How does a seismograph predict voloanic eruptions?
A seismograph is only one tool scientists are using, in an attempt to LEARN how to predict volcanos and earthquakes. If the technique had already been developed, then many lives would have been saved in the last several years. What a seismograph detects is the movement of ground in the area of the instrument. They are pretty sensitive and can detect, even very slight movements, such as the passing of nearby automobiles, and, man made explosions many miles away. SOME of these movements can detect imminent volcanic activity, but, scientists do not, yet, know exactly which of these tremors mean eruptions, and which are, merely, earthquakes. What the instuments CAN do is give scientists warning that SOMETHING is going on, and, in the vicinity of an existing, active volcano, people can be advised to move out of the area, just in case. In the massive eruption of Mt. St. Helens, in Washington state, geologists’ instruments detected movement, and many speculated that an eruption could occur ve
