LAGUNA NIGUEL LANDSLIDE OF MARCH 19, 1998
By Doug Morton
Photos of the area
In the early morning hours of March 19, 1998 a rather dramatic landslide occurred in the city of Laguna Niguel. The location of the landslide is just north of Crown Valley Parkway between Allcia Parkway and Clubhouse Drive. The material comprising the landslide is reported to be engineered fill that had been showing some signs of distress for several years. Apparently three-to four days prior to the 19th signs of distress within the fill slope noticeably increased. A number of homes located in the area of the upper part of the fill slope were "red-tagged" and the occupants vacated their homes. About 2AM on the 19th part of the fill slope failed as a type of landslide termed a "slump" (see the accompanying sketch for the anatomy of a slump). Two homes were located in the headward part of the slump and were destroyed as they were carried downward on the upper part of the slump. Three other homes were left partly cantilevered over the crown and main scarp of the slump. On the 20th one of the partly cantilevered homes was destroyed as it fell over the main scarp of the slump.
As the displaced material comprising the slump moved downslope, the toe ( the most distal part) of the landslide moved against and destroyed five condominiums at the base of the fill slope. It is reported the residents of the condominiums had little warning of the rapidly approaching landslide material and had but a very short time to evacuate. Fortunately none of the residents were injured.
Although the Laguna Niguel landslide origination predates this winter’s El Nino, the heavy rainfall associated with this winter’s El Nino probably significantly contributed to the acceleration of the landslide development.
