A powerful earthquake off the coast of Oregon has sent tremors through several cities along the US West Coast, with authorities bracing for potential aftershocks in the coming days.

The seismic event, measuring 6.0 in magnitude, struck in the Pacific Ocean about 180 miles from the shore at 10:25 p.m. ET on Thursday night.

The US Geological Survey (USGS) reported a subsequent 3.1 magnitude aftershock occurring three hours later in the early hours of Friday morning. Experts indicate a 65 percent probability of additional aftershocks impacting the region over the weekend.

Oregon residents reported feeling the quake’s effects as far away as Portland, approximately 300 miles from the epicenter.

Communities in Dallas, Eugene, Salem, and Coos Bay experienced mild shaking, prompting the region’s tsunami alert system to be activated as a precaution.

Concerningly, this latest quake took place along the Juan de Fuca Plate, which drives the Cascadia Subduction Zone (CSZ) – a nearly 700-mile-long fault line off the West Coast of North America. 

Scientists have long warned that the zone is overdue for a catastrophic event, with many nicknaming it the ‘Sleeping Giant.’

Simulations have shown the fault is capable of a magnitude 9.0 earthquake that would impact most of the Pacific Northwest, including major cities such as Seattle and Portland.

A magnitude 6.0 earthquake was detected Thursday night near the Oregon coast and more aftershocks have been predicted to strike over the next seven days

The Cascadia Subduction Zone extends along a nearly 700-mile strip of the Pacific Ocean off the coast of southern Canada, Washington, Oregon, and northern California

The National Weather Service’s Tsunami Warning System noted that no dangerous waves were produced by the late night earthquake and there was no threat to the US coastline.

USGS has placed the odds of another significant earthquake stronger than magnitude 5.0 striking the area over the next week at 1-in-50.

A catastrophic rupture along this fault line stronger than magnitude 7.0 is not expected at this time, with the agency giving it a less than one percent chance.

Despite the odds, an April 2025 study found that a colossal earthquake along the CSZ was almost assured to take place by 2100, with a 37 percent chance it’ll happen at any point over the next 50 years.

The CSZ sits along the coast of the US and Canada in the Pacific, where the Juan de Fuca tectonic plate slides beneath another, known as the North American Plate.

It stretches from northern Vancouver Island in Canada to the southern half of the US West Coast, running all the way to California.

If an earthquake between 8.0 and 9.0 in magnitude struck today, scientists have estimated that the shockwave could produce a 100-foot-tall mega tsunami which wipes out most of the nearby coastline.

A 2022 emergency report from the Federal Emergency Management Agency (FEMA) estimated that there would be over 100,000 people injured and over 618,000 buildings damaged or destroyed during the next major CSZ earthquake.

The Cascadia zone, which sits under Washington, Oregon, and northern California, is said to be ‘overdue’ for another major earthquake. The last one struck in 1700

Thursday and Friday’s seaquakes took place right alone the Juan de Fuca Plate off the coast of Oregon

There were no reports of injuries or property damage connected to this latest major quake or its aftershock.

The last mega earthquake along the CSZ struck on January 26, 1700. Historians and scientists have estimated that it was a magnitude 9.0 which unleashed a mega tsunami that destroyed the village of Pachena Bay in British Columbia.

Records of the event revealed that waves up to 100 feet high struck just 30 minutes after the quake, leaving no survivors.