The latest quake, which was recorded at a depth of 0km in North Hamgyong province, is smaller than usual quakes that take place when North Korea carries out its nuclear tests. He added that they were still analysing the tremors, but they were "unlikely man-made".
The natural disaster, which South Korea's Meteorological Agency put at magnitude 3.0, was detected 30.4 miles from Kilju in North Hamgyong Province, where North Korea's known Punggye-ri nuclear site is located, the official said. North Korea has one nuclear test site - Punggye-ri.
With North Korea and the USA exchanging bellicose rhetoric over Pyongyang's relentless pursuit of its nuclear ambition, the world has braced itself for another show of force by the North, which threatened to carry out an atmospheric nuclear test. He said the action "was a somewhat unexpected move and we appreciate it".
Saturday's detection comes at a time of rising tensions between the United States and North Korea, with North Korean dictator Kim Jong Un and President Donald Trump engaging in an escalating war of words.
Park said analysts could not rule out the possibility that a natural quake occurred because of a nuclear test.
Trump's broadside follows a rare statement issued by Kim, branding the US president as "deranged" and warning he will "pay dearly" for his threat to "totally destroy" the North if it attacks.
"Kim Jong Un of North Korea, who is obviously a madman who doesn't mind starving or killing his people, will be tested like never before!" the president tweeted.
Trump has also signed a new order that boosts sanctions against North Korea over its nuclear weapons programme.
This article was first published at 3:10 a.m.
BEIJING (AP) - China announced Saturday that it will limit energy supplies to North Korea and stop buying its textiles under United Nations sanctions imposed over its nuclear and missile development, further reducing support from Pyongyang's last ally. So we're doing more of the same.
Also Thursday, Trump issued an executive order expanding the Treasury Department's ability to target anyone conducting significant trade in goods, services or technology with North Korea and to ban them from the US financial system.
The Chinese Ministry of Commerce said in a written statement that it will restrict exports of refined petroleum products from October 1, and ban the export of condensate oil and liquefied natural gas immediately. Beijing has cut off imports of coal, iron ore, seafood and other goods in line with United Nations sanctions.
Exported refined oil products must be used fully on civil purposes, not for nuclear and ballistic missile programs, or other activities banned by the UN Security Council, the ministry said.