Publication Date:
2023-10-26
Description:
In volcanic areas, accurate localization of earthquakes requires detailed velocity and, possibly, attenuation
models, taking into account wide lithological variability and high geothermal gradients. Ischia island (Campania region, Italy) is a seismically-active volcano recently affected by a Mw 3.9 event (Casamicciola, August 21, 2017, 1 km depth). Due to the lack of a specific velocity model, the earthquakes occurred on the island were localized using the one developed for the nearby Campi Flegrei caldera. The aim of this work is the definition of a mean representative 1D shear-wave velocity (Vs) and attenuation (Q) model of the shallower crust (up to 2 km depth) of Ischia. Seismic noise array and spectral ratios techniques were applied to broad band seismic signals recorded by temporary and permanent networks updated after the August 2017 earthquake. The values of both shear-wave velocity (Vs) and quality factor (Q) are realistic, with Q values comparable with those obtained for Campi Flegrei and Stromboli volcanic areas. By taking into account stratigraphic information from deep wells and ultrasonic measurements of velocity on granite and trachytic lava samples, a geological interpretation of the resulting velocity model is provided. Such a model can have significant implications for understanding the dynamics of a volcano, mainly those leading to seismic activity.
Description:
Published
Description:
106970
Description:
1T. Struttura della Terra
Description:
JCR Journal
Keywords:
Ischia volcanic island
;
Shear wave velocity model
;
Seismic attenuation
;
Seismic noise
;
Velocity and Attenuation model
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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