land damage caused by earthquakes

7/30/2019 Land Damage Caused by Earthquakes

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Page 2Land Damage Caused By Earthquakes

11/6/2012 8:24:32 PMhttp://www.stfrancis.edu/content/ns/bromer/earthsci/student2/Earthquake%20Land%20Damage.htm

Types of faults

For more information on faults, click here,http://encarta.msn.com/index/conciseindex/30/0307B000.htm?z=1&pg=2&br=1 Ground FailureLiquefaction Induced - Is not a type of ground failure. It is a physical process thattakes place during some earthquakes that may lead to ground failure. As aconsequence of liquefaction, clay-free soil deposits, primarily sands and silts,temporarily lose strength and behave as viscous fluids rather than as solids.Liquefaction takes place when seismic S waves pass through a saturated granular soillayer, distort its granular structure, and cause some of the void spaces to collapse.


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Example of Liquefaction

Liquefaction causes three types of ground failure: (1) lateral spreads (2) flow failures(3) loss of bearing strength.

Lateral Spreads - Lateral spreads involve the lateral movement of large blocks of soil asa result of liquefaction in a subsurface layer. Movement takes place in response to theground shaking generated by an earthquake.

Flow Failures- Flow failures, consisting of liquefied soil or blocks of intact materialriding on a layer of liquefied soil, are the most catastrophic type of ground failurecaused by liquefaction. Flow failures can originate either underwater or on land. Manyof the largest and most damaging flow failures have taken place underwater in coastalareas.Loss of Bearing Strength - When the soil supporting a building or some other structureliquefies and loses strength, large deformations can occur within the soil, allowing thestructure to settle and tip. (#3)For pictures and information on land damage due to ground failure, click here,http://www.es.ucsc.edu/~es10/fieldtripEarthQ/Damage1.html Landslides


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A landslide is a descent of a mass of earth and rock down a mountain slope.Landslides may occur when water from rain and melting snow sinks through the earthon top of a slope, seeps through cracks and pore spaces in underlying sandstone, andencounters a layer of slippery material, such as shale or clay, inclined toward thevalley. The water collects along the upper surface of this layer, which it softens. If thesupport is sufficiently weakened, a mass of earth and rock slides down along the well-lubricated layer. Earthquakes and volcanic eruptions can also cause severe, fast-

moving landslides. Landslides that suddenly rush down a steep slope can cause greatdestruction across a wide area of habitable land and sometimes cause floods bydamming up bodies of water. (#5)

Example of a Landslide

For pictures of landslide damage, click here,http://landslides.usgs.gov/html_files/landslides/slides/landslideimages.htm

Tsunamis

Japanese word meaning, "harbor wave" and used as the scientific term for seismic seawave generated by an undersea earthquake or possibly an undersea landslide or volcanic eruption. When the ocean floor is tilted or offset during an earthquake, a setof waves is created similar to the concentric waves generated by an object dropped into


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the water. Most tsunamis originate along the Ring of Fire, a zone of volcanoes andseismic activity, 32,500 km (24,000 mi) long, which encircles the Pacific Ocean.(#8)

Tsunamis Wave Example of Tsunamis Damage

To view an animation of a tsunamis, click here,http://www.pbs.org/wnet/savageearth/animations/tsunami/index.html

Land damage due to earthquakes is pretty much the same all over the world. Major earthquakes cause more damage than minor earthquakes, but in general, the type of land damage caused is the same no matter where an earthquake occurs in the world.For a Real-Time Earthquake Map of California, click here, http://quake.wr.usgs.gov/recenteqs/latest.htmFor a Real-Time Earthquake Map of Japan, click here, http://neic.usgs.gov/neis/current/

japan.htmlFor more information on earthquakes, click on the following links:USGS National Earthquake Center: http://neic.usgs.gov/neis/Links to other earthquake related sites: http://www.sristi.org/earthquake/read_exp.html

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land damage caused by earthquakes

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