Three earthquakes rattled the U.S. West Coast on Wednesday, serving as another reminder that one of North America’s most dangerous seismic zones lies just offshore.
The strongest of the trio struck off the southern Oregon coast, where the U.S. Geological Survey reported a magnitude-5.7 earthquake approximately 100 miles west of Pistol River. The quake occurred at a depth of roughly 10 kilometers (6 miles) within the offshore Blanco Fracture Zone, a geologically active area where several tectonic plates interact. According to the USGS and the National Tsunami Warning Center, no tsunami threat was generated by the event.
The Oregon quake was accompanied by two additional earthquakes elsewhere along the West Coast on the same day. While none caused significant damage or injuries, the cluster attracted attention because of its proximity to one of the most closely watched seismic regions in North America, let alone the entire world.
@abc7newsbayarea According to the USGS, a 5.7 quake hit off the coast of Crescent City near the Oregon-California border at 3:53 a.m. A 5.1 quake then hit off the coast of Eureka at 5:45 a.m. More at the link. #earthquake #quake #norcal #usgs #abc7news
For some, the region of the shakes should ring a bell.
SURFER has previously reported on the Cascadia Subduction Zone, a massive offshore fault system stretching from Northern California to British Columbia. Scientists believe the zone is capable of producing a magnitude-9.0 megathrust earthquake and a devastating tsunami that could impact hundreds of miles of coastline. The last known Cascadia event occurred in 1700, generating tsunami waves that traveled across the Pacific and reached Japan.
Related: Catastrophic Mega-Tsunami Will Devastate West Coast, Experts Warn
As mentioned before, according to recent study from the Proceedings of the National Academy of Sciences, there’s a 15% chance of a rupture in the Cascadia Subduction Zone in the next 50 years, and a 29% chance by the year 2100.
Estimates of just how destructive, and how large the resulting tsunami from a rupture in the Cascadia Subduction Zone vary wildly. Some say 100 feet; some say 1,000.
However, Thursday’s earthquakes did not occur on the Cascadia Subduction Zone itself. The largest event was associated with the Blanco Fracture Zone, a separate fault system located offshore of Oregon. Still, any seismic activity in the Pacific Northwest tends to draw heightened interest because of Cascadia’s long-term potential.
The USGS notes that earthquake prediction remains impossible. As the agency states, “No one can predict the exact time or place of any earthquake.”
Thursday’s quakes were far from the catastrophic scenario scientists worry about. No tsunami warnings were issued, no significant damage was reported, and coastal communities carried on as usual.
But for anyone who spends time in the ocean—from Oregon to California—the tremors served as another reminder that the Pacific coastline sits atop a powerful and ever-moving geological system. And it’s not a matter of if, but rather, when.
Related: 1,500ft Mega-Tsunami Hit Alaska, Second Largest Ever (Video)