Record Details
Seismic precursors linked to super-critical fluids at oceanic transform faults
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Seismic precursors linked to super-critical fluids at oceanic transform faults |
| Names |
Géli, Louis
(creator) Piau, Jean-Michel (creator) Dziak, Robert (creator) Maury, Vincent (creator) Fitzenz, Delphine (creator) Coutellier, Quentin (creator) Henry, Pierre (creator) |
| Date Issued | 2014-10 (iso8601) |
| Note | To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Nature Publishing Group and can be found at: http://www.nature.com/ngeo/index.html. |
| Abstract | Large earthquakes on mid-ocean ridge transform faults are commonly preceded by foreshocks[superscript 1–3] and changes in the seismic properties of the fault zone³. These seismic precursors could be linked to fluid-related processes[superscript 2,3]. Hydrothermal fluids within young, hot crust near the intersection of oceanic transform faults are probably in a supercritical condition⁴. At constant temperature, supercritical fluids become significantly more compressible with decreasing pressure, with potential impacts on fault behaviour. Here we use a theoretical model to show that oceanic transform faults can switch from dilatant and progressive deformation to rupture in response to fluid-related processes. We assume that the fault core material behaves according to a Cam-clay-type⁵ constitutive law, which is commonly used to account for the behaviour of clays. According to our model, we find that the fault is initially stable, with stresses gradually increasing over a timescale of years in response to tectonic loading. The fault evolves into a metastable phase, lasting a few days, during which the fault rocks dilate and pore pressures decrease, causing the compressibility of the supercritical fluids to increase. This in turn triggers fault-slip instability that creates foreshock swarms. In the final phase, the fault fails in the mainshock rupture. Our results imply that seismic precursors are caused by changes in fluid pressure which result in variations in fluid compressibility, in response to rock deformation just before rupture. |
| Genre | Article |
| Identifier | Géli, L., Piau, J. M., Dziak, R., Maury, V., Fitzenz, D., Coutellier, Q., & Henry, P. (2014). Seismic precursors linked to super-critical fluids at oceanic transform faults. Nature Geoscience, 7(10), 757-761. doi:10.1038/ngeo2244 |
