When Southern California was rattled by strong back-to-back earthquakes in July, it marked the region's strongest shaking in years.

But along with familiar names -- like Loma Prieta and Northridge -- that evoke frightening memories, there are thousands of earthquakes each year in California that are too small to be felt.

So, what do those earthquakes look like when compared to the likes of the powerful Ridgecrest quakes? The Pacific Tsunami Warning Center created the map above to offer some context.

The animation covers a period from 1989 to 2019. Large-magnitude quakes are detailed with larger circles, like the magnitude-6.9 Loma Prieta earthquake that pops up to start the video. That was the quake that struck just before the start of the October 1989 World Series.

Here are some of the more notable earthquakes included in the animation.