Moment of Science: Volcanoes
If you learn enough here, you get to graduate “magma cum laude”.
Last week, we talked about plate tectonics, fault lines, and all the pressure they can produce -- but a big side effect making the headlines recently provides quite the visual example for a release valve: volcanoes! Highlights:
- There are some 1500 active volcanoes worldwide -- and over 1000 of them lie around the “Ring of Fire”. That’s where those continental plates grind against each other, but there’s a key difference here compared to the others. “Subduction” involves part of Earth’s crust dipping under itself, melting as it gets driven down into that molten mantle layer. That newly-liquefied magma is lighter than the solid cap above, so it finds a weak point to get back to the surface.
- Hawaii or La Palma are great examples of volcanic islands, though Africa’s Mount Kilimanjaro formed from plates spreading apart, allowing magma to bubble up more gradually.
- Many volcano deaths don’t come from lava, but the ash and rock cascading down the hillside. That “pyroclastic flow” can reach over 400 miles an hour... so it’s not hard to see why so many victims of Mount Vesuvius appeared frozen in time in ancient Pompeii. That ash also kills crops, halts air traffic, creates acid rain, and even makes its own lightning.
- Volcanoes aren’t just limited to our corner of the solar system. Mars, Mercury, Venus, and some moons of Jupiter have evidence of volcanic activity.
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