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No. 68: Mar-Apr 1990

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Quiet sun: violent earth

When R.B. Stothers, at NASA's Goddard Institute for Space Studies, decided to look into the possible correlation of solar activity and terrestrial volcanism, he fully expected to find no connection at all. After all, what force generated by small changes in the sun's output could stir up the earth's magma from a distance of 93 million miles? Stothers was surprised.

"Stothers analyzed two immense catalogs, published in the early 1980s, that list more than 55,000 known eruptions since the year 1500. Concentrating on several hundred of the moderate-to-large eruptions, he found statistically significant patterns in eruption frequency that match the solar cycle. Eruptions seemed most numerous during the weakest portions of the solar cycle."

Further, there was a 97% confidence that the correlation was not a statistical accident.

The only cause-and-effect explanation offered by Stothers was negative and indirect. During periods of abundant sunspots, increased solar emissions jar the earth's atmosphere slightly. Communicated to the crust, these slight taps trigger tiny earthquakes that relieve stresses beneath volcanos, thus delaying their eruptions until solar acitivity dies down. Not especially convincing!

(Anonymous; "Volcanos on Earth May Follow the Sun," Science News, 137:47, 1990.)

Comment. Down the years, many scientists and laymen have tried to correlate sunspots and earthquake frequency. The results have been murky and sometimes contradictory. For more on this subject, see GQS1 in our catalog: Earthquakes, Tides. Details on this volume here.

From Science Frontiers #68, MAR-APR 1990. 1990-2000 William R. Corliss