Modeling ground deformations of Panarea volcano hydrothermal/geothermal system (Aeolian Islands, Italy) from GPS data |
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Authors: | Alessandra Esposito Marco Anzidei Simone Atzori Roberto Devoti Guido Giordano Grazia Pietrantonio |
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Institution: | 1. Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143, Rome, Italy 2. Dipartimento Scienze Geologiche, Università Roma Tre, L.go S. L. Murialdo 1, 0146, Rome, Italy
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Abstract: | Panarea volcano (Aeolian Islands, Italy) was considered extinct until November 3, 2002, when a submarine gas eruption began
in the area of the islets of Lisca Bianca, Bottaro, Lisca Nera, Dattilo, and Panarelli, about 2.5 km east of Panarea Island.
The gas eruption decreased to a state of low degassing by July 2003. Before 2002, the activity of Panarea volcano was characterized
by mild degassing of hydrothermal fluid. The compositions of the 2002 gases and their isotopic signatures suggested that the
emissions originated from a hydrothermal/geothermal reservoir fed by magmatic fluids. We investigate crustal deformation of
Panarea volcano using the global positioning system (GPS) velocity field obtained by the combination of continuous and episodic
site observations of the Panarea GPS network in the time span 1995–2007. We present a combined model of Okada sources, which
explains the GPS results acquired in the area from December 2002. The kinematics of Panarea volcano show two distinct active
crustal domains characterized by different styles of horizontal deformation, supported also by volcanological and structural
evidence. Subsidence on order of several millimeters/year is affecting the entire Panarea volcano, and a shortening of 10−6 year−1 has been estimated in the Islets area. Our model reveals that the degassing intensity and distribution are strongly influenced
by geophysical-geochemical changes within the hydrothermal/geothermal system. These variations may be triggered by changes
in the regional stress field as suggested by the geophysical and volcanological events which occurred in 2002 in the Southern
Tyrrhenian area. |
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