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Seismic tomography of Central São Miguel, Azores |
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| Authors: | Daria Zandomeneghi Javier Almendros Jesús M Ibez Gilberto Saccorotti |
| Institution: | aInstituto Andaluz de Geofísica, Universidad de Granada, Campus de Cartuja, 18071 Granada, Spain bDepartamento de Física Teórica y del Cosmos, Universidad de Granada, Campus de Fuentenueva, 18071 Granada, Spain cIstituto Nazionale di Geofisica e Vulcanologia (INGV)-Osservatorio Vesuviano, Via Diocleziano 328, 80124 Napoli, Italy |
| Abstract: | We determine the three-dimensional distribution of P- and S-wave velocities for Central São Miguel Island (Azores, Portugal) by tomographic inversion of local earthquake arrival times. We use P- and S-phases from 289 earthquakes recorded by a network of 20 seismometers. The model shows good resolution in the shallowest 5–6 km, as illustrated by different resolution tests. There are several velocity anomalies, interpreted as pyroclastic deposits, intrusive bodies, geothermal fields, and the effects of tectonics. A low Vp zone marks Furnas caldera, probably evidencing volcaniclastic sediments with development of intense geothermal activity. Another low Vp zone extends in correspondence of the highly fractured area between Fogo and the north coast. Conversely, strong positive anomalies are found south of Fogo and northwest of Furnas. They are interpreted in terms of high-density deposits and remnants of a plutonic intrusion. These interpretations are supported by the distribution of Vp/Vs, and are consistent with previous geological, geochemical, and geophysical data. |
| Keywords: | Seismic tomography Volcano seismology Crustal structure Azores |
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