Seismic structure of the Iceland mantle
Cecily J. Wolfe, Ph.D.
Woods Hole Oceanographic Institution
Wednesday, May 13, 1998
3:30 p.m.¾ Pacific Forum
Understanding the geometry of upwelling mantle flow and the characteristics of melting
beneath hotspots and mid-ocean ridges is of fundamental importance for topics ranging from
the formative processes for the crust and lithosphere to the large-scale dynamics and
chemical makeup of the mantle. One of the most studied regions is Iceland, a hotspot
centered on the Mid-Atlantic Ridge, yet previous seismological and geodynamic studies have
been unable to constrain the width, temperature, and depth extent of the plume.
ICEMELT was a regional broadband seismometer array designed to resolve the detailed
characteristics of the upper-mantle seismic structure beneath Iceland. We obtain the
three-dimensional seismic velocity structure of the upper mantle using the relative travel
times of body waves from teleseismic earthquakes recorded across the ICEMELT array.
Inversion solutions show a cylindrical zone of low P-wave and S-wave velocities that
persists from 100 km to at least 400 km depth beneath central Iceland, which can be
interpreted as the locus of the active Iceland mantle plume. The radius of the
low-velocity anomaly is about 150 kilometers, and the magnitude of the velocity anomaly is
2% for P waves and 4% for S waves. This high-resolution upper mantle image indicates that
Iceland is underlain by a hot and narrow plume of upwelling mantle.
deformation from holocene earthquakes
Last updated: December 19, 2000