UNDATED (AP) — Airplanes are being warned to avoid airspace near an erupting Alaska volcano as it spews ash 30,000 feet above sea level.

The National Weather Service said Saturday ash is being blown to the west and northwest of Pavlof Volcano.

Pavlof began erupting three days ago, pushing lava out from a vent near its summit. On Friday, the ash cloud reached 16,000 feet.

Alaska Volcano Observatory Geophysicist Dave Schneider says the eruption intensified at 6 a.m. Saturday, sending the ash cloud higher.

Schneider says it's not clear how long the eruption will last. He says Pavlof's eruptions may last for weeks or months with varying levels of intensity.

Pavlof is Alaska's most active volcano. It sits along international air routes connecting Europe, North America and Asia.

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