VOLCANOES AND JAPAN
eruption of Usu volcano
on Hokkaido Japan is home to 108 of the world’s 1,500 or so active volcanoes, including more than 10 percent of the active volcanoes that are a threat to human populations. Volcanoes in Japan are ranked A to C in accordance with the degree of their volcanic activity, with A being the most active. Some A volcanoes have erupted 400 times a year. Mt. Fuji is classified as an active volcano even though it hasn't erupted since 1707.
A volcano is a vent, or opening, in the earths's crust from which hot rock has been ejected sometime in its history. It is fueled by magma (molten rock found deep in the earth) that flows upwards in fissures in the earth’s crust. Most volcanoes are the size of mountains. Materials ejected by them during eruptions include lava (molten rock), ash, steam and a variety of gases. Some eruptions are quite large, with thousands, even millions, of tons of material being ejected. Related to volcanoes are geysers and fumaroles which are small vents from which materials are ejected.
Volcanoes are often described as active, dormant or extinct. An active volcano is one that has erupted in some way relatively recently: say, within the last few hundred or few thousand years. A dormant volcano is one that hasn't erupted for some time, perhaps several hundred or thousand years, but is still is considered likely of erupting sometime in the future. Extinct volcanoes are ones that are considered incapable of erupting. Some volcanoes labeled as extinct, however, such as Mt. St. Helens, have erupted quite violently.
Volcanoes generally occur in three places: 1) rift zones, where the earth's tectonic plates are pulled apart; 2) subduction trenches, where two plates collide, with the overlapping plate forcing the other one down; and 3) hot spots, where a plate floats over a source of magma coming up from deep inside the earth. Rift zone volcanoes, most of which are located on the bottom of the sea floor, and hot spot volcanoes produce basaltic lava which generally flows out without massive explosions and don’t kill anyone. These are the kind of eruptions that take place in Hawaii. Explosive eruptions like those at Mt. St. Helens and Krakatau generally occur along subduction zones.
Websites and Resources
Links in this Website: VOLCANOES AND JAPAN Factsanddetails.com/Japan ; MAJOR VOLCANOES AND ERUPTIONS IN JAPAN Factsanddetails.com/Japan ; EARTHQUAKES AND JAPAN Factsanddetails.com/Japan ; EARTHQUAKES AND LIFE IN JAPAN Factsanddetails.com/Japan ; LARGE EARTHQUAKES IN JAPAN Factsanddetails.com/Japan ; KOBE EARTHQUAKE OF 1995 Factsanddetails.com/Japan ; LARGE EARTHQUAKES IN JAPAN IN THE 2000s Factsanddetails.com/Japan ; TSUNAMIS IN JAPAN Factsanddetails.com/Japan
Good Websites and Sources on Volcanoes: USGS Volcanoes volcanoes.usgs.gov ; Volcano World volcano.oregonstate.edu ; How Volcanoes Work geology.sdsu.edu ; Volcanoes.com volcanoes.com ; Smithsonian Global Volcanism Program volcano.si.edu Electronic Volcano dartmouth.edu/~volcano ; Volcano Tourism volcanolive.com ; Protection from a Volcano Report from FEMA fema.gov/hazard/volcano ;Wikipedia Volcano article Wikipedia
Volcano Pictures Volcano Photo Gallery decadevolcano.net/photos ; Archive of Volcano Photos doubledeckerpress.com ; Volcano Eruptions: Ancient and Modern from Life Magazine life.com/image/first ; Google Map Look at Active Volcanoes geocodezip.com/v2_activeVolcanoes. ; Volcano Videos Discovery Channel dsc.discovery.com/videos/volcano-video ; National Geographic nationalgeographic.com/video
Volcano Information in Japan: Volcano Research Center at Tokyo University eri.u-tokyo.ac.jp ; Volcano Information from Japan Meteorological Agency Japan Meteorological Agency ; Tectonics and Volcanoes of Japan volcano.oregonstate.edu ; Laboratory of Volcano Physics at the University of Hokkaido uvo.sci.hokudai.ac ; Hayakawa Paleovolcanology Laboratory (last updated in 2000) edu.gunma-u.ac.jp ; Wikipedia List of Volcanoes in Japan Wikipedia ; USGS Volcanoes of Japan vulcan.wr.usgs.gov/Volcanoes/Japan and vulcan.wr.usgs.gov/Volcanoes/Japan/Maps ; Volcano and Earthquake Map homepage3.nifty.com ;
U.S. Professor Disappears During Volcano Hike cnn.com/2009 ; Earthquakes in Japan japan-guide.com
Many geological features and phenomena are explained in terms of plate tectonics, a geological theory that gained credibility in the 1970s and now is accepted as fact. According to theory the earth's surface is fragmented into large plates that can range in size from a small country to a continent. These plates float along the mantel under the earth's surface. In places where plates meets faults form and earthquakes occur.
At a subduction zones two plates collide head on, with one plate going over he top, forcing the other one down. In some cases the motion produces a descending convection current that sucks down the ocean floor. In these places deep seas trenches form; mountain building activity and earthquakes occur; and millions of tons of rock sink into the crust everyday.
Subduction faults are usually angled at about 10 to 15 percent and often located where major oceans and continents meet. Where ocean crust, pushed down by the weigh of ocean water, is shoved under the thick crust of continents, the rock is heated, causing water and gases to bubble out. As they rise they melt the rock above it, creating magma that can fuel volcanoes.
Rift zones are where the earth's tectonic plates are pulled apart as new material rises from inside the earth, sometimes volcanically, creating millions of tons of new crust every day and causing the plates to spread.. Mountains and volcanoes rise form here as they do in subduction zones but for different reasons. Most rift zones are in the middle of the oceans. The Mid-Atlantic Ridge, which runs north-to-south the entire length of the Atlantic is one.
What generates all this activity is the slow release of heat from the interior of the earth. This heat is produced by the radioactive decay of elements such as uranium, potassium and thorium. The heats causes rock to liquify into magma and creates pressures that makes the plates move.
Subduction Zones and Conical Volcanoes
Subduction zone volcanoes are fueled by the heat generated from the friction of the two plates colliding together and the release of water and gases, which diffuses upwards and soaks into the mantle rock, causing it to melt and form magma.
Conical volcanoes are found along subduction zones. Potentially dangerous, they are created by successive mountain building eruptions and can erupt on an annual basis or lie dormant for centuries and suddenly explode. Frequently erupting volcanoes are much less dangerous than those that lie quiet and build up pressure and finally explode with catastrophic force.
Subduction zone volcanoes are more explosive than rift zone volcanoes in part because their magma composition is different. The basalt that emerges from rift zone volcanoes is relatively uniform and fluid and tends to flow like a river. Conversely, the magma and lava found in subduction zones is less uniform and fluid. It is formed from the melting and merging of basaltic rock and sediments, mixed with water and goes, and tend to much more viscous. As a result it doesn’t move smoothly out of cracks or flow like a river like basalt does. Rather it congeals in the throats of the volcanoes, causing pressure to build up that can cause a massive explosion.
Regions of an
erupting volcano The main parts of a volcano are 1) the crater, a depression at the top of the volcano from which volcanic material has been ejected; 2) the vent, the conduit between crater and the magma; and 3) the cone, the area around the crater at the top of the volcano, made up of material ejected during an eruption. Many volcanoes have several craters, cones and vents.
Volcanoes have been described as “inherently unstable structures” vulnerable to landslides and collapses. According to an article in Natural History magazine, “They are made of intermixed layers of solid lava and flows and fragmented material, all of which has been weakened by hot gases and fluids and shaken by earthquakes. A host of other factors contribute to their instability: steep slopes, stress that arises from faulting and from the intrusion of hot magma into vertical fractures, or dikes, and weak, sloping foundations.”
Some volcanoes have lava tubes. A lava tube is an unusual environment. They are empty caverns that are not penetrated by rainstorms or roots and thus experience no erosion. Hardened drops of lava hang from the ceiling like stalactites. The floor often looks like solidified bubbling porridge. In places where there is drop off there s a solid cascade.
Volcanic Rocks and Ash
medium volcanic bombs Among the materials that are released during an eruption are: 1) lava (molten rock), 2) ash (fine particles of volcanic material); 3) bombs (lava rocks), 4) cinders (rough pieces of stone that are formed during an explosion and have hardened very quickly); 5) gases (carbon dioxide and various compounds with chlorine and sulfur); and 6) steam.
The rocks and minerals associated with volcanoes are: 1) basalt, a dark, heavy type of volcano that usually comes from rift zone and hot spot volcanoes; 2) rhyolite, a type of solidified of lava that is usually a pale shade of green, red or gray; 3) pumice, a porous, hole-filled kind of rhyolite that is produced when melted rock contains gas bubbles; and 4) obsidian. a grasslike lava that is produced when certain kinds of lava cool quickly and the individual minerals do not crystalize.
Ash ejected by large eruptions can spread a layer of upper-atmosphere dust are the globe that can block sunlight and lower world temperatures. It also poses a serious threat to commercial jets. Since 1980 more than 100 commercial jets have suffered significant damages after unknowingly flying into volcanic ash clouds. In at least 10 cases the aircraft lost power minutes after their jet engines sucked in ash that melted in their turbines. No fatalities have occurred but serious crashes have come very close to happening. One of the main reasons problems is that satellites have difficulty telling the difference between weather clouds and volcano ash clouds.
Beach eruption A volcanic eruption is regarded as violent release of material. Many volcanoes release steam and gas around the clock, year after year. These are regarded as releases not eruptions. In some volcanic areas steam and gas are emitted from vents called fumaroles. Some produce a the rotten egg smell of hydrogen sulphide and coat boulders with a layer of sulphur.
A volcano erupts when magma in the magma chamber rises due to changes in pressure between the magma and the surrounding rock and changes in the chemical and physical composition of the magma. The presence of magma near the crater is often an indication that a major eruption is imminent. Before many eruptions the pressures inside the volcano are so great the entire mountain swells.
There are basically two kinds of eruptions: 1) explosive ones in which large amounts of ash, gas, and steam are ejected in a relatively short period id time; and 2) less explosive “effusive” ones in which volcanic rock emerges like a fountain or fireworks explosion or simple pours from a crater or vent.
During small eruptions material is ejected in rhythmic bursts that occur several seconds or a few minutes apart. When the material is released over a period of time a lava dome often forms around where the material emerges.
Large eruptions often produces wild streaks of pink, blue and yellow lightning caused by a build-up of static electricity in the cloud of erupting ash, produced by friction among the swirling particles with the cloud.
What Makes a Volcano Erupt
one explantion Scientists are only now beginning to understand the mechanism of what makes a volcano erupt and have gained insight into why the same volcano sometimes erupts with massive, violent explosions and other times ooze out lava in relatively peaceful “effusive” eruptions. [Source: James Glanz, New York Times, November 18, 2003]
Scientists believe the mechanism for an en explosive eruption are as follows: 1) Magma becomes saturated with dissolved gases. 2) Bubbles form and enlarge as the magma rises and pressure on it drops. Sometimes the bubbles occupy as much 90 percent of the volume of the magma 3) Highly viscous magma, rising swiftly and cools, forming a plug. An explosive eruption occurs when the pressure of the bubbling magma exceed the strength of the plug and blows out the plug like a cork on a bottle of champagne.
Scientists believe the explosive energy of volcano is associated with the effect of bubbles and water on the viscosity of the magma, with the viscosity increasing as the presence of bubble and water rises. Sometimes the difference between a violent explosion and peaceful one can be slight differences in amount of bubbles. If the lava remains fluid it can ooze peacefully out of the volcano. If it becomes too viscous it behaves like a solid and is more likely to form a potentially explosive plug Sometimes changes in the amount of water in magma-lava by a factor of 10 can affect the viscosity of the magma-lava by a factor of a million.
Events Before an Eruption
Chris Newhall, a volcanologist with USGS and the University of Washington, told National Geographic that six events occur in order of appearance before a volcano eruptions: 1) large amounts of carbon dioxide are released from a volcano’s fumaroles, indicating that magma is rising below the surface; 2) a slight swelling occurs over a large area of the volcano’s surface, showing the magma is rising closer to the surface; 3) hundreds of small earthquakes shake the mountain, indicating the magma and volcanic fluids are forcing their way through cracks in the earth towards the surface.
As the volcano gets nearer to erupting Newall said: 4) the small earthquakes suddenly decrease, an event sometimes accompanied by a rise in sulfur dioxide emissions, indicating that possibly the magma has stalled just below the surface and an explosive event is imminent; 5) a large bulge within a few hundred meters of the volcano’s vent forms, indicating an influx of magma or an increase magma pressure near the surface; and 6) the release of large amounts as steam as the magma comes into contact with trapped pocket of groundwater, which pulverize the last bits of rock between the magma and the surface.
