Hi Chris. You are correct, but in this instance the butterfly’s wings is the classic analogy for the sensitivity of criticality. The link given by Petra was the one Tom Jordan was referring to. Take Care…Don in creepy town

This unique data set shows the detailed response of crustal rock to a comparatively minor disturbance at a considerable distance. The data have not yet been fully interpreted and contain several puzzles, including the varying durations and forms of the anomalies, that are likely to yield crucial information about how rocks deform. What they do clearly demonstrate is the sensitivity of crustal rock to small disturbances. A mb 4 earthquake with the same energy release as the small-scale seismic activity at 70 km is a comparatively small earthquake, yet its effects are observed at a distance of several hundred times its likely source diameter. Such sensitivity is far too great to be explained by a conventional brittle-elastic crust, where stress is proportional to strain, but is expected in a compliant crack-critical (CCC) crust verging on criticality as implied by the success of the APE mechanism of deformation. The butterfly's wings in Brazil causing the tornado in California is the classic analogy for the sensitivity of criticality. Thus, although the geometry of the SMS is not optimal for monitoring stress-induced changes by shear-wave splitting, the SMSITES experiment has recorded a unique data set. These data verify that the crust is highly compliant and go some way to confirm both the science and technology of SMSs for stress-forecasting the times and magnitudes of impending large earthquakes in a CCC crust.