Volcanoes are one of those great forces of nature that we take almost for granted on Earth. I am not sure that I would take it for granted if I lived right next to a volcano but on the overall scheme of things they are part of the Earth’s make up and mold the Earth revitalising it.
Volcanoes do play a large part on Earth but do they play a large part elsewhere? Before we jump around the solar system lets have a look at how volcanoes are formed on earth.
Taking classes can teach you these topics in-depth but to start there are two basic types of volcanic processes that exist, effusive and explosive. The effusive process is when the magma just oozes out of the volcano and slowly covers everything around. This is quite an easy type of volcano to get away from although some flows are faster than others.
An explosive eruption is a much more frightening event to witness. Basically the volcano blows its top throwing out lots of ash and magma. These must be great to watch from a distance although if you are anywhere close then it is worth running away very quickly.
There are plates that cover the Earth and these are involved in a process called plate tectonics. Where these plates separate from each other (divergent plate boundary) the Earth’s crust is forced upwards but allows thinning of the crust and this is where the volcano breaks through. Volcanoes produced by divergent tectonic plates mostly happen at the bottom of oceans.
It is easy to see then that when tectonic plates join they push against each other and one gives way going underneath the other one. As the plate goes down underneath the other plate it takes with it water and other gases which start the magma formation by lowering the melting temperature. If you really want to know this is called hydration induced melting (Yes, volcanoes are produced by melting!). The result of this is to produce volcanoes along a convergent plate boundary.
The Earth is not perfect and certain parts of the crust of the Earth are thinner than the rest. This thin piece of crust is susceptible to breaking and can be where mantle plumes of magma breakthrough. These are called hot spot volcanoes an example being Hawaii. Hawaii has formed from a hotspot that has been moving with a plate across the surface of the Earth. This hotspot has just enough time to produce a volcano as it is forced to move south as the plate moves producing another one. Eventually a whole string of volcanoes are produced. What must be remembered here is that these volcanoes have been formed over millions of years.
The processes needed for a volcano then are plate tectonics or hot spots or perhaps just some other outbreak in the surface of the planet. A hot interior is obviously needed and quite a bit of time as well.
The only way we know that the Earth has a molten core is because of the volcanic activity and seismic readings that tell us what the Earth is made of.
So, does the moon have volcanic activity? If it did then we would be seeing eruptions and lava flows. There is evidence that once the moon did have volcanic activity and was probably all molten when the solar system was being created. Signs of volcanic activity can be seen on the surface of the moon but, luckily for Neil Armstrong, it is not volcanic now although the core may contain a little heat.
Venus is very similar to Earth but has a runaway atmosphere that has heated up the planet causing a greenhouse effect. There has been volcanism on Venus in the past and about 500 million years ago (not a long time in geological terms) the surface of Venus probably had a major resurface due to a volcanic activity. Venus doesn’t have plate tectonics but the pressure of the magma causes a catastrophic release of lava over quite a lot of the surface every now and then. At the moment it is believed there could be a little volcanic activity but nothing can be said for sure as this is quite a hard planet to explore as the clouds in its atmosphere make seeing its surface very hard. At Venus’s highest volcano, though, the Magellan probe has seen ash flows indicating that there might be volcanic activity today.
Mars has had a very volcanic past, there is even evidence that there may have been recent volcanic activity. The Tharsis region is an area of major volcanoes including the highest in the solar system Olympus Mons. There are another 20 named volcanoes across the surface of Mars and counting. It is believed that the largest volcanoes exist on Mars because of the lack of plate tectonics. This lack of movement of the surface means that volcanoes are allowed to build up in one place and therefore get quite high.
Io is an interesting place. Should I rephrase that? Io is an interesting place to look at from a distance but not to go for a stroll on. It is the most volcanically active body in the solar system and is active today. This volcanic activity makes the face of Io look a bit like a pizza. Io has no plate tectonics so where does its volcanic activity come from? Io is a moon of Jupiter and Jupiter is absolutely massive compared to Io. This means that Jupiter’s high gravity has a large effect on the bodies around it and causes tidal heating. This tidal heating is like a pulling and pushing and heating up of Io’s interior causing magma build-up and the eventual eruption of volcanoes due to the internal pressure. This means that the surface of Io is being continually resurfaced and reshaped and would not be a great place to live on.
The solar system does have a few other volcanoes but these are not quite the same. Europa has volcanic activity which is in entirely the form of water which freezes into ice on the frigid surface. The Cassini mission has taken a few great shots of eruptions spewing ice and water into space. This type of organism is called Cryovolcanism.
Triton a moon of Neptune, Enceladus a moon of Saturn and Titan another moon of Saturn all have Cryovolcanism.
Volcanoes over the long term are a very useful piece of planetary equipment. They resurface and renew the surface of planets and satellites, having the greatest effect on Earth and Io. On Earth the long-term benefits outweigh the short term problems volcanoes cause. We are lucky that Earth’s surface is nothing like Io’s as it would be very hard to keep the beer and wine cool.