Aseismic transient slip on the Gofar transform fault, East Pacific Rise
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Abstract
Oceanic transform faults display a unique combination of seismic and aseismic slip behavior, including a large globally averaged seismic deficit, and the local occurrence of repeating magnitude (M) ∼6∼6 earthquakes with abundant foreshocks and seismic swarms, as on the Gofar transform of the East Pacific Rise and the Blanco Ridge in the northeast Pacific Ocean. However, the underlying mechanisms that govern the partitioning between seismic and aseismic slip and their interaction remain unclear. Here we present a numerical modeling study of earthquake sequences and aseismic transient slip on oceanic transform faults. In the model, strong dilatancy strengthening, supported by seismic imaging that indicates enhanced fluid-filled porosity and possible hydrothermal circulation down to the brittle–ductile transition, effectively stabilizes along-strike seismic rupture propagation and results in rupture barriers where aseismic transients arise episodically. The modeled slow slip migrates along the barrier zones at speeds ∼10 to 600 m/h, spatiotemporally correlated with the observed migration of seismic swarms on the Gofar transform. Our model thus suggests the possible prevalence of episodic aseismic transients in M ∼6∼6 rupture barrier zones that host active swarms on oceanic transform faults and provides candidates for future seafloor geodesy experiments to verify the relation between aseismic fault slip, earthquake swarms, and fault zone hydromechanical properties.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Aseismic transient slip on the Gofar transform fault, East Pacific Rise |
| Series title | Proceedings of the National Academy of Sciences |
| DOI | 10.1073/pnas.1913625117 |
| Volume | 117 |
| Issue | 19 |
| Year Published | 2020 |
| Language | English |
| Publisher | National Academy of Sciences |
| Contributing office(s) | Earthquake Science Center |
| Description | 7 p. |
| First page | 10188 |
| Last page | 10194 |
| Google Analytic Metrics | Metrics page |