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SCIENTISTS-UNIQUE-SEISMIC PATTERN
Scientists find unique seismic pattern preceding earthquakes in central
Alaska
WASHINGTON, June 7, 2018 (BSS/Xinhua) – Researchers from the University of
Alaska Fairbanks claim to have found evidence of slow geological processes
prior to full-blown earthquakes, offering potential possibility for
earthquake prediction in the region.
Seismologist Carl Tape and his colleagues said they have found evidence
for accelerating activity before a 2016 earthquake in central Alaska’s Minto
Flats. The activity included a series of long, low-frequency waves recorded
by seismic stations.
Tape said this kind of slow event transitioning into a rupture had
previously only been seen in laboratory experiments.
Similar patterns also showed in 2015, when the seismic stations recorded a
long-duration, very low-frequency process, normally only seen in deep
subduction zones. This event showed a small amount of activity gathering, or
nucleating, in a central area below the surface. But it did not lead to an
earthquake.
“The leap we make, and maybe the more controversial thing, is that this
emergent long-period signal only seen on top of the fault is a low-frequency
signal that can sometimes turn into an earthquake and sometimes not,” said
Tape.
Tape and his colleagues published their work this week in the Nature
Geoscience journal.
While studying how low-frequency waves can trigger or transition into
full-scale ruptures could help scientists improve earthquake prediction
models, researchers believe that the patterns found at Minto Flats are unique
to the region’s fault complex.
Minto Flats has a deep sedimentary basin, strike-slip faulting, active
tectonics and deep earthquakes. It is an unusual site.
“In some ways, I wish there wasn’t anything special. I wish it was a
global phenomenon that we discovered, but it’s not,” Tape said. “It appears
there is something special about the conditions in Minto Flats.”
BSS/XINHUA/FI/ 1056 hrs