Some volcanoes are more dangerous than human calculations

Through studying the eruption of Chaitén volcano, Chile, the scientific group came to the conclusion that some dangerous volcanoes in the world can erupt much faster than calculated.

Often scientists can track geological activities that occur before a volcano erupts for weeks or months, when the magma inside it just starts moving slowly to the surface.

But when people in the area near the Chaiten volcano sensed earthquakes on April 30, 2008, they had only 30 hours to evacuate before the long volcano remained still and began erupting.

On March 3, 2008, the magma flowed in the earth's crust, passing 5 km of the earth after 4 hours to reach the surface of Chaiten volcano. A column of dust and smoke as high as 19 km rises into the sky.

Thousands of people in Chaiten town have had enough time to evacuate. But it is likely that future victims, who live in similar volcanoes (known as rhyolit volcanoes), will not be so fortunate.

The rhyolite volcano has the main fuel of silicon dioxide, a kind of low flow magma. They tend to accumulate with tremendous pressure before erupting violently.

Large rhyolite volcanoes exist in Yellowstone region of Wyoming, Long Valley, California state and Valles, New Mexico state. The islands of Japan and Taupo and New Zealand are also places where these volcanoes exist.

Rhyolite volcano rarely erupts, so the scientific community has little opportunity to observe their activity. The operation cycle can even amount to tens of thousands of years. Research co-author Jonathan Castro said: 'The biggest eruptions on earth are rhyolite volcanoes. '

Buried alive

Castro and his colleagues investigated the evidence of pressure, water volume and temperature of magma before Chaiten began working to understand why the volcano could erupt so quickly.

The results will be published in Nature, deep inside volcanic rhyolite, magma is composed primarily of silicon dioxide which is diluted with water and other liquids.

A column of dust from the Chaitén crater in Chile on May 31, 2008. (Photo: Alvaro Vidal / AP)

Pressure from above keeps the water in place. But when the magma rises to the surface level, the pressure drops until almost all of the water drains out, leaving behind the most flexible solution known in nature.

Meanwhile, the drawn water forms a bubble, increasing the pressure on the surrounding magma.
Finally, this pressure bursts on the surface layer in the form of an explosion, like when you open the lid of a well-stocked soda bottle.

Currently, the state of eruption still occurred, continuing to change the shape of Chaiten's mouth. Donald Dingwell, co-author of the study, the University of Munich in Germany, described: 'Dust ash and large blocks are about the same size as a house, flushing together.'

'They can spray straight up or spill out around the mountain. The lava flows are very hot and very fast flowing. They will choke you, burn, bury you alive or bury you under the rubble. '

Increase alert

Castro and Dingwell both emphasized the need to closely monitor the rhyolite volcanoes, even those mountains that have not been active in the last 10,000 years.

John Pallister, staff of the US Geological Survey's Volcanic Survey Program, agreed with the idea and added that sensitive monitoring equipment should be placed on each volcano to provide super shock or other signs foreshadowing the eruption.

Pallister, a geologist who was not involved in the study, said: Remote geological meters often ignore early warning signs of volcanic activity - before Chaiten started operation in 2008, the machine. The nearest geological measurement is located up to 200 km away.

'When people feel the ground starts to shake, that's when the volcano is about to arrive.'