Episodic Tremor and Slip - Geological Interpretation

Geological Interpretation

Tremor is commonly associated with the underground movement of magmatic or hydrothermal fluids. As a plate is subducted into the mantle, it loses water from its porespace and due to phase changes of hydrous minerals (such as amphibole). It has been proposed that this liberation of water generates a supercritical fluid at the plate interface, lubricating plate motion. This supercritical fluid may open fractures in the surrounding rock, and that tremor is the seismological signal of this process. Mathematical modelling has successfully reproduced the periodicity of episodic tremor and slip in the Cascadia region by incorporating this dehydration effect. In this interpretation, tremor may be enhanced where the subducting oceanic crust is young, hot, and wet as opposed to older and colder.

However, alternative models have also been proposed. Tremor has been demonstrated to be influenced by tides or variable fluid flow through a fixed volume. Tremor has also been attributed to shear slip at the plate interface.