Seeming correlation between time of day and earthquakes?

Question

I live in a generally geographically active area (Southern California, near the San Andreas fault, if that matters), that has had two relatively minor earthquakes that I have felt in the last week (in the 3-4 range on the Richter Scale, I believe), as well as frequently in the past. I am used to this, being born and raised in the region.I was talking about these phenomena with a colleague who recently moved to the area from a non-earthquake prone place, and was not used to them. I realized that both of the earthquakes were late at night, when I was in bed, and searching my memory I can only recall encountering these minor earthquakes at similar times.My question, therefore, is if there is any correlation between time of day and earthquakes? Or to put it another way, is my observation based on anything more than the fact that I am more likely to note and recall a minor earthquake what I am not engaged in another activity?

Answer 1

Hi! This is an amazing question! The occurrence of earthquakes is driven by geological factors and tectonic activity, not by the time of day. Earthquakes result from the release of strain that builds up along faults in the Earth's crust due to the motion of tectonic plates, which is not impact by time of day. This geological activity does not have a daily cycle, hence, earthquakes can and do happen at any time of day or night.

Your perception that earthquakes are more frequent at night could indeed be due to the circumstances you described. When you're not engaged in other activities, you're more likely to notice subtle sensations such as the trembling caused by a minor earthquake. During the day, these sensations might be drowned out by other activities and stimuli.

In other words, there's no scientific evidence to suggest a correlation between the time of day and the likelihood of an earthquake. If a pattern seems to appear, it's most likely due to human perception and recall rather than any physical or geological phenomena. :)