Scaling relations for seismic cycles on mid-ocean ridge transform faults

• Published in: Geophysical research letters 2009-11, Vol.36 (21), p.n/a
• Main Authors: Boettcher, Margaret S., McGuire, Jeffrey J.
• Format: Article
• Language: English
• Subjects: Centroids; Earth sciences; Earth, ocean, space; Earthquakes; Exact sciences and technology; Faults; Geophysics; Marine; Marine geology; Mid-ocean ridges; oceanic transform faults; Plate tectonics; Rayleigh waves; scaling relations; Seismic activity; seismic cycles; Seismic engineering; Seismic phenomena; Seismology; Stresses; Transforms
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2009GL040115

Mid‐ocean ridge transform faults (RTFs) have thermal structures that vary systematically with tectonic parameters, resulting in predictable seismic characteristics and clear seismic cycles. We develop a scaling relation for repeat time, tR, of the largest expected earthquake, MC: tR = μ−1Δσ2/3CMc1/3AT1/4V−1, where μ is the shear modulus, Δσ is the stress drop, CMc is a constant, AT is the area above 600°C, and V is the slip rate. We identify repeating MC earthquakes by measuring differential arrival times of first orbit Rayleigh waves to determine centroid offsets between pairs of events. Comparing our observations of tR (5–14 years for earthquakes on Gofar and Blanco RTFs) with predictions from our scaling relation, we can constrain RTF stress drops. Specific tests of this scaling relation are proposed for earthquakes on Blanco, Gofar, Discovery, and Clipperton RTFs, which are all expected to have large ruptures in the next few years.