Slab plume interaction beneath the Pacific Northwest
Richard M. Allen,1
and Shu Huei Hung3
Received 1 April 2010; revised 4 June 2010; accepted 16 June 2010; published 22 July 2010.
 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 deploy-
ment 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.