A multitude of mini earthquakes dot a map of Southern California in a video illustrating the aftershocks of the recent earthquakes.

The animated video tweeted out by the U.S. Geological Survey on Monday shows how the earthquakes increased in the hours before the 6.4-magnitude earthquake hit July 4 through after the second 7.1-magnitude quake that struck a day later.

Back-to-back quakes, some of the biggest in California’s history, rattled the region and left residents in a state of fear last week. The temblors caused power outages, fires, and damage to homes and buildings in a remote region of Los Angeles and were felt as far away as Las Vegas.

A second video, with more detail on the magnitude of each aftershock, was later tweeted out by the USGS.

Read more:

California had its largest earthquake in years — then an even bigger one hit

Video: The scene after a 7.1-magnitude earthquake struck Southern California

Analysis: Earthquake readiness