The 3D Attenuation Structure of Deception Island (Antarctica)

• Published in: Surveys in Geophysics
• Main Authors: Prudencio J., De Siena L., Ibanez J. M., Del Pezzo E., Garcia-Yeguas A., Diaz-Moreno A.
• Other Authors: Ibanez J.M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: Antarctica; Attenuation; Scattering; Tomography; Bransfield Trough; Deception Island; Inner Bay; Antarc*
• Online Access: https://hdl.handle.net/11585/944875; https://doi.org/10.1007/s10712-015-9322-6

The seismic and volcanological structure of Deception Island (Antarctica) is an intense focus topic in Volcano Geophysics. The interpretations given by scientists on the origin, nature, and location of the structures buried under the island strongly diverge. We present a high-resolution 3D P-wave attenuation tomography model obtained by using the coda normalization method on 20,293 high-quality waveforms produced by active sources. The checkerboard and synthetic anomaly tests guarantee the reproduction of the input anomalies under the island down to a depth of 4km. The results, once compared with our current knowledge on the geological, geochemical, and geophysical structure of the region, depict Deception as a piecemeal caldera structure coming out of the Bransfield Trough. High-attenuation anomalies contouring the northeastern emerged caldera rim correlate with the locations of sediments. In our interpretation, the main attenuation contrast, which appears under the collapsed southeastern caldera rim, is related to the deeper feeding systems. A unique P-wave high-attenuation spherical-like anomaly in the inner bay extends between depths of 1 and 3km. The northern contour of the anomaly coincides with the calderic rim both at 1 and 2km, while smaller anomalies connect it with deeper structures below 3km, dipping toward the Bransfield Trough. In our interpretation, the large upper anomaly is caused by a high-temperature shallow (1–3km deep) geothermal system, located beneath the sediment-filled bay in the collapsed blocks and heated by smaller, deeper contributions of molten materials (magma) rising from southeast.