What is the largest earthquake attributable solely to volcanic activity

Volcanic Earthquakes: When Volcanoes Rumble More Than They Roar

Volcanoes and earthquakes – they often feel like two peas in a pod, right? But figuring out exactly how they’re connected? That’s where things get tricky. Sure, a massive eruption can definitely shake things up, but pinpointing the biggest earthquake caused only by a volcano? Now that’s a real head-scratcher. It’s a bit like trying to separate the yolk from the white after you’ve already scrambled the egg! We’ve got to be able to tell the difference between quakes caused directly by magma moving around, and those that just happen to be hanging out near a volcano.

Decoding Volcanic Tremors

So, what exactly is a volcanic earthquake? Well, it’s pretty much what it sounds like: an earthquake that happens when a volcano’s doing its thing. These can be anything from tiny little tremors that you’d barely notice, to bigger events that can really make the ground roll. Generally, we break them down into a couple of main types:

• Volcano-tectonic earthquakes (VTs): Think of these as the “fault line neighbors” of volcanoes. Volcanoes often sit in spots where the Earth’s crust is already a bit weak, and the volcano’s weight just adds to the stress. While sometimes magma moving in or out can trigger them, a lot of the time they’re just responding to the same forces that cause regular earthquakes.
• Long-period earthquakes (LPs): These are the telltale signs of magma on the move. They’re like the volcano’s heartbeat, caused by the vibrations of magma or other fluids sloshing around inside. If you see LPs, chances are something’s brewing beneath the surface.

The Attribution Game: A Seismic Whodunit

Here’s the million-dollar question: how do we know for sure that an earthquake is only because of a volcano? Big earthquakes are often complicated beasts, and it’s tough to say for sure what percentage of the shaking came from the volcano and what came from other stuff going on in the Earth’s crust. It’s like trying to figure out who ate the last cookie when everyone in the house denies it!

The Usual Suspects: Biggest Volcanic Quakes

Okay, so we might not have a clear winner, but let’s look at some of the contenders for the title of “Largest Volcanic Earthquake:”

• Mount Tambora, 1815: This one’s a heavyweight. The eruption of Mount Tambora was absolutely colossal – the biggest volcanic bang we’ve ever recorded. Seriously, it was a VEI 7, which is off the charts! And guess what? It was preceded and accompanied by some serious shaking, felt for hundreds of kilometers. Some folks estimate the biggest quake might have been around a 6.8 or 7. But here’s the catch: some scientists think that tectonic movements around the volcano might have played a role, too. The Tambora eruption was so big that it threw something like 150 cubic kilometers of stuff into the atmosphere, leading to the infamous “Year Without a Summer” in 1816. I mean, can you imagine?
• Cordón Caulle, 1960: Talk about bad timing! Right after the biggest earthquake ever recorded – the magnitude 9.5 Valdivia earthquake in Chile – the Cordón Caulle volcano decided to erupt. Now, everyone thinks the big quake triggered the eruption, but remember, the Valdivia earthquake was a tectonic monster, not a volcanic one. Still, it shows you how interconnected everything is down there.
• Mount St. Helens, 1980: Ah, St. Helens. I remember watching this one on TV as a kid. The eruption was preceded by a magnitude 5.5 earthquake. Significant? Sure. But not in the same league as Tambora or the earthquake that started things off at Cordón Caulle.

So, Why No Gold Medal?

Why can’t we just say definitively, “This was the biggest!”? A few reasons:

• Old data is fuzzy: Back before we had all our fancy seismographs, records of earthquake sizes are often a bit sketchy.
• Volcanoes are messy neighbors: Volcanic areas are often already prone to earthquakes, so it’s hard to untangle what’s volcanic and what’s just the Earth doing its thing.
• Magnitude scales can be confusing: There are different ways to measure earthquakes, and some are better than others, especially for the really big ones.

The Bottom Line

Figuring out the single biggest earthquake caused only by a volcano is tough. Tambora in 1815 is probably the best bet, but even then, there’s some debate. The way volcanoes and the Earth’s crust interact is a complex puzzle, and scientists are still working to put all the pieces together. It’s a good reminder that our planet is a dynamic, ever-changing place!