Project description

The lithosphere is the thin outer shell of the Earth that supports the weight of mountains, plate tectonic forces, and stores the elastic energy that is released during earthquakes. The strength of the lithosphere directly controls the formation of tectonic plates and the generation and propagation of devastating earthquakes.

The strongest part of the lithosphere is where the deformation processes in rocks transition from brittle fracture to plastic flow. Earthquakes seem to stop below this transition, but we do not know exactly how deep they can propagate or nucleate. The transitional regime also marks the locus of the recently discovered low frequency earthquakes and tremors, which are currently not well explained.

Despite its fundamental importance, the transitional behaviour remains very poorly understood. In this regime, we still do not know how rock deformation processes and properties evolve with depth and, critically, time. We also do not know exactly where the transition occurs in nature, if and how it may move over time, and what are the prevailing conditions there.

This long-term project, initiated via an ERC Starting Grant (2019-2024), aims to bring quantitative experimental constraints on the mechanisms of the brittle-plastic transition in rocks, to characterise the seismic and fluid transport properties of rocks at the transition, and to formulate flow laws that could be used in large scale geodynamic and fault dynamics simulations.

Project duration

2019 - 

Funding agencies

Past funding from ERC Starting Grant "RockDeaf" (held at UCL 2019-2024)