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Wednesday November 9, 05:45 AM 
Tremor research could predict
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With the devastation of last month's Pakistan earthquake still
fresh in the mind, scientists say they have developed a way of
predicting the size of a tremor even as it starts.
Seismologists have tried and failed for years to predict where
and when quakes will happen and how big they will be.
Now there is a glimmer of light on the horizon - at least for the
latter goal, according to scientists at the University of
California, Berkeley.
"We can determine the magnitude within a couple of seconds of
initiation of rupture and predict the ground motion from seconds to
tens of seconds before it is felt," said lead researcher Richard
Allen.
Although that time frame would be far too short for people to
react and evacuate, it could be enough to tell local emergency
services almost instantaneously the scale of the disaster they are
likely to be facing when the dust settles.
It could also set off alarm bells in far flung centres so they
could begin to mobilise support earlier.
Up to now, the cascade theory of earthquakes that portrays them
as acting like a row of dominoes, with one action triggering another
in sequence, has meant it has been impossible to gauge the scale of
the quake until it has ended.
By that time communications could well have been destroyed
leaving local emergency services in an information black hole.
But the study led by Allen and co-author Erik Olson, published in
the latest edition of Nature science journal, uses a different
theory.
It suggests the size, type and depth of the first break on the
fault line - that can be measured as it happens - gives a very good
indication of the earthquake's eventual reach.
"Most seismologists are surprised, and frequently sceptical, that
you can predict the magnitude of an earthquake before it has ended,"
Allen said in a statement from Berkeley.
"But this is telling us that there is something very different
from what we thought about the physics of the processes involved in
the rupture."
In a commentary on the research also published in Nature, Rachel
Abercrombie of Boston University said the new theory had crucial
implications but that more work was needed.
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