So I’m aware of the gambler’s fallacy. If an event has a set probability of happening and hasn’t happened yet, that doesn’t mean it’s *due* and now more likely to happen. Just because the coin landed on heads just now doesn’t mean it’s more likely to land on tails the next time.
So intuitively we could think just because an earthquake hasn’t happened in a while doesn’t mean it’s “overdue” and increasingly likely to happen in the future.
BUT, it’s my understanding that part of what causes earthquakes is a buildup of tension in the tectonic plates, which builds and builds until it’s finally too much to bear and there’s a sudden jerking motion as the plates snap or slip or whatever, and resettle to new positions, resulting in an earthquake. So if tension is always building up, does that mean for every day we don’t have an earthquake, the *next* day is more likely to have one?
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Stress does build up in the plates until they give, so the longer the period without an earthquake the more likely an earthquake is to release the stress built up by the pressure. However when an earthquake happens the stress is relieved in that location, but it may transfer the stress to a new location making another earthquake in a new location more likely; so you can get a cascade of earthquakes in a region once one occurs a series of earthquakes could be triggered. https://youtu.be/SaXc4LwAVT0
Assuming that there is no other way to relieve the tectonic pressure, then yes, the longer an area goes without an earthquake, the more likely an earthquake becomes or the more severe the next earthquake is likely to be.
Yes, earthquakes become more likely the longer there isn’t one.
The gambler’s fallacy applies to *independent* events…the probability of a thing happening doesn’t depend on what happens before. The system has no “memory”.
That’s not true for earthquakes; as you note, they’re caused by built-up stress in the tectonic plates. An earthquake relieves at least some of the stress, so prior earthquakes *do* influence the conditions for future ones, the system has “memory”, and the events are NOT independent so gambler’s fallacy doesn’t apply.
This is part of the reason the Pacific NorthWest in N. America is getting a bit freaked out about “the big one”…the fault up there hasn’t slipped in any major way for several hundred years. All that stress that gets relieved in California every time they have an earthquake is still locked in in Oregon/Washington/British Columbia, which is making it more and more likely that an earthquake will happen and that it will be big when it does.
Edit: clarified that the fault in the Pacific NW isn’t the same as the one in California
In the gambler’s fallacy, each event is completely independent of the next event like in roulette or flipping coins. You could flip a coin 10 times in a row and get 7 heads and 3 tails. The next coin flip is still 50/50. Each day, on a fault line more and more pressure builds up until it fails and causes an earthquake. It’s more like Black Jack than it is roulette if you were going to compare it to gambling. If you were the last person to be dealt cards on the table and you have an 8 and a 7, you’re looking for 6 or lower card. If the people in front of you get a bunch of 6s you know you’re now more likely to bust because the card that’s going to be dealt to you is dependent on what happened between the shuffle and when you’re dealt the card.
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