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***SPECIAL EDITION***
December 2, 1998

NSF-Funded Research Highlighted at the American Geophysical Union (AGU) Meeting in San Francisco, December 6-10

For more information on these science news and feature story tips, please contact the public information officer at the end of each item at (703) 292-8070. Editor: Cheryl Dybas

LIMITS OF LIFE ON EARTH: ARE THEY KEY TO LIFE ON OTHER PLANETS?

From scalding hot places that rival Dante's Inferno to frigid locations colder than the dark side of the moon, scientists are searching for life forms on Earth that may provide insight about possible life on other planets. They will present results of their research in a special conference session on life in extreme environments.

"Life flourishes on Earth in an incredibly wide range of habitats," explains Mike Purdy, director of NSF's division of ocean sciences, and coordinator of NSF's Life in Extreme Environments (LeXeN) program. Purdy will co-chair the special session with Michael Meyer of NASA's astrobiology program. Many of the scientists presenting research results are funded by NSF's LeXeN program. "These environments may be analogous to the harsh conditions that exist now, or have existed, on Earth and other planets. The study of microbial life forms and the extreme environments they inhabit can provide new insights into how these organisms adapted to diverse environments, and shed light on the limits within which life can exist," Purdy said.

Scientists participating in the special session will address such topics as: life at the cold limit -- Earth, Mars, and beyond; the subseafloor microbial biosphere; environments for life in the outer solar system; ice cores as archives for microorganisms; and biology at deep-sea hydrothermal vents. Session U06 (Wednesday AM).

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IS SEISMIC HAZARD IN THE CENTRAL U.S. LESS THAN THOUGHT?

Considerable attention -- including a widely touted earthquake prediction in 1990 -- has been paid in recent years to the possibility of large earthquakes in the Central U.S. The area in question, the New Madrid Seismic Zone, was shaken by a series of major earthquakes during the winter of 1811-12. This zone remains the most seismically active region in North America east of the Rocky Mountains, although it is in the middle of the North American continent.

Geologists have been trying to decide what causes such great earthquakes and how often they might recur. A surprising new answer is emerging from recent studies using the Global Positioning System (GPS), conducted by geologists from Northwestern University, the University of Missouri, the University of Miami, and Grand Valley State University, with technical assistance from the University NAVSTAR Consortium (UNAVCO).

Using GPS, the positions of a network of geodetic markers in Missouri, Tennessee, Illinois, Arkansas and Kentucky have been measured to accuracies of less than an inch. The results show little or no motion across the seismic zone, implying than it would take more than 2,500 years to accumulate the large motions presumed to have occurred in the great 1811-12 earthquakes. It is even possible that no strain is accumulating on the fault, says geologist Seth Stein of Northwestern University in Evanston, Illinois. Hence the time between earthquakes seems to be much longer than the 500-1,000 years traditionally assumed, and the seismic hazard of a great New Madrid earthquake may have been greatly overestimated, according to Stein. Session G21A-02 (Tuesday AM).

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NEW, LOW-COST "GPS" CAN MONITOR VOLCANOES, FAULTS AND STORMS

The Global Positioning System (GPS), which gives geologists the ability to measure ground motions of less than an inch, has proven to be an important tool for both geophysical and atmospheric research. The high cost (about $20,000) of GPS installations, however, has limited their number, making it harder to study rapidly-changing phenomena like volcanoes, faults, and weather.

Now researchers at the University NAVSTAR Consortium (UNAVCO), an international organization of more than 80 universities and other research institutions, have developed a new high-precision GPS system. The system's cost is low enough for it to be deployed in large numbers.

Dense arrays of 15 to 30 instruments will be used to investigate features such as volcanoes and faults. Researchers have installed the first such network in the Long Valley, California, volcanic region, and will install others next year at volcanoes like Popocatepetl, near Mexico City.

Receivers continuously transmit GPS data through a radio modem/repeater network to a base station. Hence even if some sites are destroyed by a volcano or earthquake, other sites will transmit data, according to Charles Meertens of UNAVCO, lead scientist on the project. Session U12C-12 (Monday PM).

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