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Crustal architecture of the Cascadia Forearc

January 1, 1994

Seismic profiling data indicate that the thickness of an accreted oceanic terrane of Paleocene and early Eocene age, which forms the basement of much of the forearc beneath western Oregon and Washington, varies by approximately a factor of 4 along the strike of the Cascadia subduction zone. Beneath the Oregon Coast Range, the accreted terrane is 25 to 35 kilometers thick, whereas offshore Vancouver Island it is about 6 kilometers thick. These variations are correlated with variations in arc magmatism, forearc seismicity, and long-term forearc deformation. It is suggested that the strength of the forearc crust increases as the thickness of the accreted terrane increases and that the geometry of the seaward edge of this terrane influences deformation within the subduction complex and controls the amount of sediment that is deeply subducted.

Publication Year 1994
Title Crustal architecture of the Cascadia Forearc
DOI 10.1126/science.266.5183.237
Authors A.M. Trehu, I. Asudeh, Thomas M. Brocher, James H. Luetgert, Walter D. Mooney, J.L. Nabelek, Y. Nakamura
Publication Type Article
Publication Subtype Journal Article
Series Title Science
Index ID 70017677
Record Source USGS Publications Warehouse
USGS Organization Earthquake Science Center