Kyoichi Sasazawa and Takashi Ito wrote in the Yomiuri Shimbun, “Generally, a mountain body swells when magma accumulates underground, causing the distance between observation points to become longer. When magma is released through eruptions, the mountain body will contract and observation points move closer together. There are exceptions, however. Eruptions have continued to take place on Sakurajima in Kagoshima, for example, but the mountain's body is swelling because the amount of magma accumulating underground is larger than the volume released through the eruptions.” [Source: Kyoichi Sasazawa and Takashi Ito, Yomiuri Shimbun, January 30, 2011]
On Mt. St. Helens earthquakes began rumblings weeks before the eruption, followed by plumes of smoke. On the eve of the eruption the northern flank of the mountain began bulging outward up to two meters a day.
Among the most destructive eruptions are ones in which the volcano collapses. Scientist break these down into three types: 1) lateral blasts like the one at Mount St. Helens, where a structural failure leads to a rock slippage around the magma that in turn leads to a sudden lateral explosion; 2) an early slide blast in which the rock slides but the explosion is upward rather than lateral; and 3) a non magma blast in which the release of gas and ash alone is enough to make a volcano collapse.
pyroclastic flow from Unzen eruption
The eruption at Mount St. Helens is one of the most studied volcanic blasts and one of the few in which detailed photographs of the eruption itself exist. It was previously thought that an explosive blast from inside the mountains blew away the side of Mount St. Helens. A careful look at the photographs of the blast and the material left behind by the eruption, however, reveal that an enormous block of the mountain, including part of the summit, broke away first—perhaps jarred loose by an earthquake and pressure in the volcano—and that paved the way for the explosion.
Before the eruption at Mount St. Helens the block of mountains had acted as cork, holding the magma in the mountain. Its sudden removal depressurized the magma, causing a violent, sideways, explosion of rock, gas and ash. The blast destroyed everything in its path over a 180 degree, 230 square kilometers area. A fast-moving avalanche caused by collapsing mountain swept into Spirit Lake, causing an 850-foot-high tsunami that rose above the shore, scouring the mountainside down to the bedrock. The avalanche itself was so large it traveled down into a valley and then up over a ridge.
The horseshoe-shape crater left behind at Mt. St. Helens is found on other volcanoes, suggesting that these kinds of events are not uncommon. Examples of mountain collapse have found on more that 400 volcanoes in a variety of locations worldwide and are now regarded as the most common cause of large-scale eruptions. The destructive potential of these eruptions are higher now than ever because so many people lie on the path of a destructive blast or avalanche. . .
A lava dome sometimes grows larger and larger due to a continuous supply of magma, although there are exceptions. For example, on Mt. Showa Shinzan in Sobetsucho, Hokkaido, lava domes cooled as soon as they formed, raising the height of the peak from 1944 to 1945.
Viscid magma and lava domes are often associated with pyroclastic flows. The magma was is viscid at Fugendake peak in the Unzen mountain range in Nagasaki Prefecture, where large pyroclastic flows were observed in the 1990s. A large lava dome was observed in the crater at that time, and was the source of pyroclastic flows for a long time.
Deaths and Destruction From Volcanoes
explanation of pyroclastic
flows on Unzen People generally die in eight different ways from volcanic eruptions: 1) by being buried under a landslide or a massive amounts of ash during catastrophic eruptions such as the ones that occurred at Mount St. Helens, Vesuvius, or Pinatubo; 2) by suffocating on ash during similar eruptions; 3) by being knocked on the head by rocks, known as volcanic bombs, hurled out of the crater; 4) by burning to death in a pyroclastic flow; 5) by drowning in a tsunami generated by the shock waves of a massive eruption such as the one that occurred at Krakatau; 6) by enormous landslides created when a cone is built up too steeply or part of the volcano collapses or breaks off; 7) by being buried or swept away by a lahar (See Below); 8) by dying of starvation when crops are destroyed by a blanket of as;
People rarely die from flowing lava. There is usually enough time for people to get out of the way, but property is often lost when lava flows reach it. Generally the only people that die from lava are tourist who approach too close and fall in when recently hardened lava near a lava flow collapses.
