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42-401: There were three plans to convert the railway cutting left behind by the disused Helsinki harbour rail to a new use. Of the three plans, the bicycle and pedestrian alternative prevailed in the end. The modification to bike and pedestrian use took several years. The name Baana (Finnish slang word for (rail)way coming from Swedish bana and German Bahn ) for the new route was obtained through

84-403: A debris flow or mud flow . However, also dry debris can exhibit flow-like movement. Flowing debris or mud may pick up trees, houses and cars, and block bridges and rivers causing flooding along its path. This phenomenon is particularly hazardous in alpine areas, where narrow gorges and steep valleys are conducive of faster flows. Debris and mud flows may initiate on the slopes or result from

126-405: A cut as "a passage cut for the roadway through an obstacle of rock or dirt." Cuts can be created by multiple passes of a shovel , grader , scraper or excavator , or by blasting . One unusual means of creating a cut is to remove the roof of a tunnel through daylighting . Material removed from cuts is ideally balanced by material needed for fills along the same route, but this is not always

168-466: A depth from few decimeters to some meters) is called a shallow landslide. Debris slides and debris flows are usually shallow. Shallow landslides can often happen in areas that have slopes with high permeable soils on top of low permeable soils. The low permeable soil traps the water in the shallower soil generating high water pressures. As the top soil is filled with water, it can become unstable and slide downslope. Deep-seated landslides are those in which

210-544: A low shearing resistance. On the slopes, some earthflow may be recognized by their elongated shape, with one or more lobes at their toes. As these lobes spread out, drainage of the mass increases and the margins dry out, lowering the overall velocity of the flow. This process also causes the flow to thicken. Earthflows occur more often during periods of high precipitation, which saturates the ground and builds up water pressures. However, earthflows that keep advancing also during dry seasons are not uncommon. Fissures may develop during

252-445: A naming competition. Baana was opened to the public on Helsinki Day, 12 June 2012. Baana begins between Helsinki Music Centre and Kiasma . It runs to a new separated-grade vehicle/bicycle junction called Länsilinkki (Western Link) near former level crossing of Hietalahdenranta street with a total length of 1.5 kilometres (0.93 mi) and an average depth of 7 metres (23 ft). There are several staircase exits for pedestrians and

294-530: A reconstruction of the evolution of a particular landslide. Therefore, landslide hazard mitigation measures are not generally classified according to the phenomenon that might cause a landslide. Instead, they are classified by the sort of slope stabilization method used: Climate-change impact on temperature, both average rainfall and rainfall extremes, and evapotranspiration may affect landslide distribution, frequency and intensity (62). However, this impact shows strong variability in different areas (63). Therefore,

336-542: A slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall , an earthquake , a slope cut to build a road, and many others), although this is not always identifiable. Landslides are frequently made worse by human development (such as urban sprawl ) and resource exploitation (such as mining and deforestation ). Land degradation frequently leads to less stabilization of soil by vegetation . Additionally, global warming caused by climate change and other human impact on

378-631: A sloped exit for bikes. The pedestrian lane has chairs fixed to asphalt. In the wide part near Ruoholahdenkatu sports-related facilities have been provided for skateboarding and table tennis . Baana's eastern end connects directly to the Kaisantunneli cycling and pedestrian tunnel underneath Helsinki Central Station , and via that to the city's eastbound cycling routes. Baana provides a speedy way to bike through western Helsinki downtown and adds to non-commercial space in heart of downtown. It has been very popular especially during prime biking season. There

420-422: A transportation route alongside of, or around a hill, where the slope is transverse to the roadway or the railway. A sidehill cut can be formed by means of sidecasting, i.e., cutting on the high side balanced by moving the material to build up the low side to achieve a flat surface for the route. In contrast, through cuts, where the adjacent grade is higher on both sides of the route, require removal of material from

462-430: A very wide range, from as low as 1 mm/yr to many km/h. Though these are a lot like mudflows , overall they are more slow-moving and are covered with solid material carried along by the flow from within. Clay, fine sand and silt, and fine-grained, pyroclastic material are all susceptible to earthflows. These flows are usually controlled by the pore water pressures within the mass, which should be high enough to produce

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504-518: A wide range of ground movements, such as rockfalls , mudflows , shallow or deep-seated slope failures and debris flows . Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides . Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make

546-542: Is a bike counter which shows bike count for today and for this year. It can also be viewed online. Baana chasm has been used for performances during annual festival Night of the Arts . Baana received a special mention in European Prize for Urban Public Space competition in 2014. The name Baana has later been put for a wider use to describe multiple different cycling paths (such as Pohjoisbaana in north-south direction) and also

588-719: Is an appropriate tool because it has functions of collection, storage, manipulation, display, and analysis of large amounts of spatially referenced data which can be handled fast and effectively. Cardenas reported evidence on the exhaustive use of GIS in conjunction of uncertainty modelling tools for landslide mapping. Remote sensing techniques are also highly employed for landslide hazard assessment and analysis. Before and after aerial photographs and satellite imagery are used to gather landslide characteristics, like distribution and classification, and factors like slope, lithology , and land use/land cover to be used to help predict future events. Before and after imagery also helps to reveal how

630-434: Is determined by certain geologic factors, and that future landslides will occur under the same conditions as past events. Therefore, it is necessary to establish a relationship between the geomorphologic conditions in which the past events took place and the expected future conditions. Natural disasters are a dramatic example of people living in conflict with the environment. Early predictions and warnings are essential for

672-514: Is essentially due to a decrease in the shear strength of the slope material, an increase in the shear stress borne by the material, or a combination of the two. A change in the stability of a slope can be caused by a number of factors, acting together or alone. Natural causes of landslides include: Landslides are aggravated by human activities, such as: In traditional usage, the term landslide has at one time or another been used to cover almost all forms of mass movement of rocks and regolith at

714-457: Is fluid-like and generally much more rapid. This is usually a result of lower shear resistances and steeper slopes. Typically, debris slides start with the detachment of large rock fragments high on the slopes, which break apart as they descend. Clay and silt slides are usually slow but can experience episodic acceleration in response to heavy rainfall or rapid snowmelt. They are often seen on gentle slopes and move over planar surfaces, such as over

756-544: Is provided below. Under this classification, six types of movement are recognized. Each type can be seen both in rock and in soil. A fall is a movement of isolated blocks or chunks of soil in free-fall. The term topple refers to blocks coming away by rotation from a vertical face. A slide is the movement of a body of material that generally remains intact while moving over one or several inclined surfaces or thin layers of material (also called shear zones) in which large deformations are concentrated. Slides are also sub-classified by

798-462: The Earth's surface. In 1978, geologist David Varnes noted this imprecise usage and proposed a new, much tighter scheme for the classification of mass movements and subsidence processes. This scheme was later modified by Cruden and Varnes in 1996, and refined by Hutchinson (1988), Hungr et al. (2001), and finally by Hungr, Leroueil and Picarelli (2014). The classification resulting from the latest update

840-444: The advantage of comparatively lower noise pollution than elevated or at-grade solutions. In river management , the term cut or cutting is also used, which refers to the action of short-cutting a meander , in order to speed a waterway's flow. The term cutting appears in the 19th century literature to designate rock cuts developed to moderate grades of railway lines. Railway Age's Comprehensive Railroad Dictionary defines

882-626: The area of the Val Pola disaster (Italy). Evidence of past landslides has been detected on many bodies in the solar system, but since most observations are made by probes that only observe for a limited time and most bodies in the solar system appear to be geologically inactive not many landslides are known to have happened in recent times. Both Venus and Mars have been subject to long-term mapping by orbiting satellites, and examples of landslides have been observed on both planets. Landslide mitigation refers to several human-made activities on slopes with

