navigation bar Houghton Mifflin History-Social Science Neighborhoods
Weekly Reader ® Current Events

Volcano Watch

A giant volcano on the island of Hawaii is becoming active, scientists say. A volcano is an opening in the earth through which gases, ashes, and melted rock may come. Sometimes these materials erupt, or come out, with such force that they rise high into the air. Other times, they flow out. A mountain formed by these materials is also called a volcano.

Hawaii is a state that is made up of different islands. One of these islands is also called Hawaii. The Hawaiian volcano is a mountain called Mauna Loa (mow nuh LOH uh). Mauna Loa is Hawaiian for “Long Mountain.” It is the largest volcano on the earth. Mauna Loa makes up half of the island of Hawaii.

The last time Mauna Loa erupted was in 1984. A river of hot liquid rock flowed from the volcano for three weeks. This hot liquid rock is called lava. The lava can reach temperatures of nearly 2,100°F. That is much hotter than the oven in your kitchen can get. Most kitchen ovens can only go up to about 500°F. Lava can burn everything in its path.

Recently, scientists have noticed changes in Mauna Loa. The top of the volcano is growing a little bit. Hot, liquid rock is rising into the volcano.

When Will the Lava Flow?

Since 1984, people have moved to places around Mauna Loa. They have built homes on the volcano's sides. If the volcano erupts now, lava could burn and bury those homes.

For now, experts say that people should not worry too much about Mauna Loa erupting. “We're at a stage where it's months to years, rather than days to weeks [before it erupts again],” said scientist Peter Cervelli. Until then, scientists will continue to keep track of changes in the volcano.