HR: 15:10h
AN: V12G-07    [PDF]
TI: Magma inflow into Katla, one of Iceland's most hazardous volcanoes
AU: * Sturkell, E
EM: erik@vedur.is
AF: Icelandic Meteorological Office, Reykjav¡k, B£stadavegur 9, Reykjav¡k, 150 Iceland
AU: Sigmundsson, F
EM: fs@norvol.hi.is
AF: Nordic Volcanological Institute, Grens svegur 50, Reykjav¡k, 108 Iceland
AU: Einarsson, P
EM: palli@raunvis.hi.is
AF: Science Institute, University of Iceland, Dunhagi 3, Reykjav¡k, 107 Iceland
AU: Geirsson, H
EM: dori@vedur.is
AF: Icelandic Meteorological Office, Reykjav¡k, B£stadavegur 9, Reykjav¡k, 150 Iceland
AU: Roberts, M J
EM: matthew@vedur.is
AF: Icelandic Meteorological Office, Reykjav¡k, B£stadavegur 9, Reykjav¡k, 150 Iceland
AB: Katla is one of Iceland's most active volcanoes, with twenty large eruptions in the last 1100 years. A seismic survey suggests the presence of a magma chamber under the volcano at 4-5 km depth. The volcano is ice-capped, thus making Katla eruptions phreatomagmatic and capable of triggering jokulhlaups. A minor jokulhlaup in July 1999 associated with an episode of continuous seismic tremor was probably the first sign of resumed magmatic activity under the volcano. GPS measurements on nunataks at the rim of the subglacial caldera, have revealed steady inflation due to magma accumulation from 1999 onwards. These measurements show uplift and horizontal displacement of the nunatak stations at a rate of up to 2 cm/yr, and horizontal displacement of the far field stations at about 0.5 cm/yr away from the caldera centre. Findings suggest progressive caldera inflation over time. Inflation was modeled with a point-source, giving an uplift rate of about 2 cm/yr since 2000. Recent magma inflation falls below the volume of that previously extruded in 1918. The agitated state of the Katla volcano is further expressed by increased earthquake activity that has remained abnormally high and continuous since 2001. Historic Katla eruptions have initially been explosive, allowing high rates of enthalpy extraction due to profuse melting of the glacier base. Floodwater gathers rapidly in a large and inherently unstable water reservoir that bursts suddenly to produce a cataclysmic jokulhlaup that peaks within a few hours. The proximity of the Katla volcano to populated areas and international flight paths makes this volcano one of Iceland's most potent geological hazards.
DE: 8414 Eruption mechanisms
DE: 8434 Magma migration
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting