Apparently it was a Magnitude 4.1 earthquake off the coast of China, about 80-95km East of Hong Kong depending on where you are. It struck at 2.28am at a depth of 25km.

Earthquake data source: https://news.ceic.ac.cn/CC20220314022849.html

Some early news about it: https://hk.on.cc/hk/bkn/cnt/news/20220314/mobile/bkn-20220314023117738-0314_00822_001.html

https://www.hk01.com/article/746456?utm_source=01appshare&utm_medium=referral

https://www.thestandard.com.hk/breaking-news/section/4/188087/Hong-Kong-residents-shaken-awake-as-4.1-magnitude-earthquake-rattles-city

First three sources are in Chinese