la conchita landslide 2005 case study

in the mountain area is very heavy and the mountain high slope is steep, and the water content of soil is overly saturated ... ← CASE STUDY SUMMARY_TODD. Since then, debris flow has not occurred in the Laogan Ravine. unstable, they often cause serious geological calamities such as landslide, collapse, debris flow, etc., and Landslide areas were mapped in detail to classify the different failure types and parts. The 2005 La Conchita Landslide occurred at the end of a 15–day period of near-record rainfall levels. 2005 La Conchita landslide The 2005 La Conchita Landslide occurred at the end of a 15–day period of near-record rainfall levels . Physical characteristics for a debris flow: 30. At 2:05 pm on Monday January 10, 2005, a steep slope behind the housing development at La Conchita, failedcascading approximately 400,000 tones of debris, and killed 10 people,buried 13 homes and damaged 18. the southern of China continuously, in the area of Wuyishan and Xianxialing it meets the cold air current which comes from hills area, and the domestic geological conditions are very complicated. Analyses of major events that have struck northern Italy over the last 35 years have provided numerous useful data for the recognition of various rainfall-triggering processes and their sequence of development in relation to the intensity and duration of rainfall. 27. Mitigation Measures Were Taken To Reduce/prevent Future. September 15, 2016, was investigated. The most tragic event was a landslide (mudslide) at La Conchita, a coastal community about 112 km west of Los Angeles. In addition, it can trigger landslid, collapse, and some other secondary disasters, that is, reservoir induced seismicity has dual danger. This debris flow control project was completed in 1994 with total investment of 1.372 million Yuan. Part III presents a case study comparison between La Conchita and Laguna Beach. Santa Barbara County Ventura County Pacific Ocean Santa Barbara Ventura Ojai 1 0 1 1 50 1 50 33 La C onchita C a l i f o r n i a N. ¾180-m-high bluff ¾~350 slslope ¾Monterey Formation in … Events. The area upstream of the landslide dam is submerged under water and the downstream area is flooded when the landslide dam breaks. Next, the rational method, combined with a number of equations, was proposed to estimate peak flow-discharges in the river produced by extreme rainfall events. Rain destabilizes slope: 28. The unstable areas frequently create debris flows and debris slicing affecting the human settlements. 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). All rights reserved. For a USGS rerpot on this event, please see USGS Open-file report, "Landslide Hazards at La Conchita, California." 2005 La Conchita landslide In 2005, an additional landslide occurred at the end of a 15–day period of near-record rainfall levels . An average sorting coefficient of 3.94 indicates poor sorting, although somewhat better than in many glacial tills which the flow deposits strongly resemble. irrigation canal, total economic losses was 19.5 million Yuan. International Journal of Erosion Control Engineering. HISTORY OF INSTABILITY Terms River-bed morphology is extensively modified, with erosional and depositional processes which can locally undermine the stability of structures and infrastructures. They can be a result of Structural measures for control of debris flows, such as check dams, are at present unreliable due to lack of rational design criteria. The landslide occurred on part of a previous landslide that occurred in 1995. & This study investigates the mechanism and the entire process of rainfall-induced deep-seated landslides forming two massive dams in the Kuridaira and Akatani valleys, respectively. Morphological comparison of the Carlson landslide with lobate martian landslides suggests a role for water in the martian landslides. In 2005 a landslide with over 400,000 tons of mud destroyed over 20 houses and killed ten people. The USGS classified the 2005 event as a debris flow. Next: La Concitas Comparison - Up: Case Studies Previous: Arent 3 Soil Description. Although the slope Details. This can provide important information about avalanche speeds. Also, the conventional theory will result in lower speed estimates than the new formulation for the same amount of superelevation. At the same time this essay will contribute to the study of geological disaster such as earthquake ,landslide and debris flow. LA CONCHITA, CA - DECEMBER 07: A man bicycles past bluffs burned in the Thomas Fire on December 7, 2017 in La Conchita, California. The violent flow causes severe problems mainly along valley bottoms of rivers with basins up to 2000 km2 in area. all of them have