The South Korea earthquake is unlikely to have been caused by North Korea’s nuclear weapon test. Here’s why.
During Reddit’s Ask Science Discussion this was brought up: “South Korea just got hit with a 5.4 magnitude earthquake. 3 days ago, North Korea carried out a nuclear weapons test that caused a 5.3 magnitude seismic event. Is it possible that today’s earthquake is a result of the nuclear testing several days ago?”
There were several intelligent answers/theories, but this explanation from seis-matters was ranked at the top for getting 3649 points. Here?s an excerpt of what he said:
?If you are asking if the test explosion in North Korea Physically triggered this earthquake in South Korea, you can think of it in the same terms of natural earthquake triggering. There are two physical mechanisms where earthquakes can trigger one another. One of these is static stress triggering and one is dynamic stress triggering.?
He further explained that earthquakes did trigger other earthquakes in the past across long distances through dynamic stress triggering (1000+km). This happens if you have an already stressed fault which is about to hit its breaking point. If large earthquake surface waves pass by to throw that last straw on top it will cause a full rupture of the fault.
Then there?s also a static triggering which causes a domino effect. This happens when a small part of a fault ruptures and puts more stress on an adjacent fault. This pushes it over the brink which leads it to rupture. But this is only relevant to distances that is one fault length. Therefore, over a few hundred kilometers for M8 or 9 but smaller distance for an M6 or less.
In short, since the North Korean test was relatively small and it?s distance is 500 km away from the South Korean earthquake, its strain transfer is considered too localized to cause static triggering. Besides, the earthquake occurred days after the nuclear test so the effect is too late for dynamic triggering.
US On High Alert, Precautionary Measures Taken
Whether or not the earthquake was triggered by North Korea’s nuclear weapon testing, this should be considered a serious matter by the international community. While North Korea has taken their efforts up a notch to improve their nuclear tech and warhead delivery methods, the United States and ally South Korea have agreed in return to deploy the Terminal High Altitude Area Defense system. This is a US army anti-ballistic missile system that is designed to shoot down any short, medium, or intermediate range ballistic missiles. This can be done during their terminal phase by using a hit-to-kill approach.