Scientists find odd twist in slow ‘earthquakes’: Tremor running backwards. Posted by Anonymous on May 24, 2011 Earthquake scientists trying to unravel the mysteries of an unfelt, weeks-long seismic phenomenon called episodic tremor and slip have discovered a strange twist.
The tremor can suddenly reverse direction and travel back through areas of the fault that it had ruptured in preceding days, and do so 20 to 40 times faster than the original fault rupture. “Regular tremor and slip goes through an area fairly slowly, breaking it. Then once it’s broken and weakened an area of the fault, it can propagate back across that area much faster,” said Heidi Houston, a University of Washington professor of Earth and space sciences and lead author of a paper documenting the findings, published in Nature Geoscience.Episodic tremor and slip, also referred to as slow slip, was documented in the Pacific Northwest a decade ago and individual events have been observed in Washington and British Columbia on a regular basis, every 12 to 15 months on average.
Largest Earthquake Recorded - World's Biggest Earthquake. "The Great Chilean Earthquake" The World’s largest earthquake with a instrumentally documented magnitude occurred on May 22, 1960 near Valdivia, in southern Chile.
It has been assigned a magnitude of 9.5 by the United States Geological Survey. It is referred to as the "Great Chilean Earthquake" and the "1960 Valdivia Earthquake. The United States Geological Survey reports this event as the "largest earthquake of the 20th Century".