A "suspected explosion" near the China-North Korean border caused a small earthquake on Monday, Chinese seismology authorities said, less than an hour after news broke about Chinese President Xi Jinping's upcoming trip to Pyongyang.
According to the China Earthquake Networks Center, the 1.3-magnitude earthquake with a zero-metre depth occurred at 19:38 pm (1138 GMT) in Hunchun city in northeastern Jilin province.
It was unclear what caused the explosion.
In the past, nuclear tests by Pyongyang have caused tremors around the northern border China shares with North Korea.
But the latest incident occurred more than 200 kilometres (125 miles) from Punggye-ri, the North's nuclear site under Mount Mantap.
Analysts played down the tremor, saying it may have been caused by a number of factors.
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"Don't be alarmed just yet folks," tweeted Vipin Narang, a security studies professor at the Massachusetts Institute of Technology. "Mining explosions for example can cause small tremors." An official at South Korea's meteorological administration said there was "nothing in particular that can be detected through the seismic waves", according to the country's Yonhap news agency.
In September 2017, a test conducted at North Korea's nuclear site at Punggye-ri triggered a 6.3-magnitude earthquake that was felt across China's northern border. Chinese seismologists later concluded that Pyongyang's main nuclear test site had partially collapsed, rendering it unusable, following the massive bomb blast -- which the North claimed was a hydrogen bomb test.
Experts later cast doubt on that claim, with Jeffrey Lewis of the Middlebury Institute of Strategic Studies commenting that there was "no evidence" that it was unusable.
In January 2016, Chinese border residents in northern Jilin province were evacuated from buildings after feeling tremors from a North Korean nuclear test.