Some time ago, someone came up with the idea that earthquakes were triggered by the position of the sun and moon. Since the moon and the sun exert a gravitational pull on the earth, it seemed logical that this force might set off earthquakes. Many scientists have since discounted the theory, but I've been paying attention to news reports for several decades now and I think there might be something to it.

It's a well known fact that the moon's gravity exerts a force on the earth's oceans and causes tides. Less well known is the fact that the sun, which is larger, but much furter away, also exerts
tidal forces. The moon causes tides of a meter or so (more or less depending on location)while the sun only pulls a few centimeters. When the sun and moon are lined up as they are at the new moon and full moon, the solar and lunar tides work together to cause slightly higher and lower tides. During the first and third quarter, the sun actually works against the moon to slightly limit tidal movement.

I'll get back to earthquakes in a minute.

An even lesser know fact is that there are tides in the crustal rocks of the earth, but they probably could be measured in millimeters.

Since earthquakes are caused when rocks shift along a fault, the crustal tides could actually increase or decrease friction along a fault. That could cause an earthquake. More likely it would be an earthquake that was about to happen anyway, and the slight tidal movement in the crust could hurry it up a bit. In that case, more earthquakes would happen during the time of the new moon, or to a slightly lesser degree, the full moon.

The last two nights there have been earthquakes in the southeastern US, so I checked the calendar and sure enough, the new moon is tomorrow. I feel cheated because I slept through both 'quakes, but those who noticed them said they were stronger than the ones we usually have in this region.

From what I have notice in news reports, earthquakes usually come a day or two ahead of the new or full moon. I'm not sure why.

This theory is based only on stronger 'quakes, ignoring the too-mild-to-be-felt tremors that happen almost daily all over the earth.

But I am convinced that newsmaking earthquakes are related to the position of the sun and moon with respect to the earth. Any thoughts on this?
Howard