Boom!

[Guest guest]

If Mt. Redoubt blows, Alaskans may get a light show

By Pete Spotts | 01.31.09

E-mail a friend Print this Letter to the Editor Republish ShareThisGet

e-mail alerts RSS

(Newscom)

 

Lightning stabs the darkness during an eruption of the Tolbachik

volcano on Russia's Kamchatka Peninsula.

 

 

--

The volcano watch for Alaska’s Mt. Redoubt continues apace.

 

According to the Anchorage Daily News:

 

An observation flight by scientists this afternoon reported no sign of

ash emission yet, but discovered significant steaming from a new melt

depression at the mouth of the summit crater….

 

That flight took place Jan. 30.

 

But towering clouds of ash aren’t the only things to watch for if

Redoubt romps. Lightning is another byproduct of such eruptions. In

fact, Ronald Thomas and colleagues have suggested that volcanoes can

act as “dirty thunderstorms.â€

 

Dr. Thomas is an electrical-engineering professor at New Mexico

Institute of Mining and Technology in Soccoro. He focuses much of his

work on devising techniques to map and study lightning.

 

The eruption in 2006 of another Alaskan volcano, Mt. Augustine, gave

Thomas and researchers at the Alaska Volcano Observatory a chance to

monitor the eruption’s output of lightning. Applying some of the

mapping techniques Thomas has developed, the team gathered what it

called the most detailed information to date (as of February 2007) on

volcanic lightning.

 

The scientists monitored four explosive bursts from the mountain over

two days. Storms prevented the team from seeing the effects directly.

But the radio detectors they set up uncovered a “spectacular†sequence

of lightning activity. It came with the first, and largest, blast.

 

The team found two distinct types of discharges.

 

One presented their sensors with an almost constant stream of radio

emissions. The team suggested that the radiation came from large

numbers of small discharges that occurred near the summit as the hot

ash and gas hurtled skyward.

 

The second type began three minutes after the biggest blast. For the

ensuing 10 minutes, the researchers counted some 300 individual

lightning strokes that appeared to drift along with the wind-driven

ash plume. One of the last strokes occurred some 13 miles from the

summit.

 

The team figured that the close-to-the-cone discharges occurred

because the material ejected carried strong electrical charges from

the get-go. As that material moved into the plume and away from the

summit, colliding ash, rock fragments, and ice particles in the plume

increased the electrical charge. This led to the additional

discharges, which the team suggest took place mostly within the plume.

 

Volcanoes, the team wrote, “are known to release copious amounts of

water, and may behave as ‘dirty’ thunderstorms.†The results appeared

in the Feb. 23, 2007, issue of Science.

 

 

 

 

 

" Our enemies are innovative and resourceful, and so are we.

They never stop thinking about new ways to harm our country and our people, and

neither do we. "

--George W. Bush