| The Weeks Creek landslide is located on the western slope of the northern Santa Cruz Mountains in San Mateo County, California. The active portion of the landslide covers an area of approximately 10 hectares. This study was undertaken to assess the relationship between precipitation, groundwater level, and slope stability. The groundwater level reaches the ground surface in a year of heavy precipitation and rises to about 1 m below ground surface in a year of average precipitation. The landslide becomes unstable if the amount of precipitation exceeds 70 cm per year or if the water table rises above 2 m below ground surface. The active sliding area will increase from about 300 m to about 500 m in length if an earthquake were to occur on the nearby San Andreas fault. |
