One of North America’s most active faults came to life Tuesday after a swarm of more than 50 earthquakes, ranging from a magnitude of 3.5 to 5.8, has rocked the Oregon coast, attracting the attention and concern of millions of people in the region.
The series of earthquakes, which began early Tuesday morning and continued into Wednesday, clustered 200-250 miles in the ocean west of the Oregon coastal city of Newport, far enough away to be undetected in land, but given the area’s seismic history, it’s creating quite a stir, CNN reported.
The earthquakes varied in strength, with many of magnitude between 4.0 and 5.8. The US Geological Survey (USGS) recorded more than 50 in a 24-hour period.
All of the earthquakes were recorded about 6 miles below the surface. The USGS reported no injuries or damage.
There was no tsunami threat after the earthquakes.
Portland State University geology professor, Scott burns, told KOIN that it normally takes an earthquake of magnitude 8.0 or higher to see a tsunami threat in that area.
“We had 10 large earthquakes. That’s a lot, ”Burns said. “(They were) off the coast, in deep water, so the damage is minimal.”
The earthquakes occurred in the area of the Blanco fracture zone, a common place for earthquake swarms, said KOIN chief meteorologist Natasha Stenbock. More serious would have been if they had been in the Cascadia subduction zone.
This fault is located about 275 miles west of the Oregon coast and about 200 miles west of the Cascadia Subduction Zone, where the largest and most destructive earthquakes in the Northwest have historically occurred.
The Dr. Lucy Jones He said on Twitter: “The current swarm is in the Fractura Blanco zone, between the Juan de Fuca plate and the Pacific plate, less than 100 km from the oceanic crest where the Juan de Fuca plate is formed, so that the plate is thin and hot. An adjustment where it is difficult to accumulate stress ”. And he clarified: “We tend to see these types of swarms (many earthquakes close to the largest size) in areas of low confinement stress. Those areas generally don’t have really big earthquakes. “
The fault line responsible for the earthquakes is the White Fracture Zone. According to an analysis by Oregon State University, it is more active than the infamous San Andreas fault in California, having produced more than 1,500 earthquakes of magnitude 4.0 or more since the 1970s.
Not all earthquakes are the same
Most impressive of this week’s Oregon earthquakes is that the swarm has included at least 9 tremors that reach a magnitude of 5.0 to 5.8, and most occur at a shallow depth of only 10 km.
The large number of earthquakes of magnitude 5.0 or greater in the region triples the annual average (three 5.0+ earthquakes per year) since 1980, according to the USGS database.
However, seismic activity has raised concern for some, as the region is among the most earthquake-prone areas in North America And it has already produced one of the largest earthquakes in the continental United States, on January 26, 1700.
The earthquake happened in the neighboring Cascadia Subduction Zone, a fault much closer to earth, where the Juan de Fuca plate dives below the North American Plate. This fault can not only trigger devastating tsunamis, but also destructive shocks.
This phenomenon should not be alarming for the population, according to experts, and it is not indicative that a large, very destructive earthquake is going to occur, as has been feared for decades on the West Coast.
It may interest you:
– Cascadia, the fault that threatens to cause a major earthquake in the US
– What is the “Big One”, the devastating earthquake that California expects in the San Andreas fault at any moment
– California: Swarm of earthquakes in the Salton Sea raises fears that the San Andrés Fault will be affected