FRICTION
*Friction EP* is a sonic exploration of the frictional processes at play as geological faults (breaks in the Earth) slide past each other at depth in the Earth's crust. Microscopic processes occurring on tiny roughnesses or asperities play a huge role in determining Earthquake slip. This soundtrack is inspired by laboratory friction experiments and immersive sound design.
This EP is a collaboration between Elliot Termote (sound design) and Karen Mair (geoscience and sound recording). This work was supported by the Centre for Integrated Earth Science Education (iEarth), a Norwegian Centre of Excellence (https://www.iearth.no/).
FRICTION
SOUND DESIGNS
*Stable Sliding*: Nothing and everything all at once. During stable sliding, the strength of a fault on the large scale is fairly constant but at the microscopic scale, thousands of tiny grains are interacting - rolling, grinding, jostling and breaking up.
*Stick Slip*: Repetitive stick slip is a dramatic expression of unstable sliding and a model for how Earthquakes work. We hear the small scale processes associated with cycle of: gradual build up - rapid release - quiet / gradual build up - rapid release - quiet / gradual build up - rapid release - quiet.
*Healing*: Between major slip events, frictional healing occurs on faults as microscopic contacts deform and grow. These welding-like processes increase with time so the longer a fault sits and 'waits' the stronger it becomes and the larger earthquake occurs when it finally slides. Here, two slide-hold-slide experiments simulate sliding, healing during the 'hold' and release when sliding restarts. Release is much larger after the second longer hold, where more healing and strengthening has had the chance to occur.
*Melting*: Frictional melts form when faults slip rapidly, generating enough frictional heating that their walls melt and solid rock turns to a thick liquid. Rock fracture, flash melting at tiny protrusions, injection of melt into side fractures and dissolving of rock fragments occur along the way. Initially this lubricates the fault, dramatically reducing friction and allowing slip to progress more easily. However, as the melt cools it solidifies acting as a brake to slow or stop sliding. Pseudotachylytes (cooled frictional melts) are thought to be the geological signature of ancient earthquakes. *Melting*:
Images
- *Cover* - SEM micrograph of grain fracture
- *Stable sliding* - Spectrogram showing Stable Sliding sound design
- *Stick slip* - Spectrogram showing Stick Slip sound design
- *Healing* - Spectrogram of Healing sound design
- *Melt* -Spectrogram of Melting sound design