Spatial distribution of intrinsic and scattering seismic attenuation in active volcanic islands – II: Deception Island images

• Published in: Geophysical Journal International
• Main Authors: Prudencio, I., Ibanez, J., Garcia-Yeguas, A., Del Pezzo, E., Posadas, A. M.
• Other Authors: Prudencio, I.; Instituto Andaluz de Geofısica, Campus de Cartuja, University of Granada, E-18071 Granada, Spain, Ibanez, J.; Instituto Andaluz de Geof´ısica, Campus de Cartuja, University of Granada, E-18071 Granada, Spain, Garcia-Yeguas, A.; Instituto Andaluz de Geofısica, Campus de Cartuja, University of Granada, E-18071 Granada, Spain, Del Pezzo, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia, Posadas, A. M.; Departamento De Quımica y Fısica, Canana de San Urbano, University of Almerıa, E-04071 Almerıa, Spain, Instituto Andaluz de Geofısica, Campus de Cartuja, University of Granada, E-18071 Granada, Spain, Instituto Andaluz de Geof´ısica, Campus de Cartuja, University of Granada, E-18071 Granada, Spain, Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia, Departamento De Quımica y Fısica, Canana de San Urbano, University of Almerıa, E-04071 Almerıa, Spain
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell 2013
• Subjects: Seismic attenuation; Seismic tomography; Volcano seismology; Wave scattering and diffraction; Wave propagation; 04. Solid Earth::04.06. Seismology::04.06.07. Tomography and anisotropy; 04. Solid Earth::04.06. Seismology::04.06.08. Volcano seismology; 04. Solid Earth::04.06. Seismology::04.06.09. Waves and wave analysis; Deception Island; Inner Bay; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/2122/8836; https://doi.org/10.1093/gji/ggt360

In this work, we present regional maps of the inverse intrinsic quality factor (Qi −1), the inverse scattering quality factor (Qs −1) and total inverse quality factor (Qt −1) for the volcanic environment of Deception Island (Antarctica). Our attenuation study is based on diffusion approximation, which permits us to obtain the attenuation coefficients for every single couple source-receiver separately. The data set used in this research is derived from an active seismic experiment using more than 5200 offshore shots (air guns) recorded at 32 onshore seismic stations and four ocean bottom seismometers. To arrive at a regional distribution of these values, we used a new mapping technique based on a Gaussian space probability function. This approach led us to create ‘2-D probabilistic maps’ of values of intrinsic and scattering seismic attenuation. The 2-D tomographic images confirm the existence of a high attenuation body below an inner bay of Deception Island. This structure, previously observed in 2-D and 3-D velocity tomography of the region, is associated with a massive magma reservoir. Magnetotelluric studies reach a similar interpretation of this strong anomaly. Additionally, we observed areas with lower attenuation effects that bear correlation with consolidated structures described in other studies and associated with the crystalline basement of the area. Our calculations of the transport mean-free path and absorption length for intrinsic attenuation gave respective values of ≈950 m and 5 km, which are lower than the values obtained in tectonic regions or volcanic areas such as Tenerife Island. However, as observed in other volcanic regions, our results indicate that scattering effects dominate strongly over the intrinsic attenuation. This work has been partially supported by the Spanish project Ephestos, CGL2011–29499-C02–01, by the EU project EC-FP7 MEDiterranean SUpersite Volcanoes (MED-SUV), by the Basque Government researcher training program BFI09.277 and by the Regional project ‘Grupo de ...