If the earth experiences an increase in solar radiation due to a decrease in atmospheric shielding will there be a proportional increase in either frequency or size of volcanic activity? Will this also cause an increase in seismic activity? Is there any evidence of an increase in volcanic and seismic activity prior to the onset of an ice age and then a decrease in this activity after the onset of an ice age?

Daniel H. Thomas

I don't think that changes in solar activity can directly affect volcanic activity. The energy that drives volcanism is internal to the Earth -caused by the long-term radioactive decay of naturally-occuring elements. However, there are ways in which ice ages (which may be triggered by solar activity) could affect volcanism. These ways involve the changes in gravitational loading by both ocean water and ice. There is evidence that the loading of big icecaps on Iceland changed the style of volcanism there and the subsequent unloading when the ice age ended also had an effect. There is also evidence that added ocean water weight that occurs during warm periods can have an effect on island and/or coastal volcanoes. The relationships have not all been worked out, and in fact this is an area of present research, especially because we humans seem to be raising sea level all by ourselves.

Sincerely,
Scott Rowland

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