7,000 high-risk landslide zones in Portland area; check if you live in one

7,000 high-risk landslide zones in Portland area; check if you live in one »Play Video
Geologists have mapped the Portland metro area and have found 7,000 high-risk zones for landslides.

Geologists have probably studied the terrain under your house.

Oregon's state geology department maintains a map of "danger zones" in the Portland metro area where the conditions are right -- or wrong -- for landslides.

Scientists identified 7,000 locations in the Portland metro area, according to geologist Bill Burns.

"It's a big concern for us," said Burns.

The risky areas are concentrated in the hilly areas, not surprisingly, and include sections of Washington Park and the Oregon Zoo in Portland, along with large areas of residential neighborhoods nearby.

One risk zone stretches from Washington Park into downtown, reaching the flat urban areas near Lincoln High School.

Clackamas County also has its share of dangerous zones.

Burns estimates 30 percent of the entire county's land could fall into its risk zone.

Geologists base the risk zone on data showing recent and historical landslides.

The three main risk factors are steep terrain, weak underlying geological conditions, and an excess of water.

In Portland's West Hills, for instance, the ground is made of relatively unstable soil and weak bedrock prone to landslides if saturated with too much water.

"The water leaches out of the hills days after it stops raining," said Darden Thomsen, who lives in the southwest hills near the Zoo.

Thomsen found out her house was built on top of a high-risk zone when she and her husband bought it back in 2005 -- but her neighbor, Michelle Sullivan, had no clue.

"We moved here because of the landscape," said Sullivan.

You can take steps to reduce the chance of landslides and also understand warning signs.

Cracks, stuck doors and leaning fences or utility poles could be a sign something's wrong.

Minimize the amount of water spilling onto hills, such as by clearing storm drains.

You can map your house using the state's geology mapping tool on its website.

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