caused casualties and brought great losses. Almost every year, landslides, mud flows and debris flows in the Alpine areas and flooding in the Po flood plain cause severe damage to structures and infrastructure and often claim human lives. The Red Mountain fault extends In this, Extreme heavy rainfall due to Typhoon Talas on September 2–4, 2011 in the Kii Peninsula, Japan, triggered numerous floods and landslides. La Conchita landslide on January 10, 2005 was a remobilization of a larger slump from 1995. This is Part I of a two-part causation analysis of the January 10, 2005 La Conchita, California, USA landslide. By Nick Madigan and Charlie Leduff. This is Part I of a two-part causation analysis of the January 10, 2005 La Conchita, California, USA landslide. Where do they occur? It is a highly probable that the town will be affected again by landslides and debris flows. This research is therefore helpful for hazard assessment of slopes that are susceptible to deep-seated landslides and other sequential processes in areas with geology and geomorphology similar to that of the Kii Peninsula. Christina Kennedy, 45 . This abundance of landslide dams is probably caused by the geotectonic background of this area, which is located at the western end of the “Fossa Magna” major tectonic line. Explain: 31. The 1995 movement at La Conchita has been classified by the USGS as a complex slide. | Figure 5: Essentially the same tragedy strikes La Concitas (Conchita) a decade after the first landslide. This area has experienced two massive landslides in the past decade: March 4, 1995, and January 10, 2005. One sample of the fluid debris had a density of 2.4, indicating a water content of 25–30 per cent by weight. Thus the mechanism(s) responsible for causing anomalous runout in large dry landslides could operate in moist and water-saturated landslides as well. From MSNBC. The January 10, 2005 La Conchita Landslide Philip J. Shaller 1 , Parmeshwar L. Shrestha 1 , Macan Doroudian 1 , Douglas L. Hamilton 1 , and David W. Sykora 2 1 Exponent, 320 Goddard Way Suite 200, Irvine, CA 92618 2 Exponent, 9 Strathmore Road, Natick, MA 01760 View desktop site. Landslide Case study- La Canchita La Conchita is a very small community, located on the southern California coastline between Ventura and Santa Barbara. You can request the full-text of this article directly from the authors on ResearchGate. Therefore ,it is necessary to summarize the geodetic datum and tech of, The geological hazards pose a serious challenge to the ecological system in the region of the Three Gorges Reservoir area, which include landslides, rockfalls, debris flow, earthquake, and so on. 2005 La Conchita Landslide Review of Landslides 1 What is it? MJO: 2004-05 winter season OLR Anomalies Enhanced Convection Phase 1 18 Dec Phase 2 19-24 Dec Phase 3 25 Dec-2 Jan Phase 4 3-8 Jan ... Case study 5-15 January 2005: sensitivity experiments From these variables a hierarchical heuristic model was applied in which three levels of weights were designed for classes, variables, and criteria. The simulation results are examined in accordance with the observed on-site geomorphic features and recorded data to explain the possibility of sliding processes. The premise of the case brought against the ranch owners was that irrigation was the cause of the 1995 landslide, because irrigation has the tendency to raise the water table and potentially cause weakness in hill slopes. Improved prediction of debris flow characteristics is needed so that reliable modification of debris flow behaviour might eventually become possible, without unacceptable environmental and social impacts. This paper describes the geology and geomorphology of the event, which killed 10 persons and damaged or destroyed 36 residences. The total volume of loose solid matter of Sanyanyu valley is about 40 794 200 m3, which can convert to debris flow nearly 26 445 400 m3 (64. Three major landslide regions are recognized in the study area: coastal hills with rockfalls, shallow debris flows and old rotational rockslides denudational slopes in limestone, with very large deep-seated rockslides related to tectonic activity and the Sierra de Caujerí scarp, with large rockslides. PART 4: LA CONCHITA CASE STUDY La Conchita is a small coastal community near Ventura, CA. Nanping City is located in the north of Fujian province, among Fujian province. Debris or earth material that moves downslope due to the combination of an outside force and gravity. LA CONCHITA, CALIFORNIA 2005 RICHARD HANSON, KRISTEN DALRYMPLE, BRACKON TAYLOR LOCATION La Conchita Study Resources In 1995, A Large Landslide Occurred, Damaging About A Dozen Homes. There are likely to be social and political difficulties