How A 'Weather Bomb' Measured In Japan Helps Uncover Earth's Secrets


Scientists in Japan have detected a series of tremors that reverberated through the ocean from the other side of the globe and quietly shook the seafloor in the region.

However, these tremors were not caused by an earthquake. Instead, they were caused by a rare phenomenon known as a "weather bomb," according to a new study.

Weather Bomb

In a new report, a team led by professors Ryota Takagi and Kiwamu Nishida of the University of Tokyo explained how they detected an amplification of a noise that hummed across the interior of Earth.

With the use of seismometers, researchers were able to pick up these vibrations that are likely caused by ocean waves, tidal forces, deep-lying earthquakes and other disturbances. As it turns out, the hum was produced by a specific weather bomb that formed just off the coast of Iceland and Greenland in 2014.

A weather bomb is a powerful cyclone during which strong waters beat against the seafloor. The cyclone unleashes seismic energy known as microseisms that reverberate through the interior and surface of Earth, scientists said.

Here is what happened: the atmospheric pressure quickly dropped as a storm system hovered over the North Atlantic Ocean. The weather bomb triggered pressure waves to move from the surface of the ocean to the ocean floor. Because of this, vibrations were absorbed by the seabed and tremors were felt even in Japan — the opposite side of the North Atlantic.

What's most fascinating about the report is that the Japanese scientists recorded P-waves and S-waves. The latter, which are also called transverse waves, are rare and feature side-to-side vibrations that are perpendicular to the direction in which they travel.

Uncovering Earth's Secrets

Authors of the new research believe that studying the microseismic waves produced by the weather bomb can help gather a collection of data that opens up a different perspective in exploring the deep interior of the Earth, particularly in the absence of earthquakes.

Seismologist Peter Gerstoft of the University of California, San Diego said detecting both S-waves and P-waves can provide experts more information. Because S-waves contain shorter wavelengths than P-waves, different lateral and vertical variations in the structure of our planet can be imaged, he said.

Geophysical oceanographer Peter Bromirski, co-author of a Perspective on the report, said the discovery of S-waves gives scientists a new tool to uncover the secrets of the Earth.

"New discoveries of any kind are always exciting," said Bromiski.

Details are published in the journal Science.

Photo: Graham Cook | Flickr

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