HR: 1330h
AN: V22A-0576    [PDF]
TI: Dike Models of Tiltmeter Data From the 1984 Rifting Event at Krafla, Iceland: Testing for a Vertical Component to the Propagation Direction
AU: * Richard, D
EM: drich@usc.edu
AF: Earth Science Department, University of Southern California, 3651 Trousdale Parkway, Los Angeles, CA 90089
AU: Owen, S
EM: owen@terra.usc.edu
AF: Earth Science Department, University of Southern California, 3651 Trousdale Parkway, Los Angeles, CA 90089
AU: Sigmundsson, F
EM: fs@norvol.hi.is
AF: Nordic Volcanological Institute, Grensasvegur 50, Reykjavik, IS-108 Iceland
AB: The September 4th 1984 Krafla fissure eruption occurred in northern Iceland at the end of the 1975-1984 rifting episode. The surface deformation resulting from the propagation of the feeder dike was monitored by three continuously recording tiltmeters located around the southern end of the ~ 8.5 km long fissure, within the Krafla caldera. The tiltmeter time series (east and north components) were compared to models of dike propagation and magma chamber deflation by computing model-predicted tilt from both a growing dislocation and a deflating Mogi source in an elastic half-space. End-member models (vertical vs. lateral propagation) favored vertical dike propagation, indicating that there was an important vertical component to the propagation direction. However, dike propagation models that combined lateral and vertical dike propagation indicated that, below ~ 1 km, the continuous tiltmeter network was inadequate for determining the depth at which the dike initiated vertical propagation. We also found that the fit to the continuous tiltmeter time series was improved by adjusting some of the dike and magma chamber model parameters. These parameters had been estimated based on EDM, leveling, and optical tilt data that spanned different time periods. We ran inversions of EDM, leveling, and optical leveling tilt data with the continuous tilt data to provide a realistic model for the dike and magma chamber parameters. Results from this study can improve our understanding of the magma transport mechanisms at Krafla and similar volcanic systems such as mid-ocean ridges.
DE: 1200 GEODESY AND GRAVITY
DE: 8434 Magma migration
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting