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All nine magmatic eruptions at Pavlof Volcano in six of the years from 1973 to 1984 have occurred between September 9 and November 20. Volumes of erupted material range from 0.1 to 15.9 × 106 m3 (dense rock equivalent) at an average rate of ∼3 × 106 m3 yr−1. The volumes are estimated from eyewitness reports for two eruptions; the others are estimated from a relationship that we derive between eruption volume and harmonic tremor duration and amplitude. The volume of lava erupted is approximately time predictable. A significant correlation exists between the eruptions and yearly nontidal variations in sea level and may result from ocean loading. Calculated volume changes beneath the volcano due to ocean loading are from 0.02 to 2 times eruption volumes, and we postulate that the volcano acts as a long-period (several month) volume strain meter, with lava being preferentially erupted when strain beneath the volcano is compressive. The volcano did not erupt during the period 1978–1980, when tilt, seismic data, and sea level data indicate that deep aseismic slip may have occurred. Models of this event predict a volume increase beneath the volcano that might have compensated strain from magma injection. These observations indicate that Pavlof Volcano may be responsive to small, slow changes in ambient stresses or strains and that these changes may modify or trigger eruptions.

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Journal of Geophysical Research, v. 92, issue B11, p. 11509-11523

Copyright 1987 by the American Geophysical Union.