The biggest tsunami ever measured occurred in Lituya Bay, Alaska, on July 9, 1958. It was 1,720 feet high - that's taller than any building in the world, almost 300 feet taller than the Sears Tower in Chicago, and about 350 feet taller than the World Trade Center in New York City was.

The trigger was a 7.5 magnitude earthquake, but the tsunami itself was created by a landslide that followed the earthquake.

"Big chunks of ice were falling off the face of (the glacier) and falling into the water," said an observer who watched from a fishing boat. "They came off the glacier like a big load of rocks spilling out of a dump truck."

That's what Hermann Fritz attempted to replicate using a smaller model at the Wave Research Laboratory at Oregon State University on Thursday.

"Warning systems are designed for earthquake-generated tsunamis," Fritz said Thursday. But about 10 percent of tsunamis are created by landslides, often triggered by earthquakes but much harder to detect.

"A landslide offshore," Fritz said, "you wouldn't feel it necessarily."

But you would notice the tsunami that followed.

Fritz is an assistant professor at the Georgia Institute of Technology and has been in Corvallis since October, conducting experiments in the tsunami wave basin at OSU. His research is funded by the Network for Earthquake Engineering Simulation, which is part of the National Science Foundation. The OSU laboratory is the largest in the world for studying the effects of tsunamis.

Fritz's experiments are designed to study how a landslide can create a huge wave like the one in Lituya Bay.

"Tsunamis you don't usually get to see," Fritz said. "That makes it difficult for us to develop numerical models."

And without those models, it's hard to predict what will happen and how to warn people who might be affected.

If you can't observe a tsunami in the wild, you make one.

In Thursday's experiment, Fritz and his crew filled a hopper with gravel. Then they loaded the gravel into an angled tray that simulated a mountain slope that runs down into the water. There was a removable gate so they could release the gravel on cue, and let it slide.

Compressed air released through hoses at the top of the slope would add force to the gravel slide. When the gravel hit the water, it would travel at the same velocity it would get from a 3,200-foot drop rather than the 15 feet it actually fell.

Observers watched from the sides as Fritz and his team set up the experiment. Air compressors roared. A huge overhead crane lowered the gravel into place. A shout from Fritz and whoosh - the gravel shot down the slope, propelled by compressed air.

Gravel slid into the thigh-high water of the tsunami wave basin and started a ring of waves, like in a giant bathtub, radiating out. The underwater cameras showed almost a mushroom cloud-like effect. One big wave, then a trough and another wave.

"It's exciting to do an experiment on such a large scale," Fritz said. "This was run 62, this morning."

Size matters, according to Harry Yeh, an OSU professor of civil engineering who was helping with Thursday's experiment.

A tsunami from a massive earthquake, such as the 2004 Indian Ocean quake that caused a shift of the ocean floor running for hundreds of miles, is hard to miss. It is a gigantic event that spans thousands of miles.

"Tsunamis caused by landslides are more localized," said Yeh. But they can be devastating, although on a smaller scale. A 1992 landslide on Flores Island in Indonesia caused a tsunami that leveled villages and killed hundreds of people. No one saw the landslide happen.

Similar events have occurred around the world - in Java, Norway and Japan, among other locations.

It could happen here. Even a mild earthquake off Oregon's coast could trigger an underwater landslide. All a person onshore would see would be the ocean drawing back - until a wall of water appeared, and then it would be too late.

"Warning is hard to give when (a landslide) is near the shore," Fritz said.

It's important to know the signs, such as the retreat of the ocean. Then the goal is to get to higher ground as soon as possible.

There's no fear Corvallis could get hit, though. Even a 1,720-foot wave wouldn't make it over the Coast Range. The only tsunamis Corvallis is likely to experience are the ones created at OSU.

Gwyneth Gibby is a reporter for the Corvallis Gazette-Times. She can be reached at 758-9548 or gwyneth.gibby@lee.net.