Ambient Seismic Noise

This movie is about a cutting edge topic in seismology: the study of the ambient noise field in the Earth. We show the average ocean wave height in the northern hemisphere oceans, and you hear the ambient seismic noise for the entire year of 2012, in which Hurricane Sandy occurred in the Atlantic ocean. One year is compressed to 4 minutes and 53 seconds.

Why do we juxtapose this animation with this sound? In every seismogram (data recorded at a seismometer), there are constant small amplitude vibrations at 7-10 seconds period. These vibrations, we now know, are created by ocean waves that push down on the seafloor and generate vibrations that travel throughout the solid earth. The images in this movie are the average ocean wave height (data from NOAA, Tolman 2009 and Ardhuin et al., 2011) measured by satellites globally every 3 hours. The sound is simply the seismic data from two seismometers (red dots) in the northeastern US and central Japan, filtered at a band that includes the noise but suppresses the large amplitude earthquakes (around 7-10 seconds).

Lucia Gualtieri, Ben Holtzman, Douglas Repetto, Jason Candler CC licence seismicsoundlab.org