A study published yesterday by the School of Environment and Sustainability at Royal Roads University in Canada suggests that conditions in the Pacific Northwest are ripe for another megaquake on the order of the one that struck the region 313 years ago and swamped most of the area with tsunamis and devastating quakes. The area in question stretches from northern Vancouver Island to northern California, and includes major cities such as Vancouver, Seattle and Portland. The researchers extracted sediment cores that they were able to radiocarbon in order to precisely date past megathrust earthquakes that took place along the Cascadia subduction zone.
The 1700 quake was a megathrust event. It reached between 8 and 9 on the Richter scale and caused major tsunamis as far away as Japan. The 2004 Indian Ocean earthquake and tsunami was a megathrust event, as was the 2011 Japan earthquake that destroyed the Fukushima Daiichi power plant. Last October, a 7.7 quake took place in the region, but it was not due to a megathrust. They tend to take place as part of large-scale ‘quake clusters,’ but it is not clear that the region is experiencing such a cluster now. The last event took place 313 years ago, and the region is due for another one. The study appears in the Canadian Journal of Earth Sciences.