A lahar is a type of mudflow composed of pyroclastic material and water that flows down from a volcano, typically along a river valley. Mudslide redirects here it is also the name of a cocktail. A mudflow or mudslide is the most rapid (up to 80 km/h / 50 mph Pyroclastic rocks or pyroclastics (derived from the Greek πῦρ, meaning fire and κλαστός, meaning broken are Clastic rocks Water is a common Chemical substance that is essential for the survival of all known forms of Life. Plate tectonics and hotspots Divergent plate boundaries At the "Riverine" redirects here For the use of that term in Maritime geography, see there In Geology, a valley (also called a vale, dale, glen or strath and near or in Appalachia, a draw) is [1] The term 'lahar' originated in the Javanese language of Indonesia. Javanese is the language of the people in the central and eastern parts of the island of Java, in Indonesia. The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia.
Lahars have the consistency of concrete: fluid when moving, then solid when stopped. Concrete is a construction material composed of Cement (commonly Portland cement) as well as other cementitious materials such as Fly ash and Slag [2] Lahars can be huge: the Osceola lahar produced 5,600 years ago by Mount Rainier in Washington produced a wall of mud 140 metres (460 ft) deep in the White River canyon and extends over an area of over 330 square kilometres (130 sq mi) for a total volume of 2. Mount Rainier is an active Stratovolcano (also known as a composite volcano in Pierce County Washington, located southeast of Seattle, Washington Washington ( is a state in the Pacific Northwest region of the United States. The White River is a River in the US state of Washington. It flows about 75 miles (121 km from its source the Emmons Glacier on Mount 3 cubic kilometers (0. 55 cubic miles). [3]
Lahars can be extremely dangerous, because of their energy and speed. Large lahars can flow several dozen meters per second and can flow for many kilometres, causing catastrophic destruction in their path. [4] The lahars from the Nevado del Ruiz eruption in Colombia in 1985 caused the Armero tragedy, which killed an estimated 23,000 when the city of Armero was buried under 5 metres (16 ft) of mud and debris. Nevado del Ruiz, also known as Mount Ruiz, is an Andean Stratovolcano in Caldas Department, Colombia. Colombia (kəˈlʌmbɪə officially the Republic of Colombia () is a country in northwestern South America. Year 1985 ( MCMLXXXV) was a Common year starting on Tuesday (link displays 1985 Gregorian calendar) The Armero Tragedy (Tragedia de Armero was the aftermath of the November 13, 1985 Nevado del Ruiz Volcano eruption in Tolima, Colombia Armero tragedy Armero, or Armero-Guayabal, is a municipality in the Tolima Department, Colombia. [5] New Zealand's Tangiwai disaster in 1953, where 151 people died after a Christmas Eve express train fell into the Whangaehu River, was caused by a lahar. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island The Tangiwai disaster on December 24 1953, was the worst rail accident in New Zealand. Year 1953 ( MCMLIII) was a Common year starting on Thursday (link will display full calendar of the Gregorian calendar. Events 563 - The Byzantine church Hagia Sophia in Constantinople is dedicated for the second time after being destroyed by Earthquakes The Whangaehu River is a large river in central North Island of New Zealand.
Lahars have several possible causes:[2]
- Snow and glaciers can be melted by a pyroclastic flow during an eruption
- A flood caused by a glacier, lake breakout, or heavy rainfall can release a lahar, also called glacier run or jökulhlaup. "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. A pyroclastic flow (also known as a pyroclastic density current) is a common and devastating result of some volcanic eruptions. A flood is an overflow of an expanse of water that submerges land a deluge Lake breakout is a Geological term that refers to the collapse of a (usually high-altitude lake A glacial lake outburst flood (GLOF can occur when a lake contained by a glacier (called Jökulhlaup if it was a Subglacial lake, Marginal lake drainage A glacial lake outburst flood (GLOF can occur when a lake contained by a glacier (called Jökulhlaup if it was a Subglacial lake, Marginal lake drainage
In particular, although lahars are typically associated with the effects of volcanic activity, lahars can occur even without any current volcanic activity, as long as the conditions are right to cause the collapse and movement of mud originating from existing volcanic ash deposits.
