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 GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center

nachricht Cyclic change within magma reservoirs significantly affects the explosivity of volcanic eruptions
30.11.2016 | Johannes Gutenberg-Universität Mainz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>