A new lava dome was observed in the summit crater of Cleveland volcano prompting the Alaska Volcano Observatory to upgrade the Color Code/Alert Level to ORANGE/WATCH on January 17, 2019. No explosive activity has been detected or observed in seismic or infrasound data at the time.
According to satellite data, this lava dome was observed as early as January 12 and likely began extruding after the last explosion at the volcano on January 9, AVO reported in a daily update issued 21:10 UTC, January 17, 2019.
The presence of the lava dome may increase the likelihood of explosive activity at the volcano.
Periodic explosions are common at Cleveland and will likely occur without warning.
A short-lived explosion was detected at Cleveland volcano early December 29, 2018. Ash cloud was reported rising up to 5.2 km (17 000 feet) above sea level.
Most explosions have a short duration and only present a hazard to aviation in the immediate vicinity of the volcano.
Larger explosions that present a more widespread hazard to aviation are possible, but less likely and/or frequent.
Cleveland volcano is monitored by only one seismic station, which restricts AVO's ability to detect precursory unrest that may lead to an explosive eruption.
Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, lightning, and satellite data.
The web camera, one seismic station, and the local infrasound array are offline due to a equipment failure on September 23, 2019. This hampers efforts to rapidly detect explosive activity. Cleveland remains monitored with a single seismic station and regional instruments.
Unrest continues at Veniaminof and Great Sitkin volcanoes. Both of them have Color Code and Alert Level at Yellow / Advisory.
Seismic tremors at Veniaminof remain at low levels. Weak to moderately elevated surface temperatures were observed in satellite views and a steam plume was observed in web camera views on January 17. Eruptive activity consisting of lava effusion and/or ash emissions could resume at any time without significant seismic precursors.
There is no unusual activity observed in seismic data or partly cloudy satellite views available over the past 24 hours. No explosive activity was detected on a regional infrasound array on Adak Island.
Featured image credit: NASA/JSC/EOL