Lahars are mudslide-like floods of rain-soaked ash that swamp and suffocate everything in their path. They often flow down major drainage channels, in some cases burying entire villages and towns in stinking, gooey mud. Lahars can ravage an area for years after the volcano erupted. Each year during the rainy season, new lahars are created that slide down slopes at speed up to 25mph and clog up river, swamp rice fields and smothers town and villages up to 35 miles away from the volcano. See Mt. Pinatubo in Philippines.
Lahars can travel to distances of 30 kilometers away from the crater. They can be hot or cold, and can move quickly or slowly. They often leave behind layers of mud that is like concrete when it hardens. Lahars can also occur when ice, mudflows and landslides are released on snow-capped volcanoes by an eruption or earthquake as was the case at Nevado del Ruiz in Columbia.
A pyroclastic flow is a huge fire-ball-like wall of incandescent gas that rolls down a volcano like fiery avalanche. Often produced by the collapse of a lava dome inside the crater, they can travel more than 15 kilometers from a crater and reach speeds of 250 kilometers per hour. Temperatures inside one can reach 500̊C. See Mt. Unzen, Japan, Vesuvius, Mt. Pele, French Antilles.
Mt. Asama There are about 1,500 active volcanoes in the world today (not counting hundreds of undersea volcanoes). They are defined as volcanoes that have erupted in the last 10,000 years. An estimated half a billion people live within 60 miles of these volcanoes. Most are located on the same faults that produce earthquakes.
The world's dangerous volcanoes (as judged by their potential for a dangerous eruption and nearness to major population areas): 1) Merapi (Indonesia); 2) Taal (Philippines); 3) Unzen (Japan); 4) Sakurajima (Japan); 5) Ulawun (Papua New Guinea); 6) Mauna Loa (the United States); 7) Rainier (the United States); 8) Colima (Mexico); 9) Santa Maria/ Santiaguito (Guatemala); 10) Galeras (Columbia); 11) Teide (Canary Islands); 12) Vesuvius (Italy); 13) Etna (Italy); 14) Santorini (Greece); 15) Niragongo (Zaire). [Source: International Association of Volcanology and Chemistry of the Earth's Interior]
Volcanologists rank large eruptions as: Level 5) like the ones at Mount St. Helens in 1980 and Mt. Vesuvius in the A.D. 1st century that occur every 10 years and release less than a hundred cubic kilometers of material; Level 6) like the ones at Mount Pinatubo in 1991 and Krakatoa in 1883 that occur every 100 years and release more than a hundred cubic kilometers of material; Level 7) like the one at Tambora in Indonesia in 1815 that occur every 1,000 years and release more than a 1,000 cubic kilometers of material; and Level 8) like the ones at Toba 750,000 years ago and Yellowstone 2.1 million years ago that occur every 50,000 to 100,000 and release 2,500 to 3,000 cubic kilometers of material. The largest volcanic event known is an eruption in Colorado 28 million years ago that released more than 5,000 cubic kilometers of material.
A Level 8 is regarded as a supervolcano. The threat posed by a supervolcano is regarded as worse and ten times more likely to happen than an asteroid impact. If one were to occur today it could kill millions with the initial eruption and kill perhaps billions if a natural “nuclear winter” were triggered.
Volcanoes After They Erupt
after an eruption A volcano after an eruption if one of the world's most desolate and lifeless places. The seeds for life the form of water and chemicals exist in the volcanic material left behind. Often what determines how life will take hold is composition of this volcanic material. Life has difficulty taking root on basalt flows, which are and hard and shed water and don't have many cracks where seeds can lodge themselves. Sometimes it takes centuries for life to establish itself.
Life has an easier time taking root in loose lava and ash, which absorbs water and has plenty of cracks and loose material where seeds can lodge themselves and plants can take root. Even so it still takes a while for life to establish itself. This is mainly because the ash and lava are so loose they are often washed away in rainstorms.
The first arrivals in areas that are devoid of life after an eruption are plants with light fluffy seeds that can be blown hundreds of miles and insects like moths and flies that get blown to the volcanic areas by accident. These early arrivals die soon because there are no nutrients for them or food to eat. They however produced nutrients that accumulate in cracks and depressions and provide nutrients for forms of life that appear later.