with this policy, which is however technically feasible. Unfortunately, such an event has not been uncommon to the area in the last few hundred years. It could, therefore, be used to determine the peak flow-discharge for extreme rainfall events. Figure 5: Essentially the same tragedy strikes La Concitas (Conchita) a decade after the first landslide. The conventional approach for estimating speeds is mathematically equivalent to one developed from equations based on fluid mechanics with a balance between fluid pressure force and centrifugal force to yield a simple expression which relates channel radius, avalanche speed, and superelevation geometry. The results showed that the proposed method is able to estimate the flow-discharge in the Gao-ping river with reasonable accuracy if the flow rate of interest is greater than 5000 cms or the return period of interest is more than 100 years. This lobe exhibits characteristic debris flow textures, including raised lateral levees and a surface pattern of ridges and troughs. No breaker-like motion was evident, although the top of the front tended to shoot ahead of the base. 2005 landslides (Fig. By viewing the case study photographs provided in lab and in Figure 12.5, answer the following questions. rainfall more common in winter.Geomorphic instability processes are very common. The high intensity and accumulation of rainfall induced floods, landslides and debris flows. Both events were preceded by major rainfall events, which contributed to the mass wasting. It was triggered by two weeks of heavy rainfall, which initiated a failure in the backscarp of a large slump that had occurred ten years earlier. Question: PART 4: LA CONCHITA CASE STUDY La Conchita Is A Small Coastal Community Near Ventura, CA. Events. La Conchita is an important case history because the 2005 landslide was largely a consequence of decisions taken after the 1995 failure. study, the destructive flood in the Gao-ping river in southern Taiwan, caused by Typhoon Morakot, was selected as an area for case analysis. In more viscous surges a bouldery embankment developed at the front and was shoved along by the material following behind. The volcano is prone to landslides due to its loose vulcanoclastic sediments that are dragged by the streams and torrents during the rainy season. Question: PART 4: LA CONCHITA CASE STUDY La Conchita Is A Small Coastal Community Near Ventura, CA. The fundamental mode of Sanyanyu Gully loose mass converted to the components of debris flow included collapse and landslide deposited directly or fluvial eroded and transported by jamming trench: The fine grain material of gully slope's remnant slope sediment, the landside mass, the collapse body flowed into the trench under the rainfall's surface erosion function, supplied the debris flow and increased its viscosity; The early debris flow deposit in trench was eroded and transported directly, constituted the debris flow mass. Debris basins are structurally simple but need reliable predictions of debris-flow volume. Mitigation measures were taken to reduce/prevent future. From MSNBC. the north of China to form a stationary front, which brings continuous storm, causing floods and geological calamities. landslide (mudslide) at La Conchita, a coastal community about 112 km west of Los Angeles. In an earlier tragedy at La Conchita, Ventura County was not held liable after 600,000 tons of mud and rock slid down the hill into the ocean-side town in 1995, destroying nine homes. Southwestern mountainous areas, which can be of great reference value for the research of the similar places with regards to its hydrology, geology, geological structure and ground. Nanping City is an area where geological calamities occur frequently Sometimes when avalanches descend, they encounter curved channel bends, which cause the flowing material to superelevate or climb up on the wall of the channel bend so that the level of the flowing snow is higher on the outside of the bend than at the center of the channel. Intense shattering and rapid weathering of the bedrock (Pelona schist) within the San Andreas rift zone at this location contributed materially to preparing debris for flowage. Flowing avalanches are those with a dense core of flowing granular material at the base, which dominates the dynamics causing friction. Why do they occur? As a prevention to future debris flow, have been constructed walls of containment (gabions) along the principal channel of the river La Ciénaga, nevertheless in every rainy season the gabions are saturated and frequently destroyed, which shows the intense activity of the remove gravitational processes. From Figure 6, notice the March 4,1995 slide occurred approximately one month after the period of heavy rainfall ended. 