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Washington Dept. of Natural Resources, Stephen Slaughter, Associated Press
This March 27, 2013 photo provided by the Washington Dept. of Natural Resources, shows a home near the edge of a massive landslide that damaged one home and isolated or threatened more than 30 others near Coupeville, Wash. Geologists and engineers are assessing what might happen next after a large landside thundered down the scenic island hillside overlooking Puget Sound.

COUPEVILLE, Wash. — Authorities Thursday assessed the damage and danger from a massive landslide on a scenic Washington state island as nervous residents waited for more detailed information about how safe the area is.

One home was heavily damaged and 33 others were ordered evacuated after the landslide early Wednesday on Whidbey Island, about 50 miles north of Seattle. No one was injured.

On Thursday, "road closed" signs were being posted to prevent access to some areas as geologists continued to examine the site where 400 to 500 yards of a hillside plunged toward Puget Sound.

Pete Kenny was on a vacation to help move his grandmother to Illinois and heard the landslide as he watched power line transformers explode.

"The landslide started right at the property line and went south of us," he said Thursday.

Kenny said crews were going to go house-to-house, tagging structures with different colors, with red meaning mandatory evacuation. Details on exactly how many homes were still off limits were not available Thursday afternoon.

Kenny said his grandmother's home and neighbor to south have not been evacuated. That neighbor lost part of their yard.

"It's a real sad situation. I just hope everything works out," he said.

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 Thursday.

Terry Swanson, a geologist at the University of Washington and a Whidbey Island resident, said more detailed studies are needed.

"Not all bluffs act the same. We have landslides here every year," Swanson said of the island, which is about 35 miles long, north to south, and just a mile or two wide in places. "People understand that yes, these are clearly hazards, but there are different types of hazards for different types of slopes."

Residents of about 15 homes higher up the hillside were told by authorities Wednesday evening that they could return. Eleven people from 16 homes along a road close to the water were evacuated by boat because the road was blocked by the landslide. Swanson said access to those houses would remain a challenge.

"That part of the road is gone," he said.