Transitions in subduction zone properties align with long-term topographic growth (Cascadia, USA)

Michel-Wolf, L., Ehlers, T. A. and Bendick, R. (2022) Transitions in subduction zone properties align with long-term topographic growth (Cascadia, USA). Earth and Planetary Science Letters, 580, 117363. (doi: 10.1016/j.epsl.2021.117363)

Abstract

Simple mechanical models of the earthquake cycle assume that interseismic elastic deformation is recovered during earthquakes, closing the strain budget of steady and episodic slip on the deep and shallow subduction interfaces, respectively. However, elevated topography in the forearc high requires that some deformation is not recovered over each elastic cycle. Here, we compare constraints on deformation over decadal to million-year timescales to disentangle contributions from elastic (recoverable) and inelastic (unrecoverable) deformation within the Olympic Mountains of the Cascadia Subduction Zone. Over timescales of 103 – 106 yrs, elevated topography, permanent deformation, and denudation (from thermochronometry and cosmogenic nuclide data) accumulate in an area adjacent, but not identical, to the maximum in geodetically observed reduced vertical velocity and surface upwarping over tens of years. The domains of geodetic and geomorphic maximum uplift occur over a 20-60 km wide zone overlying the up-dip limits of the zone of conditional frictional stability at the subduction interface. We attribute geologic-scale orogenesis, accumulation of topography and advection of rocks in the active orogen to unrecoverable deformation as stress is relayed up-dip through parts of the subduction interface and dissipated in the overriding plate.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Ehlers, Professor Todd A.
• Authors: Michel-Wolf, L., Ehlers, T. A., and Bendick, R.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Earth and Planetary Science Letters
• Publisher: Elsevier
• ISSN: 0012-821X
• ISSN (Online): 1385-013X
• Published Online: 24 January 2022
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Earth and Planetary Science Letters 580: 117363
• Publisher Policy: Reproduced under a Creative Commons licence