EARTHQUAKE AFTERSHOCK

Tuesday's Quake

According to Julie Mack's report in the July 2, 2015 Kalamazoo Gazette, the earthquake that occurred at 11:42 A.M. Tuesday was a 3.3 magnitude one and an aftershock of the 4.2 one May 2.  I have two comments that I think may be of interest about the two that are not likely to be considered by the earthquake experts.

FRACKING?

First, although I agree it is appropriate to label it an aftershock, the assumption that the depth of over three miles detaches the question of fracking being part of the cause is most likely but not necessarily correct for two reasons.  Fissures and boreholes could possibly divert fracking fluids to greater depths; I think that is not likely, but possible.  Of greater probability is the fact that if fracking fluids are spread in the quake region but at considerably shallower depths, they could detach the overlying strata from the ones below and reduce resistance to movement at different rates in the separated strata.  THE SLIPPING LAYER COULD BE EITHER ABOVE OR BELOW A FRACKED LAYER.  Although that should be true, it also seems that in reference to surrounding areas the upper layers would be more likely to demonstrate movement.

THE MOON?

Second, the timing of both quakes came near the approaching full moon's peak effect on tides that may have a cyclic effect on stresses of continental plates.  I presented this as a possibility in the blog of May 3,[ http://evolutioninsights.blogspot.com/2015/05/earthquake-and-continental-drift.html ].  If I had more confidence in this as a partial cause, I would look up the phase of the moon, to see if was either near full or near new moon status on August 10, 1947, when a 4.6 magnitude quake was the strongest recorded in Michigan.  The three quakes seem to be clustered in the same fault system.

I think that years ago I saw some data presented showing tides exist in the crust of one or both bodies of the earth-moon system.  They were of much smaller magnitude than the movement seen in ocean tides.

The effect of the moon would seem to peak near noon and midnight (ignoring the position of the sun).  The monthly peak of those peaks would be near the new moon and the full moon - about every 14 days.  It seems, if quakes correlate with the lunar cycle, a scatter graph of earthquakes by intensity and time of the lunar monthly cycle and another by intensity and time of the lunar daily cycle might reveal if the moon has an affect.  Possibly smaller quakes would be more likely the ones to reveal effects by such a process.

The problem may be much more complicated than I have suggested.  Anyone familiar with tides along our coasts knows the delay in tide arrival is not very closely correlated with the time of maximum lunar and solar gravity attraction maximums.  Tidal and moon effects are not true causes of earthquakes, they only affect the timing of quakes due to gradual accumulation of stresses from crustal movements.  But the possible result is to make a quake occur sooner than the gradual accumulation would otherwise cause it.  Thus the quakes along a fault may release the energy in smaller quakes than the ones only triggered by the gradual buildup of stress.


Joseph G. Engemann   Kalamazoo, Michigan   July 2, 2015