This is Faith Lapidus.
And this is Steve Ember with EXPLORATIONS in VOA Special English. On May eighteenth, nineteen eighty, a volcano exploded in the northwestern state of Washington. It killed fifty-seven people and destroyed huge areas of forest. Recently, that volcano has become active again. Today, we tell about the famous Mount Saint Helens volcano.
The Native American Indians in the state of Washington still call Mount Saint Helens by its Indian name -- Loowit. It means "Lady of Fire." In the past two weeks, this famous "Lady of Fire" has been waking up after twenty-four years of sleep.
The last major explosion of Mount Saint Helens took place in nineteen eighty. The volcano expelled fire, rock and volcanic gas with a force of four hundred eighty kilometers an hour. That explosion was three hundred fifty times more powerful than the explosions of the first nuclear bombs.
Recent earthquakes near Mount Saint Helens were a sure sign that something was happening deep under the ground. Scientists also knew there is a huge area of melted rock deep underneath the mountain. This liquid rock creates pressure. The pressure can cause more earthquakes. When thousands of small earthquakes began to happen, scientists knew Mount Saint Helens was becoming active once again.
Experts began to closely observe the huge volcano. They placed scientific instruments in many areas on the mountain. These observations are still taking place twenty-four hours a day.
Scientists said the evidence showed a seventy percent chance the volcano would do something. They were not sure exactly what it would do. But they were sure it would not be anything like the huge explosion in nineteen eighty.
Volcano experts first observed increased underground activity near the mountain on September twenty-third. The experts said this activity continued to increase. This evidence led the experts to believe it might produce a volcanic event.
Scientists observed more underground activity in the next few days. Then the volcano expelled steam and ash thousands of meters into the air. Experts declared the volcano could once again be a danger. At first, they said the volcano was mostly a danger to aircraft. They said the ash could damage an aircraft's engines.
The Mount Saint Helens area is a huge National Park. Thousands of people visit each year to look at the large volcano and to learn about the violent explosion in nineteen eighty. When there is no danger, visitors can even ask for a permit to climb Mount Saint Helens. They can walk near the top and see down into the area called the crater.
The recent underground activity forced park officials to close the visitor's center closest to the volcano. The Johnson Ridge Observatory is only eight kilometers from the mountain. Park officials told visitors to leave the area immediately.
The volcano expelled large amounts of steam for about thirty minutes on Monday, October fourth. Scientists said it was mostly water that had been super-heated by the liquid rock far below.
The next day, however, the volcano once again began expelling steam and ash several thousand meters into the air. Winds pushed the steam and ash toward the northeast part of the state. When the ash came down, it made driving a car difficult in some areas.
Again, scientists said evidence gathered from the volcano showed more explosions were possible. Experts also warned that explosions of steam and ash were not the only concerns.
Extreme heat near the top of the volcano could melt the huge formations of ice on the mountain. Some areas of ice are more than one hundred eighty meters deep. Experts said extreme heat could melt the ice and start huge floods and mudslides down the mountain.
By last Tuesday night, Mount Saint Helens had stopped most activity. Instruments that measured underground activity showed very low levels. The earthquakes had almost stopped.
Tom Pierson is a scientist with the United States Geological Survey. Mister Pierson said most evidence showed the possibility of more activity. However he says there is still a good chance the volcano might go back to sleep. Other experts said all volcanoes go through periods of activity and rest. This could go on for days, weeks or even months. Officials lowered the threat level by the end of last week.
By Monday, October eleventh, Mount Saint Helens was still producing steam. Cool weather made the steam look more threatening than it was. Research teams were able to measure the heat from near the top of the volcano. The highest surface temperatures were between two hundred and three hundred degrees Celsius.
Experts say Mount Saint Helens could still explode if there were an increase in the amount of underground activity. They say the explosion could take place suddenly or with very little warning.
Experts say it is extremely difficult to tell what a volcano will do. For example, strong earthquakes and other underground activity near the volcano produced good evidence. Earthquakes under Mount Saint Helens were measured at about one each minute for long periods last week. These were very small earthquakes. Most measured only about one on the Richter scale.
But volcano experts cannot always tell what this evidence means. They cannot tell when an earthquake will grow stronger. And they cannot always tell what the hot liquid rock called magma is going to do. It is also difficult to measure the pressure created by the magma deep inside the volcano.
Most often scientists use all the information they can gather and try to make a good guess. Above all, they try to provide the best warnings when they believe the volcano may become a threat.
Around the world there are more than six hundred active volcanoes – those that have exploded within the past two hundred years. There are more than fifty active volcanoes in the United States. The most active ones are in the states of Alaska, Hawaii, California, Oregon, and Washington. There are twelve major volcanoes in an area of mountains called the Cascade Range. These are in northern California, Oregon and Washington.
Volcanoes produce many different effects that can kill people and destroy property. Extremely large explosions can threaten people and property hundreds of kilometers away. Volcanoes can also affect the weather on Earth.
Mount Saint Helens is just one of a large number of volcanoes that form a circle around the Pacific Ocean. This circle is called the Ring of Fire. Beginning in Japan, the ring of volcanoes extends south through the Philippines and Indonesia to New Zealand.
Across the Pacific, the ring begins again at the southern end of South America and extends north along the Pacific Coast to Peru, Colombia, Mexico, and California. The ring stretches up the American Pacific Coast to Alaska and then across to the Kamchatka Peninsula of Russia. The Ring of Fire includes about three-fourths of the world's volcanoes.
Many of them have a tragic history of death and destruction. For example, in nineteen eighty-five, more than twenty-five thousand peopled died as a result of the explosion of Mount Ruiz in Colombia. That volcano caused huge mudslides that covered many villages and towns.
In Mexico, millions of tons of ash from El Chichon volcano killed more than two thousand people in nineteen eighty-two.
Recently, an earthquake in the central part of California measured six on the Richter scale. Scientists say that earthquake and volcanic activity at Mount Saint Helens are not linked. However, they say the two events have a common cause. The land mass deep under the Pacific Ocean and the land mass of the Pacific coast are moving toward each other. These land masses float on liquid rock deep within the Earth.
This movement is called plate tectonics. It causes earthquakes. It also builds mountains and causes liquid rock deep in the earth to flow near the surface and form volcanoes.
As long as these huge land masses continue to move, people will continue to observe and study earthquakes. And they will study volcanoes like Loowit -- the Lady of Fire -- Mount Saint Helens.
This program was written by Paul Thompson. It was produced by Mario Ritter. This is Steve Ember.
And this is Faith Lapidus. Join us again next week for EXPLORATIONS in VOA Special English.