Category: Cascadia

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Cascadia SZI Events

Cascadia subduction zone initiation

Schematic tectonic reconstruction of the Cascadia SZI event (modified from Stern and Dumitru et al., 2019 and Wells et al., 2014). A trench jump occurred due to the accretion of the Siletzia and Yakutat large igneous province (LIP) formed by the Yellowstone plume, initiating the new Cascadia subduction zone. Shown are the new subduction zone (pink line), other active (solid purple lines) and inactive (dashed purple lines) subduction zones, and spreading ridges (solid red lines).

The Cascadia subduction zone initiation event, occurring between 53–43 Ma, involved the subduction of the Farallon and Kula plates beneath North America. It was linked to the trench jump caused by Siletzia’s accretion and possibly the Yellowstone mantle plume, with supporting geological evidence from volcanic rocks in the region.