May 6, 2013
Alaskan Volcano Eruption On Saturday Forces Aviation Authorities To Divert Some Traffic
Lawrence LeBlond for redOrbit.com - Your Universe Online
An Alaskan volcano roared to life on Saturday spewing a cloud of ash, steam and gas into the atmosphere, potentially disrupting a major air traffic route, according to scientists.The Cleveland Volcano, which sits at the western end of Chuginadak Island (part of the Aleutian Islands), erupted in at least three low-level explosions that were not severe enough to cause significant threats to air travel, but did force federal aviation authorities to divert some flights farther north of the volcano as a precaution, said Rick Wessels, a USGS geophysicist based at the Alaska Volcano Observatory (AVO).
AVO experts raised the alert status at Cleveland to Orange after a series of eruptions were detected. According to a report by Wired Mag´s Erik Klemetti, no visual confirmation of the eruption could be made due to visibility issues, so the AVO relied on infrasound to confirm the eruptions.
Infrasound, which detects very low frequencies (typically those under 20 Hz), can detect eruptions up to thousands of miles away because it easily travels through water, air and land. Numerous infrasound receivers planted around the area easily picked up the presence of an eruption. The infrasound technology has been around for decades, but this is a relatively new way for experts to track volcanic activity, and has been valuable in monitoring volcanic eruptions that are not easily detected because of visual obstructions.
According to the AVO, the Cleveland Volcano was continuing as an ongoing low-level eruption. However, seismic and infrasonic measurements have shown that the peak activity has decreased since Saturday evening. Satellite data did confirm that a continuous emission of low-level gas, steam and ash extended eastward below 15,000 feet. The data also continue to show highly elevated surface temperatures at the summit.
“Based on the signals we can see, we think it's continuously in an eruption right now,” Wessels said.
The volcano, located some 940 miles southwest of Anchorage, could continue to erupt with little or no warning, sending more ash, gas and steam as high as 20,000 feet into the air. AVO experts said that if a large ash-producing event occurs, nearby seismic, infrasonic, and volcanic lightning networks should alert AVO staff as quickly as possible.
However, because Cleveland Volcano does not have a local seismic network and is only monitored using distant seismic in infrasonic instruments and satellite data, a delay of several hours is likely before AVO experts can get word of further eruptions.
The FAA was not immediately available for comment on flight re-routing, but it is a safe bet that more delays and air traffic diversions would be likely if more eruptions occur.
Cleveland Volcano started becoming restless in mid-2011 when it began unleashing sporadic explosions. As many as 20 to 25 such explosions have occurred since. However, this weekend´s trio of explosions was a new turn of events for the volcano, said Wessels.
“We haven't seen a phase like this where we've had multiple explosions,” he said, as cited by Mail Online.
So far, the ash plume has leveled out below 15,000 feet, far below the 35,000-foot cruising altitude for most jet airliners. But further eruptions could send ash farther up into the air, which could pose a risk for air travel, he said.
Wessels said scientists are now on around-the-clock duty tracking Cleveland. “It's got us all paying attention. We're not sure if it will escalate or do what Cleveland does, which is to settle down after small explosions,” he added.
Saturday´s eruptions began at 5 a.m. local time. Two subsequent eruptions occurred at 9:17 a.m. and 11:44 a.m. local time. Saturday´s explosions were the most significant events for Cleveland since a trio of explosions in February 2001 sent ash clouds as high as 39,000 feet above sea level. That eruption also produced a lava flow and hot avalanche that reached the sea.
A smaller ash plume also erupted from Cleveland in November 2012.
AVO will continue to monitor Cleveland Volcano and issue additional alerts if necessary. The National Weather Service (NWS) is also monitoring activity and may issue an alert to mariners if more explosions occur. American-Asian air travel could also be further affected if ash clouds rise significantly higher.