fishersofmen
November 24th, 2007, 04:01 PM
http://www.sciencedaily.com/releases/2007/11/071122151210.htm
ScienceDaily (Nov. 24, 2007) — For more than a decade geoscientists have detected what amount to ultra-slow-motion earthquakes under Western Washington and British Columbia on a regular basis, about every 14 months. Such episodic tremor-and-slip events typically last two to three weeks and can release as much energy as a large earthquake, though they are not felt and cause no damage.
Now University of Washington researchers have found evidence that these slow-slip events are actually affected by the rise and fall of ocean tides.
..........
And while previous research turned up suggestions of a tidal pulse at 12.4 hours, this is the first time that a second pulse, somewhat more difficult to identify, emerged in the evidence at intervals of 24 to 25................
"We expected that the added water of a rising tide would clamp down on the tremor, but it seems to have had the opposite effect. It's fair to say that we don't understand it," Vidale said...............
"Earthquakes don't behave this way," he added. "Most don't care whether the tide is high or low."
ScienceDaily (Nov. 24, 2007) — For more than a decade geoscientists have detected what amount to ultra-slow-motion earthquakes under Western Washington and British Columbia on a regular basis, about every 14 months. Such episodic tremor-and-slip events typically last two to three weeks and can release as much energy as a large earthquake, though they are not felt and cause no damage.
Now University of Washington researchers have found evidence that these slow-slip events are actually affected by the rise and fall of ocean tides.
..........
And while previous research turned up suggestions of a tidal pulse at 12.4 hours, this is the first time that a second pulse, somewhat more difficult to identify, emerged in the evidence at intervals of 24 to 25................
"We expected that the added water of a rising tide would clamp down on the tremor, but it seems to have had the opposite effect. It's fair to say that we don't understand it," Vidale said...............
"Earthquakes don't behave this way," he added. "Most don't care whether the tide is high or low."