Slow earthquakes and low frequency shaking in active faults of the Earth’s crust: from field observations to laboratory experiments
Event details
| Date | 08.03.2011 |
| Hour | 12:00 |
| Speaker | François Renard |
| Location |
GC A1 416
|
| Category | Conferences - Seminars |
In the past ten years, geophysical observations have demonstrated that many active faults in the Earth’s host slow motions and periods of low frequency vibrations, known as slow earthquakes and tremors, respectively. Such mechanical behaviour is different from that in most active faults known to produce earthquakes. To unravel some physical processes at work during slow motion, we developed analogue laboratory friction experiments.
Solid friction is a force resisting the slip when two bodies slide past each other. Laboratory slider block experiments show either stick-slip or stable sliding. Both behaviours are encapsulated in the rate-and-state friction law and are considered to be analogous of seismic and aseismic movements on active faults, respectively. Using a salt slider, a surrogate for natural faults, allows for the two processes, friction and creep, to be efficient on the same time scale when the slider is pushed at low velocity. We observe that both the amplitude of the stick-slip oscillations and the waiting time decrease over several hundreds of cycles, eventually reaching the stable sliding regime. Concomitant with this continuous change towards stable sliding are the ageing of the frictional interface and the development of a striated morphology. We also show a systematic correlation between the onset of slip acceleration and the emission of tremor-like signals. When applied to the Earth’s crust, our results suggest that the generation of tremors and slow earthquakes patterns are similar to what is observed in in nature, and could be related to the dynamics of fault interface morphology.
Practical information
- General public
- Free
Contact
- Jean-François Molinari