HR: 1330h
AN: V22A-0563    [PDF]
TI: Marine Geophysical Investigations of Vestmannaeyjar and the Reykjanes Ridge, Iceland
AU: * Hey, R N
EM: hey@soest.hawaii.edu
AF: Univ. of Hawaii, 2525 Correa Rd, Honolulu, HI 96822 United States
AU: Hoskuldsson, A
EM: armh@hi.is
AF: Univ. of Iceland, Sudurgata 101, Reykjavik, 101 Iceland
AU: Driscoll, N
EM: ndriscoll@ucsd.edu
AF: Scripps Inst. of Oceanography, GRD, La Jolla, CA 92093 United States
AU: Detrick, R
EM: rdetrick@whoi.edu
AF: Woods Hole Oceanographic Inst., 360 Woods Hole Rd, Woods Hole, MA 02543 United States
AB: In July-August 2003 we conducted brief surveys of the Vestmannaeyjar area, south of Iceland, to try to determine whether or not the recent volcanic eruptions here result from nascent plate boundary processes. We used the SIO SUBSCAN chirp seismic system to collect seismic profiles and sidescan sonar swaths from the R/V Bjarni Saemundsson, and the EM300 system on the R/V Arni Fridriksson to acquire swath bathymetry and backscatter data. Vestmannaeyjar, including the recently active eruptive centers of Surtsey and Heimaey, may be forming at the tip of the reorganizing North America - Eurasia plate boundary system, where the seafloor spreading on Iceland appears to be shifting from the Western Volcanic Zone to the Eastern Volcanic Zone (EVZ). A linear chain of small islands and seafloor eruptions is consistent with Vestmannaeyjar being the southern extension of the EVZ. The seafloor volcanic pattern shows large spatial variability, with only a few indications of tectonic rift structures seen in either the seafloor or subsurface data. If this is the tip of a propagating rift, the rifting has not yet focussed the volcanic eruptions into a single coherent eruptive segment. Alternatively, these eruptions could result from plume flank volcanism, or some other process. In contrast to Vestmannaeyjar, a brief EM300 survey of the first Reykjanes Ridge segment offshore of the Reykjanes Peninsula shows that seafloor spreading here has been active long enough that the volcanism has coalesced into a focussed volcanic system. Few rift structures are visible here either, perhaps because shallow explosive eruptions tend to bury them. The approximately 20 degree change in azimuth between the en echelon volcanic system trends on the Reykjanes Peninsula and those observed on the Reykjanes Ridge occurs within this first offshore segment.
DE: 3035 Midocean ridge processes
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 8150 Plate boundary--general (3040)
DE: 8164 Stresses--crust and lithosphere
DE: 8400 VOLCANOLOGY
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting