WILLMAR 11/1/00 -- We endure bone-numbing cold, blizzards, floods and tornadoes for the privilege of thumbing our noses at Californians and telling them: "At least we don't have to worry about earthquakes.''

Well, guess what? We have those too.

The ground we like to call terra firma in west-central Minnesota can ripple, shake and boom just like the stuff in California, and has.

Just ask Wilma Kroening of Morris, who felt the earth "shaking under her feet'' as she and her husband, Norman, enjoyed a round of golf one summer day at the Pomme de Terre Golf Course.

Or, ask C. Frederick Farrell Jr., of Morris, who was in his house when the dwelling boomed and shook so hard his frightened poodle flattened herself against the floor and left him convinced a violent explosion had occurred.

Better yet, ask Pam Gades, who is compiling these and other personal recollections from residents of west-central Minnesota who experienced the earthquakes that rattled this region on July 9, 1975, and again on June 5, 1993.

Gades remembers the 1975 quake best. She was getting ready for her job at the A & W in Morris when she heard a boom so loud that she feared a large truck had just slammed into the kitchen of her home. "My mother, who had never been out of Minnesota, said 'I think we just had an earthquake.'''

Of course mother was right, but the daughter may yet have the last word. Gades is taking down the experiences of the region's earthquake witnesses as part of her master's project in educational technology. She is working with Peter Whelan, a professor of geology at the University of Minnesota-Morris.

Gades has created a Web site where the stories of this region's earthquake survivors are posted. She also is filling the site with information on earthquakes and Minnesota's experiences with them, including a chronology of quakes going back to1860.

Along with links to other Web sites and classroom ideas, Gades is developing her site so that it can be used by teachers in elementary, junior and senior high schools. Students will be able to use the site to enhance their understanding of geology and plate tectonics, while having loads of fun.

Gades sure is, ever since she began collecting the stories of those who have been shaken up by Minnesota quakes. "What is really turning out to be fun is the human aspect of it, talking to people and hearing their stories,'' she said.

Gades is hoping to expand her research into quakes by learning about a Feb. 9, 1994, quake that was felt primarily in this area. Its epicenter was located about three miles north of Granite Falls. It struck sometime between 2:45 and 3:15 a.m. and measured 3.1 on the Richter scale.

Stories about this quake are limited, said Gades, because most people slept right through it.

There were very few people sleeping when the 1975 quake struck about mid-morning on a warm summer day. The quake measured 4.6 to 4.8 on the Richter scale, and had its epicenter between Alberta and Chokio in Stevens County.

The 1993 quake measured 4.1 on the Richter scale and is known as the Morris quake, but had its epicenter near Dumont in Traverse County. It struck around 8:25 p.m. and certainly was noticed.

Those who have shared their experiences with Gades told about watching windows vibrate, floors shake and hearing what they thought were sonic booms or explosions.

One farmer, who had witnessed atomic explosions as a serviceman, was working inside his grain bin when the quake boomed and rattled the metal. Gades said he told her he made his way out of the bin certain that he'd see a mushroom cloud rising on the horizon.

People were certainly rattled, but fortunately, neither the 1975 nor 1993 quakes caused serious injury or damage, said Gades.

If the 1975 quake had occurred in a major urban area, geologists believe it would have caused significant damage and possible injury, she added.

Still, a 4.6 or 4.8 earthquake doesn't pack anywhere near the punch of a 7.1 earthquake, which hit the San Francisco Bay area in October 1989. The San Francisco earthquake was about 1,500 times as powerful as the 1975 quake felt here.

Do we need to worry about a big one here? Geologists don't think so, since a San Andreas-type fault does not lie beneath Minnesota, said Gades.

The geology here does make it likely that the state will continue to experience relatively mild quakes. There's a statistical likelihood of a 3.5 magnitude earthquake every five years, and a 5.0 quake every 90 years, she said.

There are different theories in the scientific community about why this region experiences earthquakes.

The 1975 and 1993 quakes occurred along the Great Lakes Tectonic Zone, a roughly 30-mile-wide band which runs from Traverse County to the Duluth area.

She said one theory holds that quakes have occurred along this zone, probably an ancient fault line, as the earth "bounces back'' from the weight of the long-gone glacial ice.

Another more widely accepted theory holds that the zone is feeling the stresses created as the North American continental plate moves westward from the Atlantic ridge.

The 1994 quake near Granite Falls is believed to have occurred along the Yellow Medicine shear zone, which is not associated with the Great Lakes Tectonic Zone.

In any case, don't panic. The earth's shift during the San Francisco quake was measured at nearly 20 feet, said Gades. The shifts in this region during the 1975 and 1993 quakes were estimated to be a matter of inches.