While seismic records are currently being searched for more small events, it is unlikely that any large signals were missed. The event sent an ash plume to about 1,850 meters above the volcano and peppered the crater floor with ballistic blocks. The spacing between 15-minute lines was widened during the event in order to preserve the signature. This signature is similar to those from the smaller events, although higher in over-all amplitude and longer in duration. Plumes were confirmed during several of the larger events, but at least three did not generate a steam or ash plume.
Geologists measure deformation of the dome from a site at the north end of the crater.
Many instrument sites close to and on the dome, including a key deformation instrument site near the dome, were destroyed during the series of explosions. Photograph by E. W. Wolfe, February 14, 1991. Labeled sites are referenced elsewhere in text. Several of the eruptions involved both explosive and dome-building activity. The last magmatic eruption was a dome-building eruption in October 1986.