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Is it true that a series of small magnitude earthquakes help prevent a large magnitude eartquake? Aren't earthquakes basically independent events from a statistical point of view?
H2Bro said:Yes it is true, usually. Smaller earthquakes let out some of the pressure built up along a fault line.
The amount of slippage depends on the force integrated since the time of the last slippage. If a fault sticks for a very long time, for whatever reason, the amount of energy released will be greater as energy released is proportional to distanceXmass of the moved plate.
USGS said:You can prevent large earthquakes by making lots of small ones, or by "lubricating" the fault with water
FICTION: Seismologists have observed that for every magnitude 6 earthquake there are about 10 of magnitude 5, 100 of magnitude 4, 1,000 of magnitude 3, and so forth as the events get smaller and smaller. This sounds like a lot of small earthquakes, but there are never enough small ones to eliminate the occasional large event. It would take 32 magnitude 5's, 1000 magnitude 4's, and 32,000 magnitude 3's to equal the energy of one magnitude 6 event. So, even though we always record many more small events than large ones, there are far too few to eliminate the need for the occasional large earthquake. As for "lubricating" faults with water or some other substance, if anything, this would have the opposite effect. Injecting high- pressure fluids deep into the ground is known to be able to trigger earthquakes—to cause them to occur sooner than would have been the case without the injection. This would be a dangerous pursuit in any populated area, as one might trigger a damaging earthquake.
H2Bro said:Interestingly, when there is slippage between points A and B on a fault, additional stress builds up along the fault just beyond points A and B. You can imagine this as just inside points A and B there has been some movement, but just outside no movement, and this difference in movement in a solid body produces shear strain.
I think this is the usual cause of afterschocks, which are smaller earthquakes following a larger one.
manojr said:If you haven't already read this, six Italian scientists have been convicted of involuntary manslaughter because they were "criminally mistaken" in "falsely reassuring" people that major earthquake is unlikely after series of some low-level tremors.
The theory behind this idea is that by having a series of smaller earthquakes, the built-up stress and energy in the Earth's crust is released in smaller increments rather than all at once, reducing the likelihood of a larger earthquake occurring.
Scientists use a variety of methods to measure and analyze the effects of small earthquakes on preventing larger ones. This includes using seismometers to detect and track seismic activity, studying fault lines and other geological features, and analyzing data from previous earthquakes.
While the theory of small earthquakes preventing larger ones is widely accepted, there is still ongoing research and debate about the extent of their effectiveness. Some studies have shown a correlation between small earthquakes and a decrease in the likelihood of larger ones, while others have found no significant impact.
There is some evidence that artificially induced small earthquakes may have a similar effect in releasing built-up stress in the Earth's crust. However, this method is still being researched and there are concerns about the potential risks and unintended consequences of intentionally triggering seismic activity.
While some patterns and trends have been observed in the occurrence of small earthquakes before larger ones, there is no reliable method for predicting the exact timing or magnitude of a future earthquake based on small earthquake activity. Earthquakes are complex and unpredictable events, and multiple factors must be considered in any prediction attempts.