Geological hazard: Difference between revisions
moved 'liquefaction' to rapid phenomena as resulting from earthquakes |
deletion of 'air and snow' because an avalanche always contains air |
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'''Sudden phenomena include:''' |
'''Sudden phenomena include:''' |
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* [[avalanche]]s (snow |
* [[avalanche]]s (snow or rock) and its runout |
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* [[earthquake]]s and earthquake-triggered phenomena such as [[tsunami]]s |
* [[earthquake]]s and earthquake-triggered phenomena such as [[tsunami]]s |
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* [[forest fire]]s (espec. in Mediterranean areas) leading to [[deforestation]] |
* [[forest fire]]s (espec. in Mediterranean areas) leading to [[deforestation]] |
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* [[geomagnetic storms]]<ref>[http://www.nationalatlas.gov/articles/geology/a_geohazards.html ''Geologic Hazards'' NationalAtlas] {{webarchive|url=https://web.archive.org/web/20100430002306/http://www.nationalatlas.gov/articles/geology/a_geohazards.html |date=2010-04-30 }}</ref> |
* [[geomagnetic storms]]<ref>[http://www.nationalatlas.gov/articles/geology/a_geohazards.html ''Geologic Hazards'' NationalAtlas] {{webarchive|url=https://web.archive.org/web/20100430002306/http://www.nationalatlas.gov/articles/geology/a_geohazards.html |date=2010-04-30 }}</ref> |
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* [[ice jam]]s (Eisstoß) on rivers or [[glacial lake outburst flood]]s below a [[glacier]] |
* [[ice jam]]s (Eisstoß) on rivers or [[glacial lake outburst flood]]s below a [[glacier]] |
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* [[landslide]] ( |
* [[landslide]] (displacement of earth materials on a slope or hillside) |
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* [[mudflow]]s (avalanche-like muddy flow of soft/wet soil and sediment materials, narrow landslides) |
* [[mudflow]]s (avalanche-like muddy flow of soft/wet soil and sediment materials, narrow landslides) |
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* [[pyroclastic flows]] |
* [[pyroclastic flows]] |
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* [[rockfall| |
* [[rockfall|rockfalls]], [[rock slide]]s, ([[rock avalanche]]) and [[debris flow]]s |
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* torrents ([[flash flood]]s, rapid floods or heavy current creeks with irregular course) |
* torrents ([[flash flood]]s, rapid floods or heavy current creeks with irregular course) |
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*[[liquefaction]] (settlement of the ground in areas underlain by loose saturated sand/silt during an earthquake event) |
*[[liquefaction]] (settlement of the ground in areas underlain by loose saturated sand/silt during an earthquake event) |
Revision as of 07:02, 22 January 2021
This article needs additional citations for verification. (December 2009) |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/0/01/Laconchita1995landslide.jpg/200px-Laconchita1995landslide.jpg)
A geologic hazard is one of several types of adverse geologic conditions capable of causing damage or loss of property and life. These hazards consist of sudden phenomena and slow phenomena:
Sudden phenomena include:
- avalanches (snow or rock) and its runout
- earthquakes and earthquake-triggered phenomena such as tsunamis
- forest fires (espec. in Mediterranean areas) leading to deforestation
- geomagnetic storms[1]
- ice jams (Eisstoß) on rivers or glacial lake outburst floods below a glacier
- landslide (displacement of earth materials on a slope or hillside)
- mudflows (avalanche-like muddy flow of soft/wet soil and sediment materials, narrow landslides)
- pyroclastic flows
- rockfalls, rock slides, (rock avalanche) and debris flows
- torrents (flash floods, rapid floods or heavy current creeks with irregular course)
- liquefaction (settlement of the ground in areas underlain by loose saturated sand/silt during an earthquake event)
- volcanic eruptions, lahars and ash falls.
Gradual or slow phenomena include:
- alluvial fans (e.g. at the exit of canyons or side valleys)
- caldera development (volcanoes)
- geyser deposits
- ground settlement due to consolidation of compressible soils or due to collapseable soils (see also compaction)
- ground subsidence, sags and sinkholes
- sand dune migration
- shoreline and stream erosion
- thermal springs
Sometime the hazard is instigated by man through the careless location of developments or construction in which the conditions were not taken into account.
Geologic hazard evaluation and mitigation
Geologic hazards are typically evaluated by engineering geologists who are educated and trained in interpretation of landforms and earth process, earth-structure interaction, and in geologic hazard mitigation. The engineering geologist provides recommendations and designs to mitigate for geologic hazards. Trained hazard mitigation planners also assist local communities to identify strategies for mitigating the effects of such hazards and developing plans to implement these measures. Mitigation can include a variety of measures:
- Geologic hazards may be avoided by relocation.
- The stability of sloping earth can be improved by the construction of retaining walls, which may use techniques such as slurry walls, shear pins, tiebacks, soil nails or soil anchors. Larger projects may use gabions and other forms of earth buttress.
- Shorelines and streams are protected against scour and erosion using revetments and riprap.
- The soil or rock itself may be improved by means such as dynamic compaction, injection of grout or concrete, and mechanically stabilized earth.
- Additional mitigation methods include deep foundations, tunnels, surface and subdrain systems, and other measures.
- Planning measures include regulations prohibiting development near hazard-prone areas and adoption of building codes.
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Eisstoß Feb.2006 Vienna, Austria (Donauinsel)
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Glacier just above Grindelwald, Switzerland
See also
References
- ^ Geologic Hazards NationalAtlas Archived 2010-04-30 at the Wayback Machine