Boettcher and McGuire, Scaling Relations for Seismic Cycles on MidOcean Ridge Transform Faults , GRL
Midocean 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−1Δσ^{2/3}CMc^{1/3}AT^{1/4}V^{}^{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 (514 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.
FILE » Boettcher_McGuire_2009_57791.pdf
