Publication Date:
2023-02-03
Description:
Constraining the controlling factors of fault rupture is fundamental to understanding the earthquake cycle. Fluids can influence earthquake locations and magnitudes, although the exact pathways of fluids through the lithosphere are not well-known. Ocean transform faults are an ideal laboratory to study the factors controlling fault ruptures and fluid pathways given their relative simplicity. Here, we analyse seismicity recorded by the Passive Imaging of the Lithosphere-Asthenosphere Boundary (PI-LAB) experiment, centred around the Chain Fracture Zone. We find that earthquakes beneath mapped morphological transpressional features occur deeper than the brittle-ductile transition predicted by simple thermal models but elsewhere occur shallower. These features are characterised by multiple parallel fault segments and step overs, high b-values, gaps in large historical earthquakes, and seismic velocity structures consistent with hydrothermal alteration. This suggests that broader fault damage zones preferentially facilitate fluid transport into the lithosphere. Although this cools the mantle, it also reduces the potential for large earthquakes at punctuated locations (barriers). These barriers divide the transform into asperity segments that are shorter, thereby limiting the earthquake magnitudes in these regions.
Type:
Article
,
NonPeerReviewed
Format:
text
Format:
text
Permalink