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. It is shown that the conventional theory is physically unrealistic for flowing snow modeled as a frictional material. The January 10, 2005 La Conchita landslide was the deadliest single event triggered by the 2004-2005 storm sequence. We combined both the microtopography features from the DEM and canopy openness in the DSM to establish an assess- ment procedure for landslide hotspot extraction. On July 26, 1985 a large debris flow overturned a bus and killed 12 passengers, silted up the open railway tunnel and highway bed with total 410m long. 3. Geomorphic settings and landslide mobility are major contributing factors to the dam formation. In 1995, A Large Landslide Occurred, Damaging About A Dozen Homes. The 2005 La Conchita Landslide Overview In 2005, the small town of La Conchita, California experienced a dangerous landslide event. In continuous precipitation, in the second phase, first mud–debris flows can be triggered also in basins larger than 20 km2 in area. In recorded history, as many as 22 landslide dams have formed upstream of the Shinano River and the Hime River, in the northern, Northern Italy is a geomorphologically heterogeneous region: high mountains, wide valleys, gentle hills and a large plain form a very varied landscape and influence the temperate climate of the area. Before this event happened there were fifteen days of huge amounts of rain. The Alps region has harsh winters and moderately warm summers with abundant rainfall. The landslide is … The landslide is located in a complex and active tectonic setting. Based on the timing of the slides relative to the rainfall pattern, for which event - 1995 or 2005 - do you think the water had infiltrated deeper into the subsurface? Huftile et alii (1997) observed 34 m of vertical separation of the Punta Gorda wave-cut platform along the fault, corresponding to a dip-slip rate of about 1.5 Fig 2 - Geologic map of the 2005 La Conchita landslide and vicinity. The community lies on a narrow strip of land about 250 meters (820 feet) wide between the shoreline and abutting a … All right reserved. Field validation indicated that the landslide-prone area and subsidence features on the forest canopy could be recognized using a sky-view factor relief and local relief model. Earlier mudflows have occurred here, and others will undoubtedly take place in the future. La Conchita Landslide (between Santa Barbara and Ventura): 10 people killed. 8%). GEOS 3310 Lecture Notes, Spring 2006 This paper describes the development and application of a two-dimensional finite difference model (FLO-2D) model to simulate the debris flow over a fixed substrate. Debris was transported 15 miles by the mudflow, and on a gradient as low as 75 feet per mile at the outer extremity. Mitigation Measures Were Taken To Reduce/prevent Future. The range of weight values and the number of existing landslides is registered for each class. Over 30,000 m3 of wet debris was mobilized in the event, which formed two distinct lobes of debris. The complete lack of historical landslide information and geotechnical data precludes the development of quantitative deterministic or probabilistic models. Tributaries swell the main stream, which is already in a critical condition. 28. In this study, the large-scale landslide that occurred in Hongye Village, Taitung County in Eastern Taiwan, on, Large landslides or debris flows caused by heavy rainfall or earthquakes often block rivers in mountainous areas and form landslide dams. Morphology and sedimentology distinguish dry landslides from moist and water-saturated deposits. During the flood season, while the rainfall intensity Note: the two ovals on the topographic map in Figure 5 show the location of the 1995 and 2005 mass wasting events. This material impacted and locally breached the temporary wall, but did not flow into the community below. This sequence cannot be divided into separate phases when the events occur simultaneously because of the presence of intense rainfall pulses and the generation of very diffuse surface runoff. 