About two years after it last spewed out lava and ash into the air, the Pavlof Volcano in Southwest Alaska erupted on Sunday afternoon, sending out ash 20,000 feet to the sky.

The U.S. Geological Survey (USGS) reported that the 8,262-foot Pavlof Volcano, which sits on Alaska's Aleutian Islands, erupted at exactly 4:18 p.m. local time on March 27. The volcanic eruption caused tremors on the ground, which were recorded shortly after 4 p.m.

"Seismicity began to increase from background levels at about 3:53 p.m. ... with quick onset of continuous tremor, which remains at high levels," the Alaska Volcano Observatory (AVO) said, according to Alaska Dispatch News.

Together with the AVO, the USGS has raised the volcano alert level to "warning" and the aviation warning to "red." This meant that eruption is imminent, and there is significant ash emission into the atmosphere.

The National Oceanic and Atmospheric Administration had also issued a Significant Meteorological Information (SIGMET) or weather advisory for pilots in the area.

The Pavlof, which is about 4.4 miles in diameter, has had 40 known eruptions in the past. It is also one of the most "consistently active volcanoes" along the Aleutian arc, which consists of a number of active and dormant volcanoes.

During a previous eruption in 2013, ash plumes from the volcano had reached 27,000 feet. Other eruptions have spewed out ash plumes as high as 49,000 feet.

In 2014, the Pavlof erupted twice: first in May, and then in November.

The volcano began ejecting massive ash clouds on May 30, prompting authorities to post a red aviation warning level because airborne particles of volcanic gas can easily destroy jet engines. The volcanic activity ended in late June.

Months later, however, the Pavlof again burst out ash plumes as high as 35,000 feet in November.

The eruption was marked by small avalanches of hot rock. Geophysicist David Schneider said the eruption at that time were minor, and that it was typical Pavlof activity.

It had prompted alerts before the volcanic activity died down.

USGS geologist Michelle Coombs said the Pavlof tends to go through dramatic ups and downs during an eruptive phase.

"It could jump up again and begin to erupt with very little notice," said Coombs in 2014.

Although the Pavlof is located in an uninhabited area, it is still situated along international air routes that connect Asia, North America and Europe. The community nearest the active volcano is Cold Bay, which is about 37 miles southwest. The city of Anchorage is also 625 miles southwest of the volcano.

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