Fourth quake in four days hits off Oregon Coast

The site of one of many earthquakes off of the Oregon Coast in 2010.
The site of an earthquake off of the Oregon Coast on Monday, March 15, 2010 - the fourth ocean-floor earthquake in the area in four days.

The fourth earthquake in four days hit off the coast of Oregon Monday. There were no immediate reports of it being felt or causing damage, and there is no danger of it generating a tsunami.

PORTLAND, Ore. – The fourth earthquake in four days hit off the coast of Oregon Monday.

Monday's 4.6 quake occurred at a depth of 6.2 miles at 5:37 a.m. All of the quakes within the past four days range between 4.1 to 4.9 on the Richter Scale.

All also are in close proximity to each other. These quakes are centered about 330 miles west-southwest of Portland at a depth of six miles - shallow in earthquake terms, said Geophysicist Randy Baldwin.

On Friday the sea floor was hit with the largest of the four quakes. The National Earthquake Information Center in Golden, Colo., reported a magnitude 4.9 quake Friday night off the Oregon coast. There were no immediate reports of it being felt or causing damage.
     
Baldwin said quakes of that magnitude are common in that area. They occur as part of the Juan de Fuca Plate, and there is no danger of it generating a tsunami. A tsunami is likely only if the earth shifts vertically and that vertical shift is a rarity off the Oregon Coast, according to a source at the Oregon Department of Geology and Mineral Industries.