A volcanic eruption over the border in Alaska in the coming months is considered likely. Its possible effects on the Yukon, if any, are less predictable.

On March 11, the Alaska Volcano Observatory put out a notice stating that there was an increased likelihood of Mount Spurr, an active volcano about 125 kilometres west of Anchorage, having an eruption within the coming weeks or months. The volcano has previously erupted in 1992 and 1953.

Matt Haney, a scientist-in-charge at the Alaska Volcano Observatory said the observatory has seen general unrest at the volcano for around a year. They鈥檝e seen signs like small earthquakes, the surface of the volcano inflating outwards, as well as a lake of melted ice and snow at the summit crater, said Haney.

However, when observation flights took place around the volcano on March 7 and 11 they saw something new: higher-than-usual levels of volcanic gases around the summit crater and the crater peak vent where the volcano erupted in 1992 and 1953.

鈥淪o that was that caught everyone's attention at the observatory, because that's the vent that the most recent eruptions came from,鈥� said Haney.

Prior to the discovery of the volcanic gas emissions, Haney said the observatory had estimated there was an equal likelihood of an eruption and a non-eruptive magma intrusion.

鈥淏ut then, because of these new measurements of elevated gas emissions, now we concluded that an eruption like 1992 and 1953 is the most likely scenario going forward,鈥� said Haney.

Haney said the most likely scenario is that the volcano erupts before the end of the year.

Mount Redoubt, a volcano near Mount Spurr, had similar levels of volcanic gas emissions one to two months before it erupted in 2009, said Haney.

He said one of the indicators that scientists are looking for next is called a volcanic tremor: a earthquake that is constant and can last for a whole hour, unlike the small second-long earthquake 鈥渏olts鈥� currently happening around Spurr.

鈥淚n 1992 the scientists at AVO at that time began to see those signals three weeks before it erupted. So they began to see shallow volcanic tremor in early June 1992 and then its first eruption was in late June 1992 so we're looking closely for that kind of signal, and then that should give us even more clarity, you know, and even more warning that the volcano is continuing to progress towards eruption,鈥� said Haney.

Eruptions at Mount Spurr are explosive and produce clouds of ash, said Haney. In 1992, an eighth of an inch of ash fell on Anchorage.

Ash could interrupt the aviation sector, said Haney, noting that in the 1992 eruption, the Anchorage International Airport was closed for 20 hours because of the ash fall.

鈥淲hen a volcano erupts, it explosively makes an ash cloud, you know, this ash cloud could go up to 50,000 feet into the atmosphere,鈥� said Haney.

Of course, where the volcanic ash lands depends on the wind direction the day of the eruption, he said. The volcano actually erupted three times in 1992: in June, August and September. Only during the August eruption did the winds blow the ash onto Anchorage, he said.

The September eruption did see ash blown into the Yukon, said Haney. The farthest reported ashfall was in Carmacks 鈥� 860 kilometres from the crater peak vent.

Haney said Anchorage residents are advised to have N95s and disaster kits for general emergencies, but said that ashfall will likely be more of a nuisance.

He said the Alaska Volcanic Observatory is continuing to monitor the volcano with flights measuring gas emissions. He said the observatory also receives seismic data and deformation data from remote stations.

Melanie Kelman, a volcanologist at Natural Resources Canada, told the News that the eruption would have to be very big to result in ashfall on the Canadian side of the border, since Mount Spurr is quite a distance away.

鈥淚f there was a lot of ash and there was ash fall on the ground, most likely it would be very light in Canada, because it is so far,鈥� she said.

鈥淚t depends on how big the eruption is and what the wind conditions are. Generally, the bigger the eruption, the more likely it is that some ash is going to make it into Canada.鈥�

Volcanic ash is essentially tiny, pulverized pieces of rock that are electrically charged, said Kelman. Ash is very abrasive and it can cause issues for machinery and electronics, make roads slippery, and pose health hazards.

鈥淚 would be aware, but not anxious,鈥� said Kelman. She recommended the public check out the and websites for practical responses for ashfall events, like saran-wrapping electronics, closing your windows, and not wearing contact lenses.

Kelman said the other area of impact for Canada would be aviation, recalling the volcanic eruption in Iceland in 2010 that tangled European air travel.

Volcanic ash poses a hazard to aircraft, and there are mechanisms in place to prevent aircraft from encountering ash, said Kelman. The World Group of Volcanic Ash Advisory Centres has locations in Anchorage and in Montreal, she said, and when there are volcanic eruptions, ashfall trajectories are forecast to protect aircraft.

鈥淚 wouldn't be worried taking a flight anywhere in that area, because we have a really robust system for dealing with it,鈥� said Kelman.

鈥淭here's the potential for flights getting redirected or canceled, and that's inconvenient, but, you know, we have a good system in place.鈥�

The Yukon has historically been influenced by volcanoes, Alaskan and otherwise, according to Maurice Colpron, head of bedrock geology at Yukon Geological Survey.

He said the eruption of Mount Churchill in the St. Elias mountains is the most recent volcanic event that affected the Yukon.

鈥淭hat's probably the most recent,鈥� said Colpron. 鈥淚 think this is around 1,100, 1,200 years ago.鈥�

The eruption coated the area in white volcanic ash: you may see it at its thickest in soil around Carmacks and Pelly Crossing.

Fort Selkirk and Rancheria are areas with volcanic rock, said Colpron, estimating the rocks in Selkirk to be seven to ten thousand years old and the most recent volcanic rock in the area, while the rock in Rancheria is maybe 200,000 to 500,000 years old.

Whitehorse also has evidence of the Yukon鈥檚 volcanic past: there are 9-million-year-old lava flows in the area of Mount Sima, he said. Miles Canyon, or Kwanlin, also has 9-million-year-old volcanic rocks, he said.

Colpron said Mount Spurr is a more dramatic, potentially explosive type of volcano known as a subduction volcano, but the ancient volcanoes in the Yukon would have been fissure volcanoes, with lava oozing out, sans explosion.

In the territory now, there are not any active volcanoes that scientists are aware of, said Colpron.

Contact Talar Stockton at talar.stockton@yukon-news.com