We have the good fortune of living in a beautful corner of the planet where spectacular coast mountain scenery borders the temperate Pacific Ocean. But this priviledge comes at a price. The same forces that lift the coast mountains from the sea are responsible for one of the most powerful of natural disasters: earthquakes. In this talk, I will discuss several distinct classes of earthquake that occur in the Pacific Northwest and the seismic hazard they pose. This list includes the highly anticipated magnitude 9 "megathrust" event that will rupture the entire Cascadia plate boundary from offshore northern Vancouver Island to northern California. It also includes less predictable "crustal" earthquakes up to magnitude 7.5 that can occur on faults anywhere in the region, and deep "intraslab" earthquakes up to magnitude 7 directly beneath major population centers such as Seattle, Victoria and Vancouver. "Slow earthquakes" with magnitudes of up to 6.5 represent a recently discovered class of tremor that goes essentially unnoticed by the general public but which occurs at regular ~14 month intervals below Vancouver Island. Although earth motion during slow earthquakes is too protracted to generate significant seismic waves, these events may serve as harbingers for the next megathrust event as they transfer stress along the Cascadia plate boundary.
Michael Bostock is Professor of Seismology in the Department of Earth, Ocean and Atmospheric Sciences at the University of British Columbia. His research focusses on the structure and seismicity of subduction zones, both active…
June 06, 2017 at 6:00pm
Roundhouse Community Centre - Room B - (181 Roundhouse Mews, Vancouver, B.C.)