what is the landslide type of the la conchita?

In the 1909 slide, a train was buried. Other classification systems incorporate additional variables, such as the rate of movement and the water, air, or ice content of the landslide material. The failure is caused by liquefaction, the process whereby saturated, loose, cohesionless sediments (usually sands and silts) are transformed from a solid into a liquefied state. 13. An idealized slump-earth flow showing commonly used nomenclature for labeling the parts of a landslide. This dynamic tectonic environment has created a spectacular landscape of rugged mountains and steep-walled valleys that compose much of the regions scenic beauty. Debris flows are commonly caused by intense surface-water flow, due to heavy precipitation or rapid snowmelt, that erodes and mobilizes loose soil or rock on steep slopes. Necessary cookies are absolutely essential for the website to function properly. The term "landslide" describes a wide variety of processes that result in the downward and outward movement of slope-forming materials including rock, soil, artificial fill, or a combination of these. There is a good web site where you can read and see pictures about the slide in La Conchita: By reading it I can tell you that the bluff above La Conchita has produced a variety of landslides over an extended period of time. The landslide entered the La Conchita neighborhood destroying 13 houses and severely damaging 23 others. 1) (34.4 degrees north, 119.5 degrees west). After covering the road with 7-8 feet of debris, the slide stabilized. [3] Historical accounts support this. Currently, we have insufficient data and understanding of the failure mechanisms of this landslide to adequately answer these questions, but it is clear that the hazard from renewed landslide movement is considerable. For those who aren't, La Conchita a small (population about 340 people), unincorporated seaside village located on the Pacific coast north of Los Angeles (Fig. Deformation continued as the rainy season began, and by December 1994, several open cracks on the hillside were channeling surface runoff into the subsurface. The USGS has conducted hazard assessments forpost-wildfire debris flowsfor four recent fires in southern CA, as well as numerous fires across the Western U.S. including central and northern California. 2023 California Landslide Response 13, 60 p. National Oceanic and Atmospheric Administration, 1994b, Climatological dataCalifornia, OctoberDecember 1994: National Climatic Data Center, v. 98, nos. A slide happens when a section of soil or rock suddenly gives way and moves down a slope. Maps displaying where shallow landslides are most likely to occur are based on observation of previous landslide activity, topographic slope, and information on the bedrock material (seePreliminary soil-slip susceptibility maps, southwestern California-Open-File Report 2003-17). The landslide scenarios sketched above potentially could impact any part of the La Conchita community. Rockslides and other types of slides involve the displacement of material along one or more discrete shearing surfaces. The project also helps to. Morton, D.M., 1971, Seismically triggered landslides above San Fernando Valley: California Geology, v. 24, no. Morton, D.M., and Campbell, R.H., 1989, Cyclic landsliding at Wrightwood, southern California, in Sadler, P.M., and Morton, D.M., eds., Landslides in a semiarid environment with emphasis on the inland valleys of southern California: Inland Geological Society, Riverside, Calif., v. 2, p. 174182. [5] The Ranch was found 50% negligent because it did not provide for adequate drainage of its orchards during torrential rains and settled the suit. Secure .gov websites use HTTPS In 1994-1995, the seasonal rainfall at Ojai (20 kilometers (12 miles) northeast of La Conchita) from October 1 through March 3 (the day before the landslide occurred) was 761 millimeters (29.96inches), approximately twice the normal amount. What caused the Los Angeles landslide in 1995? The 1995 landslide was a deep, coherent slumpearth flow that deformed plastically and moved slowly enough that people could get out of its way. On January 10, 2005, a landslide struck the community of La Conchita in Ventura County, California, destroying or seriously damaging 36 houses and killing 10 people. The 2005 landslide was a shallower remobilization of the very same material into a rapid, highly fluid debris flow that buried 10 people. 1012. La Conchita, CA. Jibson, R.W., 1989, Debris flows in southern Puerto Rico, in Schultz, A.P., and Jibson, R.W., eds., Landslide Processes in Eastern North America and Puerto Rico: Geological Society of America Special Paper 236, p.2955. Publications. O'Tousa, James, 1995, La Conchita landslide, Ventura County, California: Association of Engineering Geologists AEG News, v. 38, no. The 2005 La Conchita landslide occurred on January 10. Please select which sections you would like to print: Geographic Database Manager and Geographic Information Systems Analyst, Department of Geography, Royal Holloway, University of London, Egham, Surrey, U.K. Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. { "10.01:_Why_It_Matters" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "10.02:_Classifying_Mass_Movements" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "10.03:_Erosion_and_Deposition_by_Gravity" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "10.04:_Driving_and_Resisting_Forces" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "10.05:_Landslide_Types_and_Processes" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "10.06:_Putting_It_Together" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "00:_Front_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "01:_Science_of_Geology" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "02:_Rock_Forming_Minerals" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "03:_Rocks_and_the_Rock_Cycle" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "04:_Soil" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "05:_Plate_Tectonics" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "06:_Earth\'s_Interior" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "07:_Crustal_Deformation" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "08:_Earthquakes" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "09:_Volcanic_Activity" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "10:_Mass_Movement" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "11:_Hydrology" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "12:_Geological_Implications" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "zz:_Back_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, [ "article:topic", "showtoc:no", "license:ccby", "licenseversion:40" ], https://geo.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fgeo.libretexts.org%2FBookshelves%2FGeology%2FFundamentals_of_Geology_(Schulte)%2F10%253A_Mass_Movement%2F10.05%253A_Landslide_Types_and_Processes, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), Original content from Kimberly Schulte (Columbia Basin College) and supplemented by, Creative Commons Attribution 4.0 International, Combination or two or more principal types of movement. Parise, Mario, and Jibson, R.W., 2000, A seismic landslide susceptibility rating of geologic units based on analysis of characteristics of landslides triggered by the January 17, 1994 Northridge, California, earthquake: Engineering Geology, v. 58, p. 251270. The primary regions of landslide occurrence and potential are the coastal and mountainous areas of California, Oregon, and Washington, the States comprising the intermountain west, and the mountainous and hilly regions of the Eastern United States. La Conchita is a small Pacific coastal community that lies between Santa Barbara, CA and Ventura, CA. Although there are multiple types of causes of landslides, the three that cause most of the damaging landslides around the world are these: Original content from Kimberly Schulte (Columbia Basin College) and supplemented by Lumen Learning. In 2005, an additional landslide occurred at the end of a 15day period of near-record rainfall levels. The lower part of the slope is siltstone, sandstone, and mudstone of the Pliocene Pico Formation (O'Tousa, 1995). Examine Figure 1 (an oblique air photo of the slide features on the coast at La Conchita), Figure 2 (a close-up view of the 1995 landslide), and Figure 3 (some common types oflandslides). 1995 La Conchita, California, landslide. There were 10 confirmed fatalities. Creep is indicated by curved tree trunks, bent fences or retaining walls, tilted poles or fences, and small soil ripples or ridges (fig. Figure 8 shows an aerial photograph of La Conchita taken in September 2004. [2] The County of Ventura immediately declared the whole community a Geological Hazard Area, imposing building restrictions on the community to restrict new construction. Examine Figure 1 (an oblique air photo of the slide features on the coast at La Conchita), Figure 2 (a close-up view of the. On January 10, 2005, a landslide struck the community of La Conchita in Ventura County, California, destroying or seriously damaging 36 houses and killing 10 people. This mode of movement suggests that the landslide formed as a result of rising groundwater levels in response to deep infiltration of antecedent seasonal rainfall. Contact between the flowing mass and the underlying material can be distinct, or the contact can be one of diffuse shear. Landslides are described and classified in various ways depending upon the material (s) involved, mode of movement, rate of movement, and the water, air or ice content of the landslide material (see Figure 4). 