The ocean floor off the Oregon coast has been rattled by more than 50 earthquakes. The image is from the US Geological Survey.
The ocean floor off the Oregon coast has been shaking with more than 50 earthquakes in the past two days. Scientists say the earthquake swarm has a low risk of threatening life or property.
The largest of the 55 quakes was 5.8 magnitude and was the most widespread, according to the U.S. Geological Survey. They happened in the area known as the Blanco Fault Zone, which is prone to moderate-sized earthquakes.
There are fears that earthquakes in the Blanco Fault Zone will add strain to the faults in the Cascadia Subduction Zone. There are faults that are capable of producing large earthquakes. Seismologists say that is not a threat.
Harold Tobin, the director of the Pacific Northwest Seismology Network at the University of Washington, told CNN that there is a lot of distance from the earthquakes to the Cascadia Subduction Zone. Stress doesn't change on the subduction zone because of the best current understanding of how stress transfers through the crust and mantle.
The Blanco Fault Zone is close to the Cascadia Subduction Zone. The Juan de Fuca plate is under the North American plate. Large, devastating earthquakes can be produced by this diving motion. The subduction zones have the potential to create dangerous tsunamis.
The fault zone is called Blanco. The Juan de Fuca plate and the Pacific plate are next to each other. The transform fault zone is also known as a strike-slip boundary. The plates slip past each other with very little motion. The lack of vertical motion on the fault means that the risk of a tsunami from a Blanco quake is low.
According to that post, the Blanco Fault Zone's crust is relatively young and warm, as compared with the more brittle continental crust found at a fault. Younger, warmer crust breaks more easily in smaller events and the waves don't travel as far as in older crust. The waves from the larger earthquakes at the Blanco Fault Zone don't reach land because the fault zone is far offshore.
Scientists aren't alarmed by this week's earthquake swarm.
There have been earthquakes of magnitude 5.0 or larger on the Blanco in the past 20 years. "These happen a lot!"
Live Science published the original article.
