In the early morning of June 1, 2005, a landslide began moving in the Bluebird Canyon area of Laguna Beach, California. No rainfall or earthquake activity occurred during or immediately before the landslide movement. This movement is almost certainly related to the extremely heavy winter rains that occurred from December through February. Rainfall from the winter season has been slowly percolating downward through the soil and is gradually raising ground-water levels. As ground water rises, slopes can become unstable and begin to move, even if no rain is presently occurring. The current landslide might enlarge to include areas upslope or other adjacent areas within the next few days and weeks. The continuing infiltration of water from the winter rainy season could trigger other deep landslides in the southern California region over the next few weeks and months.
On February 15, 2005, USGS issued an advisory that landslides could continue to occur long after the winter rainfall ended: "An additional consequence of the above-normal rainfall in January in southern California is the potential for activation of deep-seated, slow-moving landslides. Rainfall is moving slowly through soil and bedrock, and over time (days to months), may result in destabilization of some hillslopes." (http://www.usgs.gov/newsroom/article.asp?ID=674)
In light of this most recent landslide, we now reiterate this advisory that after very wet winters, deep landslides can continue to become active for many months, extending well into the summer. The present landslide is occurring in the same general area as a 1978 Bluebird Canyon landslide that affected about 3.5 acres and damaged or destroyed 50 homes.
To view a fact sheet containing general landslide information and issues related to landslide hazards, visit http://pubs.usgs.gov/fs/2004/3072 or call USGS National Landslide Hazard Information Center at 1-800-654-4966. The USGS serves the nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.