According to the U.S. Geological Survey, there have been more than 950 earthquakes and aftershocks recorded on Puerto Rico since Dec. 31, though many were weak and could not be felt.

For more info, please read the original article by USA Today:
https://www.usatoday.com/story/news/nation/2020/01/10/puerto-rico-earthquake-swarm-tectonic-plates/4420857002/