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Palos Verdes Peninsula landslides

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The Palos Verdes Peninsula, a coastal region of the Los Angeles metropolitan area, has a long history of landslides and land movements.[1][2][3][4][5][6][7] The Palos Verdes Peninsula is home to the cities of Palos Verdes Estates,[8] Rancho Palos Verdes,[9] Rolling Hills[10] and Rolling Hills Estates,[11] and the unincorporated communities of Academy Hills and Westfield.[12]

History

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As early as the 1920s, the area was identified as a potentially hazardous landslide area, yet real estate construction and development gained traction in the 1940s and 1950s.[13] In 2024, the Palos Verdes Peninsula was rocked with another round of landslides.[14]

Palos Verdes Estates

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In December 2022, a coastal cliff landslide was recorded in Palos Verdes Estates (33.804, -118.394).[15][16]

Rancho Palos Verdes

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The city of Rancho Palos Verdes sits on four out of five sub-slides of the Ancient Altamira Landslide Complex,[17] also referred to as the Greater Portuguese Bend Landslide Complex.[18] The Complex encompasses four historically active landslide areas within the city limits: Abalone Cove Landslide; Beach Club Landslide; Klondike Canyon Landslide; and Portuguese Bend Landslide; as well as the areas outside of the city’s border of those named landslides.[18][19][17][20]

1956 Portuguese Bend Landslide

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The Portuguese Bend landslide was activated in 1956, before Rancho Palos Verdes was incorporated as a city.[21] Beginning in September 1956 and continuing until early 1957,[22] the area experienced a landslide concurrent with the construction of a road (the Crenshaw Boulevard extension, south of Crest Road) along the top of an ancient landslide complex.[3][13][23][24] The impacted areas ranged from several acres to roughly two square miles[25][23] A 1958 video newsreel showed the effects of the landslide’s impact: 140 of the 170 homes in the area were destroyed or displaced.[26]

In 1961, area homeowners filed a lawsuit against Los Angeles County and won a settlement of roughly $10 million.[13][27]

Abalone Cove Slide

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From 1974 to 1978, an 80 acre landslide[28][29] occurred in the Abalone Cove area.[2][13][25] The lower part of the landslide started to move in February 1974.[28] The "Abalone Cove Slide" was moving so slow that geologists did not verify that it was an actual slide until 1976, after it had damaged roughly twenty homes.[30] It is estimated that the landslides damaged nearly 50 homes and depressed property values.[29]

In 1978, residents noticed cracks on Palos Verdes Drive South, and the upper part of the slide may have started to shift.[28][29] That same year, the city restricted building new homes in the areas impacted by the landslides, "Landslide Moratorium Map."[2][25] Since 1980, efforts to control landslide movement have involved removing ground water from the landslide mass.[28]

Beach Club Landslide

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The Portuguese Beach Club landslide is a minor slide within the area's landslide complex.[17][20] In 2024, residents of Seaview and the Beach Club filed a lawsuit against the City of Rancho Palos Verdes.[6] In 2024, the Beach Club area experienced major deformation along Seawall Road, approximately four to five feet across the beach, and potentially into an offshore slide area.[31]

Klondike Canyon Landslide

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The Klondike Canyon has been noted for landslides.[17][20] Renewed movement occurred in 1979,[32] and a Geologic Hazard Abatement Districts was created to study the Klondike Canyon landslides in 1982.[32]

Portuguese Bend and Seaview Landslide

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The Portuguese Bend Landslide is a highly active landslide area that covers approximately 240 acres.[33][34] Since Spring 2023, there has been noticeable land movement and collateral damage in the Portuguese Bend Beach Club, Portuguese Bend Community Association, and Seaview neighborhoods.[1][19] Several miles of trails have closed in the Abalone Cove Reserve, Filiorum Reserve, Forrestal Reserve, and Portuguese Bend Reserve areas.[20][31] In September 2024, more than 200 homeowners had to evacuate the Portuguese Bend and Seaview areas.[35] Several homes have collapsed or have been made unlivable.[36] The city issued an evacuation warning for residents; the landslides are moving at a rate of three-fourths to one foot per week.[1][5][35] Gas to the Portuguese Bend neighborhood has been shutoff since August 2024.[17][35] For safety reason, local utility companies planned to terminate all electricity for impacted residents.[5][35]

On September 3, 2024, California Governor Gavin Newsom declared a state of emergency in the City of Rancho Palos Verdes.[5][19][35] The city has extended a construction moratorium for the landslide areas[5][34] until October 2025.[35]

