Southern Californians were on edge this week after an elevated earthquake risk warning was issued for the San Andreas fault. The announcement was prompted by a swarm of 150 or more small tremors centered on the Salton Sea, on a fault line running parallel to San Andreas, along its southern edge.

But if you live along Hollywood’s favorite fault, don’t panic. Seriously: Don’t panic. First, the time of elevated risk has already passed. Second — and perhaps most importantly — the risk of an imminent quake was pretty low, even at its height. The scientists at California’s Office of Emergency Services forecasted a 0.03 to 1 percent chance of a magnitude-7 quake on the southern San Andreas over a one-week period. Given the possible consequences of a quake, that’s definitely scary. But it’s not exactly an “OMG she’s ready to blow!”

What set panic off was a series of earthquake swarms, which are clusters of tremors in a short period of time. Sometimes these can destabilize nearby faults and cause major quakes, but this isn’t guaranteed. It is true that southern parts of San Andreas, where a bit of jolt hasn’t occurred for three centuries, are at higher risk than northern portions, which have released built-up tension more recently.

Seismologists tracked an earthquake swarm in the Salton Sea, California, in late September.
Seismologists tracked an earthquake swarm in the Salton Sea, California, in late September.

It’s also true that anywhere there are fault lines, earthquakes are inevitable. It’s just not easy to say when, where, and how big. That’s why it’s so important to always be ready.

Earthquake risk is a hard thing for humans to know what to do with. Even if you understand how risk calculations work, it’s easy to be lulled into inaction. And even though big earthquakes will definitely happen along big faults, the chances of them happening on any given day, or week, or year, are quite low. Because the imminent risk is almost always negligible, logic says we can safely put off investments of time and resources in getting prepared for an eventual disaster.

And yet, if you live in coastal California, The Big One could happen any time, so really, you should always be prepared, and if you’re not, there’s a very small chance you could be in very big trouble. Earthquake warnings may lead to unwarranted panic that exaggerates the real risk, but if it gets people thinking about how they could be better prepared when the day finally comes, that’s not a bad thing.

Photos via Governor's Office of Emergency Services, Warner Bros./YouTube (1, 2)

Jacqueline Ronson is a science writer based on Vancouver Island, Canada. Before that she lived way up in Whitehorse, where she reported for the Yukon News. These days she likes to talk to smart people about the future of the planet, ride her bicycle, play her banjo, and frolic.