(From The New York Times)

Earthquakes of magnitudes exceeding 7.0 struck Japan and Ecuador just hours apart on Saturday. Are the two somehow related?

Rescue workers search for survivors in quake-hit Kyushu, Japan
Rescue workers search for survivors in quake-hit Kyushu, Japan

No. The two quakes occurred about 9,000 miles apart. That’s far too distant for there to be any connection between them.

Large earthquakes can, and usually do, lead to more quakes — but only in the same region, along or near the same fault.

These are called aftershocks. Sometimes a large quake can be linked to a smaller quake that occurred earlier, called a foreshock. In the case of the Japanese quake, seismologists believe that several magnitude-6 quakes in the same region on the previous day were foreshocks to the Saturday event.

But the two earthquakes are similar in some ways, aren’t they?

Not really. The magnitude-7.8 quake in Ecuador was what would be considered a classic megathrust event, a type that was first identified through the work of George Plafker, a United States Geological Survey geologist, on the great Alaskan earthquake of 1964. A megathrust quake occurs in the boundary zone where one of the planet’s tectonic plates is sliding under another, a process called subduction. Read More

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