The 1999 eruption of Shishaldin Volcano, Alaska: monitoring a distant eruption

摘要: Shishaldin Volcano, in the central Aleutian volcanic arc, became seismically restless during summer of 1998. Increasing unrest was monitored using a newly installed seismic network, weather satellites, and rare local visual observations. The culminated large eruptions on 19 April 22–23 1999. opening phase eruption produced sub-Plinian column that rose to 16 km before rapidly dissipating. About 80 min into event we infer style transitioned vigorous Strombolian fountaining. Exceptionally tremor heralded 23 eruption, which thermal anomaly observable by satellite, but only modest, 6-km-high plume. There are no ground-based observations this eruption; however there renewed, Smaller low-level ash-rich plumes were through end May lava erupted evolved basalt with about 49% SiO2. Subsequent field investigations have been unable find distinction between deposits from each two major eruptive episodes.