Vol. 47, n.1-2, March -June 2006
Complex wave propagation in the Campi Flegrei Caldera, Italy, from source- and receiver-array analysis of sea-shot recordings
V. Nisi and G. Saccorotti
Received June 9, 2005; accepted August 9, 2005
We investigate wave propagation in the complex shallow crust of Campi Flegrei Volcanic Complex, Italy, using array recordings of air-guns. We apply source- and receiver-array analysis to define the independent variation of horizontal slowness at both the source and receiver regions. This method allows the identification of asymmetric ray-paths associated with near-source and near-observer velocity heterogeneities. P-wave wave-vectors at both the source and receiver arrays depict discrepancies as large as 50� with respect to the values expected for the 3D velocity structure of the Gulf. At the source region, these discrepancies may be associated with either un-modelled complexities in the geometry of the buried caldera rim, or with velocity variations beneath the source-array. At the receiver array, the inferred anomalies may be attributed to velocity variations marking the Solfatara crater rim, or to a near-receiver, low-velocity body whose position would coincide with negative gravimetric anomalies and a low Vp/Vs ratio region inferred by independent geophysical and seismological studies.
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