The Lake Oswego street where a home stood before it slid down a 200-foot hillside Friday was marked on state geologists' maps as a landslide hazard zone years ago, but Oregon law doesn't require that those living in such risky designations be notified.

Sky-8 photo

The mud slide hit the back of the Lake Oswego home.

Experts say that if more people living on especially hazardous land were warned, more of them would take steps to protect their homes and families.

They could improve drainage to rainwater from saturating the ground and triggering a slide and buy landslide insurance, which is not often included in standard policies.

"The important thing is to get people in Portland and the rest of this area to ask the question, 'What can I do to prevent landslides on my property?"' said Scott Burns, a professor of geology at Portland State University and an authority on slides.

More: Statewide landslide map

Almost every winter, destructive slides wreak havoc on the region. Oregon has its fair share of the three components that cause landslides: steep slopes, loose soil and water.

After landslides killed five people in 1996 in western Oregon, state geologists developed taxpayer-funded maps, which put some Lake Oswego areas in an extreme hazard zone.

But some local officials complained that too many areas were labeled hazardous, which would restrict development. The state never formally adopted the maps.

Lake Oswego, however, recognized Woodhurst Place, where the Friday landslide happened, as a risky site using earlier maps. The city ordered a geotechnical assessment before construction began on the destroyed home, said Stephan Lashbrook, community development director.

"The reality is that the places we're experiencing problems today are in an area where we consider there to be hazards," he said.