masswastproc

masswastproc - Mass Wasting Processes EENS 204 Tulane...

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This page last updated on 04-Mar-2004 EENS 204 Natural Disasters Tulane University Prof. Stephen A. Nelson Mass-Wasting and Mass-Wasting Processes Mass-Wasting and its Human Impacts Mass-Wasting is defined as the down slope movement of rock and regolith near the Earth's surface mainly due to the force of gravity. Mass-wasting is an important part of the erosional process, as it moves material from higher elevations to lower elevations where transporting agents like streams and glaciers can then pick up the material and move it to even lower elevations. Mass-wasting processes are occurring continuously on all slopes; some mass- wasting processes act very slowly, others occur very suddenly, often with disastrous results. Any perceptible down slope movement of rock or regolith is often referred to in general terms as a landslide . However, as we will see, landslides can be classified in a much more detailed way that reflects the mechanisms responsible for the movement and the velocity at which the movement occurs. As human populations expand and occupy more and more of the land surface, mass-wasting processes become more likely to affect humans. The table below shows the impact of mass- wasting processes on human life over the last century. Year Location Type Fatalities 1916 Italy, Austria Landslide 10,000 1920 China Earthquake triggered landslide 200,000 1945 Japan Flood triggered landslide 1,200 1949 USSR Earthquake triggered landslide 12,000-20,000 1954 Austria Landslide 200 1962 Peru Landslide 4,000-5,000 1963 Italy Landslide 2,000 1970 Peru Earthquake related debris avalanche 70,000 1985 Columbia Mudflow related to volcanic eruption 23,000 1987 Ecuador Earthquake related landslide 1,000 In a typical year in the United States, landslides cause over $1.5 billion in damages and 25 to 50 deaths. In other countries, especially less developed countries, the loss is usually higher because of higher population densities, lack of zoning laws, lack of information about mass- wasting hazards, and lack of emergency preparedness. Knowledge about the relationships between local geology and mass-wasting processes can lead to better planning that can reduce vulnerability to such hazards. Thus, we will look at the Mass Wasting Processes 3/4/2004 Page 1 of 5
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various types of mass-wasting processes, their underlying causes, factors that affect slope stability, and what humans can do to reduce vulnerability and risk due to mass-wasting hazards. Types of Mass-Wasting Processes
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masswastproc - Mass Wasting Processes EENS 204 Tulane...

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