Semisopochnoi is monitored with an on-island seismic network and remotely by satellite and lightning sensors. An infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a slight delay (approximately 13 minutes) if atmospheric conditions permit.
Aug 29, 2019 22:08 – Low-level eruptive activity has likely declined at Semisopochnoi. Seismic activity over the past day has been relatively minor and the levels of seismic tremor have declined. Nothing significant was observed in cloudy satellite images.