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924-538: The area since it cannot be dumped alongside the route. A ledge is a cut in the side of a cliff well above the bottom of a gorge . A lock cut is a section of a river or other inland waterway immediately upstream and downstream of a lock which has been modified to provide locations for boats to moor while waiting for the lock gates to open or to allow people to board or alight vessels. Landslide Landslides , also known as landslips , or rockslides , are several forms of mass wasting that may include

966-509: The case when cut material is unsuitable for use as fill. The word is also used in the same sense in mining, in particular Open-pit mining . The use of cuttings often provides byproducts as a form of mineral extraction , commonly sand, clay or gravel; the cost of building drains, reinforcing banks against landslide and a high water table are factors which commonly limit its use in certain areas. There are at least two types of cut, sidehill cut and through cut . The former permits passage of

1008-521: The cycling network ( Baanaverkko ) as a whole. Cut (earthworks) In civil engineering , a cut or cutting is where soil or rock from a relative rise is removed. Cuts are typically used in road , rail , and canal construction to reduce a route's length and grade . Cut and fill construction uses the spoils from cuts to fill in defiles to create straight routes at steady grades cost-effectively. Cuts are used as alternatives to indirect routes, embankments , or viaducts . They also have

1050-579: The development of guidelines for sustainable land-use planning . The analysis is used to identify the factors that are related to landslides, estimate the relative contribution of factors causing slope failures, establish a relation between the factors and landslides, and to predict the landslide hazard in the future based on such a relationship. The factors that have been used for landslide hazard analysis can usually be grouped into geomorphology , geology , land use/land cover, and hydrogeology . Since many factors are considered for landslide hazard mapping, GIS

1092-468: The effects of climate change on landslides need to be studied on a regional scale. Climate change can have both positive and negative impacts on landslides Temperature rise may increase evapotranspiration, leading to a reduction in soil moisture and stimulate vegetation growth, also due to a CO2 increase in the atmosphere. Both effects may reduce landslides in some conditions. On the other side, temperature rise causes an increase of landslides due to Since

1134-406: The environment , can increase the frequency of natural events (such as extreme weather ) which trigger landslides. Landslide mitigation describes the policy and practices for reducing the risk of human impacts of landslides, reducing the risk of natural disaster . Landslides occur when the slope (or a portion of it) undergoes some processes that change its condition from stable to unstable. This

1176-452: The fluidization of landslide material as it gains speed or incorporates further debris and water along its path. River blockages as the flow reaches a main stream can generate temporary dams. As the impoundments fail, a domino effect may be created, with a remarkable growth in the volume of the flowing mass, and in its destructive power. An earthflow is the downslope movement of mostly fine-grained material. Earthflows can move at speeds within

1218-713: The form of the surface(s) or shear zone(s) on which movement happens. The planes may be broadly parallel to the surface ("planar slides") or spoon-shaped ("rotational slides"). Slides can occur catastrophically, but movement on the surface can also be gradual and progressive. Spreads are a form of subsidence, in which a layer of material cracks, opens up, and expands laterally. Flows are the movement of fluidised material, which can be both dry or rich in water (such as in mud flows). Flows can move imperceptibly for years, or accelerate rapidly and cause disasters. Slope deformations are slow, distributed movements that can affect entire mountain slopes or portions of it. Some landslides are complex in

1260-462: The goal of lessening the effect of landslides. Landslides can be triggered by many, sometimes concomitant causes. In addition to shallow erosion or reduction of shear strength caused by seasonal rainfall , landslides may be triggered by anthropic activities, such as adding excessive weight above the slope, digging at mid-slope or at the foot of the slope. Often, individual phenomena join to generate instability over time, which often does not allow

1302-480: The landscape changed after an event, what may have triggered the landslide, and shows the process of regeneration and recovery. Using satellite imagery in combination with GIS and on-the-ground studies, it is possible to generate maps of likely occurrences of future landslides. Such maps should show the locations of previous events as well as clearly indicate the probable locations of future events. In general, to predict landslides, one must assume that their occurrence

