catching lightning in a bottle has been easier than reproducing a range of earthquakes in the laboratory, according to a team of seismologists who can now duplicate the range of fault slop modes found during earthquakes, quiet periods and slow earthquakes.
Catastrophic earthquakes, the kind that destroy buildings and send people scurrying for doorways and safe locations are caused when two tectonic plates that are sliding in opposite directions stick and then slop suddenly, releasing a large amount of energy, creating tremors and sometimes causing destruction. Along regions of faults that do not produce earthquakes, the two sides of the fault slowly slip past each other in a stable fashion. Slow earthquakes occur somewhere between the stable regime and fast stick slip.
Regular earthquakes take place rapidly, while slow slow earthquakes occur on time scales that may range up to months. They can be as large as magnitude 7or more and may be precursors to regular earthquakes. However, slow earthquakes propagate slowly and do not produce high-frequency seismic energy. They exist in the regime between stable slipping and regular earthquakes.
The researchers applied stress perpendicular to the direction of shear and then applied forces to shear the ground quartz. By altering the amount of stress placed in the perpendicular direction,they could achieve the audible crack of a regular earthquake, stable slippage and a wide range of slip-stick behaviors including slow earthquake.
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