The earthquake swarm off the Oregon coast has continued, with about 100 quakes in the last 48 hours, but scientists say there is no need for concern.
The main concern with large earthquakes distant from land is the possibility of tsunamis, albeit “the quakes that have occurred thus far in the swarm should not create detectable tsunamis,” according to the US Geological Survey.
Furthermore, the Blanco Fracture Zone, where the swarm occurs, travels side to side and is not the sort of megathrust fault that displaces ocean water to generate tsunamis. On neighboring fault lines, such tsunami-producing earthquakes are more likely.
According to the survey, the most significant tsunami hazard for the Pacific Northwest is the Cascadia subduction zone, which is 360 kilometers (220 miles) to the east of this series. Meanwhile, the Blanco Fracture Zone shaking might last for days to weeks or end abruptly at any time.
The quakes, which began early Tuesday morning and persisted into Thursday, are located between 200 and 250 miles west of the coastal town of Newport, Oregon – far enough away to go unnoticed on land.
According to an Oregon State University investigation, the Blanco Fracture Zone is more active than the iconic San Andreas Fault in California, has caused more than 1,500 earthquakes of magnitude 4.0 or more since the 1970s.
The most notable aspect of this week’s tremors is that the swarm contained at least nine earthquakes measuring between 5.0 and 5.8 on the Richter Scale, most of which occur at a shallow depth of roughly 10 kilometers (6.2 miles).
According to the USGS database, magnitude 5.0 or more significant earthquakes in the region have more than quadrupled since 1980. There were further swarms in June and July of 2008 and in August of 2009, UGS adds.
Though the Blanco Fracture Zone, the site of this week’s swarm of quakes, is among the most seismically active in North America, it seldom results in devastating earthquakes.
The fault is 275 miles west of the Oregon coast and about 200 miles west of the Cascadia Subduction Zone, producing the most significant and deadly Northwest earthquakes.
According to seismologist Dr. Lucy Jones, there have been more than 133 quakes of magnitude 5.0 or more on the Blanco Fracture Zone since 1980, but none have been followed by something on land.
Although there have been a significant number of magnitude 5.5+ quakes in a short period, experts claim this is not frightening, but more so seismologically intriguing.
