A magnitude 2 earthquake releases ~30x the energy as a magnitude 1 earthquake. A magnitude 3 releases ~900x the energy of a magnitude 1. You can see where this is going. (Note, the "shaking intensity" of the earthquake doesn't increase as quite as rapidly as the amount of energy released, but the relationship depends on a lot more than the earthquake's size.)
Let's say we were to trigger many magnitude 5's. We'd need to trigger 810,000 of them to equal the energy released in a Mw 9.0 earthquake.
Interestingly, though, there are other types of earthquakes that _do_ release accumulated elastic strain over large areas. Cascadia is actually where they were first noticed.
Every ~11 months, the cascadia subduction zone has a magnitude 6 or 7 earthquake. You'll never notice in Seattle, though, because it occurs over about a month.
These "slow earthquakes" _do_ release significant amounts of accumulated strain. Sometimes they trigger "normal" earthquakes and vice versa. We don't really understand the details. The most interesting part (and the part most relevant for seattle) is that the same fault can have both these "slow earthquakes" and a full on >Mw 9 "normal" earthquake.
This is one of the "hottest" topics in earthquake seismology and convergent margins research at the moment.
So, my understanding from what you wrote is that it may indeed be possible to slowly release the accumulated pressure, but we don't really understand how that occurs naturally yet, let alone how to trigger it artificially.
Given the regularity of previous large quakes, and the fact that the described magnitude 6 quake takes place over a month, it would take longer to relieve the pressure via month-long magnitude 6 quakes than we have until the next large quake. Best case scenario - you could put it off for a few dozen years.
Even if you could relieve some of the pressure, you could theoretically make the big one less intense. It sounds like we're not even remotely close to being able to do it in practice though. (Although if we were, there's no reason why the described magnitude 6 over a month would be a limit.)
Making the big one less intense may or may not be possible. There may be some threshold pressure that needs to be reached. If there is a threshold, then it will either happen or not, depending on the rate at which we relieve pressure with smaller quakes.
I imagine the difference is what we can do vs. what is far beyond today's ability. And triggering a quake is fine even if it releases full force assuming the payoff is we get (for example sake only) a 7.1 quake today and avoid a 9.1 in 100 years.
A magnitude 2 earthquake releases ~30x the energy as a magnitude 1 earthquake. A magnitude 3 releases ~900x the energy of a magnitude 1. You can see where this is going. (Note, the "shaking intensity" of the earthquake doesn't increase as quite as rapidly as the amount of energy released, but the relationship depends on a lot more than the earthquake's size.)
Let's say we were to trigger many magnitude 5's. We'd need to trigger 810,000 of them to equal the energy released in a Mw 9.0 earthquake.
Interestingly, though, there are other types of earthquakes that _do_ release accumulated elastic strain over large areas. Cascadia is actually where they were first noticed.
Every ~11 months, the cascadia subduction zone has a magnitude 6 or 7 earthquake. You'll never notice in Seattle, though, because it occurs over about a month.
These "slow earthquakes" _do_ release significant amounts of accumulated strain. Sometimes they trigger "normal" earthquakes and vice versa. We don't really understand the details. The most interesting part (and the part most relevant for seattle) is that the same fault can have both these "slow earthquakes" and a full on >Mw 9 "normal" earthquake.
This is one of the "hottest" topics in earthquake seismology and convergent margins research at the moment.