EQF, John V., anyone else who knows the answer:
Are earth tides as simple as just the position of the sun and moon? Ocean tides certainly are not-they vary by location, water depth, and the way the currents sweep around...(OK, poor explanation, but something like that). Would not earth tides be affected by composition of crust, etc...? I'm sure the answer is known-earth tides are measured by gravimeters (my first geoscience job in about 1980 was taking gravity measurements for minimum wage). I would not be surprised if earth tides could be measured by satellite-it is satellite altimetry that was done by Sandwell (and Smith?) to get the gravity field of the ocean and hence the depth....

So, this comes down to whether the earth tides that EQF calculates are the same as measured earth tides. I guess it is safe enough to say that at certain times (new and full moons)the earth tides should be larger.

It does seem logical that earth tides should be capable of triggering earthquakes. But, the fact that is has rarely been demonstrated may mean that is is more complicated than most people are looking for.....could be that if it induces certain stresses, only faults of a particular type and orientation would be susceptible in any one place and time....

Caution-not my field. Chris