Short-time scale correlation between slow slip and tremor in Cascadia

J. C. Hawthorne, A. M. Rubin

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


We use borehole strain and seismic data to show that slow slip and tremor in central Cascadia are correlated on a range of time scales shorter than 1 day. The recorded strain rate is our proxy for the slow slip moment rate, and the seismic amplitude is our proxy for the tremor amplitude. We find that, on average, the strain rate is higher when the seismic amplitude is larger. This correlation persists on time scales between 15 min and 16 h, and it can be seen in each of the five slow slip events between 2007 and 2011. Our results imply that the slow slip moment rate varies by a large amount even at these short time scales. For instance, we observe a factor of 2 variation on time scales shorter than 4 h. This apparently aperiodic variation is larger than the previously observed variation in moment rate resulting from tidal forcing. It is a lower bound on the actual moment rate variation, as we detect only changes in slow slip that are correlated with tremor amplitude. Key Points Slow slip and tremor are correlated on timescales of hours Short-timescale variations in aseismic moment rate are large Large variability is not obviously periodic

Original languageEnglish (US)
Pages (from-to)1316-1329
Number of pages14
JournalJournal of Geophysical Research: Solid Earth
Issue number3
StatePublished - Mar 1 2013

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


  • borehole strain data
  • slow earthquakes
  • tremor


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