There have been more than 4,700 earthquakes since Thursday’s 6.4-magnitude event, according to John Bellini, a geophysicist with the USGS. 

“They are coming in every 30 second, every minute," he said.

Since Friday night's 7.1-magnitude quake, there have been three quakes with magnitudes of 5 or greater. Those three all occurred within the first hour after the 7.1 quake; one was a 5.5 magnitude and there were two 5.4 quakes.