Assessing the depth resolution of tomographic models of upper mantle structure beneath Iceland

Earlier inversions of body wave delay-time data recorded during the ICEMELT portable broadband experiment imaged a cylindrical plume-like low-velocity anomaly extending to at least 400 km depth beneath Iceland, but the depth extent of the anomaly resolvable by tomography has recently been called into question. We have performed several additional resolution tests to evaluate the depth resolution of tomographic models of the Icelandic upper mantle. The distribution of paths of body waves recorded by ICEMELT can distinguish among three different types of models: (a) a wide and shallow anomaly, (b) a narrow and deep anomaly, and (c) a narrow and shallow anomaly. While tomographic models contain an element of nonuniqueness, these tests illustrate that the depth resolution of passive seismic experiments spanning subaerial Iceland is adequate for distinguishing among alternative geodynamic models.This work was supported by the National Science Foundation under grants EAR-9316137, OCE-9402991, and OCE-9618125. We thank two anonymous reviewers for their constructive comments. School of Ocean and Earth Science and Technology, University of Hawaii, contribution number 5874. Hawaii Institute of Geophysics and Planetology contribution number 1184.Peer Reviewe