How do you rate the current level of volcanic activity on earth in comparison to what you know about historic activity? I think volcanic activity has increased in the past 2-3 years...Do you agree? Also, is recent activity related to underground nuclear testing?

rocky Barb Stein

Dear Barb,

McClelland and others (1989) discussed changes in volcanism through time from about 1850 to 1985. Their graph shows many peaks and valleys in activity, an overall gradual climb in the number of active volcanoes reported each year up to about 1950, and, from 1950-1985, a leveling off in the number of active volcanoes reported each year. Within the period 1950-1985 there are peaks and valleys that reflect maybe 10 volcanoes erupting compared to the previous year (the average number is about 50). McClelland and others pointed out that global events play a role in the number of eruptions reported each year. For example, during the World Wars there was a dramatic decrease in the number of reported eruptions. People were too busy to make the reports. McClelland and others also pointed out that big eruptions, like Krakatau and Mt. Pelee, raised people's awareness of volcanoes and prompted more eruptions to be reported in subsequent years. It is certainly possible that volcanic activity has increased in the past 2-3 years (maybe 5-10 more volcanoes are erupting) but compilations of activity have not yet been published. I wonder if the eruption of Mt. Pinatubo in 1991 raised people's awareness of volcanoes?

Thanks for an interesting question.

Steve Mattox, University of North Dakota

Source of Information:
McClelland, L., Simkin, T., Summers, M., Nielson, E., Stein, T.C., 1989, Global volcanism 1975-1985: Prentice Hall, Englewood Cliffs, New Jersey, and American Geophysical Union, Washington DC, 655 p. 

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