Is the Recent Earthquake Swarm in Oregon Cause for Concern?

An event that scientists are calling an “earthquake swarm” pounded the Oregon coast in December 2021.  All told, a whopping 40 quakes were recorded in less than 24 hours along the Blanco Fracture Zone fault line, at least 9 of which reached a magnitude of 5.0 or higher.  This is triple the average of three 5.0+ earthquakes per year in the U.S. since 1980.

Is the Oregon Earthquake Swarm Cause for Concern for Utilities?

The good news is that the December earthquake swarm did not pose an immediate threat and did not trigger any tsunami activity.  That said, it should serve as a stark reminder to residents and the local utility companies that a major catastrophe at some point in the future is a real possibility.

In general, the region is among the most quake-prone areas in North America, responsible for one of the largest earthquakes in U.S. history about 400 years ago.  In fact, the Blanco Fracture Zone fault line is even more active than California’s San Andreas fault.

The fault line is about 275 miles out to sea off the Oregon coast and has generated 133 quakes of a magnitude of 5.0 or higher in the last 40 years.  Clearly, this represents an extremely high frequency, but on the plus side, the severity of these quakes has been limited because the fault line typically produces “strike-slip” events which involve lateral movements instead of up and down displacement.  The result is that very little water gets displaced, which all but eliminates the risk of a tsunami.

That being said, from an emergency preparedness perspective, there is always the possibility that the “big one” will hit at some point in the future.  It comes down to the law of averages, and earthquake swarms are becoming more common (for example, an earthquake swarm hit Southern California in mid-2021).

Bottom line is that this is yet another reason why utilities need to follow best-in-class emergency preparedness protocols.  Simply put, you never know when the “big one” will hit.