One of Alaska's most active volcanoes may soon erupt for the third time this year, scientists have warned. For the past week, the Alaska Volcano Observatory has noticed an increase in seismic activity and steam emissions from the Pavlof Volcano, located in the south-western end of the Alasaka peninsula.
Pavlof is a stratovolcano covered in snow and ice and is about 7 km (4.4 miles) in diameter. It has active vents on the north and east sides, close to the summit.
The most recent update about its activity was published on 4 July 2016, revealing that low-level tremor activity had been recorded at the volcano over a 24 hours period.
Though no eruption is likely in the coming days, the data suggests the volcano could potentially produce another big eruption like the one that occurred on 27 March 2016.
Large explosive eruption
The March eruption produced lava and an ash plume that quickly rose to 20,000ft (6,000m) altitude. The volcano's activity then continued over the next 24 hours, with a sustained, continuous ash plume extending more than 400 miles (700 km) to the north-east of Alaska with a maximum height of 37,000ft altitude.
Two months later, in May, new seismic data suggested that another smaller eruption had occurred. However, the volcano's activity quickly decreased after that, and the alert level was downgraded to "green" – no risk of eruption.
However, scientists from the Alaska Volcano Observatory say pauses in activity of days to weeks are common during eruptive episodes of Pavlof Volcano, so a return to eruptive activity remains possible and could occur with little or no warning.
On 2 July they upped the alert level to "yellow" due to renewed activity. It means the experts will closely monitor on a daily basis how the situation evolves. They will analyse tremor activity, as well as cloudy satellite and web camera views of the volcano.
Pavlov has had 40 known eruption. Although the March eruption was particularly intense, it was not unprecedented in all of the volcano's history. Some eruptions have produced even more massive ash plumes, rising to 49,000ft altitude.