Publication Date:
2017-04-04
Description:
A scattering image of the Campi Flegrei caldera has been obtained using coda wave envelopes from local microearthquake data
recorded at a portable 12-station digital network. This was operated during the paroxysmic phase of the ground uplift (bradyseism)
that occurred in the years 1983–1984. The Nishigami technique has been used to obtain the 3D distribution of the strong scatterers
in an earth volume with a horizontal extension of 20 km×20 km and a vertical thickness of 6 km. This earth volume was segmented
in blocks of 2 km×2 km×2 km for the outer section, and in blocks of 1 km×1 km×1 km for the inner section. The inversion
was performed using a hybrid jackknife-SVD method that has allowed qualitative control of the stability and robustness of the
solution. The results show that the scatterers revealed by the coda envelopes, which were band-pass filtered at a center frequency of
18 Hz, match the inner border of the caldera rim, which is well outlined on land by geological observations. The scatterer position
also delineates this border well beneath sea level. These results are in close agreement with recently obtained seismic velocity
tomography. The scatterers imaged at the 6 and 12 Hz band-pass frequencies are located around the zone of maximum uplift,
beneath Solfatara crater, where most of the present residual volcanic activity is concentrated.
Description:
Published
Description:
269-280
Description:
reserved
Keywords:
Scattering tomography
;
Campi Flegrei caldera
;
Seismic attenuation
;
Inversion techniques
;
04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
Format:
1232383 bytes
Format:
application/pdf
