what is the landslide type of the la conchita?

Where did the La Conchita . 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 failure starts suddenly in a small area and spreads rapidly. The town of La Conchita, California, experienced major landslides in 1995 and 2005. After the 1995 landslide, the town of La Conchita built a retaining wall at the foot of the hill. Deformation continued as the rainy season began, and by December 1994, several open cracks on the hillside were channeling surface runoff into the subsurface. 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. Falls are abrupt movements of masses of geologic materials, such as rocks and boulders, that become detached from steep slopes or cliffs (fig. During the winter season in California, beaches typically erode thereby allowing waves to reach further inland and to inundate the bottoms of coastal cliffs. Solved A) La Conchita, California The community of La - Chegg Another factor that affects the shear strength of a slope-forming material is the spatial disposition of its constituent particles, referred to as the sediment fabric. Coastal cliff failuresmay also occur simply as a result of heightened precipitation as well wave action makes cliffs inherently unstable, and rainfall may be the ultimate trigger for failure, even during times with little to no wave action. Fast-moving, highly destructive debris flows triggered by intense rainfall are one of the most dangerous post-fire hazards. URL: https://pubs.usgs.gov/of/2005/1067/508of05-1067.html The La Conchita area has experienced, and will likely continue to experience, a rather bewildering variety of landslide hazards. In La Conchita, there was a landslide and earthflow in the spring of 1995 (see figure 1). 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. 1B, p. S319S332. A. Weathering affects rocks from the outside in, forming an outer weathered zone or rind. Some are triggered by earthquakes, but more frequently landslides are caused by intense and/or prolonged rainfall. Study with Quizlet and memorize flashcards containing terms like A comprehensive term for any type of downslope movement of Earth materials is, What strategy has been suggested to stabilize the La Conchita, California, landslide?, In Yosemite National Park, strong bedrock influences the formation of what types of hillslopes? Landslides in La Conchita - ArcGIS StoryMaps 1 What type of slide is the La Conchita slide? There are four different types of mass movement: The landslide, which occurred about 130 km northwest of Los Angeles, California, mobilized over 40,000 cubic yards of wet debris into a large scale debris flow (commonly referred to in the media as a mudslide) that flowed into a residential community at the foot of the slope, killing 10 persons and damaging or . Future earthquakes, of course, also could trigger landsliding in the area (Harp and Jibson, 1995, 1996). Earlier that morning, debris flows from canyons northwest of La Conchita reached Highway 101. Publications. Sometimes more than one type of movement occurs within a single landslide, and analysis of each requires detailed interpretation of landforms and geological sections. It does not store any personal data. (See avalanche.) In southern California, at least 25 cm (10 in) of rainfall during the winter is needed to nearly saturate the ground. Click the image to open a larger version in a new window. Prudence would certainly dictate, however, that we anticipate renewed landslide activity during or after future periods of prolonged and(or) intense rainfall. Debris avalanche: This is a variety of very rapid to extremely rapid debris flow (fig. [2] The dimensions of the slides were approximately 120 meters (390 feet) wide, 330 meters (1,080ft) long, and 30 meters (98ft) deep. These maps em, 12201 Sunrise Valley Drive Reston, VA 20192, Preliminary soil-slip susceptibility maps, southwestern California, Southern California LandslidesAn Overview, Map of Historic and Prehistoric Landslides in Pacific Palisades, Landslides in Santa Monica Mountains and Vicinity, Preliminary Soil-Slip Susceptibility Maps for Southwestern California, Map of Fatal or More than $1 Million Damage in California from 1906 to 1984, Landslide Hazards at La Conchita, California, Southern CaliforniaWildfires and Debris Flows, National Assessment of Shoreline Change Part 4: Historical Coastal Cliff Retreat along the California Coast, Emergency assessment of post-fire debris-flow hazards for the 2013 Springs Fire, Ventura County, California, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, National assessment of shoreline change, part 4: Historical coastal cliff retreat along the California coast, Southern California Wildfires and debris flows, Southern California landslides-an overview, Landslide hazards at La Conchita, California, Groundwater and Streamflow Information Program, Geology, Minerals, Energy, and Geophysics Science Center, Soil slips, debris flows, and rainstorms in the Santa Monica Mountains and vicinity, southern California. La Conchita landslide verdict - The Landslide Blog - AGU Blogosphere The landslide occurred after a 15-day period of unprecedented records of rainfall in Southern California. 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. What type of slide is the La Conchita slide? - Heimduo These tools and the accessible reader may be obtained free from Adobe at Adobe Access. Morton, D.M., 1971, Seismically triggered landslides above San Fernando Valley: California Geology, v. 24, no. As such, the maps offer a partial answer to one part of the three parts necessary to predict the soil-slip/debris-flow process. Major landslides in La Conchita, California, La Conchita Community Organization (LCCO), Recent Landslides In La Conchita, California Belong To Much Larger Prehistoric Slide, Landslide Hazards at La Conchita, California, "Recent Landslides in La Conchita, California Belong to a Much Larger Prehistoric Slide, Report Geologists", Landslide Hazards at La Conchita, California. The KCALTV video indicates that the landslide material mobilized simultaneously and nearly instantaneously into a highly fluid, rapidly moving debris flow. The upper part of the slope consists of interlayered siliceous shale, siltstone, and sandstone of the Middle to Upper Miocene Monterey Formation. A type of landslide in which the distribution of particle velocities resembles that of a viscous fluid is called a flow. The developed part of the slope where the houses were impacted has a flatter slope, and so the flow probably slowed to no more than 5 m/s (15 ft/s) in the neighborhood. Separation occurs along discontinuities such as fractures, joints, and bedding planes, and movement occurs by free-fall, bouncing, and rolling. What about the remaining 1995 deposit? By clicking Accept All, you consent to the use of ALL the cookies. In 1995, after a very wet January, the landslide did not move until more than a month later, during which time very little rain fell (fig. In 2005, after a 15-day period of near-record rainfall, a larger area failed rapidly, remobilizing part of the 1995 slide. 10.5: Landslide Types and Processes - Geosciences LibreTexts The video shows relatively intact vegetation being rafted on the surface of the rapidly flowing mass, which indicates that much of the landslide mass simply was being carried on the fluidized layer at depth, which presumably was much more saturated. The slippery zone is often made up of wet sediment. This mode of movement would most likely be relatively slow (compared to 2005) but still could pose serious hazards to property and, perhaps, life. Photo taken March 8, 1995. These reports and maps can be used as examples of what may occur during the upcoming 2015-2016 El Nio season if heavy precipitation occurs. On January 10, 2005, a major landslide occurred in La Conchita. [6] Or will it remain metastable? Over time, upslope ponding of water by such back-tilted blocks can enlarge the area of instability, so that a stable condition is reached only when the slope is reduced to a very low gradient. La Conchita (1995) La Conchita landslide, Ventura County. Saturated soil (soil filled with water) flows down a slope. 3H). 7). The main mass that failed is on the southeastern margin of the larger ancient landslide that encompasses the entire front of the bluff (see fig. Of primary interest to the general public and various Governmental entities is the current state of hazard at La Conchita. The neighborhood of La Conchita has suffered from large landslides in the recent past that have wiped out homes and even killed people. The lower part of the slope is siltstone, sandstone, and mudstone of the Pliocene Pico Formation (O'Tousa, 1995). Although it is not uncommon for subsidiary debris flows to occur from the toes or scarps of existing landslides (Morton and Campbell, 1989), that is not what happened in 2005. The movement of the same landslide mass in 1995 and 2005 by two very different mechanisms, and with markedly different results, is difficult to explain.
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