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  • General

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  • 由重力侵蚀和沉积形成的地貌

    Landscape showing ash flows and devastation four months after Mt. Merapi eruption.

     

    What can cause devastation four months after a volcanic eruption?
    ::在火山爆发四个月后,什么能造成破坏?

    Four months after Mt. Merapi in Indonesia erupted, there is more devastation.  Rain  continually washes ash downslope in massive ash flows. Residents are unable to live well under these conditions.
    ::在印度尼西亚的Merapi山爆发四个月后,破坏更加严重。 雨水不断将灰尘冲刷成大量的灰尘流。 居民无法在这些条件下过上良好生活。

    Landforms and Gravity
    ::地形和重力

    Gravity is responsible for  erosion  by flowing  water  and  . That’s because gravity pulls water and ice downhill. These are ways gravity causes erosion indirectly. But gravity also causes erosion directly. Gravity can pull  soil , mud, and   down cliffs and hillsides. This type of erosion and deposition is called  mass wasting . It may happen suddenly. Or it may occur very slowly, over many years.
    ::引力是水流侵蚀的原因。 这是因为引力拉动水和冰下坡。 这些是引力间接造成侵蚀的途径。 但重力也直接造成侵蚀。 重力可以拉动土壤、泥土以及下悬崖和山坡。 这种侵蚀和沉降被称为大规模浪费。 它可能突然发生。 或者可能发生许多年来非常缓慢的情况。

    Landslides
    ::滑石

    Landslides  are the most dramatic, sudden, and dangerous types of mass wasting. Landslides are sudden falls of rock; by contrast,  avalanches  are sudden falls of  snow .
    ::滑坡是最戏剧化、最突然和最危险的大规模浪费类型。 滑坡是岩石突然倒塌;相反,雪崩是雪的突然倒塌。

    Weathered material may fall away from a cliff because there is nothing to keep it in place. Rocks that fall to the base of a cliff make a  talus slope . Sometimes as one rock falls, it hits another rock, which hits another rock, and begins a landslide.
    ::天气物质可能会从悬崖上掉下来,因为没有任何东西可以维持悬崖。 落到悬崖底部的岩石会形成塔卢斯斜坡。 有时,当一块岩石倒塌时,它会撞到另一块岩石,再撞到另一块岩石,并开始滑坡。

    A landslide can be very destructive ( Figure   ). It may bury or carry away entire villages. Air trapped under the falling rocks acts as a cushion that keeps the rock from slowing down. Landslides can move as fast as 200 to 300 km/hour.
    ::山崩具有很强的破坏性(图 ) 。 它可能埋没或带走整个村庄。 被困在坠落岩石下的空气起到使岩石不减速的垫子的作用。 山崩可以以200至300公里/小时的速度移动。

    A blocked highway with a large landslide of rocks in California.

     

    This landslide in California in 2008 blocked Highway 140.
    ::2008年加利福尼亚山崩封锁了140号公路。

    Landslides often occur on steep slopes in dry or semi-arid climates. The California coastline, with its steep cliffs and years of  drought  punctuated by   of abundant rainfall, is prone to landslides. Wet soil becomes slippery and heavy.   often trigger landslides. The shaking ground causes soil and rocks to break loose and start sliding.
    ::山崩往往发生在干燥或半干旱气候中的陡坡上。 加利福尼亚海岸线的陡峭悬崖和多年干旱因降雨量充沛而支离破碎,很容易滑坡。 湿的土壤变滑和变重,常常引发山崩。 摇晃的地面导致土壤和岩石散落并开始滑动。

    Mudflows and Lahars
    ::泥流和拉哈德

    A  mudflow  is the sudden flow of mud down a slope because of gravity. Mudflows occur where the soil is mostly clay. Like landslides, mudflows usually occur when the soil is wet. Wet clay forms very slippery mud that slides easily. Mudflows follow  river  channels, washing out bridges, trees, and homes that are in their path.
    ::泥土流是指泥土因重力而突然从斜坡上流下来的泥土。 泥土流发生在土壤主要是泥土的地方。 像泥土流一样,泥土流通常发生在土壤湿润时。 湿泥土形成非常滑滑的泥土,很容易滑动。 泥土流沿河道而流,冲刷桥梁、树木和在路上的房屋。

    A  lahar  is mudflow that flows down a  composite volcano  ( Figure   ). Ash mixes with snow and ice melted by the  eruption  to produce hot, fast-moving flows. The lahar caused by the eruption of Nevado del Ruiz in Columbia in 1985 killed more than 23,000 people.
    ::火山灰与雪融化的雪和冰融为一体,以产生快速的热流。 1985年哥伦比亚的Nevado del Ruiz火山爆发引发的火山泥流造成23,000多人死亡。

    A landscape showing a lahar flow with rocky debris and snow-capped mountains in the background.

     

    A lahar is a mudflow that forms from volcanic ash and debris. This lahar comes off of Tunguragua volcano in Ecuador.
    ::火山灰和残骸形成的泥流是火山灰和残骸造成的,从厄瓜多尔的通古拉瓜火山中流出。

    Slump and Creep
    ::贫民窟和克里普

    Less dramatic types of mass wasting move Earth materials slowly down a hillside.  Slump  is the sudden movement of large blocks of rock and soil down a slope. ( Figure   ). All the material moves together in big chunks. Slumps may happen when a layer of slippery, wet clay is underneath the rock and soil on a hillside. Or they may occur when a river (or road) undercuts a slope. Slump leaves behind crescent-shaped scars on the hillside.
    ::岩浆是大块岩石和土壤的突如其来的向坡移动。(图 ) 所有材料都以大块块块一起移动。当岩石和山坡的土壤下有一层滑滑的、湿的粘土时,可能会发生贫民窟。或者当河流(或道路)侵蚀斜坡时,可能会发生贫民窟。贫民窟在山坡上留下新月形状的疤痕。

    Showing a hillside with a visible depression caused by slump and creep.

