[1] LOUD TO SOFT, LONG TO SHORT

This Demo/Unit should give you a sense of the broad range of information about the Earth that is contained in different kinds of seismic data, moving from Loud to Soft, or large signals to small ones, and from long times to short times…

Our collaborator Joachim Gossmann made this movie of 20 years of earthquakes larger than Magnitude 5.0, as they happen on the globe. What patterns do you see/hear ?

Here is another way of representing the same kind of data, showing smaller earthquakes, in more regional settings. The sounds for this one are samples of real seismic data:

We’ll start “local”– Here is the San Andreas fault in California, for 7 years:

And here is the same time frame, but zoomed out to see Western North America (and showing only earthquakes greater than Mag 4.0):

Here is the “catalog movie” for the Caribbean, for 7 years that included the Haiti Earthquake in 2010:

And Japan, including the Tohoku Earthquake of 2011:

Now here is a visualization and sonification of the “seismic wave field” in the Earth for two hours after the 2011 Mag 9.0 Tohoku Earthquake. The sound is directly sonified real data from 8 stations around the planet. The animation is data from a simulation of wave propagation using SPECFEM and rendered with “yt”. Two versions are presented, one where the sound and images are filtered to emphasize the ” surface waves, and the second to emphasize the “body waves”, each played at two speeds. What do you see, and hear ?

So those are the sounds from earthquakes. What about the vibrations, or the “ambient noise” that is always present, even when there are no earthquakes ?  Here, we have rubbed out the earthquakes for one year, and coupled the sounds with an animation of the average ocean wave height measured from satellites. We now know that it is interactions of these waves with each other and with the ocean floor that generate the ambient noise in the Earth. And so, remarkably, you can hear the weather ! Listen to Hurricane Sandy:

NOW– there are many forces that occur on different time scales that deform the Earth that we are coming to understand better and use to study the planet’s interior, including various tidal forcings, the seasonal changes in snow loading, etc… The most subtle of these, that causes vibrations of the surface a million times smaller (in amplitude) than the ambient noise is the “gravitational wave”. One of the most expensive and sensitive instruments in the world was recently built to detect these waves, if they existed as Einstein predicted, emitted from black holes that collide. In its first week in operation, the LIGO observatory did detect very clear gravitational waves. Here is a clear video on the phenomenon, and its measurement:

And here is their sonification of the data:

And here is a sound that we made, generated from the same data, with a very different method: