Slab-Plume Interaction beneath the Pacific Northwest

Mathias Obrebski
Richard M. Allen
University of California, Berkeley
Mei Xue
Tongji University
Shu-Huei Hung
National Taiwan University

Geophys. Res. Lett. , 37 L14305, doi:10.1029/2010GL043489, 2010

Download a reprint: ObrebskiEtAlDNA09grl2010.pdf
Includes the manuscript and the supplementary text and figs.

Data products:
Download the DNA09-P&S model data file, or view the model in the IRIS EMC: DAN09-P&S

dna.berkeley.edu makes the DNA09 P- and S-velocity models available

Abstract
The Pacific Northwest has undergone complex plate reorganization and intense tectono-volcanic activity to the east during the Cenozoic (last 65 Ma). Here we show new high-resolution tomographic images obtained using shear and compressional data from the ongoing USArray deployment that demonstrate first that there is a continuous, whole-mantle plume beneath the Yellowstone Snake River Plain (YSRP) and second, that the subducting Juan de Fuca (JdF) slab is fragmented and even absent beneath Oregon. The analysis of the geometry of our tomographic models suggests that the arrival and emplacement of the large Yellowstone plume had a substantial impact on the nearby Cascadia subduction zone, promoting the tearing and weakening of the JdF slab. This interpretation also explains several intriguing geophysical properties of the Cascadia trench that contrast with most other subduction zones, such as the absence of deep seismicity and the trench-normal fast direction of mantle anisotropy. The DNA09 velocity models are available for download and slicing at http://dna.berkeley.edu.

Media coverage
MSNBC/OurAmazingPlanet | Underground column of molten rock found at Yellowstone | pdf
DiscoveryNews | Yellowstone hotspot shreds ancient pacific ocean | pdf

© Richard M Allen