Study compares sound from exploding volcanoes with jet engines

Apr 08, 2009
Scripps researchers are using infrasound recording to study Tungurahua volcano in Ecuador. Credit: D.Fee/University of Hawaii

New research on infrasound from volcanic eruptions shows an unexpected connection with jet engines. Researchers at Scripps Institution of Oceanography at UC San Diego speeded up the recorded sounds from two volcanoes and uncovered a noise very similar to typical jet engines. These new research findings provide scientists with a more useful probe of the inner workings of volcanic eruptions. Infrasound is sound that is lower in frequency than 20 cycles per second, below the limit of human hearing.

The study led by Robin Matoza, a graduate student at Scripps Oceanography, will be published in an upcoming issue of the journal , a publication of the American Geophysical Union (AGU). Matoza measured infrasonic sound from Mount St. Helens in Washington State and Tungurahua volcano in Ecuador, both of which are highly active volcanoes close to large population centers.

"We hypothesized that these very large natural volcanic jets were making very low frequency jet noise," said Matoza, who conducts research in the Scripps Laboratory for Atmospheric Acoustics.

Scripps researchers installed an array of microbarometers at Mount St. Helens in November 2004 to collect infrasound near the site. Credit: Scripps Institution of Oceanography, UC San Diego

Using 100-meter aperture arrays of microbarometers, similar to weather barometers but sensitive to smaller changes in and low-frequency infrasonic microphones, the research team tested the hypothesis, revealing the physics of how the large-amplitude signals from eruptions are produced. Jet noise is generated by the turbulent flow of air out of a jet engine. Matoza and colleagues recorded these very large-amplitude infrasonic signals during the times when ash-laden gas was being ejected from the volcano. The study concluded that these large-scale volcanic jets are producing sound in a similar way to smaller-scale man-made jets.

"We can draw on this area of research to speed up our own study of volcanoes for both basic research interests, to provide a deeper understanding of eruptions, and for practical purposes, to determine which eruptions are likely ash-free and therefore less of a threat and which are loaded with ash," said Michael Hedlin, director of Scripps' Atmospheric Acoustics Lab and a co-author on the paper.

Large-amplitude infrasonic signals from are currently used in a prototype real-time warning system that informs the Volcanic Ash Advisory Center (VAAC) when large infrasonic signals have come from erupting volcanoes. Researchers hope this new information can improve hazard mitigation and inform pilots and the aviation industry.

"The more quantitative we can get about how the sound is produced the more information we can provide to the VAAC," said Matoza. "Eventually it could be possible to provide detailed information such as the size or flow rate of the volcanic jet to put into ash-dispersal forecasting models."

Source: University of California - San Diego (news : web)

Explore further: NASA provides double vision on Typhoon Matmo

add to favorites email to friend print save as pdf

Related Stories

Wireless system to monitor volcanoes

Sep 23, 2004

Seismologists, Ecuadorian officials, area residents could benefit from improved data A rumbling South American volcano has gone wireless: Computer scientists at Harvard University have teamed up with seismologists at the Unive ...

Volcanic blast influences climate

Aug 12, 2005

The volcanic ash cloud created by a volcanic blast can alter interactions between the atmosphere and sun, affecting climate patterns, say U.S. scientists.

Double volcanic eruption in Eastern Russia

Mar 10, 2005

Acquired from orbit 800 kilometres away, this Envisat image shows two volcanoes erupting simultaneously on Russia's snowy Kamchatka Peninsula this week. Located in the Russian Far East, the Kamchatka Peninsula is ...

Recommended for you

Jeju Island is a live volcano, study reveals

10 hours ago

In Jeju, a place emerging as a world-famous vacation spot with natural tourism resources, a recent study revealed a volcanic eruption occurred on the island. The Korea Institute of Geoscience and Mineral ...

Has Antarctic sea ice expansion been overestimated?

10 hours ago

New research suggests that Antarctic sea ice may not be expanding as fast as previously thought. A team of scientists say much of the increase measured for Southern Hemisphere sea ice could be due to a processing ...

User comments : 0