Triggered Seismic Events Along the Eastern Denali Fault in Northwest Canada Following the 2012 M-W 7.8 Haida Gwaii, 2013 M-W 7.5 Craig, and Two M-W > 8.5 Teleseismic Earthquakes
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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-w 7.8 Haida Gwaii and 2013 M-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-w 9.0 Tohoku-Oki and 2012 M-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-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.