WHY DO VOLCANOES BLOW THEIR TOPS?

The Bergers present another solid and readable title in the Question and Answer Series, giving brief answers to tough questions about volcanoes and earthquakes: Where do they occur? What causes them? How do we measure them? Can we predict them? Do all volcanoes look alike? How often do earthquakes occur? Competent illustrations extend the text throughout, showing the reader the difference between a crater and a caldera, for instance, or mapping major plates of the earth’s crust, and illustrating three kinds of volcanoes and three different types of eruptions. There are the predictable “disaster” illustrations, as well: San Francisco on fire in 1906 and earthquake damage in Alaska in 1964. One minor concern with the format is that some of the questions appearing in red type on a blue background are hard to read. The brief text is factual and somewhat understated. For example, the authors say, “Number 1 on the Richter scale can be seen on a seismograph, but can’t be felt. Number 5 on the Richter scale is about as powerful as the explosion of a nuclear bomb. Anything over 8 means total destruction, usually with much loss of life.” They do not explain, however, that an increase of one whole number on the scale indicates a ten-fold increase in the magnitude of the quake. Nor do they make clear how a nuclear bomb causes less than total destruction. No sources or notes are given for the information included. Still, there’s a lot of information in this glossily bound package. With the glowing red volcano on the cover, clear white spaces, snappy question-and-answer format, and brief index, this title will have wide appeal for science readers and browsers. (Nonfiction. 8-12)