THE 2011 TOHOKU TSUNAMI GENERATED MAJOR ENVIRONMENTAL CHANGES IN A DISTAL CANADIAN FJORD

Abstract:

Tsunamis triggered by powerful earthquakes cause extensive damage and loss of life within many regions of the World Ocean. Although coastal inundation from major tsunamis is becoming increasingly well understood, we know little about the broader aspects of such events on distal marine systems. We use time series from moored oceanic sensors to show that the March 2011 Tohoku tsunami generated days of surge-like currents and turbulent mixing in the inner basin of an anoxic fjord located on the west coast of Vancouver Island, British Columbia, more than 7,000 km from the seafloor rupture zone. Mixing, combined with the inflow of more oxygen-rich water from the adjoining outer basin of the fjord, led to abrupt changes in the hydrodynamics, bottom sedimentation, and zooplankton behavior in the basin. These findings help define mechanisms by which major transoceanic tsunamis can significantly alter coastal marine environments located far from the source area.