Chances for predicting earthquakes and saving lives fell dramatically last month when President Bush slashed the budget for earthquake research in 1992 by 35 percent, geologic scientists say.

"We're looking at an extremely bleak future," says Max Wyss, a University of Colorado scientist who used historical data and state-of-the-art equipment to predict in 1985 that an earthquake would hit near Stone Canyon in California within a year. An earthquake hit in 1986.Scientists had no warning of the killer earthquake that rattled Costa Rica and Panama this week. It was followed by four strong aftershocks, and there could be an even larger shock during the next 48 hours that brings more devastation, scientists say.

The same area of eastern Costa Rica experienced a quake of 7.4 magnitude on April 24, 1916, followed two days later by an aftershock measuring 7.1, says Karen McNally, director of the Charles F. Richter Seismological Laboratory at the University of California, Santa Cruz. That timing "leaves us uneasy" about the possibility that a large aftershock may be imminent, she says.

Wyss is predicting a 6.0 earthquake near Parkfield, Calif., for sometime between now and next March. But if the proposed budget cuts aren't restored, the lessons learned at Parkfield can't be applied elsewhere, he says.

"Everybody will be doing less work, finding out less about earthquakes," says Wyss. "And they'll have much less hope in learning how to predict them."

Hundreds of instruments measuring tiny movements in the Earth are set up near Parkfield, midway between Los Angeles and San Francisco, with hopes that when the temblor occurs there, scientists can begin to understand where future earthquakes might occur.

If those instruments had been in Costa Rica, something might have raised a red flag, and that warning could have saved lives, scientists agree. But there are limited numbers of instruments and limited dollars, and there are many false signals, the same scientists say.

Earthquake scientists use densely packed seismographs, creep monitors, satellite technology and calculus to measure previously undetectable movements in the Earth.

Seismographs record the shock waves that quakes send through the Earth, said John Minsch, geophysicist with National Earthquake Information Center (NEIC) in Golden, Colo.

Essentially, the instrument is a coil moving in a magnetic field, suspended by a spring or lever. When shock waves pass beneath the instrument, one part moves while the rest stays still. That generates a small electrical current that is amplified and recorded.

Seismographs packed every few miles near Parkfield can give readings of tremors less than 2.0 on the Richter scale just a few minutes after the event, says Colorado geologist Carl Kisslinger.

Other signals that indicate an earthquake: if the ground starts tilting suddenly, if the ground creeps, if there is unusual quiet or if there are changes in the speed with which waves go through the Earth.