PORTLAND, Ore. (KOIN) — A series of earthquakes off the Oregon coast were recorded Tuesday and Wednesday, but they are not expected to trigger a much larger quake.
The quakes happened in the Blanco Fault Zone, a commonplace for earthquake swarms, KOIN 6 News Chief Meteorologist Natasha Stenbock said. The more serious occurrence would have been if they had been in the Cascadia Subduction Zone.
A magnitude 4.0 quake was recorded about 7 a.m. about 283 miles west of Coos Bay. Another magnitude 4.0 quake happened around 11:15 a.m. in about the same location.
Around 1:30 p.m., a 5.5 magnitude quake rolled through the same spot, followed 27 minutes later by another 5.5 quake in that location. Two hours later, another quake, this one 4.4 magnitude, rumbled in that area. Then at 4:17 p.m. another 4.9 magnitude quake was recorded. Just 19 minutes later, a 5.8 magnitude quake hit that area.
Then a rapid sequence of quakes, between 4.0 and 5.8 magnitude, happened in the same area at
4:52 p.m., 5:07 p.m., 5: 21 p.m., 5:38 p.m., 6:55 p.m., 7:14 p.m and 7:54 p.m.
Quakes continued through the night into early Wednesday morning. Over a dozen quakes were recorded at 1:35 a.m., 1:56 a.m., 2:02 a.m., 2:14 a.m., 2:50 a.m., 2:59 a.m., 3:29 a.m., 4:12 a.m., 4:25 a.m., 5:30 a.m., 5:45 a.m., 5:57 a.m, 6:34 a.m., 6:46 a.m., 7:05 a.m and 7:38 a.m.
Over 50 earthquakes have been recorded in the area in nearly 24 hours.
All the earthquakes were recorded about 10 kilometers below the surface. No injuries or damage was reported by the US Geological Survey.
A 2019 article in Scientific American said the “Blanco Fault Zone earthquake is fun, not fearsome.”
In part, the article states: “The BFZ is a nice transform fault zone that’s a bit like the San Andreas, only underwater and much less dangerous to humans. It forms the boundary between the Juan de Fuca and Pacific plates, and is around 200 kilometers west of the Cascadia subduction zone, where the Juan de Fuca dives under the North American plate. This may not seem like a great distance on a global scale, but it’s pretty darned far when it comes to separation between fault zones.”
Portland State University geology professor Scott Burns spoke with KOIN 6 News about Tuesday’s earthquakes.