Volcanoes Make Worlds What They Are
I just returned from a week in Iceland, which is a marvel of volcanism. It lies astride a spreading center where two of Earth’s tectonic plates are moving apart. In the process, lava wells up and creates new land. It’s one way that Earth keeps forming, some 4.5 billion years after it began to accrete.
Iceland is completely volcanic. Everywhere you look are basaltic lava flows of various ages. Volcanoes such as Eyjafjallajökull and Hekla and Bárðarbunga periodically spew lava out. In addition to creating new surface area, the high heat melts glaciers and sends water rushing across the surface. The land around the spreading center is filled with hotspots where geysers send heated water to the surface. Lava flows deep underground heat the water, which makes its way to the surface over and over again.
The heated water also provides geothermal power for the island, in abundance. Sure, Iceland’s volcanoes occasionally disrupt life on the island and beyond, but the fact is, they also create breathtakingly gorgeous scenery and help the locals out with their power needs.
Venus and Volcanism
Volcanic action doesn’t just take place on Earth. Venus is quite active, and its volcanoes appear to be flowing into modern times. In particular, the Venus Express mission (sent by the European Space Agency) mapped recent flows in a place called Idunn Mons, in the southern hemisphere of the planet. Normally you can’t see anything happening on the planet due to the cloud cover, but the instruments aboard the orbiter were able to slice through and do an infrared scan of the surface.
How recent are these flows? The scientists aren’t saying yet, but in geologic terms, “recent” means in the last few million years. Chances are they’re much younger than that, since Venus is known to be very active. Its flows have built up a number of high mountains on the planet, while in other places hot spots create pancake domes and spidery-looking cracks where lava wells out. So, like Earth, Venus is still building itself after all these billions of years.
Volcanoes Elsewhere
We also know that Mars has volcanic mountains and that it was geologically active earlier in its history. Is it still active deep down? Future missions will look for geothermal activity deep beneath the surface, heated by the last remaining hotspots in Mars (if there are any). Farther out in the solar system, active volcanoes exist on Jupiter’s moon Io. It vents lava and sulfurous compounds and is the most distant of the rocky moons to do so. Beyond it lie ice worlds, and they also exhibit their own forms of volcanism. Europa, Enceladus, Titan, and Triton, and even Pluto are known for their cryovolcanic action. It happened to other ice worlds in the past, and their surfaces show the evidence.
Volcanism in all its forms is a powerful surface-changing process on worlds in the solar system. It played a role in shaping (and sometimes wiping out) life on Earth, and in other forms on ice worlds may play a role in providing a safe, warm haven for developing life. For those reasons, and many others, planetary scientists investigate volcanic activity no matter where they find it. It’s the continuation of starbirth and planetary formation in a very local, fascinating way.
