Publication Date:
2017-04-04
Description:
Here, we propose a method for the determination of Vp/Vs ratios
in a horizontally layered propagation media using maximization of a coherency
function along theoretical travel-times of PS reflected phases. The theoretical
travel-times are computed using the information about the propagation media
that is extracted by velocity analysis or by topographic analysis performed on
the first arrivals. The method is also a valid tool for the identification of the PS
phases associated with a fixed seismic reflector, and it is particularly suitable for
data that is stored in common mid-point and common conversion point bin-
ning; for this kind of data the hypothesis of horizontally and layered media can
usually be verified.
We applied the method to both simulated and real datasets. The use of the real
data that was acquired in the Campi Flegrei caldera (southern Italy) allowed us
to estimate a relatively high Vp/Vs ratio (3.5 ± 0.6) for a very shallow layer
(maximum depth, 600 m). This hypothesis has been tested by theoretical rock
physical modeling of the Vp/Vs ratios as a function of porosity, suggesting
that the shallow layer appears to be formed of unconsolidated, water-saturated,
volcanic and marine sediments that filled Pozzuoli Bay during the post-caldera
activity.
Description:
I.N.G.V.
Description:
Published
Description:
1.4. TTC - Sorveglianza sismologica delle aree vulcaniche attive
Description:
open
Keywords:
Converted phase identification
;
Flegrei caldera
;
04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
report
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