In Summer 2024, City officials informed residents that they have identified additional land movements and landslides for Rancho Palos Verdes.[21][31] The new, deeper slide appears to be moving faster and deeper, shifting the city's strategy from individual landslide event response to a broader strategy to address all landslide hazards and issues.[31]

Portuguese Mud/Landslide Community Infrastructure Resilience Project

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In 2023, FEMA awarded a $23.3 million grant to Rancho Palos Verdes for the Portuguese Mud/Landslide Community Infrastructure Resilience Project .[33][36][37] The goal of the grant is to make improvements in the existing groundwater extraction systems and to install new subsurface water extraction systems.[33]

Rancho Palos Verdes Landslide Complex Working Group

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The RPV Landslide Complex Working Group meets virtually weekly to plan, coordinate, and implement actions for minimizing land movement and reducing community and property damages. The members of this group include representatives of Abalone Cove Landslide Abatement Districts; California Water Service; City of Rolling Hills; Klondike Canyon Landslide Abatement Districts; Los Angeles County Department of Public Works Sanitary Sewer Maintenance; Los Angeles County Sanitation Districts; Palos Verdes Peninsula Land Conservancy; Portuguese Bend Beach Club Homeowners Association; Portuguese Bend Community Association; Rolling Hills Community Association; Seaview Residential Association; Southern California Gas Company; Southern California Edison; and area residents.[31]

Rolling Hills

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Flying Triangle Landslide

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In 1979, residents in the Flying Triangle Landslide area noticed cracks in the main road leading to their neighborhood.[38] The landslide area spanned approximately 90 acres[38] and damaged and destroyed several homes.[3] Impacted homeowners received roughly $16 million in compensatory setttlements.[38]

In 1987, there was a documented landslide in the Flying Triangle area above Portuguese Bend.[29]

Rolling Hills Landslide Mitigation Project

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In 2024, Congressman Ted Lieu secured one million dollars for the Rolling Hills Landslide Mitigation Project, which is expected to improve wastewater flow and reduce the risk of additional landslides in the Flying Triangle landslide area within the city boundaries.[39]

Rolling Hills Estates

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Rollings Hills Estates is located on the northern side of the Palos Verdes Peninsula, an area that has a history of documented landslides.[40][41]

Office Park land movement

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In 1997, employees in a Rolling Hills Estates office park witnessed crumbling walls and buckling sidewalks and had to be evacuated.[3][42]

Peartree Lane Landslide

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On July 8, 2023, the Peartree Lane Landslide destroyed several homes in Rolling Hills Estates.[43][44] Townhouses in the area slumped into a canyon.[21] This land movement may have started in 2022.[40]