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1344-440: The long runout can be different, but they typically result in the weakening of the sliding mass as the speed increases. The causes of this weakening are not completely understood. Especially for the largest landslides, it may involve the very quick heating of the shear zone due to friction, which may even cause the water that is present to vaporize and build up a large pressure, producing a sort of hovercraft effect. In some cases,

1386-413: The most important factors that trigger landslides in any given location. Using GIS, extremely detailed maps can be generated to show past events and likely future events which have the potential to save lives, property, and money. Since the ‘90s, GIS have been also successfully used in conjunction to decision support systems , to show on a map real-time risk evaluations based on monitoring data gathered in

1428-431: The movement of a mass over a planar or curvilinear surface or shear zone. A debris slide is a type of slide characterized by the chaotic movement of material mixed with water and/or ice. It is usually triggered by the saturation of thickly vegetated slopes which results in an incoherent mixture of broken timber, smaller vegetation and other debris. Debris flows and avalanches differ from debris slides because their movement

1470-471: The movement of clayey materials, which facilitate the intrusion of water into the moving mass and produce faster responses to precipitation. A rock avalanche, sometimes referred to as sturzstrom , is a large and fast-moving landslide of the flow type. It is rarer than other types of landslides but it is often very destructive. It exhibits typically a long runout, flowing very far over a low-angle, flat, or even slightly uphill terrain. The mechanisms favoring

1512-451: The negative impacts felt by landslides. GIS offers a superior method for landslide analysis because it allows one to capture, store, manipulate, analyze, and display large amounts of data quickly and effectively. Because so many variables are involved, it is important to be able to overlay the many layers of data to develop a full and accurate portrayal of what is taking place on the Earth's surface. Researchers need to know which variables are

1554-402: The reduction of property damage and loss of life. Because landslides occur frequently and can represent some of the most destructive forces on earth, it is imperative to have a good understanding as to what causes them and how people can either help prevent them from occurring or simply avoid them when they do occur. Sustainable land management and development is also an essential key to reducing

1596-489: The sense that they feature different movement types in different portions of the moving body, or they evolve from one movement type to another over time. For example, a landslide can initiate as a rock fall or topple and then, as the blocks disintegrate upon the impact, transform into a debris slide or flow. An avalanching effect can also be present, in which the moving mass entrains additional material along its path. Slope material that becomes saturated with water may produce

1638-412: The sliding surface is mostly deeply located, for instance well below the maximum rooting depth of trees. They usually involve deep regolith , weathered rock, and/or bedrock and include large slope failures associated with translational, rotational, or complex movements. They tend to form along a plane of weakness such as a fault or bedding plane . They can be visually identified by concave scarps at

1680-716: The top and steep areas at the toe. Deep-seated landslides also shape landscapes over geological timescales and produce sediment that strongly alters the course of fluvial streams . Landslides that occur undersea, or have impact into water e.g. significant rockfall or volcanic collapse into the sea, can generate tsunamis . Massive landslides can also generate megatsunamis , which are usually hundreds of meters high. In 1958, one such tsunami occurred in Lituya Bay in Alaska. Landslide hazard analysis and mapping can provide useful information for catastrophic loss reduction, and assist in

1722-413: The underlying bedrock. Failure surfaces can also form within the clay or silt layer itself, and they usually have concave shapes, resulting in rotational slides Slope failure mechanisms often contain large uncertainties and could be significantly affected by heterogeneity of soil properties. A landslide in which the sliding surface is located within the soil mantle or weathered bedrock (typically to

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1764-474: The very high temperature may even cause some of the minerals to melt. During the movement, the rock in the shear zone may also be finely ground, producing a nanometer-size mineral powder that may act as a lubricant, reducing the resistance to motion and promoting larger speeds and longer runouts. The weakening mechanisms in large rock avalanches are similar to those occurring in seismic faults. Slides can occur in any rock or soil material and are characterized by

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