A strong tidal force can exaggerate an already loaded earthquake as a result pushing a small one to evolve into an acute tremor. Lead researcher Ide said, "When tides are very large, small earthquakes tend to grow a little larger."
As per a report in LA Times, the Indonesia earthquake in 2004 and the one that had hit Chile in 2010, with a magnitude of 9.1 and 8.8 respectively, occurred around the time of a full moon, close to the peak time of tidal stress, the study stated. Geophysicist Nicholas van der Elst said the observations documented were interesting and would prompt other scientists to see if they can replicate the results.
‘Earthquakes are nearly a random process, Tidal forces are just a factor in a complex process. There are a lot of other factors.’
"Personally, I hope that this observation does pan out and is reproducable, Studying how tides affect earthquakes, he said, helps explain "how earthquakes get started and how they get large," Elst added. The primary cause of earthquakes is the earth's moving tectonic plates, which are constantly grinding against each other.
Between the tectonic plates, strain builds up on faults until the pressure is released suddenly by an earthquake. "The tides just add a little - 1 percent or less - additional push on top of that tectonic loading," Elst said.
Adding, "Even though it's a small contribution, it could be just the amount of stress that is the 'straw that breaks the camel's back." "So it makes sense that an earthquake would be more likely to happen, and coalesce into a larger earthquake, if there is just a little additional push," he said. However, many earthquakes will still happen when tidal stress is low, Ide said. "Earthquakes are nearly a random process, Tidal forces are just a factor in a complex process. There are a lot of other factors," he said.
The relationship between strong tides and earthquakes has only been found in larger-magnitude earthquakes and not in smaller events.