HR: 16:00h
AN: V24B-01    [Abstracts]
TI: Magma Intrusion Mechanisms and Redistribution of Seismogenic Stress at Mt. Etna Volcano, Italy: the 1997-1998 Event.
AU: * Privitera, E
EM: privitera@ct.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Piazza Roma, 2, Catania, Ita I-95123 Italy
AU: Barberi, G
EM: barberi@ct.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Piazza Roma, 2, Catania, Ita I-95123 Italy
AU: Bonanno, A
EM: bonanno@ct.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Piazza Roma, 2, Catania, Ita I-95123 Italy
AU: Bonanno, A
EM: bonanno@ct.ingv.it
AF: Dipartimento di Scienze Geologiche, Catania University, Corso Italia, 55, Catania, Ita I-95127 Italy
AU: Cocina, O
EM: cocina@ct.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Piazza Roma, 2, Catania, Ita I-95123 Italy
AU: Neri, G
EM: geoforum@unime.it
AF: Dipartimento di Scienze della Terra, Messina University, Salita Sperone, 31, Messina, ita I-98166 Italy
AU: Salvatore, S
EM: spampinato@ct.ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Piazza Roma, 2, Catania, Ita I-95123 Italy
AB: During 1997 - early 1998 an increasing seismic rate was observed before the renewal of volcanic activity at Mt. Etna. Earthquakes were mainly localized in a highly fractured low - velocity zone located beneath the western slope of the volcano. By inversion of focal mechanisms we found stress orientations rotated (sigma1 ca. East - West) respect to the North - South, compressional regional tectonic stress. Based on the local tomographic structure available, and on the findings of the present study concerning space - time evolution of seismicity and stress orientations before the eruptive phase, we propose that lateral pressure by magma intruding and stationing in north - trending structures located in the low - velocity zone may be the source of stress leading to 1997 - 1998 seismicity. Estimates of Coulomb stress variations confirmed this interpretation because moderate opening on the order of 1m of properly located and sized dikes was found able to induce stress variations as large as 70 bars in the zone affected by seismicity.
DE: 7280 Volcano seismology (8419)
DE: 8145 Physics of magma and magma bodies
DE: 8164 Stresses: crust and lithosphere
DE: 8178 Tectonics and magmatism
DE: 8439 Physics and chemistry of magma bodies
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005