Monday, May 25, 2009

Earth vibrations indicate increased storminess

Liz Kalaugher in Environmental Research Web: Traditionally the earth vibrations caused by ocean gravity waves created by cyclonic storms have been seen as noise that distracts from the earthquake signals seismologists are looking for. But these ocean-induced microseisms can provide valuable information about how climate has changed over time.

"Ocean-generated ambient noise measured on land is an integrator of ocean wave activity along coasts, and thus complements traditional oceanic measurements," Peter Bromirski of Scripps Institution of Oceanography at the University of California, San Diego told environmentalresearchweb. "The seismic data indicate that the amount of wave energy reaching coastlines is increasing, important under rising sea levels which allows more wave energy to reach farther shoreward."

The increase in ocean wave energy along coasts also has implications for coastal erosion and coastline evolution under rising sea levels.

…The Earth's "hum", long-period oscillations thought to be excited by ocean infragravity waves, is also climate-related. That's because some of the ocean swell reaching coastlines is transformed into infragravity waves with periods of more than 50 seconds. And the amount of ocean swell depends on storm track and storm intensity.

"The direct association of storm-driven ocean waves with microseisms and hum shows that the solid Earth is not independent of the global 'climate system'," writes Bromirski in a perspective article in Science….

The photograph was taken by Sofwathulla Mohamed while standing on his doorstep. His apartment was entirely washed out damaging all his belongings. His website is and his email address is The image is not copyrighted, you may use it freely, any credit given would be appreciated.

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