Tokyo: They are some of the most destructive and unpredictable forces on the planet. But it seems some of the world’s largest earthquakes may be following a pattern after all – they seem to occur at times around the full or new moon.
This is when the gravitational pull from the moon and the sun on the Earth are at their greatest and it could be triggering fault lines into slipping, according to new research.
Geologists at the University of Tokyo in Japan have discovered that some of the largest earthquakes in recent history appear to have occurred at times when tidal stress is highest.
These included the huge Indian Ocean shock in 2004, which triggered a series of devastating tsunamis and killed 230,000 people, and the one that shook off the coast of Chile in 2010.
They also found links to the earthquake off the coast of Japan in 2011, which claimed 15,800 lives and sent a tsunami wave that sparked the Fukushima nuclear power plant meltdown.
These appear to have occurred as small failures in the fault lines cascaded into gigantic ruptures due to the strain placed on the Earth’s crust by the moon and the sun, say the scientists.
Professor Satoshi Ide, a geophysicist at the University of Tokyo who led the research, said the findings could be used to develop better ways of predicting large earthquakes.
Writing in the journal Nature Geoscience, he said: ‘Every day, numerous small earthquakes occur worldwide. A very small fraction of these events grows into giant earthquakes.
‘It is a long-standing problem as to whether we can estimate the final size of an earthquake at the moment of initiation of a dynamic rupture from a small nucleus.
‘The present results suggest that the final earthquake size can be estimated probabilistically.