That, says Parsons, means that even megaquakes shouldn't
trigger large quakes more than a couple of thousand kilometres away.
Not exact matches
The new findings show that
large early aftershocks can also be
triggered by seismic wave transients, where the locations of the main
quake and the aftershock may not be directly connected.
The trouble is that
large earthquakes generate tectonic waves that ripple around the world's surface and routinely
trigger smaller
quakes on distant faults, so increased activity in China is hardly a surprise.
After reviewing a 30 - year catalogue of events, they found no significant evidence that
large quakes regularly
trigger tectonic activity 1000 kilometres or more away.
Although there is evidence that the ground motions induced by major temblors
trigger small
quakes thousands of kilometres away, there's no sign that such
triggering occurs for
large quakes, he adds.
Their interest is more than purely academic, because
triggered tremors - if that is what they are - may warn that a really
large quake is on the way in the same place.
That process of subduction
triggers the
largest earthquakes in the world, such as the magnitude - 9.5 Chilean
quake in 1960 and the magnitude - 9.1 Sumatran
quake in 2004.
The
largest quake detected occurred on April 16 in Ecuador: a 7.8 magnitude
quake that
triggered two phones, 170 and 200 kilometers from the epicenter.
Earthquakes can genuinely be
triggered by
large scale melting, though; it seems that Norway had
quakes up to magnitude 7 during the last deglaciation:
Earthquakes can genuinely be
triggered by
large scale melting, though; it seems that Norway had
quakes up to magnitude 7 during the last deglaciation: