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(meteorobs) OCT 4 FIREBALL AND SEISMIC RECORD
More news on the CA-NM fireball....Mark
For Immediate Release
Caltech Seismo Lab gets location data on Oct. 3 meteor
PASADENA- Should anyone be inclined to do a bit of meteorite hunting this
weekend for a $5,000 reward, Caltech seismologist Kate Hutton thinks she can
provide some help.
According to Hutton, any larger chunks from the meteor that lit up the
Western skies on the night of Oct. 3 may have landed in the Rose Valley area
near Little Lake. Hutton figured this out by analyzing data from 31 of
the seismic stations belonging to the Southern California Seismographic
Network (operated by Caltech and the U.S. Geological Survey). "As it fell,
the atmospheric drag caused the meteroid to explode in mid-air at least
twice," Hutton says. "The explosions generated sound waves in the air
similar to a sonic boom, which were detected by the seismographs. Using a
procedure that is very similar to the one used to locate earthquakes
underground, I used the arrival times of the sound waves at the various
seismic stations to estimate where the explosions occurred."
Two of the explosions were well located, Hutton adds. Both were 20 to 30
miles above the Fivemile Canyon area in the eastern Sierra foothills. The
explosions were separated by about 25 seconds, and the second was about five
miles lower than the first and about a mile further eastward. Based on
this data and on eyewitness accounts provided by John Wasson of UCLA and
Mark Boslough (Ph. D. from Caltech, 1984) of Sandia National Laboratory in
New Mexico, Hutton thinks that any larger fragments that survived the firey
entry into Earth's atmosphere would have landed to the east-northeast of the
explosions, perhaps in the Rose Valley area near Little Lake. Smaller
fragments may have fallen more or less straight down from where the
explosions occurred.
The Little Lake area would probably be the more seductive area to search,
and for a very good reason. UCLA has offered a $5,000 reward for the first
fragment that weighs at least four ounces.
Hutton says the seismographic instruments didn't pick up a meteorite impact
on Earth, but this is not surprising, since a single fragment would probably
have to weigh several tons in order for its impact to be detected.
The term "meteorite," by the way, refers to chunks of extraterrestrial debris
that survive the entry into the atmosphere and end up on the ground.
"Meteoroids" are chunks that travel through space, while "meteor" is the
proper designation for the light show produced by a rock from outer space
slowing down in the Earth's atmosphere.
Any surviving meteorite fragments would probably have a fresh black matte
crust. If the meteorite struck something on the ground, part of the crust
might have chipped off to reveal a lighter interior. If anyone finds a
meteorite fragment weighing at least four ounces, he or she should get in
touch with Dr. John Wasson at UCLA. Wasson's e-mail address is
wasson@igpp.ucladot edu.
Contact: Robert Tindol
(818) 395-3631
tindol@caltechdot edu