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The Indonesian volcano Merapi,
one of the world's most dangerous active volcanoes
The Indonesian volcano Merapi,
one of the world's most dangerous active volcanoes
A hot wind blew through the dusty Indonesian village. Today was the day
that Barry Voight and his team of scientists would climb Merapi, the
9,500-foot mountain of fire whose violent eruptions had killed thousands of
people throughout the centuries.
But today, the scientists were not afraid. They had carefully studied the
volcano before the climb. They knew that the angry giant was napping. The
likelihood of their being killed by a wave of fiery melted rock, called molten lava, was less
than their chances of being hit by a car while crossing the street.
The climb would be short--only five hours or so--but it would not be easy.
Not only were the slopes crumbly and steep, especially near the top, but
the group carried packs heavy with sophisticated electronic equipment,
batteries, water and camping supplies.
They also carried the gas masks they would need to protect themselves
against the poisonous gases that seeped from dozens of cracks and openings,
called fumaroles, near the
volcano's summit. Without the masks, one hot belch of gas would scorch
their lungs instantaneously.
At left is a picture of Scientists from the U.S. Geological
Survey on a volcano expedition.
The climbers wandered through several farms on the volcano's lower slopes.
Bursting from their moist, fertile fields were sweet potatoes, soybeans and
tobacco. They followed the trail upward into a belt of humid jungle, then
out onto misty ridges and grassy slopes. Then they were above the
vegetation line. Above this point, the colder temperatures and rocky soil
prevented even the hardy grasses from growing. They crossed a plain of
enormous boulders to the foot of a huge dome of craggy rock. Then they
climbed upward, onto a small, sandy plateau. Here, on the volcano's summit, they
would pitch their tents.
Voight, who works for a branch of the government called the U.S. Geological
Survey, is a volcanologist--an expert in the science of volcanoes.
His life's work revolves around trying to pinpoint exactly the moment that
a volcano will erupt.
The equipment that he and his colleagues would install on Merapi would give
them important information about what was going on inside that
volcano--clues that might help them figure out when the mountain of fire
would erupt, spewing geysers of hot lava and ash high
into the air.
If many of the nearly one million people living around the volcano's base
were not evacuated in time, they would be burned alive by hurricanes of
fiery volcanic ash or buried by flows of mud created when a heavy rain
mixed with the ash.
An eruption of the Alaskan volcano, Mount Spurr is pictured at right.
Merapi has erupted about 70 times in the past 1,000 years, usually every
five years or so. In 1930, an eruption killed 1,300 people who lived around
the volcano's base. In 1984, there was another huge eruption. That time,
however, the people were able to evacuate, and nobody was hurt.
''A volcano is like a porthole into the inside of the earth,'' Voight says.
''It is a place where the molten material inside the earth, called magma, can get out.'' Magma that
leaves the volcano is called lava, he explains.
Voight says that the reason that most volcanoes are shaped like large,
upside-down ice-cream cones is because they are piles of lava rock and
other volcanic material that have been ejected from the volcano during many
separate eruptions over hundreds or thousands of years. Each eruption adds
another layer of material to the pile, causing the mountain to grow and
grow.
Volcanoes erupt when magma from deep within the earth rises, causing the
older rock clogging the hole in the volcano to be pushed upward or
sideways.The pressure becomes too much for the rock to withstand
and--boom!--the volcano erupts in an explosion of fiery lava, rock
fragments, steam and gas.
Voight likens the eruption to opening a well-shaken bottle of soda. The
minute you pop off the cap--whoosh!--the soda blasts out in a foamy spray
of bubbly liquid.
Before a volcano erupts, the ground swells and rumbles as the magma
squeezes into the chamber in the volcano's core. Temperatures on the
volcano's surface grow hotter and gas and steam may rise more furiously.
These are some of the signs that Barry Voight watches for at Merapi.
