Storms and tremors

The University of Hawaii has a collection of infrasound recordings, collected from various natural phenomena and converted into audible sounds:

One of the techniques we use to grasp these inaudible sounds is to make them audible through time compression (speeding up), pitch shifting (frequency transposition), or other methods...
Signal processing algorithms were used to make them audible and occasionally pleasant. Many of the sound files are complex, and superpose breaking waves, distant storms, aircraft, and volcanoes.

My favorites are this one from a hurricane, and this one from the Icelandic volcano Hekla.

Link via Bouphonia.