Air tides responsible for causing landslides.Byline: ANI London, November 2 (ANI): In a new research, scientists have found out that atmospheric tides See under Tide. tidal movements of the atmosphere similar to those of the ocean, and produced in the same manner by the attractive forces of the sun and moon. See also: Atmospheric Tide are responsible for causing landslides. According to a report in Nature News, the research was carried out by William Schulz of the United States Geological Survey The United States Geological Survey (USGS) is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. in Denver, Colorado, and colleagues, who took as their subject case the four-kilometre-long Slumgullion slum·gul·lion n. A watery meat stew. [Perhaps slum, muddy deposit in a mining sluice + dialectal gullion, mud (perhaps from Irish Gaelic goilín, pit). landslide in the San Juan Mountains San Juan Mountains Segment of the southern Rocky Mountains, southwestern Colorado and northern New Mexico, U.S. The mountains extend from southwestern Colorado along the course of the Rio Grande to the Chama River in northern New Mexico. of southwestern Colorado. At its centre, soil and weathered rocks creep downhill at an average speed of half a millimetre per hour. The movement of the landslide accelerates during the spring snowmelt snow·melt n. 1. The runoff from melting snow. 2. A period or season when such runoff occurs: streams that flood during snowmelt. period. And, puzzlingly, it is generally faster during the night than in the day. The team of researchers set out to investigate the landslide's mysterious movements. Over a period of nine months they monitored the landslide at two spots, taking hourly measurements of slide speed, the water pressure inside pores in the soil, and weather conditions. They discovered that the movements of the rubble were in sync with 'atmospheric tides' - daily highs and lows in atmospheric pressure that are excited by changing exposure to the Sun's rays and by the Moon's gravitational grav·i·ta·tion n. 1. Physics a. The natural phenomenon of attraction between physical objects with mass or energy. b. The act or process of moving under the influence of this attraction. 2. pull. The team found that during nightly hours of low atmospheric pressure, the landslide moves fastest. When air pressure increases during the day, the flow slows down or stops. The scientists suspect that changes in air pressure alter the frictional forces that hold the landslide in place. During periods of relatively low atmospheric pressure, air and water particles contained in sediment pores in the soil tend to move upwards to areas of lower pressure, easing frictional forces, they believe, and allowing easier sliding. According to the researchers, their mathematical model of the basic physical forces driving landslide movement shows that their proposed mechanism is plausible. "We do know that heavy rainfall is the most common trigger mechanism," said Falk Lindenmaier, a landslide expert at the University of Karlsruhe in Germany. "But this must not lead us to ignore other processes at play," he added. Schulz and his team suspect that atmospheric tides could be involved in other phenomena that involve sliding surfaces, including earthquakes, volcanic eruptions volcanic eruptions discharging of fumes, dust and lava from volcanoes. They have damaging potential in addition to those of being physically overpowering by the lava flow or the ash or dust fallout. and glacier movement. (ANI) Copyright 2009 Asian News International The Asian News International (ANI) agency provides multimedia news to China and 50 bureaus in India. It covers virtually all of South Asia since its foundation and presently claims, on its official website, to be the leading South Asia-wide news agency. (ANI) - All Rights Reserved. Provided by Syndigate.info an Albawaba.com company |
|
||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion