How long did the 1906 San Francisco earthquake last?

How Long Did the 1906 San Francisco Earthquake Last?

The 1906 San Francisco earthquake. Just the name conjures images of devastation, doesn’t it? It hit at 5:12 AM on April 18th, 1906, a Wednesday morning that changed San Francisco forever. Now, you might think an earthquake that leveled a city would have lasted for ages, but here’s the surprising part: the shaking itself? Less than a minute.

Yep, that’s right. Somewhere between 45 and 60 seconds of intense shaking was all it took to set off one of the worst disasters in American history. Hard to believe, isn’t it?

The epicenter was lurking near San Francisco, and the rupture tore along nearly 300 miles of the San Andreas Fault. Imagine that – a crack in the earth that long! The shaking wasn’t just felt in the Bay Area; it rippled from Oregon all the way down past Los Angeles, and even as far inland as Nevada. That’s a huge chunk of land – about 375,000 square miles, to be exact.

Now, here’s a creepy detail: a strong foreshock hit maybe 20 seconds before the main quake. Can you imagine that feeling? A little jolt, a warning sign of what was about to come. I can’t even fathom the dread.

Of course, the shaking wasn’t uniform. Areas built on soft, filled-in land got hit way harder than those on solid rock. It’s like building a house on sand versus a foundation – you know which one’s going to fare better. The areas closest to the fault line got the worst of it, with the shaking intensity through the roof.

One guy, Professor Alexander McAdie, was actually there and said the worst shaking lasted about 40 seconds. That jives with other accounts, all saying it was under a minute of pure terror.

And what did that minute of terror unleash? Collapsed buildings, broken gas lines, and then… fire. Oh, the fires. They raged for three days and caused most of the damage. Seriously, something like 80% of the destruction came from those infernos. The earthquake and fires together killed around 3,000 people and left over half the city – that’s 400,000 people – without a home. Just think about that for a second.

The 1906 quake wasn’t just a tragedy; it was a learning experience. Scientists studied it and came up with the elastic-rebound theory. It’s still how we understand earthquakes today. So, while it was a horrific event, it also helped us understand our planet a little better. It’s a sobering thought, isn’t it?