to invert Rayleigh wave dispersion curves, we applied the nonlinear inversion
method called hedgehog and retrieved average models for the first 30–35km of the
lithosphere, with the lower part of the upper mantle being kept fixed on the basis of
existing regional models.
A feature that is common to the two volcanic areas is a low shear velocity layer
which is centered at the depth of about 10 km, while on the outside of the cone and
along a path in the northeastern part of the Vesuvius area this layer is absent. This
low velocity can be associated with the presence of partial melting and, therefore,
may represent a quite diffused crustal magma reservoir which is fed by a deeper
one that is regional in character and located in the uppermost mantle. The study of
seismic source in terms of the moment tensor is suitable for an investigation
of physical processes within a volcano; indeed, its components, double couple,
compensated linear vector dipole, and volumetric, can be related to the movements
of magma and fluids within the volcanic system. Although for many recent earthquake
events the percentage of double couple component is high, our results also
show the presence of significant non-double couple components in both volcanic
areas.
Description:
Published
Description:
287-309
Description:
reserved
Keywords:
NONE
;
04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
book chapter
Format:
8247786 bytes
Format:
application/pdf
