JUNEAU (AP) — A smog-like haze that hung over part of Alaska’s Kodiak Island this week was courtesy of a volcanic eruption — 100 years ago.

The National Weather Service says strong winds and a lack of snow Tuesday helped stir up ash from the 1912 eruption of Novarupta, the largest volcanic blast of the 20th century.

This week, ash from the volcano drifted to about 4,000 feet. It traveled over the Shelikof Strait and across Kodiak Island, prompting an aviation alert. 

The news was first reported by KMXT radio.

Weather service meteorologist Brian Hagenbuch says the event isn’t unheard of, but isn’t very common either.

When Novarupta erupted in June 1912, it spit ash as high as 100,000 feet above the sparsely populated Katmai region, covering the remote valley to depths up to 700 feet.