-
- PASADENA,
Calif. (Reuters)
- The Hector Mine earthquake that rocked much of the
southwestern United
States Saturday was even more powerful than
originally estimated, scientists
said Monday as they revised the
quake's magnitude from 7.0 to 7.1.
-
- "There was 25 percent more
shaking than we originally
thought, and the earthquake released 40
percent more energy," said
seismologist Lucy Jones of the
California Institute of Technology (Caltech)
in Pasadena.
-
- The quake, which
struck at 2:46 a.m. PDT (5:46 a.m. EDT
) Saturday jolted millions of
people awake in California, Nevada and Arizona.
It was centered 32
miles north of the California desert community of Joshua
Tree, a
sparsely populated region of scrub in the Mojave Desert located
110
miles northeast of Los Angeles.
-
- The temblor, which was named the Hector Mine quake
because
it took place near an old mining town of that name, was
originally estimated
at magnitude 7.0 but was actually 7.1, experts
said Monday.
-
- Jones said the Lavic Lake fault, where the temblor occurred,
had been mapped, but it had not been studied for ground movement because
there was no evidence that it had ruptured within the past 10,000
years.
-
- "And it's only the rattlesnakes that really care
(about
desert earthquakes)," she said, adding that seismologists were
putting their energies into fault lines near densely populated
areas.
-
- "The Hector Mine earthquake may be a rare event;
one whose
occurrence could not have been anticipated based on a standard
probabilistic assessment of earthquake rates," Jones said.
-
- Only a handful of
people were injured in the quake, and
they were mostly passengers on an
Amtrak train en route from Chicago to
Los Angeles that was derailed by
the temblor. Their injuries were slight
because the carriages remained
upright when they left the tracks.
-
- Jones said the quake ruptured
the desert floor, leaving
a 25-mile) long gash that went through the
Twenty Nine Palms U.S. Marine
Base. Jones said the Marines suspended
maneuvers at the base so that eight
teams of geologists could examine
the rupture.
-
- There have been several large earthquakes in southern
California in the last decade, including a 6.1 magnitude in April 1992,
the 7.3 Landers earthquake in June of that year and the 6.7 Northridge
earthquake that hit Los Angeles in January 1994, killing more than 50
people
and causing $20 billion in damage.
-
- "It is clear these faults
are talking to each other.
What is not exactly clear is what the
pattern is," said Jones.
-
- She also disclosed that the phrase "open-ended
Richter
scale" is no longer used by seismologists in describing
the magnitude
of an earthquake.
-
- "The Richter scale in
seismology has a very specific
meaning; a scale created by Charles
Richter. We would say, 'Oh no, the
Richter scale won't work on that one
because we're talking about that one
specific method devised back in
the 1920s.
-
- "We much prefer the more general term of 'magnitude'
because there are many ways to estimate the size of an earthquake, only
two of which were devised by Richter, and the more modern ones are
considered
more reliable," Jones said.
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