What caused Alaska earthquake today?

Alaska’s Shaky Ground: What’s Behind Today’s Earthquake?

If you felt a rumble today, and you’re in Alaska, chances are it was another earthquake. Alaska and earthquakes? They go hand in hand, really. But why is that? What makes Alaska such a hotspot for seismic activity? It all boils down to what’s happening deep beneath our feet.

Think of it like this: the Earth’s crust is like a giant jigsaw puzzle, made up of massive pieces called tectonic plates. Alaska just happens to be sitting right where two of those pieces – the Pacific and North American plates – are bumping into each other. More specifically, the Pacific Plate is diving, or subducting, under the North American Plate. This isn’t a smooth, graceful slide, mind you. It’s more like a slow-motion car crash.

Now, because the Pacific Plate is denser, it gets forced downwards. This happens along the Aleutian Trench, a gash in the ocean floor that’s longer than the entire US coastline! And if you look inland from that trench, you’ll see a chain of volcanoes – another telltale sign of all this underground drama. The plates don’t just slide past each other nicely; they get stuck. Imagine trying to push a heavy box across a rough floor. It sticks, you push harder, and then suddenly it lurches forward. That lurch is an earthquake!

All that pressure builds up over time. When it finally overcomes the friction, BAM! The plates slip, releasing a huge amount of energy. That energy travels through the earth as seismic waves, and when those waves reach the surface, we feel it as an earthquake. The really big ones, the ones that can level cities, happen when the plates slip along that shallow subduction zone. Think of the Good Friday Earthquake in 1964 – a monster magnitude 9.2. Or the 1965 Rat Islands quake, clocking in at 8.7. Those were megathrust earthquakes, caused by massive slippage along that plate boundary.

But subduction isn’t the whole story. There’s another player in this game: the Yakutat Block. It’s basically a chunk of crust that’s crashing into North America, right where the plate boundary bends. This collision is building mountains and generally making things even more complicated.

Plus, all that grinding and squeezing creates faults all over Alaska. These faults are like cracks in the Earth’s crust, and they can also slip and cause earthquakes, though usually not as big as the subduction zone quakes. And sometimes, it’s not even the earth moving that causes a seismic event. Landslides, believe it or not, can do it too! A massive rockslide into the ocean can create waves big enough to register as a small earthquake.

We get earthquakes all the time here. Just this past year, we’ve had over 6,100 of them. A few days ago, there was a 4.6 near Petersville. And remember that magnitude 7.3 quake off the Aleutians a few weeks back? That one even triggered a tsunami warning! Our state seismologist, Michael West, pointed out that we’ve been seeing a lot of activity since 2020, with several magnitude 7+ quakes.

So, what caused today’s earthquake? Most likely, it’s just another consequence of the Pacific Plate doing its slow-motion dive under North America. It’s part of living in Alaska. While it can be unnerving, it’s also a reminder of the powerful forces shaping our planet. We’re constantly learning more about these processes, which helps us better prepare for the next big one. Stay safe out there, folks!