"The 1961 eruption or Kilauea Volcano, through the period February 24 to September 25, 1961, consisted of three summit eruptive phases followed by a flank eruptive phase. Tumescence of the Kilauea summit area, which began in the summer of 1960, continued virtually unchanged throughout and after the three periods of summit eruption. Rapid detumescence accompanied the flank eruption. Seismic activity during tumescence was moderate and persistent, but it gave no particular forewarning of imminent eruption. However, a swarm of relatively large earthquakes and strong harmonic tremor preceded the flank eruptive phase by about 16 hours."
Geological Survey Professional Paper 474-D
U.S Geological Survey: http://www.usgs.gov/