What might a Cascadia earthquake be like?

“Lori, you are scaring me,” said a longtime friend after reading my column last week. He might have been speaking in jest as this was nothing new to him and he knows very well that fear is never my intent.

Fear is a great way to sell newspapers and magazines and a terrible motivator for preparedness action. Don’t take my word for it — my colleague Ana-Marie Jones did an exhaustive study of the topic a decade ago (https://pubmed. ncbi.nlm.nih.gov/23315253/) and concluded fear messaging is pervasive in our culture, ineffective, and there are better ways to promote action in our woefully unprepared public.

If it’s not fear to get your attention, ignoring the elephant in the room won’t work either. And there are no two ways about it; Cascadia is the elephant of earthquakes and tsunamis in our North Coast communities. So, no hyperbole here; reducing risk isn’t glamorous but we can do it. And sometimes an inflatable elephant helps.

When I talk Cascadia, I mean an earthquake in the upper 8s to low magnitude 9 range and a fault rupture from Southern Humboldt County to Vancouver Island, Canada. Three things to emphasize: you will almost certainly survive, the area impacted will be enormous, and it will take many years to reach a new post-disaster normal.

Starting with scale. I’ve lived on the North Coast since 1978, felt many earthquakes, and studied many more. I am acknowledged as an “earthquake expert” but for Cascadia-sized earthquakes, to paraphrase Joni Mitchell, I really don’t know earthquakes at all.

It’s hard to wrap my head around just how large an area will directly participate in a Cascadia earthquake. It will likely be strong enough to cause damage in California, Oregon, Washington, and British Columbia and felt in Nevada and Idaho. But the damage won’t be uniform and downed roads and bridges mean communities will