Do Eclipses Cause Earthquakes?

As I am a member of the Torbay Astronomical Society, people seem to think (incorrectly) that I know everything about astronomy and other sciences. Recently I was chatting to a friend about the terrible earthquake at the end of March in Myanmar. She told me that her husband, a retired civil engineer, had a theory that there was a connection between eclipses and earthquakes. Over the years he and others had noticed that the two events often seem to happen at about the same time. She asked for my opinion.

I was rather sceptical, but my friend told me that her husband had raised the matter with experts on astronomy, and that their response was not to dismiss the idea out of hand.

It is well known that the Sun and Moon by virtue of gravity affect the tides on Earth. At a solar eclipse, the Sun, Moon and Earth are in alignment and their gravitational effects are at their greatest, producing tides at their highest, known as spring tides: as opposed to neap tides when the celestial bodies are not aligned. At the time of the partial eclipse on 29 March 2025 the tides were very high; for example, at Dartmouth in our area there was a 5 metre tide. I fear to think how large the tide was in the Bristol Channel. There would have been large and powerful tides all over the globe.

What I do not know is whether the gravitational pull of the Sun and Moon at the time of an eclipse, plus the extra energy in the oceans from high tides, is strong enough to affect tectonic plates, the movement of which cause earthquakes. If they affect tectonic plates at all, it may be like the last straw that breaks the camel’s back, accelerating something which was on the edge of happening in the Earth’s crust.

On a lighter note I did manage to watch the partial eclipse using a pinhole camera which I made that morning out of a shoe box. It was bit like Blue Peter, but one of the safe ways of looking at the Sun.

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