Your friends felt the earthquake. Why didn’t you?

Tuesday night, a 5.2 magnitude earthquake struck about 88 miles north of Los Angeles, originating from a fault in the Central Valley that's yet to be mapped.

While those in Bakersfield and the surrounding areas felt strong jolts, here in L.A., the experiences varied from long, rolling waves to no noticeable movement.

Why you might or might not feel an earthquake

When an earthquake occurs, waves of energy are released and travel through the earth. The larger the quake and the closer it is to the surface, the more likely you are to experience movement nearby.

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Back in 1952, the 7.5 magnitude quake in Kern County originated in the same general area as the event last night. But in that quake, buildings were damaged in L.A. and San Diego, and ground motions were felt as far away as Nevada and Arizona, according to the U.S. Geological Survey.

Tuesday's quake, which barely jostled L.A., was 200 times smaller and released 2,818 times less energy than the Kern County temblor.

The path that the energy takes to get to you also makes a difference.

"Locally, the rock type that is just underneath people's feet can significantly change how folks feel the shaking from an event," said Ole Kaven, a research geophysicist with the U.S. Geological Survey.

The waves are going to more easily pass through hard rock like granite — which if you're on a hillside, you may be on top of — versus softer, sedimentary rock like sandstone, which amplifies the waves to a greater degree.

When the waves reach the L.A. region, they reverberate around the basin — which is full of sedimentary rock — like a bowl of Jello. It's what's known as basin amplification.

The location of the water table and nearby faults can have an impact.

So it's possible that if you're located on a hillside with granite underfoot, you may experience less shaking than a friend who's located down in the flats of the L.A. basin.

Did you get an early warning?

California's robust earthquake early warning system, ShakeAlert, can give you a 10-plus second heads up when a quake is on the way. Using a widely distributed network of seismic sensors, it can detect, estimate the size and direction of an earthquake and transmit a warning to you, sometimes, before the waves get there.

I got an alert in the San Fernando Valley, while colleagues in other parts of L.A. didn't. Whether you get a heads up — assuming you have your phone setup properly — depends on the intensity of shaking your area is likely to experience. The further away you are, the more warning you'll get, and the weaker the shaking is going to be.

I use the MyShake app from UC Berkeley. You can adjust warnings based on intensity, so if you want to know about the tiniest of temblors, get ready to be inundated.

Is a bigger one coming?

As of Wednesday afternoon, there had been more than 270 aftershocks. And the U.S. Geological Survey estimates that there's a 21% chance an earthquake greater than magnitude 5 could strike some time in the next week. Those odds, however, will decrease the further we get from the main event.

Earthquake resources

We don't want to scare you, but the Big One is coming. We don't know when, but we know it'll be at least 44 times stronger than Northridge and 11 times stronger than the Ridgecrest quakes in 2019. To help you get prepared, we've compiled a handy reading list:

• Your guide to surviving the Big One
• For earthquakes, forget the 'go-bag.' Here's how to prepare
• How to not get life-threatening diarrhea after a major earthquake
• 10 earthquake-related questions to ask your landlord immediately
• How to prepare for an earthquake if you have a disability
• Listen to our podcast: The Big One: Your Survival Guide

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