Foreshock Sequences and Short-Term Earthquake Predictability on East Pacific Rise Transform Faults

Jeffrey J. McGuire, Margaret S. Boettcher, & Thomas H. Jordan

Submitted 2004, SCEC Contribution #778

Mid-ocean ridge transform faults (RTFs) have many properties that are distinct from continental transform faults: most plate motion is accommodated aseismically, many large earthquakes are slow events enriched in low-frequency radiation, and the seismicity shows depleted aftershock sequences and high foreshock activity. Because of the high ratio of foreshocks to aftershocks, RTF earthquakes cannot be explained by standard point-process models of seismic triggering, in which there is no fundamental distinction between foreshocks, mainshocks, and aftershocks. Using the post-1996 NOAA-PMEL hydroacoustic seismicity catalogs, we show from a retrospective analysis that foreshock sequences on East Pacific Rise transform faults can be utilized to achieve statistically significant short-term prediction of large earthquakes (moment magnitudes >= 5.4) with good spatial (15-km) and temporal (1-hr) resolution. The retrospective predictability of EPR transform earthquakes is consistent with a model in which infraseismic slip transients trigger earthquakes, enriche their low-frequency radiation, and accommodate much of the aseismic plate motion.

Citation
McGuire, J. J., Boettcher, M. S., & Jordan, T. H. (2004). Foreshock Sequences and Short-Term Earthquake Predictability on East Pacific Rise Transform Faults. Science, (submitted).