Deep long-period earthquakes west of the volcanic arc in Oregon: evidence of serpentine dehydration in the fore-arc mantle wedge

Geophysical Research Letters
By: , and 

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Abstract

Here we report on deep long-period earthquakes (DLPs) newly observed in four places in western Oregon. The DLPs are noteworthy for their location within the subduction fore arc: 40–80 km west of the volcanic arc, well above the slab, and near the Moho. These “offset DLPs” occur near the top of the inferred stagnant mantle wedge, which is likely to be serpentinized and cold. The lack of fore-arc DLPs elsewhere along the arc suggests that localized heating may be dehydrating the serpentinized mantle wedge at these latitudes and causing DLPs by dehydration embrittlement. Higher heat flow in this region could be introduced by anomalously hot mantle, associated with the western migration of volcanism across the High Lava Plains of eastern Oregon, entrained in the corner flow proximal to the mantle wedge. Alternatively, fluids rising from the subducting slab through the mantle wedge may be the source of offset DLPs. As far as we know, these are among the first DLPs to be observed in the fore arc of a subduction-zone system.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Deep long-period earthquakes west of the volcanic arc in Oregon: evidence of serpentine dehydration in the fore-arc mantle wedge
Series title Geophysical Research Letters
DOI 10.1002/2013GL059118
Volume 41
Issue 2
Year Published 2014
Language English
Publisher American Geophysical Union
Publisher location Washington, D.C.
Contributing office(s) Volcano Hazards Program, Volcano Science Center
Description 7 p.
First page 370
Last page 376
Country United States
State Oregon
Online Only (Y/N) N
Additional Online Files (Y/N) N