Widespread abyssal turbidites record megathrust earthquake-triggered landslides and coseismic deformation in the Cascadia subduction zone

Science Advances
By: , and 

Links

Abstract

Abyssal marine turbidites provide some of the longest and most spatially extensive records of subduction zone earthquake recurrence globally; however, correlation of these deposits over long distances and interpretation of synchronous emplacement requires both an understanding of the turbidite generating systems and precise dating. Here, we present an integrated suite of high-resolution bathymetry, subbottom profiles, and sediment cores from combined autonomous underwater vehicle, remotely operated vehicle, and ship-based studies at a key paleoseismic site in the southern Cascadia subduction zone. We demonstrate how widespread, earthquake-triggered landslides on the lower slope deposit discrete, proximal mass transport deposits (MTDs) that grade offshore into complex, interfingered abyssal turbidites, which correspond to records of megathrust earthquake history. We propose accretion and oversteepening of thrust folds on the lower slope both preconditions the slope to fail and provides a perpetual source of unstable material to fail during every earthquake cycle. Furthermore, we suggest the periodic and pervasive landsliding indicates coseismic deformation of the outer accretionary wedge during megathrust rupture.

Suggested Citation

Hill, J.C., Watt, J., Paull, C.K., Caress, D., Brothers, D., Arizmendi, K., Gwiazda, R., Kluesner, J., Lundsten, E.M., Nieminski, N.M., Padgett, J.S., Paduan, J.B., and Snyder, G.R., 2026, Widespread abyssal turbidites record megathrust earthquake-triggered landslides and coseismic deformation in the Cascadia subduction zone: Science Advances, v. 12, no. 3, eadx6028, 18 p., https://doi.org/10.1126/sciadv.adx6028.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Widespread abyssal turbidites record megathrust earthquake-triggered landslides and coseismic deformation in the Cascadia subduction zone
Series title Science Advances
DOI 10.1126/sciadv.adx6028
Volume 12
Issue 3
Publication Date January 14, 2026
Year Published 2026
Language English
Publisher AAAS
Contributing office(s) Pacific Coastal and Marine Science Center
Description eadx6028, 18 p.
Country United States
State California, Oregon
Other Geospatial Cascadia subduction zone
Additional publication details