A reflector at 200 km depth beneath the northwest Pacific

Constraints on the anisotropic contributions to velocity discontinuities at ∼60 km depth beneath the Pacific

Strong, sharp, negative seismic discontinuities, velocity decreases with depth, are observed beneath the Pacific seafloor at ∼60 km depth. It has been suggested that these are caused by an increase in radial anisotropy with depth, which occurs in global surface wave models. Here we test this hypothesis in two ways. We evaluate whether an increase in surface wave radial anisotropy with depth is ...

Slab‐plume interaction beneath the Pacific Northwest

[1] 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...

Detection of a ULVZ at the base of the mantle beneath the northwest Pacific

[1] We used the Yellowknife seismic array (YKA) to measure the slowness of 1,371 P and Pdiff waves from earthquakes occurring in the circum-Pacific region. The corresponding anomalies in P-velocity show a sharp reduction of up to 6% across a patch of the lowermost mantle beneath the Northwest Pacific with lateral dimensions of several hundred kilometers. The location of this ultra low velocity ...

Mantle dynamics beneath the Pacific Northwest and the generation of voluminous back-arc volcanism

Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. [1] The Pacific Northwest (PNW) has a complex tectonic history and over the past $17 Ma has played host to several ...

Starlings in the Pacific Northwest