Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tornadoes Tend Toward Higher Elevations and Cause Greater Damage Moving Uphill

29.08.2013
Research examined terrain damage of Joplin and Tuscaloosa tornadoes

The first field investigations of the effect of terrain elevation changes on tornado path, vortex, strength and damage have yielded valuable information that could help prevent the loss of human life and damage to property in future tornadoes.


Matt McGowan, University of Arkansas

The most severe damage caused by the EF5 tornado that struck Joplin, Mo., on May 22, 2011, occurred on flat terrain or when the tornado was moving uphill.

Engineering researchers at the University of Arkansas analyzed Google Earth images of the massive 2011 Tuscaloosa, Ala., and Joplin, Mo., tornadoes and found similarities between the two in behavior and interaction with the terrain. The findings likely apply to all tornadoes.

“We wanted to understand the impact of terrain on damage magnitude and tornado path,” said Panneer Selvam, professor of civil engineering. “Information about this interaction is critical. It influences decisions about where and how to build, what kind of structure should work at a given site.”

The researchers’ analysis led to three major observations about the nature and behavior of tornadoes as they interact with terrain:

• Tornadoes cause greater damage when they travel uphill and less damage as they move downhill.

• Whenever possible, tornadoes tend to climb toward higher elevations rather than going downhill.

• When a region is surrounded by hills, tornadoes skip or hop over valleys beneath and between these hills, and damage is noticed only on the top of the hills.

For years Selvam has studied the effect of high winds on structures and developed detailed computer models of tornadoes. He and civil engineering graduate student Nawfal Ahmed used tornado path coordinates from the National Oceanic and Atmospheric Administration and imposed this data on overlaid Google Earth images. They studied the tornadoes’ damage in depth by comparing historical images to aerial photographs taken after the events. Google Earth photographed Tuscaloosa one day after the tornado there. For the Joplin tornado, an aerial photograph was taken on June 7, 16 days after the twister.

In terms of magnitude of damage, the data clearly showed that tornadoes cause greater damage going uphill and huge damage on high ground or ridges. Damage decreased as the tornadoes moved beyond the crest of a hill and going downhill. While it seems logical, this data contradicted a finding from a previous study in which Selvam and a different student found that a hill can act as a protection wall for buildings.

The researchers also found that when approaching a geographic intersection, tornadoes climb toward ridges rather than go downhill, which is counterintuitive when one thinks about wind or water seeking the path of least resistance. With both the Joplin and Tuscaloosa tornadoes, there were several locations where the paths changed direction. At each of these locations, or intersections, the tornadoes consistently sought higher ground.

Finally, Selvam and Ahmed discovered that when a region is surrounded by hills, tornadoes tend to maintain a consistent trajectory rather than follow topographical contours. jumping over valleys to hit hilltops and ridges. With both tornadoes, Selvam said, it was clear that all highland areas suffered the most damage.

Occurring less than a month apart, the Tuscaloosa (April 27) and Joplin (May 22) tornadoes are two of the most deadly and expensive natural disasters in recent U.S. history. Tuscaloosa was an EF4, multiple-vortex tornado that destroyed parts of Tuscaloosa and Birmingham, Ala. The tornado killed 64 people and caused roughly $2.2 billion in property damage, which, at the time, made it the costliest single tornado in U.S. history. Only a month later, the Joplin tornado, an EF5 with multiple vortices, which damaged or destroyed roughly a third of the city, killed 158 people, injured 1,150 others and caused $2.8 billion in damage.

The researchers presented their findings at the 12tth Americas Conference on Wind Engineering.

Selvam is holder of the James T. Womble Professorship in Computational Mechanics and Nanotechnology Modeling. He directs the university’s Computational Mechanics Laboratory.

CONTACTS:
Panneer Selvam, professor, civil engineering
College of Engineering
479-575-5356, rps@uark.edu
Matt McGowan, science and research communications officer
University Relations
479-575-4246 or 479-856-2177, dmcgowa@uark.edu

Matt McGowan | Newswise
Further information:
http://www.uark.edu

More articles from Earth Sciences:

nachricht Filling the gap: High-latitude volcanic eruptions also have global impact
20.11.2017 | Institute of Atmospheric Physics, Chinese Academy of Sciences

nachricht Antarctic landscape insights keep ice loss forecasts on the radar
20.11.2017 | University of Edinburgh

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>