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originally posted by: SeaWorthy
How can the Hawaii volcano produce a consistent 5.3 quake exactly each day?
So if this IS truly the case then Oregon has pressure building for a potential large mag EQ........
Nearly 17,000 earthquakes of magnitude 1.0 to 6.0 have been recorded in Oregon and Washington since 1970. About 15-20 quakes a year are felt in the Northwest. Earthquakes are usually felt if they are at least magnitude 3 to 4.
These are some of the significant earthquakes that have occurred in Washington and Oregon:
February 28, 2001: 35 mile deep intraplate earthquake of magnitude 6.8 shakes the Puget Sound region, damaging the Washington State capitol and causing about $2 billion in damage.
July 2, 1999: magnitude 5.9, centered at Satsop, Wash., severely damaged the Grays Harbor County Courthouse in Montesano, Wash.
Jan. 28, 1995: magnitude 5.0, centered 10 miles southwest of Seattle, no big damage but it was the largest quake to hit the Seattle area in 30 years.
Dec. 4, 1993: magnitude 5.1, centered 10 miles northwest of Klamath Falls, light damage to buildings.
Sept. 20, 1993: magnitude 5.9 and 6.0, 15 miles northwest of Klamath Falls, two deaths and $10 million in damage, including county courthouse.
March 25, 1993: magnitude 5.6, at Scotts Mills southeast of Portland, $30 million in damage, including Molalla High School, a Mount Angel church and the Capitol rotunda in Salem. This remains the most destructive quake in terms of property loss in Oregon's history.
So if this IS truly the case then Oregon has pressure building for a potential large mag EQ........
originally posted by: jadedANDcynical
Not necessarily, although the entire Pacific Northwest is fairly seismically active, it's not Chile or Japan by any means:
"Nearly 17,000 earthquakes of magnitude 1.0 to 6.0 have been recorded in Oregon and Washington since 1970"
That's misleading, because an average of 243 years doesn't mean it happens every 243 years like clockwork, it doesn't, the time between events can vary from 190 to 1200 years. Maybe the next event will happen in 2100 for all we know. The oregon state government tells about the likelihood prediction made by scientists:
we now know that the Pacific Northwest has experienced forty-one subduction-zone earthquakes in the past ten thousand years. If you divide ten thousand by forty-one, you get two hundred and forty-three, which is Cascadia’s recurrence interval: the average amount of time that elapses between earthquakes. That timespan is dangerous both because it is too long—long enough for us to unwittingly build an entire civilization on top of our continent’s worst fault line—and because it is not long enough. Counting from the earthquake of 1700, we are now three hundred and fifteen years into a two-hundred-and-forty-three-year cycle.
The Cascadia Subduction Zone has not produced an earthquake since 1700 and is building up pressure where the Juan de Fuca Plate is subsiding underneath the North American plate. Currently, scientists are predicting that there is about a 40 percent chance that a megathrust earthquake of 9.0+ magnitude in this fault zone will occur in the next 50 years. This event will be felt throughout the Pacific Northwest.
With the current preparedness levels of Oregon, we can anticipate being without services and assistance for at least 2 weeks, if not longer, when the Cascadia Subduction Zone earthquake occurs. While this will be difficult to overcome, our citizens, businesses, schools, government, and communities as a whole can take steps to get prepared. Take action now by actively planning and preparing yourself and your community to be ready for two weeks for disasters.
The study examined the Lake Creek-Boundary Creek and Sadie Creek faults along the north flank of the Olympic Mountains, and concludes that there were three to five large, surface-rupturing earthquakes along the faults within the last 13,000 years.