In the long term, volcanoes often a positive effect. Volcanic lava and ash produces rich soil that can produce multiple harvest year after year without fertilizer. Ash produce alkaline materials that increase the fertility of soil. High volcanic peaks can generate rain.
collecting gas samples Scientists at the State University of New York have used historical records, computer modeling and laboratory experiments to determine the most likely direction of lava flows and ash deposits to determine where damage will mostly likely occur.
Scientists studying processes behind eruptions have analyzed gases trapped in volcanic glass from Mt. Vesuvius and other volcanoes and examined sound patterns in earthquakes that precede eruptions and found that sound waves that occur at long intervals seems to hint to an explosive eruption while the waves that occur at short intervals are indicative of an earthquake.
Predicting Volcanic Eruptions
Eruption are often preceded by earthquakes, the swelling of the ground on the volcano, an increases in gases released at the surface and increases of temperatures within the earth. All these things can be observed with instruments or satellites.
Scientists on the ground monitor temperature changes, gas levels and surface alterations for signs of an imminent eruption. Increases in mercury, radon, sulphur dioxide and carbon dioxide and the chlorine to sulphur ratio often indicate volcanic eruptions are imminent, but not always. Sometimes earthquakes occur and gas is released but there is no eruption. Often times nothing happened o when it doesn the scientists have given up and left or gone to sleep.
Scientists measure swelling and bulging on the surface of a volcano with ground-based devices called tiltmeters and satellite-based Interferometric Aperture Radar (InSAR). InSAR has observed “breathing volcanoes” that inflate and deflate without erupting.
Scientists in Japan have installed global positioning system (GPS) devices at 30 locations particularly active volcanoes and monitor changes in positions to predict eruptions. The instrument are so sensitive that scientists can gage activity in a magma chamber seven kilometers below the surface. The are mainly looking for swelling on the mountains that occurs before an eruption.
Monitoring Volcanoes in Japan
Sakurajima observation center The Coordinating Committee for the Prediction of Volcanic Eruptions monitors 108 volcanoes, with 41 of these receiving 24-hour attention.
The Japanese Meteorological Agency observes 30 of the most active volcanoes. A total of 20 volcanoes—including Asama, Sakurajima, Mt. Unzen, Mt. Usu, and the Miyakejima islands—are monitored around the clock by the Meteorological Agency. Data collected from sites round these volcanoes is used to predict eruptions and estimate the amount of damage they may cause.
Volcanic activity in Japan is monitored mainly by national universities across Japan as part of their research. Sakuramjima in Kagoshima Prefecture, for example, is monitored by the Tokyo Institute of Technology and Kagoshima University using 19 observation sites that monitor various things associated with volcanic eruptions. Tokyo University does the same with Mt. Asama in Nagano Prefecture and Mt. Mihara on Iz-Oshima Island.
In recent years a lack of funding as a result of government budget cuts has meant that it has become difficult to maintain the monitoring stations in the way they were meant to be maintained.
Volcanic activity is rated with five levels; 1 (calm), 2 (slight activity), 3 (small to medium activity), 4 (large activity) and 5 (catastrophic activity). A great amount of resources has been put into predicting eruptions. Scientists were able to predict the Mt. Usu eruption in 2000 and the Miyakejima eruption in 2000 but not the Asama eruption in 2004.
To control mudflows, like the one that killed 23,000 villagers in 1985 in Columbia, the Japanese government has erected steel and concrete silt dams along likely mud flow routes to halt, or a least, slow down their advance so people have enough time to be evacuated. Television cameras and sensitive instruments that take 11 different readings are also used for research and detection.
Dangerous Volcanoes and Eruptions
See Separate Article on Major Volcanoes and Eruptions
In June 2010, a 13-year-old girl died and three others were hospitalized after inhaling volcanic gasses near Sukayu hot springs in the Mt. Hakkoda area of Aomori.
Image Sources: 1) Volcano Research Center University of Tokyo (the Japan pictures); San Diego State University, U.S. Geological Survey (non-Japan pictures)
Text Sources: New York Times, Washington Post, Los Angeles Times, Daily Yomiuri, Times of London, Japan National Tourist Organization (JNTO), National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.
© 2009 Jeffrey Hays
Last updated March 2010