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 landslide hazard map was used in combination with existing information on buildings and infrastructure to prepare a qualitative risk map. Waters overflow levees, flooding villages and towns to various widths and depths and sometimes claiming casualties. Therefore, development and enlargement of debris flow in Laogan Ravine became a key blocking section of traffic not only for Dongchuan city but also for north-eastern Yunnan province therefore Laogan Ravine debris flow control was a great issue for the development of Dongchuan city. In this paper, the conventional theory is replaced by one which relates avalanche speed to basal friction (as appropriate for flowing snow), passive snow pressure (accounting for friction between snow particles), channel radius, and superelevation geometry. The landslide killed 10 people, and destroyed or damaged dozens of houses. A Descriptive Study of the 2005 La Conchita Mudslide Response Robin R. Murphy and Sam Stover Center for Robot-Assisted Search and Rescue University of South Florida Tampa, FL 33620-5930 e-mail: murphy@cse.usf.edu, slstover@cse.usf.edu Received 16 November 2006; accepted 18 June 2007 The mechanism of the rapid deep-seated landslides is examined through a series, Geomorphological information can be combined with decision-support tools to assess landslide hazard and risk. The hazard map was then divided by two scales, one with three classes for disaster managers and one with 10 detailed hazard classes for technical staff. The study is based on a terrain mapping units (TMU) map, generated at 1:50,000 scale by interpretation of aerial photos, satellite images and field data. List the physical characteristics you see in the photo that support the interpretation that this is a slide. 1995 La Conchita Landslide. La Concitas - 2005. Deeper? After Landslide, a Paradise Unlikely to Be Regained. Typically occur within proximity to mountain ranges. The Red Mountain fault is a major, active reverse fault. that: 1. of laboratory experiments on samples from sliding surfaces by using undrained high-stress dynamic-loading ring-shear apparatus. This is Part I of a two-part causation analysis of the January 10, 2005 La Conchita, California, USA landslide. and geology is, Access scientific knowledge from anywhere. He said the remaining houses are in … The total duration of rainfall usually has a greater effect on these landslides than does the number of short periods of very intensive precipitation. The resulting increasing landslide density with higher hazard classes indicates that the output map is reliable. In this study, we examined three large historical landslide dams and outburst disasters in the north Fossa Magna area. part of Nagano Prefecture in central Japan, and all except three have subsequently broken. These data are combined to deduce the factors that prompted the slope failure, the kinematics of initiation, travel, and stopping of the landslide, as well as its postemplacement degradation. The flow advanced in successive waves or surges of “slimy gray cement-like” mud containing abundant stones. GEOS 3310 Lecture Notes, Spring 2008 Today, the town is settled in the alluvial fan of the old debris flows deposit. As before, list the physical characteristics you see in the photo that indicates this is a debris flow. View Test Prep - La Conchita California 2005 from SCIENCE 201 at Brigham Young University, Idaho. The runout distance of the initial landslide was 960 m and increased to 1.23 km when the landslide transformed into debris flow in the village. Moreover, a complete landslide susceptibility assessment approach suitable for the catchment scale is presented. The results further point out that local failures are initiated from the lower middle part of the landslide bodies where the geological boundary exists. 30. Journal of Chinese Soil and Water Conservation. The immediate cause of flowage was rapid melting of deep winter snow. The La Conchita landslides that occurred in 1995 and 2005 form only a small percent of a much larger landslide complex, according to the geologists. After the 2005 tragedy, research geologist Randy Jibson of the U.S. Geological Survey authored a study of La Conchita. Investigation results show, Nanping City lies in the north of Fujian Province and the upper of Minjiang River, where belongs to middle-low mountains and La Conchita is a small Pacific coastal community that lies between Santa Barbara, CA and Ventura, CA. The Po Plain has harsh winters with long periods of subfreezing temperatures and warm sultry summers, with, Landslides in volcanic mountainous terrains covered by poorly consolidated materials are common in Mexico. It is inclinded to have a negative effect on the dam and reservoir, which can bring some troubles, such as the deformation of the dam foundations, cracking and instability of the dam, and meltdown of the reservoir. The Caujerí scarp presents the highest hazard, with recent landslides and various signs of active processes. PART 4: LA CONCHITA CASE STUDY 27. Describe two ways in which heavy rains would cause the slope to become less stable. The 2005 landslide displaced older landslide deposits derived from Tertiary sedimentary rocks. The plaintiffs who sued La Conchita Ranch Co. over