''The ground is stretching around the volcano because more and more magma
is being pumped into it,'' Voight says. ''We can measure the amount of
stretching. Before it goes, the ground may start making little creaks and
groans, which are expressed as earthquakes. We can measure those,
too.''
Lava flows down the slopes of Alaska's Mount Spurr
Voight measures the movement in the surface of the rock with three
different types of instruments. The first kind, called a tiltmeter, measures changes in the angle, or
slope, of the ground, a sign that the rock is beginning to swell or bulge.
The second, a seismograph,
measures earthquakes. The third is a mirror placed high on the mountain
that can be spotted from the valley five miles away. Scientists shoot
lasers, or beams of light, up toward the mirror. The light bounces back and
hits a device that calculates the distance between itself and the mirror.
The next time they measure, if the distance has changed, they know that the
reflector has moved, indicating that the rock is swelling.
Voight and his Indonesian and American colleagues installed all three types
of measuring devices on Merapi. They attached solar-powered radio transmitters to the
devices that beam the information to computers in Yogyakarta, a city about
20 miles away. In the center there, scientists will plug the information
into a complicated mathematical equation that will help them to determine
the rock's breaking point.
''The equation is a mathematical way of predicting when the rock is going
to fail,'' Voight says. ''We want to predict the point in time when the
magma will break through the rock and come out of the hole.''
Why do the people on the Indonesian island, called Java, keep moving
back to Merapi's foot, when they know the danger they face?
One reason, Voight says, is that the soils around the volcano are rich
with nutrients, making the land ideal for farming. The memory of the
volcano's destruction fades more quickly than the need to grow crops for
food.
Who knows when Merapi will blow next? Will it be next week, next
month, next year? Could it happen while a scientist is standing on top of
the huge crater, installing a tiltmeter or a seismograph?
''I'm not afraid on Merapi,'' says Voight. ''Not unless the monitoring shows us something unusual.''
Meanwhile, he says, he plans to keep on doing what he's doing--hiking
up huge volcanoes and studying what makes them tick.
''A volcano is one of the most marvelous spectacles,'' Voight says.
''I enjoy being outside. But on a volcano, with good companions, far away
from civilization--there's no place more enjoyable for me. It's not a
question of making money. We often do it for free. It's the romance of an
adventure, the enjoyment of being in high terrain.''
From the the rim of Merapi's crater, you can see a string of other
volcanoes sticking up like spikes through the clouds. You are so high that
there are also clouds below you inside the volcano's huge crater. And on a
quiet night, you can hear the tinkling bells of Javanese music rising from
the plains far off in the distance. These experiences, Voight says, are
well worth the risk.
An explosion that violently forces molten lava, rock, and other material out of the mouth of a volcano. A volcano erupts when magma rises from deep inside the earth. GO BACK
Breaks and cracks on the surface of a volcano through which steam and poisonous gases escape. GO BACK
A fountain of steam. GO BACK
The name for melted rock that boils and bubbles under the surface of the earth. GO BACK
The name for magma after it has been ejected from the mouth of a volcano. Lava can speed down the slopes of a volcano as fast as 200 miles per hour. After it has cooled, lava becomes solid rock. GO BACK
An open, flat area. GO BACK
An instrument that records the direction, intensity and time of earthquakes. GO BACK
Electricity derived from the rays of the sun. GO BACK
A word that is often used to describe the condition of an expanse of land. For example, "rocky terrain" describes an area whose soils are rocky. GO BACK
An instrument that detects movement of the surface of the earth. Scientists insert tiltmeters into the ground at a certain angle. If this angle changes, the scientists know that the earth is shifting. On the slopes of a volcano, shifting soils may mean that an eruption is on its way. GO BACK
This branch of government tracks earthquakes, volcanoes, and other natural phenomena. Many of the scientists who work for the U.S. Geological Survey are geologists, experts in the makeup of the earth's crust, its rocks, and its fossils. GO BACK