JUNE 2, 2015
SALEM, ORE. (KOIN)
A series of earthquakes struck off the Oregon coast early
Monday, but scientists said they weren’t strong enough to trigger tsunamis.
The first came at magnitude 5.8. It struck about midnight
Sunday and was followed by three quakes early Monday. They were of magnitude
4.3, 5 and 4.4. A fifth struck around 1:13 p.m. and registered at a 5.9
magnitude.
At 7:50 p.m., a 3.9 magnitude earthquake was recorded off
the Oregon coast. Then at 8:11 p.m., a 4.2
magnitude trembler was felt.
A ground motion sensor near Mt. Hood picked up all of the
ocean quake activity, highlighted by red indicators on screens at the U.S.
Geological Survey offices in Vancouver.
The wall of earthquake monitors at the USGS monitoring
station in Vancouver, June 1, 2015 (KOIN).
They struck at a fault nearly 300 miles west of Coos Bay,
Oregon. They were relatively shallow, at 6 miles deep.
KOIN 6 News wanted to know if these quakes could mean
we’re closer to a big offshore quake, like the one that rattled the region more
than 300 years ago.
“These earthquakes are happening in a totally different part
of the system and aren’t really relevant in a physical way,” USGS seismologist
Seth Moran said.
According to Moran, Monday’s quakes are on a fault line
farther out to sea than the much more dangerous fault line right off the Oregon
coast. That closer fault line — the Cascadia-Subduction Zone — has caused huge
quakes in the past and is currently building up pressure.
Judging from the recent earth moving activity all around the Pacific Ocean, we believe we are overdue for a big one along the west coast. We have forecast a big one (7.5-9) will happen this year. We shall see.
“The area where it’s stuck is roughly like this and if that
entire patch were to go all at once, that’s the magnitude 9,” Moran said. “It’s
a long fault, it’s a wide fault.”
Scientists at the U.S. Geological Survey said it usually
takes an earthquake of magnitude 7 or better to trigger a tsunami.
They say the fault that produced them generates frequent
earthquakes, but it isn’t the type of fault that produces the most violent
quakes.
Scientists told KOIN 6 News the action off the coast is an
“earthquake swarm,” but they are not connected to the fault line that worries
experts.
A series of earthquakes
struck off the Oregon coast early Monday, but scientists said they weren’t
strong enough to trigger tsunamis. (KOIN 6 News)