Landslides can occur when a slope becomes unstable causing soil, rock, or debris to slide down. They can be triggered by a variety of factors, including heavy rainfall, earthquakes, or human activity such as unregulated hill-cutting, construction work, logging, or mining. Landslides can cause significant damage to homes and infrastructure, as well as threaten people caught in their path.

In Thurston County, landslides are a common hazard, particularly during the rainy season. The county is located in a region with a history of landslides, and the geology of the area makes it particularly susceptible to landslides under the right conditions. 

Warning Signs of Potential Landslides

The Washington State Department of Ecology provides warning signs of earth movement that could indicate a landslide may occur. If you are impacted by or suspect an active landslide, report the problem to Thurston County Emergency Management.

If you notice signs of an impending landslide that poses imminent danger, evacuate if it is safe to do so and call 9-1-1.

Signs of an impending landslide

• Cracks in the ground that get larger
• Sounds of cracking wood or knocking boulders
• Sudden changes in creek water levels.

Landscape

• Head scarps or steep cliffs at the toe of a slope
• Large or growing cracks, downslope movement
• Exposed clays uplifted on the beach
• Trees or large blocks of clay partially buried on the beach

Built environment

• Sagging or taut utility lines
• Growing cracks in walls and window corners
• Broken water or sewer lines
• Doors that don’t close properly
• Significant cracking of pavement

Vegetation

• Tilted or curved trees
• Split trunks
• Stretched roots
• Large clusters of trees of similar age

Water

• Small ponds on sloping terrain
• Disrupted natural drainage
• Unusually heavy or muddy seepage
• Unusual increase or decrease in flow from springs or in creeks