The dots are previous earthquakes, white means shallow ones <70km from the surface... darker ones are deeper. Bigger the dot, the bigger the earthquake, vast majority are well below 5.0 in magnitude.
Proof of our dynamic planet and Plate Tectonics.
Highlights of Program:
https://earthquake.usgs.gov/?fbclid=IwAR2lsGOrsD6ZEzHoYrtEohCk1xiJFCWxhMTJJ7PaWUXpACMHQ21JUupG_Ko