There was a lot of excitement in Mt. Saint Helens, Washington. Geologists were monitoring the Mount Saint Helens volcano. Seismicity began several days before March 20, 1980, when an earthquake of 4.2 centered under the volcano commanded wide attention. The first of a series of small phreatic explosions occurred on March 27, accompanying the opening of a crater northward at the summit of the cone. Strong seismicity continued, at times bursts of deep volcanic tremor was felt statewide in early April but died away without returning. By mid-April a bulge was obvious on the north flank of the volcano. Seismicity continued into May, with fewer but larger earthquakes, and phreatic activity was intermittent.5
An earthquake registering 5.1 on the Richter scale occurred on May 18, 1980 at 8:32 A.M. This struck beneath the Mt. Saint Helens volcano. Thirteen minutes later Mt. Saint Helens erupted. …