     

    Slump material moves as a whole unit, leaving behind a crescent shaped scar.
    ::碎片物质作为一个整体移动,留下一个新月形状的疤痕。

    Creep  is the very slow movement of rock and soil down a hillside. Creep occurs so slowly you can’t see it happening. You can only see the effects of creep after years of movement ( Figure   ). The slowly moving ground causes trees, fence posts, and other structures on the surface to tilt downhill.
    ::克里普是岩石和土壤在山坡下缓慢移动。 克里普发生得如此缓慢,你看不到它发生。 你只能看到多年移动后爬行的影响(图 ) 。 缓慢移动的地面导致树木、栅栏柱和其他地表结构向下倾斜。

    Trees with bent trunks on a sloped hillside, illustrating creep movement over time.

     

    As the hillside moves down slope a tree tries to stand up straight. The tree ends up with a bent trunk.
    ::当山坡向坡下移动时,一棵树试图直立起来,树上最后有一个弯曲的树干。

    Prevention and Awareness
    ::预防和提高认识

    Landslides cause $1 billion to $2 billion damage in the United States each  year . Mass wasting is responsible for traumatic and sudden loss of life and homes in many areas of the world.
    ::滑坡每年在美国造成10亿至20亿美元的破坏,大规模浪费造成世界许多地区的创伤和突然生命和家园的损失。

    Some communities have developed landslide warning systems. Around San Francisco Bay, the National   Service and the U.S. Geological Survey use rain gauges to monitor soil moisture. If soil becomes saturated, the weather service issues a warning. Earthquakes, which may occur on California’s abundant  , can also trigger landslides.
    ::一些社区开发了山崩警报系统。 在旧金山湾附近,国家服务局和美国地质调查局使用雨量表监测土壤湿度。 如果土壤饱和,天气服务就会发出警告。 加利福尼亚富饶地区可能发生的地震也可能引发山崩。

    To be safe from landslides:
    ::避免滑坡:

    • Be aware of your surroundings. Notice changes in the natural world.
      ::注意周围的环境 注意自然界的变化
    • Look for cracks or bulges in hillsides, tilting of decks or patios, or leaning poles or fences when rainfall is heavy. Sticking windows and doors can indicate ground movement. This is because soil pushes slowly against a house and knocks windows and doors out of alignment.
      ::寻找山坡上的裂缝或巨浪、倾斜甲板或阳台、倾斜杆或雨量大时的栅栏。 粘贴窗户和门可以显示地面运动。 这是因为土壤向房屋缓慢地推来推去,把窗户和门敲到对齐之外。
    • Look for landslide scars. Landslides are most likely to happen where they have occurred before.
      ::寻找滑坡伤疤。 滑坡最有可能发生在以前发生的地方。
    • Plant vegetation and trees on the hillside around your home. This helps hold the soil in place.
      ::在你家周围的山坡上种植植物和树木,这有助于将土壤固定在原地。
    • Help to keep a slope  stable  by building retaining walls. Installing good drainage in a hillside may keep the soil from getting saturated.
      ::在山坡安装良好的排水系统可以防止土壤饱和。

    Summary
    ::摘要

    • Landslides are sudden and massive falls of rock down a slope. Landslides may be very destructive or even deadly. Slump and creep are slower types of mass wasting.
      ::山崩是突然和大规模地向坡坡下倾斜的岩石,山崩可能是非常破坏性甚强甚至致命的,贫民窟和爬虫是较慢的大规模浪费类型。
    • Mudflows or lahars, which are volcanic mudflows, are mass movements that contain a lot of water.
      ::泥流或拉哈岩是火山泥流,是含有大量水的大规模移动。
    • Mass wasting is more likely to occur on slopes that are wet, have weak rock, or are undercut. An earthquake or other ground shaking can trigger a landslide.
      ::大规模浪费更可能发生在潮湿、弱岩石或下沉的斜坡上。 地震或其他地面摇晃可能引发滑坡。
    • To avoid being in a landslide, be aware of signs in a hillside, such as cracks or bulges and old landslide scars. To keep a slope stable, install good drainage or build retaining walls.
      ::为了避免滑坡,要注意山坡上的标志,如裂缝或山崩和旧的山崩伤痕,要保持坡坡稳定,安装良好的排水系统或建造防水墙。

    Review
    ::回顾

    1. What factors make it more likely that a place will have a landslide?
      ::哪些因素使得一个地方更有可能发生山崩?
    1. Pretend that you are going to buy a house on a hill. How do you know if the house might slide or creep down the hill?
      ::你怎么知道这房子会滑下去还是从山上爬下来?
    1. What can be done to prevent landslides?
      ::如何防止山崩?
    1. How is a landslide different from a mudflow? How is a lahar different from a mudflow?
      ::山崩与泥流有何不同? 泥流与泥流有何不同?

    Explore More
    ::探索更多

    Use the resources below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    1. What is creep?
      ::什么是变态?
    1. How do trees compensate for creep?
      ::树木如何弥补爬虫?