Photo: A "weather bomb" is a storm over the ocean with intense central pressure that produces strong winds and ocean swell, resulting in wave-generated seismic activity. Credit: Carl Milner/Flickr Small, intense storms known as "weather bombs" may trigger rare tremors deep within the Earth, offering scientists a new way to study the mysterious structure and inner workings of the planet, according to a new study.
A "weather bomb" is an extratropical (outside of the tropical zone) storm in which the central pressure intensifies rapidly. These storms produce very strong winds that cause the ocean to swell, generating powerful waves. Some of the wave energy from these storms interacts with the seafloor, causing wave-generated seismic activity.
Known as microseisms, these seismic waves are detectable anywhere in the world, because they penetrate the Earth deeply and can be observed at faraway land seismic stations, the researchers said. [Hurricanes from Above: Images of Nature's Biggest Storms]
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However, observations and analysis of microseismic activity have focused mostly on P waves - the first set of waves in an earthquake that deliver a sharp jolt - because of their larger amplitudes. This gives scientists only a narrow view of the Earth's structure, because P waves typically travel in straight lines.
In their new study, the scientists detected so-called S wave microseisms, which travel much more slowly and curve through the ground but are generally more difficult to observe. The previously unobserved S waves were generated under a weather bomb between Greenland and Iceland in December 2014.