AP Photo / Ted S. Warren
An aerial photo shows before and after images of a landslide near Coupeville, Wash., on Whidbey Island, Wednesday, March 27, 2013.
A 1500-foot-deep landslide that rumbled down a scenic Washington state island shoreline early Wednesday is part of an ongoing geological movement that may date back 11,000 years, according to a preliminary report.
The dawn slide shifted the equivalent of 40,000 dump-truck loads of soil on Whidbey Island, located about 50 miles outside of Seattle.
It washed a road away, wiped out power lines and water mains, and plunged one home off the island's crumbling bluff, while threatening or cutting off access to 34 others.
An early report by the Washington State Department of Natural Resources Division of Geology & Earth Resources, published late Thursday [PDF link], said the movement was “a small portion of a much larger landslide complex, approximately 1.5 miles long, that was prehistoric and may date back as far as 11,000 years.”
Ted S. Warren / AP
An aerial photo shows a landslide near Coupeville, Wash. on Whidbey Island, Wednesday.
The slide displaced approximately 5.3 million square feet, or about 200,000 cubic yards of earth, the report said.
More homes could be lost as the ground continues to shift, officials have told residents.
“The chance of another catastrophic movement is low, but possible,” it said in its "Ear to the Ground" blog about the incident.
"I used to say 'in a million years we'll have waterfront property,' and now I can say 100 years or tomorrow. It's unbelievable," resident Nancy Skullerud told NBC affiliate KING-5 news in Seattle.
The Whidbey Island landslide has residents nervous as several homes sit precariously on the edge. Some of the evacuation orders were lifted late Wednesday but it's still dangerous for more than a dozen homeowners to return. NBC's Miguel Almaguer reports.
“It’s taken a while to soak it in to realize that life changes in five minutes,” Skullerud said. “Mother Nature always wins.”
It could be months before some residents have full access to their homes following the landslide, firefighters on Whidbey Island said Thursday, reported KING-5. Four homes were "yellow-tagged," the affiliate reported, meaning residents were allowed limited access to them.
A Red Cross relief center was set up earlier in the week for people forced to evacuate.
In Western Washington, the majority of landslides are triggered during fall and winter after storms dump large amounts of rain or snow. Landslides are relatively common in the area, but one of this magnitude is rare.
NBC's Elizabeth Chuck contributed to this report.
This story was originally published on Fri Mar 29, 2013 8:32 AM EDT