Triggered seismic events along the eastern Denali Fault in northwest Canada following the 2012 Mw 7.8 Haida Gwaii, 2013 Mw 7.5 Craig, and two Mw>8.5 teleseismic earthquakes

We conduct a systematic search for remotely triggered seismic activity along the eastern Denali fault (EDF) in northwest Canada, an intraplate strike-slip region. We examine 19 distant earthquakes recorded by nine broadband stations in the Canadian National Seismograph Network and find that the 2012 M (sub w) 7.8 Haida Gwaii and 2013 M (sub w) 7.5 Craig, Alaska, earthquakes triggered long duration (>10 s), emergent tremor-like signals near the southeastern portion of the EDF. In both cases, tremor coincides with the peak transverse velocities, consistent with Love-wave triggering on right-lateral strike-slip faults. The 2011 M (sub w) 9.0 Tohoku-Oki and 2012 M (sub w) 8.6 Indian Ocean earthquakes possibly triggered tremor signals, although we were unable to locate those sources. In addition, we also identify many short-duration (<5 s) bursts that were repeatedly triggered by the Rayleigh waves of the 2012 M (sub w) 7.8 Haida Gwaii earthquake. Although we were unable to precisely locate the short-duration (<5 s) events, they appear to be radiating from the direction of the Klutlan Glacier and from a belt of shallow historical seismicity at the eastern flank of the Wrangell-St. Elias mountain range. The fact that these events were triggered solely by the Rayleigh waves suggests a different source mechanism as compared with triggered tremor observed along the EDF and other plate boundary regions.Online Material: Description of Rayleigh-wave polarization detection; figures of spectograms, S-wave amplitudes, polarization analysis, and static stress changes; tables of earthquake catalogs and velocity model; and animations of tremors and bursts.