Explosive predictions today from the Mountain.... I guess that giant buttplug that has formed can't stop things forever! :laughing
Explosive predictions for Mount St Helens
15 December 2004
NewScientist.com news service
The recent "extraordinary" behaviour of one of the world's most notorious volcanoes, Mount St Helens in the US, may mean it is preparing for a dramatic eruption, geologists warned on Wednesday.
In late September 2004, a series of earthquakes signalled that the volcano was awakening. Since then, enough lava has oozed into the volcano's crater to build a dome the size of an aircraft carrier. The new dome, standing 275 metres off the crater floor at its highest point, is now taller than a nearby dome built by a previous set of eruptions over the course of six years.
"Something extraordinary is happening at Mount St Helens. We are scratching our heads about it," says Dan Dzurisin of US Geological Survey's Cascades Volcano Observatory (CVO) in Vancouver, Washington, US. The new dome has grown so quickly - almost four cubic metres every second - that it has bulldozed a 180-metres-thick glacier out of its way.
If this rapid growth rate continues, there is a growing risk of a dome collapse which could trigger a major eruption, researchers warned at the American Geophysical Union meeting in San Francisco.
But experts say that the pace could also soon slow down and the dome remain stable. To work out which scenario is more likely, geologists have been studying the process driving the lava flow and other factors that determine dome stability, such as the lava's physical properties.
Mount St Helens has been a hot bed of volcanic research ever since its deadly 1980 eruption - when part of its summit detached - spewed rocks and ash for hundreds of miles and created the largest landslide ever recorded in the US. Fifty-seven people were killed and thousands of animals in nearby forests were buried alive or choked by ash and debris.
Luckily today, if there were to be a major eruption, the immediate area is uninhabited and the US Army corps of engineers has built a dam in the nearby valley intended to protect against possible landslides.
But few contingency plans can protect against the clouds of ash the volcano might throw up. Such clouds could cause havoc for aircraft - whose jet engines would quickly clog in an ash cloud - and possibly create a health and traffic hazard for communities many miles away.
The researchers are not the only ones watching Mount St Helens closely. The CVO website - which carries updates and photos of the brooding volcano - has been visited more than 40 million times since the new lava dome began to swell, giving the public an unprecedented degree of access to information, says Cynthia Gardner, a researcher at CVO.
Geologists trying to forecast the future of the volcano are also benefiting from two decades of technological advances since the last major eruption, including the use of Global Positioning System receivers to monitor dome movement and three-dimensional virtual reconstructions.
These reconstructions allow geologists to "fly" through the crater image on the computer to examine changes. "The only remaining slow step is our brains in interpreting that data," says Gardner. "There are no new upgrade chips available there."