Cathryn, I don't know exactly what syzgy is, but mainly from posts here think it is just full moon and new moon. My posts on this thread were strictly referring to two quakes right at the coast in an area of very large tide range....this one at Bar Harbor, and one a couple of years ago at the coast in New Brunswick Canada (not Quebec that I posted above...I did not look at a map). The Bar Harbor quake was not at a full moon and was not near a peak in ocean tide range. There is not a M>=2.5 aftershock listed last weekend when there was a greater tide range. Two quakes like this would be meaningless anyway....there has to be a statistical analysis of lots of quakes and lots of tides. John V. has posted here that there is generally no such affect for earth tides, except in specific cases (I guess Tolstoy et al had a paper about an effect at the plate spreading center boundary offshore NW NAM, and John was co-author of his student(s) Cochrane on something. I am just saying that it is plausible (Mythbusters terminology...one step down from "Confirmed" and one above "Busted") that large ocean tides at a coast might make a different stress pattern than large ocean tides away from a coast (I don't think there are large ocean tides far from a coast). And, that eastern North American quakes are different than California quakes in that the stress everywhere is at failure and you can easily trigger shallow quakes...for example, (this is me recalling after 19 years) there is a paper on reservoir induced quakes at Monticello (?) reservoir in South Carolina (?) where very small changes in reservoir level very clearly affected seismicity. By very small, I think it was about 1 m, maybe 2. But, if there is a delay of days or weeks between the cause and effect, it would show up in a study like that....but if the Bar Harbor quake, the 3.8, was triggered by tides but there was a delay, there would be no relation between the stage of moon and the quake....
This post needs some comment by others...
Chris