3 What was the main cause of La Conchita landslide in 2005? The January 2005 landslide was a debris flow that killed 10 people, and damaged 36 residential homes. Coarse particles such as sand grains have high frictional strength but low cohesive strength, whereas the opposite is true for clays, which are composed of fine particles. U.S. Department of the Interior | U.S. Geological Survey The 2005 landslide pushed many of the houses off their foundations and into each other at the toe of the landslide (figs. What year did the landslide happen in Ventura CA? The latter landslide killed 10 people, and destroyed or damaged dozens of houses. The deposit covered approximately 4 hectares (9.9 acres), and the volume was estimated to be approximately 1.3 million cubic meters (1.7 million cubic yards) of sediment. The catastrophic movement of the 2005 landslide damaged or destroyed 36 houses and killed 10 people. Debris-flow source areas are often associated with steep gullies, and debris-flow deposits are usually indicated by the presence of debris fans at the mouths of gullies. The upper part of the slope consists of interlayered siliceous shale, siltstone, and sandstone of the Middle to Upper Miocene Monterey Formation. A lock ( Our editors will review what youve submitted and determine whether to revise the article. Eyewitnesses also reported seeing material failing from the main scarp and lateral margins of the landslide as a result of removal of lateral support. The U.S. Geological Survey, Multi Hazards Demonstration Project (MHDP) uses hazards science to improve resiliency of communities to natural disasters including earthquakes, tsunamis, wildfires, landslides, floods and coastal erosion. The 2005 landslide occurred at the end of a 15day period that produced record and nearrecord amounts of rainfall in many areas of southern California. 2). The events of Jan. 10, 2005, when 400,000 tons of mud slid down the bluff behind La Conchita, killing seven adults and three children, are frozen in the eerie tableau a reminder of the hidden dangers lurking beneath the surface. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. The landslide, a complex slumpearth flow, destroyed or severely damaged nine houses. Landslide Hazards at La Conchita, California - USGS Debris flows also commonly mobilize from other types of landslides that occur on steep slopes, are nearly saturated, and consist of a large proportion of silt- and sand-sized material. Based on the opinion that surface water infiltration from irrigation contributed to the landslide, seventy-one homeowners sued La Conchita Ranch Co. in Bateman v. La Conchita Ranch Co. Alaska and Hawaii also experience all types of landslides. Landslide | Definition, Types, Causes, & Facts | Britannica They can easily overflow channels and severely damage houses, vehicles, or other structures. 3D). Below are publications associated with this project. Similar combinations of large ancient landslides and smaller, recently active landslides also are present in areas southwest of the 1995 and 2005 landslides. Updates? A summary of recent and past landslides and debris flows caused by rainfall in Southern California. People were evacuated and the houses nearest the slide were completely destroyed. This is a typical type of landslide. NOAA uses this information to provide early warning for debris flows in areas affected by the fire. This area has experienced two massive landslides in the past decade: March 4, 1995, and January 10, 2005. After the 1995 landslide, the town of La Conchita built a retaining wall at the foot of the hill. Omissions? During the winter season in California, beaches typically erode thereby allowing waves to reach further inland and to inundate the bottoms of coastal cliffs. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. The volume of the landslide was estimated to be approximately 200,000 cubic meters with a surface 350 meters (1,150 feet) long and 80100 meters (260330 ft) wide. Schuster, U.S. Geological Survey. Historical accounts dating back to 1865 have reported landslides in the area around La Conchita as being a regular occurrence (Hemphill, 2001). Lateral spreading in fine-grained materials on shallow slopes is usually progressive. Many areas of coastal California are subject to cliff erosion and coastal landslides (see new research onEl Nio coastal hazardsin California). Reading: Landslide Types and Processes | Geology | | Course Hero In 1995, after an exceptionally wet winter, the landslide moved tens of meters (tens of yards) damaging nine houses. When coherent material, either bedrock or soil, rests on materials that liquefy, the upper units may undergo fracturing and extension and may then subside, translate, rotate, disintegrate, or liquefy and flow. The landslide destroyed 13 houses and severely damaged 23 others. As coastal populations continue to grow and community infrastructures are threatened by erosion, there is increased demand for accurate information regarding trends and rates of coastal cliff retreat. The storm of March 23 also may have played a role in triggering initial movement of the hillside, which already was approaching instability due to longerterm seasonal rises in groundwater levels.
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what is the landslide type of the la conchita? 2023