Researchers Find Possible New Method of Tsunami Detection

BY EDDIE KIM – Researchers at the University of Illinois may have discovered a new method of tracking tsunamis, which could potentially help current early-warning systems form a better picture of a destructive wave.

A team of scientists at the University of Illinois, led by engineering professor Jonathan Makela, conducted a study which captured an image of the “airglow” signature of the Tohoku tsunami that devastated Northern Japan on March 11 of this year.

A camera system based on Maui, Hawaii captured the image in the upper atmosphere, 250 km above sea level. According to the study, which was recently published in the peer-reviewed journal Geophysical Research Letters, the undulations of water as the wave moved across the ocean caused atmospheric “gravity waves” that traveled up and caused the light phenomenon known as “airglow”.

The idea that a tsunami waveform can create an airglow signature is not new and dates back to initial theories calculated in the 1970’s.  Until now, however, only complicated radio technology involving multiple satellites had been used to demonstrate the phenomenon.

The possibility of using a single-camera system to image a traveling tsunami, however, could be beneficial in providing a greater picture of how a wave is behaving and will behave on impact.  Currently, early tsunami detection primarily relies on the DART (Deep-ocean Assessment and Reporting of Tsunamis) system, which uses buoys to measure real-time activity of potential tsunami waves.

According to Stewart Weinstein, Deputy Director of the Pacific Tsunami Warning Center (based on Oahu, Hawaii), this current detection system is “effective, but has disadvantages”.

“Using buoys to track waves in the open ocean works.  However, they only tell you what the wave is doing at certain points at certain times.  The main advantage of this new airglow observation system would be to see what the entire waveform is doing over a large body of water,” Weinstein said.

Weinstein also noted, however, that a huge problem in tsunami detection today is the inability to know how destructive a wave will be upon contact with land.  It is unclear whether or not airglow measurements could provide more insight into the end behavior of a tsunami.

There are also questions surrounding the level of detection that such a system would provide.  “Will it be useful for small tsunamis as well as major ones?  The threshold of detection is important,” Weinstein said.

Makela himself told Science Daily that there was a lot of work to be done before a reliable system could be made.  A complete system would require complex algorithms that can filter usable data from raw observations, and a satellite-based camera would likely need multiple ground-based imaging systems to provide a strong, consistent method of observation.

Weinstein says that in all likelihood, atmosphere imaging would work in tandem with current buoy-based systems, as buoys collect real-wave data from ocean activity as opposed to a separated phenomenon in the sky.  But he also said that while its usefulness is so far unclear, a system of measuring tsunami-originated airglow is an “optimistic discovery for tsunami research”.

“Every and any little bit towards better detection counts,” he said.

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