News tagged with volcanic ash
Study characterizes 300-million-year-old tropical forest preserved in volcano ash
(PhysOrg.com) -- Pompeii-like, a 300-million-year-old tropical forest was preserved in ash when a volcano erupted in what is today northern China. A new study by University of Pennsylvania paleobotanist Hermann ...
Space & Earth / Earth Sciences
Feb 20, 2012 |
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Ancient sewer excavation sheds light on the Roman diet
(PhysOrg.com) -- Archaeologists working in a system of connected sewers and drains under the ancient town of Herculaneum in the Bay of Naples area of Italy have analyzed the human excrement found there and ...
Other Sciences / Archaeology & Fossils
Jun 17, 2011 |
4.3 / 5 (17) |
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Deep-sea volcanoes don't just produce lava flows, they also explode
Most deep-sea volcanoes produce effusive lava flows rather than explosive eruptions, both because the levels of magmatic gas tend to be low, and because the volcanoes are under a lot of pressure from the surrounding ...
Space & Earth / Earth Sciences
Mar 28, 2011 |
4.3 / 5 (6) |
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Researchers find smoking gun of world's biggest extinction
About 250 million years about 95 per cent of life was wiped out in the sea and 70 per cent on land. Researchers at the University of Calgary believe they have discovered evidence to support massive volcanic ...
Space & Earth / Earth Sciences
Jan 23, 2011 |
4.7 / 5 (38) |
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Volcanic ash in Meridiani Planum
Deposits of volcanic ash colour this view of the Meridiani Planum, as seen by the Mars Express High Resolution Stereo Camera. They also give clues to the prevailing wind direction in this region of Mars.
Space & Earth / Space Exploration
May 12, 2010 |
5 / 5 (5) |
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Ash shows past eruptions 'underestimated'
(PhysOrg.com) -- A study into ash fallout from the biggest volcanic eruption in almost 20 years has shown that the impact of past eruptions is likely to have been significantly underestimated as so much of ...
Space & Earth / Earth Sciences
May 06, 2009 |
4.7 / 5 (7) |
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Salamander found in China oldest of its kind
(PhysOrg.com) -- Six salamander specimens were found in an ancient dry lakebed in China recently and now the team of Ke-Qin Gao from Peking University and Neil H. Shubinb of the University of Chicago has identified ...
Other Sciences / Archaeology & Fossils
Mar 13, 2012 |
4.4 / 5 (5) |
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NASA satellite confirms sharp decline in pollution from US coal power plants
A team of scientists have used the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite to confirm major reductions in the levels of a key air pollutant generated by coal power plants in the eastern ...
Dec 01, 2011 |
4.2 / 5 (6) |
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Team discovers ancient road at Maya village buried by volcanic ash 1,400 years ago
A University of Colorado Boulder-led team excavating a Maya village in El Salvador buried by a volcanic eruption 1,400 years ago has unexpectedly hit an ancient white road that appears to lead to and from ...
Other Sciences / Archaeology & Fossils
Oct 05, 2011 |
4.6 / 5 (7) |
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Three active volcanoes spotted on satellite imagery from NASA
(PhysOrg.com) -- From space, NASA keeps a watchful eye on volcanic activity around the world with many satellites. NASA has just released satellite images showing activity this week from volcanoes in the countries ...
Space & Earth / Earth Sciences
Jul 11, 2011 |
4 / 5 (3) |
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Mars Express sees deep fractures on Mars
Newly released images from ESA's Mars Express show Nili Fossae, a system of deep fractures around the giant Isidis impact basin. Some of these incisions into the martian crust are up to 500 m deep and probably ...
Space & Earth / Space Exploration
May 06, 2011 |
5 / 5 (3) |
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Study justifies closing airports in volcano event
The disruptive closing of some European airports after last year's volcanic eruption in Iceland was the right thing to do and may have saved lives, a new study concludes.
Space & Earth / Earth Sciences
Apr 25, 2011 |
1 / 5 (1) |
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Largest spider fossil found in China
(PhysOrg.com) -- According to Paul Selden, the director of the Paleontological Institute at the University of Kansas, he and his team members have discovered the largest spider fossil. The fossil was discovered ...
Other Sciences / Archaeology & Fossils
Apr 21, 2011 |
4.2 / 5 (9) |
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Ceramic coatings may protect jet engines from volcanic ash
Last year's $2 billion shutdown of European airspace following a volcanic eruption in Iceland alerted everyone to the danger that ash clouds can pose to aircraft engines.
Apr 13, 2011 |
4.7 / 5 (3) |
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Iceland eyeing giant cable to sell power to Europe
Iceland is considering building the world's longest sub-sea electric cable to allow it to sell its geothermal and volcanic energy to Europe, the country's largest energy company said Monday.
Technology / Energy & Green Tech
Mar 07, 2011 |
4.6 / 5 (8) |
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Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than 2 millimetres (0.079 in) in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact with water causing phreatomagmatic eruptions and ejection of entrained particles during steam eruptions causing phreatic eruptions. The violent nature of volcanic eruptions involving steam results in the magma and solid rock surrounding the vent being torn into particles of clay to sand size. Volcanic ash can lead to breathing problems, malfunctions in machinery, and from more severe eruptions, years of global cooling.
Ash deposited on the ground after an eruption is known as ashfall deposit. Significant accumulations of ashfall can lead to the immediate destruction of most of the local ecosystem, as well the collapse of roofs on man-made structures. Over time, ashfall can lead to the creation of fertile soils. Ashfall can also become cemented together to form a solid rock called tuff. Over geologic time, the ejection of large quantities of ash can produce an ash cone.
For more information about Volcanic ash, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
