1998 Landslide Emergency Response - Southern California Coastal Area

5. Laguna Beach, Orange County
(OES Mission #98-SOU6117). On 02/24 DMG evaluated artificial fill pad erosion downslope from Top of the World School. The school is set back about 30 feet from the edge of the fill. Erosion of silty sand caused deep gullies where an engineered fill drain had failed. DMG determined there was no imminent danger to the building from landsliding; however, continued erosion of the fill could result in potential landsliding if not properly mitigated. The school's consultant was also on site. A report prepared by DMG geologist Russell Miller was released 03/17.

14. Laguna Beach, Orange County (OES Mission #98-SOU6123). On 03/23 OES requested technical assistance on the geologic analysis of slopes, that are in continued threat of mudslides and landslides, for preliminary determination of potential slope movement and mitigation suggestions. A report prepared by DMG geologist Tan was released 04/17. On 12/06/97 three beach-side homes were evacuated and 20 others were severely damaged (Tan, 02/11). On 02/17 a hill slipped and sent boulders tumbling toward a restaurant (Tan, 02/19). On 02/22 Laguna Canyon Road was closed due to mudslides (Tan, 03/05). On 02/23 in Canyon Acres, a home partially collapsed under a slide, and part of a bungalow on Victory Walk was crushed. Other slide areas include Laguna Canyon Road, Bluebird Canyon Drive and a trailer park near Aliso Pier (Tan, 03/05). On 02/24 the rainfall forced 550 people from their homes. A wall of mud roared down hillsides, killed one man, injured nine people and destroyed four homes in the Castle Rock community. One man was killed when a mudslide slammed into his cottage on Victory Walk. On Canyon Acres Drive, three houses were destroyed and five others damaged. Damaged houses were reported in Laguna Canyon Road. A total of at least 14 homes and several businesses were destroyed (Tan, 03/05). On 02/25 a wall of mud in Laguna Beach Canyon killed one person and injured 10, two homes were damaged, and eight homes were evacuated (Gerry Wieczorek, USGS). On 02/26 city officials alerted the residents of 25 canyon homes that their properties might be unsafe based on a city-hired geologist investigation (Tan, 03/05).

15. Laguna Niguel, Orange County. On 12/05/97 the storm increased movement on a landslide in Laguna Niguel and damaged five condominiums which were abandoned (Tan, 02/11). On 03/18 a crumbling hillside threatened to destroy at least 14 homes in Laguna Niguel. For at least five years, the 125 feet high slope has slowly slipped. The storms in December accelerated its movement and forced the evacuation of five homes at the top of the slope on Via Estoril Drive and five condominiums at the bottom of San Felipe Drive; additionally, four condominiums were threatened. The backyard of one of the Via Estoril homes dropped up to five feet (Tan, 04/02). On 03/19 two houses on Via Estoril collapsed. Seven more houses at the same street were threatened and evacuated; twelve condominiums were damaged and nine more evacuated (Tan, 04/02). On 03/20 a third home on Via Estoril toppled down the headscarp of the landslide (Tan 04/02). On 03/24 DMG received one other report from the USGS of continued movement on the Laguna Niguel landslide where at least 10 condos were evacuated and five were destroyed. On 03/29 a fourth house, adjacent to the other three collapsed homes on Via Estoril, split in half and plunged into the graben of the slide (Tan, 04/02)

16. Various locations, Orange County. On 12/06 floods and mudslides were reported in Costa Mesa, Irvine, Lake Forest, San Juan Capistrano, and Laguna Beach. Mudslides occurred in Black Star, Baker, and Santiago Canyons. Many road closures were reported along the Santa Ana Freeway at Laguna Freeway, Laguna Canyon Road, Pacific Coast Highway in Newport Beach and in Huntington Beach (Tan, 02/11). On 02/17 runoff undermined sections of Santiago Road in Orange County (Tan, 02/19). On 02/23 the storm forced the evacuation of eight to 10 residents in Holy Jim Canyon near the Orange - Riverside County line; a half-dozen other residents declined to move despite the growing slide threat (Tan, 03/05).

17. City of Orange, Orange County. On 12/23 movement of an active landslide in the Anaheim Hills accelerated. The landslide, which is located within a DMG mapped landslide area (Tan, DMG OFR 95-11), has been active for the past two years. This "Vista Summit Way" landslide damaged two to three houses and affected three city blocks. The engineer with the City of Orange has been in contact with DMG concerning this matter (Tan, 02/19).

18. Silverado Canyon, Orange County. On 12/06 four homes were condemned and evacuated due to a mudslide and rockfall (Tan, 02/11). On 02/23 one home was endangered in Silverado Canyon (Tan, 03/05).

19. Modjeska Canyon, Orange County. On 02/23 at least one house was damaged by mud (Tan, 03/05).

27. Los Angeles, Los Angeles County. On 02/06, mud crashed into an apartment building in Westlake area after the storm toppled a 15 foot retaining wall; more than 100 residents were evacuated. Water swept across Pacific Coast Highway and the Ventura, Harbor and Santa Ana Freeways (Tan, 02/11). On 02/13 a home in Los Feliz was declared unsafe because rains had eroded its foundation (Tan, 02/19). On 03/01 a slide rumbled down a slope and flattened a house in the 3900 block of Eureka Drive in Studio City, pushing it into a backyard swimming pool. The houses on both sides of the pancaked house were yellow-tagged. The slope failure left four other homes (on Laurie Drive) perched precariously at the edge of an abyss. The residents had left the destroyed house after the City of Los Angeles red-tagged the structure as a precaution (Tan 03/05). On 03/01 a moderate-size landslide cascaded from a steep slope in Studio City and destroyed a house and several cars. The house had been evacuated due to concerns about the stability of the slope. This slide occurred more than five days after the rain stopped and illustrates the problem of delayed triggering of deeper landslides (Sue Cannon, USGS, 03/02). On 03/01 in the San Fernando Valley, the City of Los Angeles red- or yellow-tagged about 50 dwellings in danger of mudslide hazard in recent weeks, mostly along the slopes of Santa Monica Mountains (Tan, 03/05).