References

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  1. ^ a b c Land Movement Updates. Rancho Palos Verdes. https://www.rpvca.gov/1707/Land-Movement-Updates
  2. ^ a b c Bernhardt, Roger, "Construction Moratorium as a Taking Monks v City of Rancho Palos Verdes, 2008." Publications. Paper 273. http://digitalcommons.law.ggu.edu/pubs/273
  3. ^ a b c d Toohey, Grace, and Nathan Solis, Connor Sheets, Jeong Park. What's causing luxury homes in Rolling Hills Estates to slide down a canyon? Here's what we know. Los Angeles Times. July 10, 2023. https://www.yahoo.com/news/whats-causing-luxury-rolling-hills-192725410.html
  4. ^ McNulty, Dr. Brendan (June 2012). "Geology of the Palos Verdes Peninsula, Los Angeles CA: A Field Guide For the Non-Geologist". California State University Dominguez Hills, Department of Earth Science. Retrieved April 10, 2019.
  5. ^ a b c d e Cann, Christopher. Power outages could last weeks in affluent SoCal city plagued by landslides. USA Today. September 4, 2024. https://www.usatoday.com/story/news/nation/2024/09/04/southern-california-landslides-rancho-palos-verdes/75067503007/
  6. ^ a b Jacobs, Lisa. Rancho Palos Verdes landslide problem is ‘bigger than our city’ say leaders, residents. Long Beach Press-Telegram. August 29, 2024. https://www.presstelegram.com/2024/08/24/rancho-palos-verdes-landslide-problem-is-bigger-than-our-city-say-leaders-residents/
  7. ^ Joannou v. City of Rancho Palos Verdes, Cal: Court of Appeal, 2nd Appellate Dist., 8th Div. 2013
  8. ^ Palos Verdes Estates. https://www.pvestates.org
  9. ^ Rancho Palos Verdes. https://www.rpvca.gov
  10. ^ Rolling Hills. https://www.rolling-hills.org
  11. ^ Rolling Hills Estates. https://www.rollinghillsestates.gov
  12. ^ About Palos Verdes. Palos Verdes Peninsula Association of Realtors. https://www.pvpar.com/aboutpv.php
  13. ^ a b c d Douglas, Robert. The Creepy (Slow Moving) Landslides of the Portuguese Bend Area. Association of Environmental and Engineering Geologists. Special Publication, No. 24. February 2014. https://documents.rpvca.gov/
  14. ^ Jacobs, Lisa. Rancho Palos Verdes residents rally to solve landslide woes on their own. Whittier Daily News. September 7, 2024. https://www.whittierdailynews.com/2024/09/07/rancho-palos-verdes-residents-rally-to-solve-landslide-woes-on-their-own/
  15. ^ Petley, Dave. Palos Verdes Estates: a coastal cliff landslide captured on video. December 4, 2022. https://blogs.agu.org/landslideblog/2022/12/14/palos-verdes-estates-1/
  16. ^ Romine, Taylor, and Ray Sanchez. Concerns of ‘more landslides’ in Southern California after portion of cliff collapses onto beach. CNN. December 10, 2022. https://www.cnn.com/2022/12/10/us/california-landslide-palos-verdes-estates/index.html
  17. ^ a b c d e Sharp, Julie. Rancho Palos Verdes faces deeper, larger landslide threat, city report says. KCAL. August 21, 2024. https://www.cbsnews.com/losangeles/news/rancho-palos-verdes-faces-deeper-larger-landslide-threat-city-report-says/
  18. ^ a b City Council Agenda Report: Consideration and possible action to receive an update report on the Portuguese Bend Landslide / Emergency Hydraugers Project and a 10-day report on the proposed extension of the Interim Urgency Ordinance. City of Rancho Palos Verdes. August 20, 2024. https://rpv.granicus.com/
  19. ^ a b c Governor Newsom proclaims State of Emergency in the City of Rancho Palos Verdes. Governor Gavin Newsom. September 3, 2024. https://www.gov.ca.gov/2024/09/03/governor-newsom-proclaims-state-of-emergency-in-the-city-of-rancho-palos-verdes/
  20. ^ a b c d Toohey, Grace. Winter rains fuel ‘unprecedented’ acceleration, expansion of landslides in Rancho Palos Verdes. Los Angeles Times. Feb. 18, 2024. https://www.latimes.com/california/story/2024-02-18/ancient-landslides-on-palos-verdes-peninsula-accelerating-winter-rains-increase-threat
  21. ^ a b c Knoll, Corina and Loren Elliott. In a Scenic California Town, Worsening Landslides Force Power Shutoffs. New York Times. Sept. 2, 2024. https://www.nytimes.com/2024/09/02/us/landslides-rancho-palos-verdes.html
  22. ^ 1957 Supporting Documents Earth Movement. City of Rancho Palos Verdes. https://www.rpvca.gov/451/Palos-Verdes-Drive-South-Landslide
  23. ^ a b Linden, Karl Vonder (December 1989). "The Portuguese bend landslide". Engineering Geology. 27 (1–4): 301–373. Bibcode:1989EngGe..27..301L. doi:10.1016/0013-7952(89)90037-9.
  24. ^ Gottlieb, Jeff (November 13, 2009). "California: Area has great view, foggy future : A legal fight continues over whether to build on the oceanfront lots of Portuguese Bend". Los Angeles Times. ISSN 0458-3035. Retrieved April 10, 2019.
