The sanctions, which could cut off one-third of North Korea's total annual exports of US$3 billion, took effect in September, but China enforced the new measures from Aug 15.
Now experts and observers to suspect the last test - which the North claimed to be of a hydrogen bomb - may have damaged the mountainous location in the northwest tip of the country, where all of North Korea's six nuclear tests were conducted.
Friday's quake was a magnitude 2.7 with a depth of 3 km in North Hamgyong Province in northern North Korea, according to the Korea Meteorological Agency.
Around 90 per cent of North Korea's documented trade was with China in 2016.
Successive rounds of United Nations sanctions have cut off more than 90 per cent of North Korea's publicly reported exports - including coal, iron ore, seafood and, most recently, textiles - and have restricted the regime's ability to earn foreign currency by sending workers overseas. But China has balked at imposing a complete trade embargo on North Korea, and continues to send the regime the crude oil it needs to keep its military and economy alive.
There are no records of seafood imports from North Korea, Huang said, while shipments of coal, iron ore and clothing all declined.
North Korea's foreign minister Ri Yong-ho said that Donald Trump had "lit the wick of war" between countries and that the USA would be forced to pay with "a hail of fire".
Though North Korea's exports declined via official channels there is evidence that the country is smuggling shipments to and from China.
A small, 2.9-magnitude natural disaster struck the area near North Korea's Punggye-ri nuclear test site, prompting concerns the Hermit Kingdom had conducted another nuclear test. The customs agency said it will publish details its trade in specific products with North Korea on Oct 23.
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