HISTORY: Some slopes in Del Norte County are susceptible to landslides, including along the main supply route on Highway 101, on a 3-mile segment called Last Chance Grade. Landslides in this stretch have been ongoing for decades, with over 200 slides mapped in the area.

In Del Norte County, most landslides occur during the winter, when the water table is high and the soil is saturated. Landslides can also occur as secondary hazards, triggered by earthquakes, heavy precipitation, floods, or fires.