Earthquake Weather? Why Scientists Say It’s a Myth

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SAN FRANCISCO – After a recent swarm of small earthquakes near San Ramon, many people across the Bay Area have been asking the same question:

“Is this earthquake weather?”

It’s a common belief, especially in California, but scientists are clear that there is no such thing.

Where the myth comes from

The idea of earthquake weather dates back centuries, long before modern seismology. People noticed that some earthquakes happened on warm, calm, or foggy days, and a connection was assumed.

But the reality is that those weather conditions are very common in California, while earthquakes happen randomly, sometimes during storms, sometimes during heat waves, sometimes on cool, cloudy days.

When the two happen at the same time, our brains naturally link them.

What actually causes earthquakes?

Earthquakes are caused by stress building up along faults deep underground, often miles below the Earth’s surface. When that stress is suddenly released, the ground shakes.

Weather systems, including rain, wind, temperature changes, or barometric pressure, simply don’t reach deep enough to trigger earthquakes.

In the case of the recent San Ramon swarm, seismologists say the shaking is tied to movement along smaller fault strands near the Calaveras Fault, a known active part of the Bay Area’s fault system.

Why swarms make people suspicious

Earthquake swarms, clusters of many small quakes over days or weeks, tend to get attention because people feel multiple shakes in a short period of time.

When those swarms happen during unsettled weather, foggy mornings, or seasonal changes, the myth resurfaces.

But scientists emphasize:

• Swarms are not unusual in the Bay Area
• They do not depend on weather
• They do not automatically mean a large earthquake is coming

Can rain or pressure changes trigger quakes?

While heavy rainfall can sometimes contribute to landslides or soil movement, there is no evidence that storms trigger earthquakes on major faults like the San Andreas or Calaveras.

Those faults are driven by tectonic plate motion, not surface conditions.

So why do earthquakes feel more common lately?

There are two main reasons why it may seem like quakes have become more common.

The first is better detection. Today’s seismic instruments detect many more small earthquakes than in the past

The second is increased awareness. Earthquake apps and alerts mean we notice every shake.

Earthquakes have always been happening — we’re just better at tracking them now.

The bottom line

Instead of worrying about the weather, experts say the best thing Californians can do is stay prepared:

• Secure heavy furniture
• Know “Drop, Cover, and Hold On”
• Have an emergency kit ready

Because while we can’t predict earthquakes, we can be ready for them.

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