Featured Research

from universities, journals, and other organizations

Tornado-like Rotation Is Key To Understanding Volcanic Plumes

Date:
March 31, 2009
Source:
University of Illinois at Urbana-Champaign
Summary:
A 200-year-old report by a sea captain and a stunning photograph of the 2008 eruption of Mount Chaiten are helping scientists better understand strong volcanic plumes.

In 2008, the Mount Chaiten eruption in southern Chile showed what appeared to be a volcanic plume wrapped in a sheath of lightning.
Credit: Photo by UPI/Landov

A 200-year-old report by a sea captain and a stunning photograph of the 2008 eruption of Mount Chaiten are helping scientists at the University of Illinois better understand strong volcanic plumes.

In a paper to appear in the March 26 issue of the journal Nature, the scientists show that the spontaneous formation of a "volcanic mesocyclone" – a cyclonically rotating columnar vortex – causes the volcanic plume to rotate about its axis. The rotation, in turn, triggers a sheath of lightning and creates waterspouts or dust devils. The origins of these volcanic phenomena were previously unexplained.

"Rotation is an essential element of a strong volcanic plume," said Pinaki Chakraborty, a postdoctoral researcher and the paper's lead author. "By taking into account the rotation, we can better predict the effects of volcanic eruptions."

In 2008, a photograph of the Mount Chaiten eruption in southern Chile showed what appeared to be a volcanic plume wrapped in a sheath of lightning. A search for references to other occurrences of lightning sheaths led Chakraborty, mechanical science and engineering professor Gustavo Gioia and geology professor Susan W. Kieffer to an obscure paper by a sea captain, published in 1811.

In that paper, the sea captain reported his observations of a volcanic vent that emerged from the sea in the Azores archipelago and formed a large volcanic plume.

According to the captain, the plume rotated on the water "like an (sic) horizontal wheel" and was accompanied by continuous "flashes of lightning" and a "quantity of waterspouts."

This conjunction of rotation, lightning and waterspouts (or dust devils on land) is characteristic of a familiar meteorological phenomenon seemingly unrelated to volcanic plumes: a tornadic thunderstorm.

The same process that creates a mesocyclone in a tornadic thunderstorm also creates a volcanic mesocyclone in a strong volcanic plume, Chakraborty said. "What happens in tornadic thunderstorms is analogous to what happens in strong volcanic plumes."

A strong volcanic plume consists of a vertical column of hot gases and dust topped with a horizontal "umbrella." A volcanic mesocyclone sets the entire plume rotating about its axis. The mesocyclone spawns waterspouts or dust devils, and groups the electric charges in the plume to form a sheath of lightning, as was so prominently displayed in the eruption of Mount Chaiten.

The rotation of strong volcanic plumes may be verified by observations from space, the scientists report. On June 15, 1991, the eruption of Mount Pinatubo in the Philippines was recorded by a satellite snapping hourly images. The images show that the edge of Pinatubo's umbrella was rotating about its center, consistent with the presence of a volcanic mesocyclone.

The images also show that after rotating for a while, the umbrella lost axial symmetry and became lobate in plan view. This loss of axial symmetry is another effect of the rotation, which destabilizes the edge of the umbrella and makes it lobate, the scientists report.

Lobate umbrellas have been found in satellite images of other volcanoes, including Mount Manam in Papua New Guinea, Mount Reventador in Ecuador and Mount Okmok in the Aleutian Islands.

Satellite images of future volcanic plumes taken at intervals of a few minutes would make it possible to trace the evolution of umbrellas in detail, Gioia said. In addition, some of the tools commonly used in the study of thunderstorms could be deployed for the study of volcanic eruptions.

"The structure and dynamics of volcanic mesocyclones, as well as the presence of lightning sheaths, might be verified with Doppler radar and lightning mapping arrays, two technologies that have been scarcely used in volcanology," Gioia said.


Story Source:

The above story is based on materials provided by University of Illinois at Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University of Illinois at Urbana-Champaign. "Tornado-like Rotation Is Key To Understanding Volcanic Plumes." ScienceDaily. ScienceDaily, 31 March 2009. <www.sciencedaily.com/releases/2009/03/090325142505.htm>.
University of Illinois at Urbana-Champaign. (2009, March 31). Tornado-like Rotation Is Key To Understanding Volcanic Plumes. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2009/03/090325142505.htm
University of Illinois at Urbana-Champaign. "Tornado-like Rotation Is Key To Understanding Volcanic Plumes." ScienceDaily. www.sciencedaily.com/releases/2009/03/090325142505.htm (accessed September 16, 2014).

Share This



More Earth & Climate News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Researchers Explore Shipwrecks Off Calif. Coast

Researchers Explore Shipwrecks Off Calif. Coast

AP (Sep. 16, 2014) Federal researchers are exploring more than a dozen underwater sites where they believe ships sank in the treacherous waters west of San Francisco in the decades following the Gold Rush. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Isolated N. Korea Asks For International Help With Volcano

Isolated N. Korea Asks For International Help With Volcano

Newsy (Sep. 16, 2014) Mount Paektu volcano in North Korea is showing signs of life and there's not much known about it. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

      Technology News



      Save/Print:
      Share:

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile: iPhone Android Web
      Follow: Facebook Twitter Google+
      Subscribe: RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins