Theory 26/Earth, Climate & Energy /Marine geochemistry
Seeps Follow Permeability
Seeps are attributed to warming hydrates. The gas may simply find a path.
Seafloor methane seepage occurs where sediment permeability crosses a threshold rather than where gas hydrate is dissociating, so seeps should be predicted from permeability structure rather than from bottom-water warming.
01The evidence
Seeps occur in clusters that align with geological structures, and many hydrate-bearing areas show no seepage.
02The tension
Models link seepage to hydrate destabilisation from warming, which predicts seepage from temperature and misses the clustering.
03The mechanism
Gas migrates through permeable pathways. Where permeability is below a threshold, gas accumulates and is retained; where it is above, gas escapes.
That makes permeability the control, and predicts seeps should cluster on structures rather than on warm patches.
04What this is not
Those models predict from temperature. This predicts from pathways, which explains clustering.
05Predictions
- P1Seeps should cluster on permeable structures.
- P2Warm hydrate areas without pathways should not seep.
- P3Permeability should predict better than temperature.
06Refutation
Seepage tracking warming at controlled permeability would restore the thermal model.
07What it changes
It would change how seep methane is inventoried.