SEATTLE >> Geologists and engineers are assessing the stability of a scenic Puget Sound area after a large landside thundered down a hillside, knocking one house off its foundation and threatening others.

That heavily damaged home and 33 others were ordered evacuated after the slide broke loose early Wednesday in the Ledgewood community on Whidbey Island, about 50 miles north of Seattle.

No one was injured.

After geologists took an initial look, residents of about 15 homes higher up the hillside were told Wednesday evening that they could return, said Central Whidbey Fire and Rescue Chief Ed Hartin. Seventeen homes were evacuated along that road and officials were still concerned about two, Hartin said.

Eleven people from 16 homes along a road close to the water were evacuated by boat because the road was blocked by the landslide, Hartin said.

Officials remain concerned about two houses in that area in addition to the one knocked off its foundation. Those 16 homes remained evacuated late Wednesday.

An older man who escaped from the damaged home was evacuated by rescuers in an all-terrain vehicle, Hartin said. Rescuers reached the man by cutting across property belonging to Microsoft CEO Steve Ballmer. Ballmer’s property was not threatened by the slide, the chief said.

Ballmer was not available for comment, Microsoft spokesman Pete Wootton said Wednesday night.

Many of the homes are summer cabins or weekend getaways and were unoccupied. Some are larger, upscale properties and others are more modest dwellings.

The slide area remains unstable.

A geotechnical engineer working for Island County and state Department of Natural Resources geologists took a preliminary look at the area Wednesday and hoped to complete a fuller assessment today.

Area residents were briefed on the status of their homes at a meeting Wednesday night.

There has been no significant rain in recent days, but the area has been prone to slides in the past.

“The west side of the island … is prone to slides because of soil conditions and water movement in the ground,” Hartin said.

“We have no specific cause as to ‘why here, why now, why this big.’ “

The slide area extends about 400 to 500 yards across the hillside and down 600 or 700 yards to the water, Hartin said.

Bret Holmes told The Seattle Times he had been staying in a home that has been in his family.

The noise he heard in the early morning darkness was “like an earthquake, it rattled the whole house,” he said.

He took a flashlight to the backyard facing the water and found that 20 or more trees had vanished.

His flashlight battery died; when he returned with a new flashlight, he told The Times, “where I had been standing was no longer there.”

By Wednesday afternoon, Holmes estimated 75 feet of the backyard was gone.

The NW Insurance Council issued a statement cautioning home and business owners that standard homeowners and business insurance policies specifically exclude damage caused by earth movement like a landslide.

Special landslide coverage is available for an added cost, said Karl Newman, council president.

Residents who heard the slide about eight miles south of Coupeville described it to KOMO-TV as sounding like thunder.

“It was a mix of rumbling and snapping trees,” Hartin said. “We were hearing the same thing when we arrived.”

Whidbey Island is about 35 miles long, north to south, and just a mile or two wide in places east to west.

A ferry ride away from the Seattle area, the island offers picturesque farm and water views and has a population of about 60,000, mostly centered around Oak Harbor and the Whidbey Island Naval Air Station.

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Information from The Seattle Times is included in this story.