Hot spot of mysterious ocean hum pinpointed in North AtlanticJanuary 9th, 2008 - 3:30 pm ICT by admin
London, Jan 9 (ANI): Researchers have discovered an area in the North Atlantic Ocean where colliding waves can produce seismic vibrations, creating a hum that can be detected for thousands of kilometers.
According to a report in Nature News, this finding confirms an old prediction that oceans can be powerful generators of seismic activity.
Wave generated seismic activity, known as microseisms, has been observed since the early twentieth century, when seismologists began installing seismometers capable of detecting their slow vibrations.
Though they were first dismissed as noise in the data, ocean microseisms have recently been heralded as a powerful way of probing the properties of the Earth’s crust.
For locating the area that produces these microseisms, the knowledge that seismic sensors in Europe, North America, Iceland, and Greenland have long pointed to the North Atlantic as a possible hotspot for microseisms, helped the researchers.
As part of the research, seismologist Sharon Kedar of the Jet Propulsion Laboratory in Pasadena, California, and his colleagues used information from satellites and buoys to connect what was happening on the oceans surface to the vibrations they detected on dry land.
The team pinpointed a microseismic hotspot stretching from the Labrador Sea to south of Iceland. In this zone, autumn and winter winds kick up rough ocean waves that travel in opposite directions.
The wavelength of the colliding surface waves and the 2-kilometre depth of the water here create a strong resonance, with the surface and bottom of the ocean forming the ends of a giant, water-filled organ pipe. The pressure from the periodic collisions creates sizeable seismic vibrations that can be detected on the coasts of North America, Greenland, and Europe.
Though the model predicting deep sea generation of seismic vibrations is more than 50 years old, this is the first real confirmation that the model is correct, said Kedar.
“Until now, we didnt have a good understanding of where that noise is coming from. People had the expectation that the sources were random in place and time, but they are not,” he added.
“This is really a first in terms of connecting real ocean-model data, which is done by oceanographers, to the seismic data, which is the realm of solid-earth scientists,” said seismologist Toshiro Tanimoto of the University of California, Santa Barbara.
But researchers have said that a more complete model is still on the horizon. (ANI)
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