AVO Staff Directory:

Tremor signals associated with the eruption of Shishaldin Volcano on 19 and 23 April 1999 were the strongest recorded anywhere in the Aleutian Arc by the Alaska Volcano Observatory (AVO) in its 10-year history. Reduced displacements (DR) reached 23 cm2 on 19 April and 43 cm2 on 23 April. During the activity, DR and spectral data with a frequency resolution of 0.1 Hz were computed and put on the World Wide Web every 10 min. These data are analyzed here. The general temporal patterns of seismicity of these eruption events were similar, but the eruptions and their effects quite different. The 19 April event is known to have culminated in a sub-Plinian phase, which ejected ash to an altitude of 16 km.

Thompson, Glenn, McNutt, S. R., and Tytgat, Guy, 2002, Three distinct regimes of volcanic tremor associated with the eruption of Shishaldin Volcano, Alaska, 1999: Bulletin of Volcanology, v. 64, n. 8, p. 535-547.