Seattle urges residents to protect themselves from mudslides

SEATTLE -- The city of Seattle has been mapping landslides large and small for many decades.

There have been few injuries or fatalities, but city disaster planning managers want residents to understand that it doesn't take an Oso-magnitude slide to cause catastrophic damage.

"It doesn't have to be a huge landslide to have a lot of personal tragedy," said Seattle Office of Emergency Management Director Barb Graff.

In a briefing to members of city council, Graff referred to a relatively small slide on Bainbridge Island in 1997 that killed a family of four.

She reported to the council that the city has extensive plans in place for emergency services, utilities and other city agencies to coordinate and respond to a large-scale disaster, such as a major landslide with casualties and victims to rescue.

As far as what causes landslides, it's technically a combination of gravity and water. But the fact is, according to Graff, most slides are caused by people.

"Eighty-four percent of the landslides that have happened in Seattle have, to some minor or major degree, human activity involved," she said.

That includes property owners removing soil from the base or "toe" of a slope, removing vegetation from a hillside, and allowing rain or other water runoff to flow down a slope.

The City of Seattle offers yearly workshops for residents interested in learning more about how to reduce landslide risk. In some cases city staff will accommodate requests for city staff to inspect areas of concern and offer advice.

City websites, including the Office of Emergency Management and the Department of Planning and Development, provide information and maps that allow residents to view where landslides have occurred near their property.