Hi Glen,

My "Forestry" training extended solely to the matter of recognizing when a tree was on fire! However I have certainly read of tree-ring dating being used in paleoseismology.

You don't actually describe the deformity, but, from memory, what has been found is that, for trees either located directly at the site of surface rupture (and possibly secondary ground displacement), or where springs, ground- or surface-water become displaced, the tree rings corresponding to that, and some subsequent years, are simply thinner due to reduced growth.

If your tree was not so located, then the deformity / year correlation is either coincidence or counting mistake leading to apparent coincidence. As for the latter, I found this during a brief search on the subject of tree-ring dating (apparently the very idea of counting tree rings to determine tree age was once controversial): "The main argument of opponents such as A. L. Child was that the number of tree rings was often wildly in excess of the known age of the tree. These inconsistencies were likely because of the inexperience of the observer, mistaking earlywood and latewood for separate rings, and the presence of a small number of false rings, sometimes called secondary rings." (from http://www.bioone.org/doi/abs/10.3959/1536-1098-62.2.51 )

Penny is certainly correct that dead tree stands were evidence of large CSZ quakes, but I'm not at all sure tree rings were involved. IIRC it was simply the existence of large stands of trees (or their stumps?) which all appeared to have died at about the same time and which were located where the ground surface was now submerged that led to the recognition that there had been widespread ground subsidence. The dating of the quakes involved other methods. As most of you know, the subsidence along the shoreline is secondary to the subduction at the subduction zone.

As for Brian's note, Susan Hough did write, in "Richter's Scale:
Measure of an Earthquake, Measure of a Man", about trees breaking during the New Madrid quakes (see first paragraph at http://press.princeton.edu/chapters/s8248.html ). BTW - I have the first two of Susan's (four?) general-audience books. She also apparently wrote one published in 2005 titled "Elastic Rebound: Past and future earthquakes on an urban planet" which I hadn't previously heard of.

Mike W.