Subduction Zone Dynamics in the Mantle and at the Earth's Surface

Subduction zone dynamics in the mantle and at Earth's surface

An educational module for the University of Maine School of Earth and Climate Sciences courses in Geophysics and Fluid Dynamics

Created by Sam Roy (Samuel.g.roy@maine.edu) on 4/28/2012 Last edited on 8/2015

Two main hypotheses to explore:

1. Mantle advection controls surface deformation through mechanical coupling of lithosphere and asthenosphere.

2. The lithosphere is non-Newtonian and exhibits strain weakening behavior, this can lead to strain localization and slab detachment. Strain rate is normally greatest in the subduction hinge therefore weakening and detachment would probably occur there.

1. Introduction:

The surface of the Earth takes many varying shapes, from high craggy peaks and steep gorges to rolling hills and flat coastal plains. But how and why does the Earth's surface takes its form? There are many processes that play an active role in the creation of topography and landforms, but in this module we will explore the role of mantle advection as the primary mechanism behind surface deformation (Figure 1). First, I will discuss our physical understanding of mantle dynamics, then we will use a physical model to explore the sensitivity of surface shape to various rheological conditions in the lithosphere and underlying mantle.