Mega-Tsunami Hotspot Rattled by Cluster of Earthquakes

Originally posted on SURFER | By Dashel Pierson | Last updated Sep 10, 2025 12:15 PM ET

Since Monday evening, a cluster of at least 10 earthquakes – ranging from magnitudes of 3.1 to 5.8 on the Richter scale – have struck off the coast of Oregon.

Alarms were raised, as this zone is home to the Cascadia Subduction Zone, a hotspot for a potential “mega-tsunami.” However, according to the National Weather Service’s Tsunami Alerts, after the onslaught of tremors, a “tsunami [was] NOT expected.”

They did, however, raise some eyebrows. Particularly after the 8.8-magnitude earthquake off Russia, which caused tsunami alerts from Hawaii to the West Coast. And also, as this area is a known hub for major earthquakes, and possibly catastrophic tsunamis.

The assemblage of quakes all struck around 100 miles off the Oregon coast, with a relatively shallow depths. There were no reports of damage or injuries.

According to the USGS, regarding this size of earthquake and the threat of tsunamis, they note that, “Magnitudes below 6.5: Earthquakes of this magnitude are very unlikely to trigger a tsunami.” However, as the magnitude rises, so do the chances of catastrophe. As for 7.9-magnitude and greater, “Destructive local tsunamis are possible near the epicenter, and significant sea level changes and damage might occur in a broader region.”

With regards to the Cascadia Subduction Zone, per a 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.

“Today, and more so in 2100 as background sea levels rise, the immediate effect of earthquake-driven subsidence will be a delay in response and recovery from the earthquake due to compromised assets. Long-term effects could render many coastal communities uninhabitable,” said lead author of the study, Tina Dura.

The last time the Cascadia Subduction Zone shifted, and caused a major tsunami, was in 1700, when an earthquake somewhere between 8.7 to 9.2 hit. During that event, the resulting tsunami struck everywhere from the West Coast to Japan.

This article first appeared on SURFER and was syndicated with permission.

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