Scientists develop new approach to understanding massive volcanic eruptions

January 04, 2021

A geosciences team led by the University of South Florida (USF) has developed a new way to reconstruct the sizes of volcanic eruptions that occurred thousands of years ago, creating a first-of-its kind tool that can aid scientists in understanding past explosive eruptions that shaped the earth and improve the way of estimating hazards of future eruptions.

The advanced numerical model the USF team developed allows scientists to reconstruct eruption rates through time by estimating the dimensions of the umbrella clouds that contribute to the accumulation of vast deposits of volcanic ash. The research is published in the new edition of the Nature Journal, Communications, Earth and Environment.

The research, which was used to decipher the 2,500-year-old eruption of a volcano in Ecuador, was led by USF doctoral candidate Robert Constantinescu in collaboration with USF colleagues Research Associate Laura Connor, Professor Chuck Connor, Associate Professor Sylvain Charbonnier, doctoral alum Alain Volentik and other members of an international team. USF's Volcanology Group is one of the world's leading centers of volcano science and hazard assessment.

When large explosive eruptions occur, they form laterally spreading umbrella clouds into the stratosphere, facilitating the transport of fine-grained ash over hundreds of miles that settles and covers large swaths of land.

Current technology allows scientists to observe ash clouds. However, past eruptions are characterized based on the geological interpretation of their tephra deposits - the pieces and fragments of rock ejected into the air by an erupting volcano. By estimating the erupted volume and mass, plume height, umbrella cloud dimensions and other characteristics, the scientists are able to understand and characterize the volcanic eruptions, therefore improving the forecast of future events.

Using a series of field techniques combined with statistical and numerical modeling, volcanologists extract information from the deposits in order to characterize and classify an eruption on one of the most commonly used scales, the Volcanic Explosivity Index (VEI). Until now, the most sought-after information is the eruption column height and the total erupted mass or volume, Constantinescu said.

But over time, deposits erode and can provide an uncertain picture of older eruptions. Also, current models have been limited in that they assume all volcanic eruptions created mostly vertical plumes, Constantinescu said, and don't account for large explosive eruptions that form laterally spreading umbrella ash clouds.

The USF team's work shows that it is the dimensions of the umbrella clouds that is the telling factor in reconstructing past large explosive eruptions.

"The better we can reconstruct the nature of past eruptions from deposit data, the better we can anticipate potential hazards associated with future explosive eruptions," the team wrote in the new journal article.

The researchers propose updating the VEI scale with the umbrella cloud dimensions, which can now be easily estimated using the mathematical models they've developed.

The researchers applied their model to the tephra deposit of the eruption of Pululagua, a now dormant volcano about 50 miles north of the capital city of Quito. Ecuador is considered one of the world's most hazardous countries for volcanoes. The volcano last erupted an estimated 2,500 years ago and the area is now a geobotanical reserve renowned for its biodiversity and lush green landscape.

There are about 1,500 potentially active volcanoes worldwide, in addition to those that lurk beneath the world's oceans. In 2020, there were at least 67 confirmed eruptions from 63 different volcanoes, according to the Smithsonian Institution Global Volcanism Program. "If in modern times the umbrella clouds of large eruptions are easily observed, we now have the ability to estimate the umbrella clouds of past eruptions," Constantinescu said. "Our numerical model enables us to better characterize past volcanic eruptions and inform models for future hazard assessment."
-end-
The USF team was joined in the research by Aurelian Hopulele-Gligor of Cluj-Napoca, Romania; Costanza Bonadonna of the University of Geneva; and Jan M. Lindsay of the University of Auckland. The research was funded in part by the National Science Foundation.

University of South Florida (USF Innovation)

Related Volcanic Eruptions Articles from Brightsurf:

New drone technology improves ability to forecast volcanic eruptions
Specially-adapted drones developed by a UCL-led international team have been gathering data from never-before-explored volcanoes that will enable local communities to better forecast future eruptions.

Volcanic eruptions may explain Denmark's giant mystery crystals
Researchers have long been stumped for an explanation of how tens of millions of years-old giant crystals known as glendonites came to be on the Danish islands of Fur and Mors.

The testimony of trees: How volcanic eruptions shaped 2000 years of world history
Researchers have shown that over the past two thousand years, volcanoes have played a larger role in natural temperature variability than previously thought, and their climatic effects may have contributed to past societal and economic change.

Indian monsoon can be predicted better after volcanic eruptions
Large volcanic eruptions can help to forecast the monsoon over India - the seasonal rainfall that is key for the country's agriculture and thus for feeding one billion people.

Volcanic eruptions reduce global rainfall
POSTECH Professor Seung-Ki Min's joint research team identifies the mechanism behind the reduction in precipitation after volcanic eruptions.

A new tool to predict volcanic eruptions
Earth's atmosphere is made up of 78% nitrogen and 21% oxygen, a mixture that is unique in the solar system.

Oral traditions and volcanic eruptions in Australia
In Australia, the onset of human occupation (about 65,000 years?) and dispersion across the continent are the subjects of intense debate and are critical to understanding global human migration routes.

'Crystal clocks' used to time magma storage before volcanic eruptions
The molten rock that feeds volcanoes can be stored in the Earth's crust for as long as a thousand years, a result which may help with volcanic hazard management and better forecasting of when eruptions might occur.

Super volcanic eruptions interrupt ozone recovery
Strong volcanic eruptions, especially when a super volcano erupts, will have a strong impact on ozone, and might interrupt the ozone recovery processes.

Rare volcanic rocks lift lid on dangers of little-studied eruptions
Unusual rocks discovered on a remote mountainside have alerted scientists to the dangers posed by a little-studied type of volcano.

Read More: Volcanic Eruptions News and Volcanic Eruptions Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.