Some more Earthquake Machine Data

Yesterday's Earthquake Machine demo yielded some nice data. Some of the force and acceleration graphs show distinct events immediately prior to a large slip event:

y-axis: Force (red) and acceleration (blue); x-axis: time (about 0.5 seconds per tick mark)

Unfortunately, nothing really showed any decent "aftershock" activity. It may be that the time interval I was measuring wasn't small enough. Or, the friction (strength) of the material was enough to avoid any noticeable aftershock behavior. I'll have to try using different "rough" substrates - perhaps I can generate aftershocks if my friction surface is sufficiently unstable. (Pea gravel, anyone?)