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Geophysics Department Seminar - "Observations of, and ruminations on, slow slip and tremor" - Dr. Allan Rubin, Princeton
Observations of, and ruminations on, slow slip and tremor
For the past several years graduate student Yajun Peng and I have been working on obtaining precise relative locations of tectonic tremor in subduction zones in Cascadia, Mexico, and most recently Japan. The method, pioneered by John Armbruster, compares seismograms from the same time window at multiple (distant) seismic stations, rather than the more "traditional" method of comparing multiple time windows at the same station. It works well when the responses at the stations to a Low Frequency Earthquake (LFE) source are dominated by the main arrival, with little coda, and when multiple sources occur within a compact space and time window. When these conditions are met, the method produces the most accurate tremor catalogs currently available. I will talk about what we have learned from these catalogs and from rate-state friction models about the kinematics and mechanics of slow slip, emphasizing the large disparity between the relatively slow propagation of the main tremor front and the much more rapid velocity of the secondary fronts that arise behind it. I will also talk about my more recent efforts with Michael Bostock to use our different tremor/LFE detection methods to make some statements about the nature of the tremor/LFE source. If I'm not too cowardly, I'll actually spend more time on the latter.