Warning Signs of an Impending Landslide--from the Washington State Department of Natural Resources www.dnr.wa.gov/geology
Landslides can be categorized as shallow or deep seated. Shallow landslides are common in Washington, often forming as slumps along roadways or fast moving debris flows down valleys or concave topography.
Deep seated landslides are often slow moving, but can cover large areas and devastate infrastructure and housing developments. Shallow landslides typically occur in winter in Western Washington and summer in Eastern Washington, but are possible at any time.
Signs of a Shallow Landslide (generally fast moving)
* Sudden increase in creek water levels, often with increased sediment in the water
* Sounds of cracking wood, knocking boulders, or groaning of surrounding group, or unusual sounds like the sound of an oncoming train, especially if the sound increases
* A hillside that has increasing springs, seeps, or saturated ground, especially if it had been dry
* Formation of cracks or tilting of trees, especially evergreens, on a hillside
Signs of a Deep Seated Landslide (generally slow moving)
* Newly developing cracks, mounds, or bulging on streets, sidewalks, or the ground in general
* Sagging or taut utility lines; leaning telephone poles, fences, or trees
* Sticking windows or doors; new and/or growing cracks in walls, ceilings, or foundations
* Broken or leaking underground or surface utilities, such as water, septic, or sewer lines
* Separation of foundation from sill plates; movement of soil away from foundation
* Changes in water well levels or cessation of well functioning
* Increase or changes in spring or seep activity; ground becoming soggy or wet