Earth Watch: Could a major earthquake soon strike the nation of South Korea?

Could a major earthquake soon strike South Korea? The Korean Peninsula is not typically an area of high seismic activity, but seismologists have been rattled by a recent series of small tremors that they warn could be a sign of a bigger earthquake to come.

A South Korean official explains about seismic wave of North Korea’s nuclear test which measured in South Korea, at National Earthquake Center in Seoul, South Korea, Monday, May 25, 2009. Seismologists in South Korea are concerned about an unusual rash of earthquakes that have shaken the peninsula in recent weeks, with some suggesting that this sudden upsurge in seismic activity might be a precursor to a major — and potentially very destructive — earthquake.

The Korean Peninsula is not traditionally considered to be a part of the so-called Ring of Fire, the seismically active fault lines that run around the rim of the Pacific Ocean. However, seismologists are looking at whether shifting tectonic plates might become a new normal for the Koreas. Last week, the Korea Meteorological Administration reported a magnitude 2.8 tremor in Wanju County, in the far southwest of South Korea. Although there was no damage reported from the weak quake and nobody was injured, this is the first time since December 2014 that a tremor with a magnitude above 2 has hit the region.

Two days before the Wanju termor, a 3.8-magnitude quake was detected in North Korea. The South’s monitoring agency quickly announced it was natural seismic activity to dispel any concerns that it might have been another underground nuclear test conducted by the regime in Pyongyang. The North conducts its atomic tests at its Punggye-ri proving grounds, in the northeast of the country, with the last detonation on September 3, 2017, of a hydrogen bomb that registered as an earthquake with a magnitude of 6.3. But of even deeper concern to the experts have been the more than 400 seismic tremors since April 26 in a single area in South Jeolla Province, in the far south-west of the peninsula. The region has not reported seismic activity since the government first began collating data in 1978.

Experts admit that they do not know for sure what is triggering the activity, but there are some theories as to why it is increasing up and down the peninsula. “We have been monitoring the South Jeolla events closely because they are very unusual and have been happening in a very short space of time,” said Hong Tae-kyung, a professor of seismology at Yonsei University in Seoul. “It is also unusual because they are happening in a very small area and they are much deeper than usual,” he said, adding that quakes on the peninsula usually occur at a depth of around 10 kilometers (6 miles). These latest tremors are happening 20 kilometers beneath the surface.  “We do not know exactly why this is happening, but there are certainly some theories that need to be verified through further research,” said Hong. “My personal speculation is that what we are seeing now is a result of the March 2011 Tohoku earthquake in Japan.”  –DW