How far was the Ridgecrest Earthquake Felt?

Remember When Ridgecrest Shook Us All? How Far That Earthquake Really Reached

Okay, let’s talk about the Ridgecrest earthquakes of July 2019. I remember exactly where I was when the magnitude 6.4 foreshock hit on July 4th – probably grilling something! But the real wake-up call was the magnitude 7.1 mainshock the next day. Those quakes weren’t just a local rumble; they sent shockwaves – literally – across a huge chunk of the Southwest.

Seriously, millions felt those tremors, not just folks in California. We’re talking a multi-state, even international, event!

The initial jolt, that 6.4 foreshock? It made its presence known to an estimated 20 million people. Can you imagine? From Sacramento way up north in California, all the way out to Phoenix, Arizona, and even down into Baja California, Mexico, people felt it. That’s a wide net!

But hold on, the 7.1 mainshock was the real headliner. A staggering 30 million people reportedly felt that one. Southern California, of course, got a good shaking, but it didn’t stop there. Arizona, Nevada, you name it. Word is, even up in the San Francisco Bay Area and Sacramento, people felt it. And yep, Baja California got a second helping. One person I know in Fresno said they felt a long, slow sway that lasted almost a full minute! Creepy, right?

Now, if you were in Ridgecrest, or nearby Trona, it was a whole different ballgame. Things got violent. I’m talking stuff flying off shelves, furniture doing the Macarena. Thankfully, newer buildings mostly held their own, but those older, unreinforced buildings? They took a beating.

And the aftershocks? Don’t even get me started. Seismologists clocked around 34,000 of them in the six months after the main events. I mean, come on! By that evening of July 5th alone, over 1,400 quakes had already hit. One of the bigger aftershocks, a magnitude 5.4, reminded everyone it wasn’t over, reaching as far as Fresno to the north, Laguna Hills (and Los Angeles) to the south, and even Las Vegas to the east.

So, what made this happen? Well, the Ridgecrest quakes happened in the Eastern California Shear Zone. Think of it as a place where the Earth’s plates are always kind of bumping into each other. Turns out, the quakes involved ruptures on a bunch of fault lines, some of which we didn’t even know were there! The mainshock basically ripped along a fault that got uncomfortably close to both the Garlock Fault to the south and the Coso geothermal field to the north. Geologists later figured out the ruptures happened along the Salt Wells Valley and Paxton Ranch Fault Zones.

These quakes weren’t just scary; they were a learning opportunity. Geologists swarmed the area, documenting all the surface ruptures and ground deformation. They even saw the Garlock Fault doing a little “creep” dance. And get this: the earthquake sequence actually changed the rock structure around the fault, causing “inelastic deformation” – basically, softening the Earth’s crust. Pretty wild, huh?