The Topographic Signature of Mantle Pressure Build‐Up Beneath Subducting Plates: Insights From Spherical Subduction Models

Abstract

AbstractSubduction zones are associated with spatially heterogeneous pressure fields that, depending on location, push/pull on Earth's surface producing dynamic topography (DT). Despite this, subduction zones, and associated pressure fields, are typically over‐simplified within global mantle flow models. Here, I use subduction models within a global domain to probe mantle pressure build‐up beneath subducting plates (SPs) and the resulting DT. Positive pressure develops beneath the SP in most subduction models. This produces positive DT (≤450 m) and tilts the SP upwards toward the trench (≤0.25 m/km). As SP size increases, the pressure magnitude increases producing greater topography/tilting. At a global scale, I find potential evidence for the modeled tilting in published residual topography. I argue that the rigorous incorporation of subduction zones into mantle flow models, and hence the inclusion of this signal, is needed to continue to bring future DT predictions and observational estimates into closer alignment.