Over 18 Offshore Earthquakes Rattle Seafloor Off Washington

The region faces significant seismic risk from the Cascadia Subduction Zone, a major offshore fault where the Juan de Fuca Plate slips beneath the North American Plate.

Kelly McBride Ni

Published: 4/13/2026, 5:13:13 PM EDT

Over 18 Offshore Earthquakes Rattle Seafloor Off Washington — (The Regional Seismic Network for Washington and Oregon)

A swarm of small to moderate earthquakes rattled the seafloor off the Washington coast early Sunday. Regional seismologists said there is no threat to coastal communities.

The Pacific Northwest Seismic Network reported 18 plus earthquakes near the Juan de Fuca Ridge beginning around midnight Pacific Daylight Time on April 12. The strongest earthquake registered a magnitude 4.2. The swarm was located about 250 miles offshore, far from the Cascadia Subduction Zone, a major fault that is capable of producing large earthquakes and tsunamis.

“These are not anywhere near the Cascadia Subduction Zone,” the Pacific Northwest Seismic Network said in a public post on its social account. “Finally, this swarm does not pose a hazard to the PNW onshore region.”

The U.S. Geological Survey recorded the swarm along the Blanco Fracture Zone, where the Pacific Plate meets the Juan de Fuca Plate. The agency’s event pages showed a series of small quakes, with magnitudes between 2.6 and 4.2, occurring west of the Washington coast.

The largest was about 254 miles west of Aberdeen at 4:48 a.m. Sunday. One person reported feeling shaking as far inland as Stevenson, according to USGS data.

The USGS explained that an earthquake swarm is a series of earthquakes without a dominant mainshock, meaning the activity does not follow the typical mainshock-aftershock pattern. Instead, the earthquakes may be similar in magnitude and may not taper off as quickly as traditional earthquake sequences.

The offshore area sits along the Juan de Fuca Ridge, a seafloor spreading center where tectonic plates pull apart and new crust forms. The ridge runs parallel to the Pacific Northwest coast and feeds a network of fracture zones, including the Blanco Fracture Zone, which is one of the most active fault areas in the region.

The swarm occurred north of Axial Seamount, an active underwater volcano on the Juan de Fuca Ridge that researchers have closely monitored for signs of inflation and possible eruption. The Pacific Northwest Seismic Network said the current swarm is “not at the Axial Seamount Volcano,” though it is on the same ridge system.

No tsunami warnings were issued, and there were no immediate reports of damage or injuries.

The region faces significant seismic risk from the Cascadia Subduction Zone, a major offshore fault where the Juan de Fuca Plate slips beneath the North American Plate.

The Cascadia earthquake of 1700 caused intense shaking and a trans-Pacific tsunami. The 2001 Nisqually earthquake also resulted in widespread damage.

“The Cascadia Subduction Zone has not produced an earthquake since 1700 and is building up pressure where the Juan de Fuca Plate is subsiding underneath the North American plate,” states the Oregon Department of Emergency Management (OEM).

“Currently, scientists are predicting that there is about a 37% chance that a megathrust earthquake of 7.1+ magnitude in this fault zone will occur in the next 50 years. This event will be felt throughout the Pacific Northwest,” according to the OEM.