Deformation Monitoring at Mount St. Helens in 1981 and 1982

See allHide authors and affiliations

Science  30 Sep 1983:
Vol. 221, Issue 4618, pp. 1378-1380
DOI: 10.1126/science.221.4618.1378


For several weeks before each eruption of Mount St. Helens in 1981 and 1982, viscous magma rising in the feeder conduit inflated the lava dome and shoved the crater floor laterally against the immobile crater walls, producing ground cracks and thrust faults. The rates of deformation accelerated before eruptions, and thus it was possible to predict eruptions 3 to 19 days in advance. Lack of deformation outside the crater showed that intrusion of magma during 1981 and 1982 was not voluminous.