2014英语四级听力练习慢速4.8(2)_大学英语听力

2014英语四级听力练习慢速4.8(2)

　　Volcanoes are also found in the middle of plates, where there is a well of melted rock. Scientists call these wells hot spots. A hot spot does not move. However, as the plate moves over it, a line of volcanoes is formed.

　　The Hawaiian Islands were created in the Pacific Ocean as the plate moved slowly over a hot spot. This process is continuing, as the plate continues to move.

　　Similar to earthquakes, volcanos can cause destruction and displace populations. Because of this, scientists are also hoping to learn more about volcanic activity.

　　Recently, the United States National Science Foundation provided financial support for research on volcanos. Geoscientists from the University of Oregon and the University of California Davis studied Mt. Hood in Oregon.

　　The scientists say that volcanos become active when the rock or magma inside becomes as hot as 750 degrees Celsius. The volcano becomes active when the hot magma from the Earth crust rises and meets cooler solid magma. This can happen in as little as a few months?time.

　　The American scientists believe the magma at Mt. Hood had been stored in the volcano for at least 20,000 years, or even as long as 100,000 years. They say that modern technology should be able to sense when the magma is getting warmer, and could possibly explode. This could prevent disasters when volcanos erupt around the world.