  25. ^ a b c Monks v. City of Rancho Palos Verdes, 167 Cal.App.4th 263, 84 Cal. Rptr. 3d 75 (Cal. Ct. App. 2008). https://casetext.com/case/monks-v-city-of-rancho-palos-verdes
  26. ^ Portguese Bend Landslide. Rancho Palos Verdes, California. https://www.rpvca.gov/DocumentCenter/View/5553/Portuguese-Bend-Landslide-PDF
  27. ^ "Portuguese Bend Earth Flow". Archived from the original on February 17, 2013. Retrieved January 9, 2013.
  28. ^ a b c d Proffer, Kathleen A. Ground water in the Abalone Cove Landslide, Palos Verdes Peninsula, Southern California (in Landslides/landslide mitigation, James E. Slosson (editor), Arthur G. Keene (editor) and Jeffrey A. Johnson (editor)). Reviews in Engineering Geology. 1992. 9: 69-82. https://pubs.geoscienceworld.org/gsa/books/edited-volume/830/chapter-abstract/4850113/Ground-water-in-the-A-baione-Cove-landslide-Palos?redirectedFrom=fulltext
  29. ^ a b c d Stein, George. Landslide Settlement Calls for Homeowners to Share $5 Million. Los Angeles Times. Sept. 13, 1987. https://www.latimes.com/archives/la-xpm-1987-09-13-cb-7355-story.html
  30. ^ Staff Report: Appeal Substantial Issue. California Coastal Commission. May 24, 2001. https://documents.coastal.ca.gov/reports/2001/6/Th18a-6-2001.pdf
  31. ^ a b c d e Sievertson, Makenna. Rancho Palos Verdes says it's dealing with a much larger and faster moving landslide. LAist. Updated Sep 4, 2024. Published Aug 21, 2024. https://laist.com/news/climate-environment/rancho-palos-verdes-landslide-the-city-changes-its-strategy-to-slow-it-down
  32. ^ a b Orme, Antony R. Mass Movement and SeaclifF Retreat along the Southern California Coast. Bulletin. Southern California Academy of Sciences. 90(2), 1991, pp. 58-79.
  33. ^ a b c California: Rancho Palos Verdes Portuguese Mud/Landslide Community Infrastructure Resilience Project. FEMA. https://www.fema.gov/case-study/california-rancho-palos-verdes-portuguese-mudlandslide-community-infrastructure
  34. ^ a b Bartholomew, Dana. Rancho Palos Verdes extends building moratorium after landslides. Emergency declaration could ban outdoor watering and require draining leaky pools. The Real Deal. November 17, 2023. https://therealdeal.com/la/2023/11/17/rancho-palos-verdes-extends-building-halt-after-landslides/
  35. ^ a b c d e f Garcia, Karen. Landslides bring uncertainty, fear to Rancho Palos Verdes. How much worse will it get? Los Angeles Times. Sept. 5, 2024. https://www.latimes.com/california/story/2024-09-05/unprecedented-landslides-have-rancho-palos-verdes-asking-how-much-worse-can-it-get
  36. ^ a b As Destructive Landslides Continue in Rancho Palos Verdes, Life Is Like Camping. AP News. September 8, 2024. https://timesofsandiego.com/life/2024/09/07/as-destructive-landslides-continue-in-rancho-palos-verdes-life-is-like-camping/#google_vignette
  37. ^ Hixon, Michael. Rancho Palos Verdes received $23 million grant to stabilize landslide area. Daily Breeze. August 30, 2023. https://www.dailybreeze.com/2023/08/30/rancho-palos-verdes-received-23-million-grant-to-stabilize-landslide-area/
  38. ^ a b c Taylor, Ronald B. Land Moves but They Won’t : Rolling Hills: The Flying Triangle is sliding again, destroying houses and leaving concrete debris perched dangerously near some residents. But those who remain have learned to adapt and are resigned to the problem. Los Angeles Times. Dec. 17, 1992. https://www.latimes.com/archives/la-xpm-1992-12-17-me-2798-story.html
  39. ^ Rep Leiu Secures Nearly $2.5 Million for Local Landslide and Flood Mitigation Efforts. Press Release. Congressman Ted W. Lieu (D-Los Angeles County). March 13, 2024. https://lieu.house.gov/media-center/press-releases/rep-lieu-secures-nearly-25-million-local-landslide-and-flood-mitigation
  40. ^ a b Ober, Holly. 2023 Rolling Hills Estates landslide likely began the winter before. Newsroom. UCLA. July 12, 2024. https://newsroom.ucla.edu/releases/2023-rolling-hills-estates-landslide-likely-began-winter-before
  41. ^ Dance, Scott. Why landslides are suddenly tearing homes apart in Southern California. Washington Post. September 3, 2024. https://www.washingtonpost.com/weather/2024/09/03/california-landslides-rancho-palos-verdes/
  42. ^ Johnson, Tracy, and Jeff Leeds. Buildings continue their slide. Los Angeles Times. February 28, 1997. https://www.latimes.com/archives/la-xpm-1997-02-28-me-33207-story.html
  43. ^ Peartree Lane Land Movement. City of Rolling Hills Estates. https://www.rollinghillsestates.gov/departments/public-safety/emergency-preparedness/peartree-lane-land-movement-incident
  44. ^ Toohey, Grace; Solis, Nathan (July 11, 2023). "'Astonishing' collapse sends Rolling Hills Estates homes toward canyon floor". Los Angeles Times. Retrieved July 11, 2023.
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