what is the landslide type of the la conchita?staff toolbox uca
Mudflow: A mudflow is an earthflow consisting of material that is wet enough to flow rapidly and that contains at least 50 percent sand-, silt-, and clay-sized particles. After this point, a rain burst of 5-6 mm (0.2 to 0.25 in) in one hour has been observed to trigger abundant shallow landslides (seeLandslides in Santa Monica Mountains and Vicinity- Prof Paper 851). In 199495, about twice as much rain761 mm (29.96 in)fell during that period (National Oceanic and Atmospheric Administration, 1994b, 1995b). The various types of landslides can be differentiated by the kinds of material involved and the mode of movement. D. All of these are correct <--------. During and just after storms, existing coastal landslides may become reactivated and seemingly stable coastal cliffs may erode and fail rapidly. 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. Figure 3. Corrections? On March 4, 1995, the hill behind La Conchita failed, moving tens of meters in minutes, and buried nine homes with no loss of life. 3G). Evacuation order lifted at La Conchita, but officials warn area is Figure 3: Some major types of mass movements. 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. Eyewitness accounts indicate, however, that similar to 2005, dust was in the air and much of the deposit included relatively dry material. Steep, recently burned areas in southern California are especially susceptible to debris flows (seeSouthern CaliforniaWildfires and Debris Flows- Fact Sheet 2001-3106). 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. Below are publications associated with this project. Casualties in the United States are primarily caused by rockfalls, rock slides, and debris flows. A) La Conchita, California The community of La Conchita in Ventura County, California experiences frequent landslides. What was the type of landslide in recent 2005 La Conchita landslide? Surface cracks in the upper part of the slope were noted as far back as the summer of 1994. Coherent blocks of material subside into the weaker substrate, and the slow downslope movement frequently extends long distances as a result of the retrogressive extension from the zone of origin, such as an eroding riverbank or coastline. This report has not been reviewed for stratigraphic nomenclature. From December 27, 2004, through January 10, 2005, the nearby city of Ventura received 378 millimeters (14.9 inches) of rainfall, only slightly less than its mean annual total of 390 millimeters (15.4 inches). [2] The County of Ventura immediately declared the whole community a Geological Hazard Area, imposing building restrictions on the community to restrict new construction. The landslide slumped as a coherent mass of material. The worst of these was the tragic slide on January 10, 2005 when a huge rain-caused side killed 10 residents. Figure 8 shows an aerial photograph of La Conchita taken in September 2004. 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. The January 2005 landslide was a debris flow that killed 10 people, and damaged 36 residential homes. 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. Historical accounts and geologic evidence show that landsliding of a variety of types and scales has been occurring at and near La Conchita for many thousands of years, and on a relatively frequent basis, up until the present. Figure 1: Air photo of La Conchita, CA taken in 2002. This cookie is set by GDPR Cookie Consent plugin. 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. In both 1889 and 1909, the Southern Pacific rail line running along the coast was inundated. They can be deadly, however, and can cost billions of dollars to clean up. People were evacuated and the houses nearest the slide were completely destroyed. The La Conchita landslide then occurred on March 4. A lock ( At the beginning of the rainy season, in December 1994, several open cracks had opened on the hillside, and surface runoff was infiltrating into the subsurface. Course Hero is not sponsored or endorsed by any college or university. The landslide recurred on part of a previous landslide in 1995.La Conchita, California. 3). These hazards are mitigated mainly through precautionary means such as restricting populations from susceptible areas, limiting land use, installing early warning systems, and building structures such as piles and retaining walls. [3] Historical accounts support this. 1995 and 2005, La Conchita, California: On March 4, 1995, a fast-moving earthflow damaged nine houses in the southern California coastal community of La Conchita. The catastrophic movement of the 2005 landslide damaged or destroyed 36 houses and killed 10 people. The La Conchita area has experienced, and will likely continue to experience, a rather bewildering variety of landslide hazards. Actually there have been several sizes, types, and ages of landslides. What kind of mitigation was done after the La Conchita landslide? A lock () or https:// means youve safely connected to the .gov website. Back scarp of ancient landslide Scarp of small recent landslide 1995 landslide Figure 2: Close-up image of the 1995 landslide event at La Conchita, CA. 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. Answer-Based on the observation from the figure. 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. Entrapped snow and ice may also help mobilize such flows, but the unqualified term avalanche is generally used to refer only to an avalanche of snow. The 2005 La Conchita landslide occurred at about 12:30 p.m. on January 10. Although landslides are primarily associated with mountainous regions, they can also occur in areas of generally low relief. Rotational slide: This is a slide in which the surface of rupture is curved concavely upward and the slide movement is roughly rotational about an axis that is parallel to the ground surface and transverse across the slide (fig. The term "landslide" encompasses events such as rock falls, topples, slides, spreads, and flows.