Several mountains in the world, including Mount Rainier in the USA, Mount Ruapehu in New Zealand, and Galunggung in Indonesia, are considered particularly dangerous due to the risk of lahars. Mount Rainier is an active Stratovolcano (also known as a composite volcano in Pierce County Washington, located southeast of Seattle, Washington The United States of America —commonly referred to as the Mount Ruapehu, or just Ruapehu, is an active Stratovolcano at the southern end of the Taupo Volcanic Zone in New Zealand. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island Galunggung, Galoen-gong, or Gunung Galunggung is an active Stratovolcano in West Java, Indonesia. The Republic of Indonesia ( (Republik Indonesia is a Country in Southeast Asia. Several towns in the Puyallup River valley in Washington state, including Orting, the closest to Mount Rainier, are built on top of lahar deposits that are only about 500 years old. The Puyallup River (pronounced pyoo-AL-uhp) is a River in the U Orting is a city located in Pierce County Washington. As of 2008 the city has a total population of 6075 according to the Washington State Office of Financial Management Lahars are predicted to flow through the valley every 500-1,000 years, so Orting, Sumner, Puyallup, Fife, and the Port of Tacoma face considerable risk. Sumner is located in North Pierce County major cities located near Sumner include Puyallup WA to the west Auburn WA to the North and Enumclaw Puyallup Washington (pjuːˈɑːləp is a city in Pierce County, Washington about five miles east of Tacoma. Fife is a city in Pierce County, Washington, United States. The population was 4784 at the 2000 census and a 2008 estimate of 7525 according to the Washington The USGS has set up lahar warning sirens in Pierce County, so that people can flee an approaching debris flow. The United States Geological Survey ( USGS) is a scientific agency of the United States government. Pierce County is the second most populous county in the US state of Washington.
A lahar warning system has been set up at Mount Ruapehu by the New Zealand Department of Conservation and hailed a success after it successfully alerted officials to an impending lahar on 18 March 2007. The Department of Conservation (In Māori, Te Papa Atawhai) commonly known by its acronym " DOC " is the state sector organisation Events 37 - The Roman Senate annuls Tiberius ' will and proclaims Caligula emperor Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
The 1991 Mount Pinatubo eruption caused lahar as well, but it was due to the passing of a major typhoon over the Philippines which resulted in a torrent of volcanic ash and water down to the rivers surrounding the volcano. Year 1991 ( MCMXCI) was a Common year starting on Tuesday (link will display full calendar of the Gregorian Calendar. Mount Pinatubo is an active Stratovolcano located on the island of Luzon The Philippines ( Filipino: Pilipinas, officially known as the Republic of the Philippines (fil ''Republika ng Pilipinas'' RP Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter Water is a common Chemical substance that is essential for the survival of all known forms of Life. "Riverine" redirects here For the use of that term in Maritime geography, see there Plate tectonics and hotspots Divergent plate boundaries At the The lahar was caused by the mixing of settled ash and water from the monsoon which occurred the day after the volcano finished erupting. Although the eruption only killed 6 people, 1500 were killed in the resulting lahar, showing the destructive nature of lahars.
See also
References
- ^ Lahar. Mudslide redirects here it is also the name of a cocktail. A mudflow or mudslide is the most rapid (up to 80 km/h / 50 mph USGS Photo Glossary. Retrieved on 2007-09-02. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 44 BC - Pharaoh Cleopatra VII of Egypt declares her son co-ruler as Ptolemy XV Caesarion.
- ^ a b Lahars and Their Effects. USGS Volcano Hazards Program. Retrieved on 2007-09-02. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 44 BC - Pharaoh Cleopatra VII of Egypt declares her son co-ruler as Ptolemy XV Caesarion.
- ^ Crandall, D. R. (1971). "Postglacial Lahars From Mount Rainier Volcano, Washington". U. S. Geological Survey Professional Paper 677.
- ^ Hoblitt, R. P. ; Miller, C. D. , and Scott, W. E. . "Volcanic Hazards with Regard to Siting Nuclear-Power Plants in the Pacific Northwest". U. S. Geological Survey Open-File Report 87-297.
- ^ Deadly Lahars from Nevado del Ruiz, Colombia. USGS Volcano Hazards Program. Retrieved on 2007-09-02. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 44 BC - Pharaoh Cleopatra VII of Egypt declares her son co-ruler as Ptolemy XV Caesarion.
External links
- Schools page about lahars and pyroclastic flows
- USGS web page about lahars
- Mount Rainier Volcano Lahar Warning System
- USGS fact sheet - "Mount Rainier -- Learning to Live with Volcanic Risk"
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