It is credible. If you read the CNN story there is seismic readings which support the claim at least partially. Plus Japan, South Korea, and the US aren't calli

It is credible. If you read the CNN story there is seismic readings which support the claim at least partially. Plus Japan, South Korea, and the US aren't calling them liars and are being very measured in what they're saying which hints to me that they think something took place.