Hurricane Season & Microseisms


Microseisms are the dominant natural noise that we record on broad-band seismographs. This noise looks like continuous harmonic motion with varying patterns of amplitude modulation. The typical wave period of the harmonic motion is 6 seconds, though it can vary from 4 to 12 seconds.


"Hurricane Season" refers to an article in the EduQuakes column of the Seismological Research Letters (go to SSA link) by L.J. Ruff. This article refers to a research project by Richard Ensign (CSDM) that was originally published in the MichSeis newsletter (on-line via the MichSeis main page). The basic idea is to look at the averaged amplitude of the microseism noise over long periods of time (days), and compare that to the oceanic sources of the noise: storms at or near the margin of North America. Anyone can "play", see the EduQuakes column for web links to oceanographic data (e.g. Click here for current global wave heights, courtesy of the US Navy)

Hurricane Bonnie: August 1998


Hurricane Georges: September 1998


Back to MichSeis main page