On the origin of microseisms

Posted by pkm at Feb 17, 2015 07:50 PM |
Jennifer Neale (1), Nicolas Harmon (1) & Meric Srokosz (2) - (1) School of Ocean and Earth Science, University of Southampton; (2) National Oceanography Centre, Southampton

For many years people have been intrigued by observations of tiny seismic motions, or microseisms, at frequencies exactly double that of nearby ocean waves.  A mathematical and physical explanation for this phenomenon was first put forward by Michael Longuet-Higgins in 1950.  He explained how opposing ocean waves of similar frequency, travelling in opposite directions, interact to produce a double frequency signal throughout the water column.  The energy transfer of energy to the solid earth generates seismic waves, mostly in the form of surface Rayleigh waves, which are recorded on seismometers around the world.  Since then, many other people have contributed to our understanding of microseism generation.  However, mysteries still remain about which ocean regions generate microseisms, the propagation of microseisms from source to seismometer, and how microseisms can be related in a quantitative and reliable way to ocean wave conditions.  This poster will give an overview of the study of microseisms from historical discoveries in the UK to recent advances and on-going research.

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