28. Newport Beach, Orange County. On 02/06 a mudslide crushed two cars (Tan, 02/11). On 02/26 parts of a yard tumbled from a hilltop home on Muir Beach Circle, blocking off an area of Goleta Point Drive, in the Spyglass Hill area (Tan, 03/05).

30. Malibu, Los Angeles County. On 12/06/97 homes in Malibu were damaged by waves and seacliff erosion. On 02/07 Malibu Canyon Road closed due to mudslides and rockfalls (Tan, 02/11). On 02/08 an ocean-eroded cliff buckled, causing one home to collapse and two others threatened. The homes along Broad Beach Road were undermined by high tides (Tan, 02/11). On 02/16 several houses along the beach of Malibu were damaged by the high surf and rainstorms (Tan, 02/19). On 02/23

Pacific Coast Highway, Topanga Canyon Boulevard, and Malibu Canyon Road were blocked by mudslides. A Union Pacific railroad trestle was undermined by the surging flows of the Ventura River and was not reopened to rail traffic for weeks (Tan, 03/05). On 02/24 in Malibu’s Las Flores Canyon, officials called for evacuation of about a dozen homes because of unstable ground. Also, more mudslides on Pacific Coast Highway forced officials to close the local courthouse (Tan, 03/05). On 02/25 a 140-foot-long retaining wall partially collapsed, damaging two homes above the slide on Calle del Barco. The 20-year-wall, along a narrow road (Rambla Orienta) just above Pacific Coast Highway, began to give away during the evening of 02/24 (Tan, 03/05).

31. Santa Barbara, Santa Barbara County. On 02/07 officials closed roads because of mudslides and evacuated a mobile home park (Tan, 02/11). A Sycamore Canyon home was ripped from its foundation by a mudflow. No injuries were reported (Wieczorek, 02/25).

32. San Clemente, Orange County. On 02/08 high tide and rain caused damage to shoreline properties; nine homes at a mobile home park were damaged (Tan, 02/11). On 03/01 a landslide forced the evacuation of four homes in the 300 block of Paseo de Cristobal, piled dirt and large boulders onto the railroad tracks and cut off rail service. One of these houses was condemned (Tan, 03/05).

33. Dana Point, Orange County. On 02/08 the Holiday Inn Express was evacuated when a mudslide flowed into the underground parking structure. Cars flowed out of the building into the street with the mud (Tan, 02/11).

34. Brea, Orange County. On 02/08 a rock and mudslide closed the Carbon Canyon Road. Other road closures occurred at Pacific Coast Highway, Laguna Canyon Road, and El Toro Road (Tan, 02/11). On 02/24 Carbon Canyon Road was closed, after a hillside slid across half of the road at the La Vida Hot Springs Resort (Tan, 03/05).

37. San Fernando Valley, Los Angeles County. On 02/13 a rain-soaked hillside collapsed in West Hills, Canoga Park, tearing away a garage, forcing the evacuation of five homes and threatening several other residences farther down the hill. The slide ripped a 200 feet long, 30 feet deep gash under a house, leaving a bedroom dangling over a chasm. The garage slid down slope 12 to 30 feet and 20 feet away (laterally), with a car still parked inside, and was wedged against the back of a downslope home (Tan, 02/19).

38. Ventura, Ventura County. On 02/14 a hillside gave way and an oil pipeline ruptured, sending 8000 gallons of crude oil flowing into the ocean and severing a natural gas line that sparked a 100 foot-flame (Tan, 02/19). On 02/22 ten people were evacuated from an apartment building threatened by a mudslide; 12 families were forced to flee from another building on the same block of west Ventura’s Cedar Street. A mudslide caused the rupture of a crude oil pipeline in the hills north of Ventura, spilling 168 gallons (Tan, 03/05). On 02/16 storms brought debris down at the bottom of Hall Canyon to form a small lake. Residents of 50 homes were notified that the dam might break and were required to evacuate. Residents of an additional 100 homes were notified that they may have to evacuate (Tan, 02/19). A 12-unit hillside apartment building was flattened by a mudslide; 300 residents were evacuated (Wieczorek, 02/25). On 03/03 previous shallow seated failures turned into deeper-seated failures; 20 percent of the buildings were red- or yellow-tagged (Bob Prodehl, City of Ventura). Well heads in the Ventura fields were damaged due to landslide activity (Ken Henderson, Division of Oil and Gas, 03/13).

39. Bel Air and Culver City, Los Angeles County. On 02/16 shallow slope failures affecting houses occurred in Bel Air and Culver City (Tan, 02/19).

41. Hollywood Hills, Los Angeles County. On 02/23 the storm threatened houses on an unstable hillside (Tan, 03/05).

42. Sherman Oaks, Los Angeles County. On 02/25 a slope failure along a 60-foot-long section of hillside closed a stretch of the 14800 block of Mullholland Drive (Tan, 03/05).

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