HR: 0800h
AN: V21D-0636    [Abstracts]
TI: Geodetic constraints on the magma chamber of the Hekla volcano, Iceland
AU: * Sturkell, E
EM: sturkell@hi.is
AF: Nordic Volcanological Center, 7 Sturlugata, Reykjavik, 101 Iceland
AU: Agustsson, K
EM: kri@vedur
AF: Icelandic Meteorological Office, 9 Bustadavegur, Reykjavik, 150
AU: Linde, A T
EM: linde@dtm.ciw.edu
AF: Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, Washington N.W., DC 20015 United States
AU: Sacks, S I
EM: sacks@dtm.ciw.edu
AF: Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, Washington N.W., DC 20015 United States
AU: Einarsson, P
EM: palli@raunvis.hi.is
AF: Institute of Earth Sciences, University of Iceland, 7 Sturlugata, Reykjavik, 101 Iceland
AU: Sigmundsson, F
EM: fs@hi.is
AF: Nordic Volcanological Center, 7 Sturlugata, Reykjavik, 101 Iceland
AU: Geirsson, H
EM: dori@vedur.is
AF: Icelandic Meteorological Office, 9 Bustadavegur, Reykjavik, 150
AU: Pedersen, R
EM: rikke@hi.is
AF: Nordic Volcanological Center, 7 Sturlugata, Reykjavik, 101 Iceland
AU: La Femina, P
EM: plafemina@rsmas.miami.edu
AF: Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, 4600 Rickenbacker Cswy, Miami, FL 33149 United States
AB: Hekla is one of the most frequently erupting volcanoes in Iceland, with at least 18 eruptions in the past 1000 years. During the last 40 years it has erupted about every 10 years. The most recent eruption occurred on February 26 - March 8, 2000. The initial sub-Plinian phase lasted less than one hour, later the eruption became effusive. The crustal deformation network around Hekla consists of strainmeters, campaign and continuous GPS, optical tilt stations and InSAR. Strain and tilt at one station were measured immediately before the 2000 eruption, but the GPS network was surveyed last in 1996. After the eruption the GPS network has been surveyed annually. The far strain stations and one tilt station are used to model the magma chamber, located at 11-km depth under the summit of Hekla. The volume of the dike is estimated from calculated erupted volumes and the ratio of volume that left the magma chamber at different times. The eruptive fissure is 6.6 km long on the surface and with a width of 0.8 m. The dike model is constrained by a strainmeter at 15 km distance and by deformation observed with the GPS network, and is estimated to be about 1 km in height, and fed by a narrow conduit. Diking associated with the 2000 eruption of Hekla appears to be limited to very shallow depth, suggesting that the dike is mostly within the topographic edifice of Hekla (about 1.5 km high). From this it seems that Hekla is presently behaving as a stratovolcano, rather than a typical Icelandic rift-zone volcano.
DE: 1213 Earth's interior: dynamics (1507, 7207, 7208, 8115, 8120)
DE: 8416 Mid-oceanic ridge processes (1032, 3614)
DE: 8419 Volcano monitoring (7280)
DE: 8485 Remote sensing of volcanoes
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005