Are Large Earthquakes Related?
Major earthquakes are clearly associated with other smaller earthquakes, known as aftershocks, which occur within a relatively small area – but with so many large earthquakes along this narrow (but long) zone within the space of a week, the question arises: could there be a relationship between them?
The answer is that, in all probability, their occurrence is pure coincidence.
A significant factor in how big an earthquake is, and how far away it is felt, is the strength of the earth’s crust: the USGS notes in Earthquake Facts and Earthquake Fantasy that this “crust is not rigid enough to transfer stress efficiently over thousands of miles”
This is particularly true in areas such as the eastern Pacific margin where the crust formed relatively recently and is, in consequence, warmer: it deforms more easily and energy is dissipated more rapidly.
Earthquakes: Major Events
Although there is speculation that major events may shift stress along a boundary and increase pressures on a different area of the crust, there is no evidence that the large ‘quakes observed this week along connected margins along the Pacific rim are linked: they are too far apart, both in terms of time and distance. Even the two which appear closest together, in Alaska and off Vancouver Island, are separated by four days and thousands of kilometers – meaning that the sequence of seismic events observed this week is almost certainly the result of chance.
USGS. Earthquake facts and earthquake fantasy. (2012). Accessed November 13, 2012.
USGS. Real time earthquake map. (2012). Accessed November 13, 2012.
Decoding Science. One article at a time.