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Old Earthquake Faults Worn Smooth Over Time Due to Friction, Research
Shows
Tuesday , March 13, 2007
By Ker Than
LS
ADVERTISEMENT
Earthquake faults are worn smooth over time by friction, like the brake
pads of an old car, according to a new study.
The finding, detailed in the March issue of the journal Geology,
suggests old and new faults might generate different types of earthquakes.
Researchers were able to see the wear patterns by using a fairly new
technology called laser imaging detection and ranging (LIDAR) to create
detailed topographical maps of the vertical sides of exposed fault
lines. Like radar, LIDAR sends out a pulse of energy and then records
information from bounced back reflections. LIDAR is more sensitive than
radar, and can collect data points as close as every 0.12 inches during
scans of enormous rock faces.
Click here for more geology news from FOXNews.com.
Over the course of two years, the researchers analyzed about 15 sites in
southern California, Oregon, Nevada and Utah. The findings support the
idea that old and young faults have fundamentally different structures
and that faults evolve over time.
The study found that while mature faults tend to be smooth at small
scales, they have regular features on larger scales. In contrast,
younger faults tend to be rough on all scales with no discernable pattern.
"The thing that was really surprising was that the mature faults have a
really distinct structure, little hills on them, at the 10-meter scale,"
said study team member Emily Brodsky, a University of California, Santa
Cruz geologist.
Click here for more geology news from FOXNews.com.
_/*This is surprising because most geologists thought fault lines are
fractal, meaning they exhibit the same structure and complexity
regardless of the scale of observation.*/_
The researchers say the next step is to figure out what implications
their findings have for earthquakes. Because old and new faults are so
different, everything about the earthquakes they generate -- their
birth, strength and propagation -- could be different as well, the
researchers speculate.
"We don't know how the amount of shaking from the same size earthquake
acts on different kinds of faults," Brodsky said. "It could be that the
smoother, mature faults give you a less bumpy ride."
Copyright © 2007 Imaginova Corp. All Rights Reserved. This material may
not be published, broadcast, rewritten or redistributed.
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Old Earthquake Faults Worn Smooth Over Time Due to Friction, Research
Shows<br>
<br>
Tuesday , March 13, 2007<br>
By Ker Than<br>
<br>
LS<br>
ADVERTISEMENT<br>
<br>
Earthquake faults are worn smooth over time by friction, like the brake
pads of an old car, according to a new study.<br>
<br>
The finding, detailed in the March issue of the journal Geology,
suggests old and new faults might generate different types of
earthquakes.<br>
<br>
Researchers were able to see the wear patterns by using a fairly new
technology called laser imaging detection and ranging (LIDAR) to create
detailed topographical maps of the vertical sides of exposed fault
lines. Like radar, LIDAR sends out a pulse of energy and then records
information from bounced back reflections. LIDAR is more sensitive than
radar, and can collect data points as close as every 0.12 inches during
scans of enormous rock faces.<br>
<br>
Click here for more geology news from FOXNews.com.<br>
<br>
Over the course of two years, the researchers analyzed about 15 sites
in southern California, Oregon, Nevada and Utah. The findings support
the idea that old and young faults have fundamentally different
structures and that faults evolve over time.<br>
<br>
The study found that while mature faults tend to be smooth at small
scales, they have regular features on larger scales. In contrast,
younger faults tend to be rough on all scales with no discernable
pattern.<br>
<br>
“The thing that was really surprising was that the mature faults
have a
really distinct structure, little hills on them, at the 10-meter
scale,” said study team member Emily Brodsky, a University of
California, Santa Cruz geologist.<br>
<br>
Click here for more geology news from FOXNews.com.<br>
<br>
<u><i><b>This is surprising because most geologists thought fault lines
are fractal, meaning they exhibit the same structure and complexity
regardless of the scale of observation.</b></i></u><br>
<br>
The researchers say the next step is to figure out what implications
their findings have for earthquakes. Because old and new faults are so
different, everything about the earthquakes they generate — their
birth, strength and propagation — could be different as well, the
researchers speculate.<br>
<br>
“We don’t know how the amount of shaking from the same size
earthquake
acts on different kinds of faults,” Brodsky said. “It could be
that the
smoother, mature faults give you a less bumpy ride.”<br>
<br>
Copyright © 2007 Imaginova Corp. All Rights Reserved. This material
may
not be published, broadcast, rewritten or redistributed.<br>
<br>
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