the deadly 2005 landslide in La Conchita agreed to a settlement that will give them the ranch, all its equipment and other assets, and $5 million â the limit on its insurance policy, an attorney announced Monday. The following summary of the 1995 La Conchita landslide is extracted from O'Tousa (1995) and Anderson (Robert Anderson, RJR Engineering, 2005, personal commun.). At 2:05 pm on Monday January 10, 2005, a steep slope behind the housing development at La Conchita, failedcascading approximately 400,000 tones of debris, and killed 10 people,buried 13 homes and damaged 18. Figure 5: La Conchita landslide events of 1995 (left) and 2005 (right). adjacent to dam. Image Dimensions: 3072 x 2048 The railway from Dongchuan to Kunming, a highway and Tuanjie irrigation canal pass through the lower reach of the Laogan Ravine. The results showed that the landslide area, mean sliding depth, and volume of the landslide in Hongye Village were approximately 4.5 ha, 5.1 m, and 22.8•104 m3, respectively. The minor lobe, comprising about 10% of the total landslide volume, was deposited in pulses that arrived from different directions at different times. To read the full-text of this research, you can request a copy directly from the authors. The volcano has the, Since the area of Southwest China crosses the first ladder and the second one ,thus it is featured with precipitous terrains. The three-phase sequence has been identified in three severe events that are analysed in this paper: Valtellina (Lombardy) in 1987, Tanaro Valley (Piedmont) in 1994 and Aosta Valley in 2000; but this sequence has also been observed during other events that occurred in northern Italy: in Piedmont in 1968, 1977, 1978, 1993 and 2000; in Lombardy in 1983 and 1992; in the Aosta Valley in 1993. fourth-highest elevation in Mexico (4,662 m a.s.l.) In 1995, a large landslide occurred, damaging about a dozen homes. Part II of this paper defines and describes the landslide issues in California. © 2018, Chinese Soil and Water Conservation Society. During early May of 1941 the southern California mountain resort of Wrightwood was partly inundated by surging flows of muddy debris which occurred daily for more than a week. The basin extends from the rim of the volcano to the foothills at an altitude of 2,850 m a.s.l. This investigation illustrates the landslides and geomorphologic changes of debris flow deposits in the town of Santa Cruz Pueblo Nuevo, State of Mexico, by using a multicriteria analysis in Geographic Information Systems (GIS) to obtain a potential hazard map. Physical characteristics for a slide: 29. In contrast, the January 10, 2005 event took place near the end of a period of particularly heavy rainfall. The landslide is compared with other terrestrial mass movements on the basis of morphology, sedimentology, log(volume) versus fall height –runout length (H/L) relations and estimated Bingham plastic yield strength. Notice the dirt road that traverses the hillside above the town. Landslide Case study- La Canchita La Conchita is a very small community, located on the southern California coastline between Ventura and Santa Barbara. Owing to such complex factors as deep valleys, steep mountains, varied topography and complex geological structures, it is extremely hard for people to obtain exact leveling data about this area. the countermeasures to prevent geological calamities are proposed. Based on what you see in the two sets of photos, which event - 1995 or 2005 - was more deeply seated and which was shallower? The loose solid matter of Sanyanyu debris flow mainly include collapse deposit, landslide deposit, eluvial deposit, talus deposit and trench deposit. This condition most probably influences the landslide initiation in the two case studies. Review of proposed mechanisms for sturzstroms (long-runout landslides), Using hydroscience and hydrotechnical engineering to reduce debris flow hazards, Mudflow of 1941 at Wrightwood, Southern California, Superelevation of flowing avalanches around curved channel bends. Among those hazards, reservoir induced seismicity is a public concern question, which is a special type of seismicity, with the characteristic of shallow source, high intensity, fast attenuation and, Typhoon Morakot struck central and southern Taiwan on August 8, 2009. The model domain consisted of 25,614 square grid cells, each measuring 1.52 m on a side, and was developed Landslide case study Cantata La Contain is a very small community, located on the southern California coastline between Ventura and Santa Barbara. During Typhoon Morakot, the flood level was beyond the design limit of many river embankments in southern Taiwan.

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