Have you ever wondered about which is the tallest active volcano on the planet? It sounds like a fairly straightforward question. But, as with all simple questions it quickly turns into a quagmire of definitions.
The first of the definitions starts out in linguistics, and that is what is the definition of “active”. It turns out that there are several active definitions of the word “active”.
The most straightforward is if the volcano has been historically active. This definition is very white male Christian-centric. More or less it requires that a male catholic priest must have witnessed the eruption and to hell with oral traditions or pesky indigenous people’s descriptions.
The other one is the more scientific one. Has the volcano showed signs of being active, like earthquake swarms, inflation, or any other measurable sign of being active? This basic part is then widened with such things as eruptions seen by volcanologists or are there active hydrothermal vents.
In this article I will use the latter description.
Then we end up with the obvious part, tallest measured from where? And this is where it almost become impossible to name the tallest volcano.
About here we are ready to go, we just have to state that we are talking about terran volcanoes, otherwise Albert will hit me over the head with a volcano on an exo-planet.
The crusty question about crust
First, we need to discuss the influence of the crust that the volcano is sitting on. Because it will cause a big difference on how the volcano will behave as it grows, and how tall it can become, and what type of tall it will be.
A thick tectonic plate will be able to carry a very tall edifice without the crust sinking downwards a lot. Therefore, most tall edifices are situated on a thick tectonic plate that has oceanic crust subducting beneath it.
If on the other hand a big volcano is situated on oceanic crust the mass will bend the crust downwards.
Highest elevation above sea level
I bet this is how most people would decide the matter. It is pretty straightforward, all you have to do is stick a GPS at the top of any volcano that meets the criteria for being active and you will end up with a winner.
So, without further expounding say hello to Nevado Ojos de Salado, the tallest active volcano on the planet, at 6 893 metres above sea level it is a honking whale of a volcano. It is located on the Argentine/Chile boarder, so it belongs to both countries.
It is situated on the Central Volcanic Belt of the Andes on the Cordillera Claudio Gay.
Nevado Ojos de Salado last erupted about 1 300 years ago, and it has an active fumarolic field. There are signs that it might have erupted at a later date than this. There is even an unsubstantiated possible eruption in 1993.
If you instead wish for an active volcano that has been seen erupting by a catholic priest, you end up with Lluillallaco at 6 793 metres as the tallest volcano counted from sea level.
Prominence is a technical term for mountains. Simplified it means the uninterrupted height difference of the mountain. You measure the difference from the highest valley floor between the top and the ocean.
If you are into mountaineering this is important because this will be the largest possible height to climb from bottom to the top.
Most people state that it is Kilimanjaro that is the most prominent volcanic edifice. But there are a lot of questions about its state as an active volcano among those who study it. So, while they are dunking each other in symposiums and papers we are safer to go with a volcano that is without a shadow of a doubt active by invoking the dual rule of catholic priests and scientific consensus (probably the only example of scientists not arguing while at the same time agreeing with catholic priests on a scientific question).
This time we end up with Mexico as the home for the heavy weight champion. Say hello to the 4 992-metre prominence of the 5 653-metre-tall volcano of Pico de Orizaba.
It is situated on the Trans-Mexican Volcanic Belt and it has been observed erupting on many occasions, last in 1846.
The watery option
Due to geopolitical reasons the United States came up with an ingenious way of getting the tallest active volcano on the planet. They measure such things from the deepest point on the ocean floor to the top, disregarding such piddly things as prominence and sea level. Instead they go for the brute force approach.
And in this case, it is gravity creating the brute force. The massive volcano of Mauna Loa and its siblings are creating enough gravity to produce a stupendous deep oceanic valley around the Island of Hawaii.
The prominence is piddly, just 2 158 metres, and the height from the ocean level is comparatively not much to write home about at 4 169 metres. It is 37 meters lower than its dormant Neighbour of Mauna Kea, but that is likely to change after a few eruptions adding height to Mauna Loa.
The height from the ocean floor is given at 9 000 metres. A height that will not be challenged soon unless Mauna Kea rumbles back into an active state.
Now, there is just one tinsy winsy problem with this. It is utter bullhork, even by its own definition.
Now over to the tallest active volcano by this definition.
And it is a true whopper at 11 874 metres of uninterrupted rise from the bottom of the Ocean. The volcano is quite piddly at 790 metres above ocean level, but who cares when you count all the way down to the Challenger Deep in the Mariana Trench.
So, please let me introduce you to the abandoned highly active volcanic island of Anatahan belonging to the Mariana Islands Chain. Technically the island belongs to the US, so the record stays firmly with them.
The last known eruption was in 2007-2008, so there is no doubt about its volcanic status. I guess the comment field will explode now with people trying to save the Hawaiian glory.
Bottom bending part II
The crafty Americans must have felt that there was a need for another way to prove that their Hawaiian volcano is the top dawg. They went even further with the bending of the crust concept and went for the measurement from the bottom of the deepest eruptive layer to the top of the edifice. This gave them a 17km high volcano.
So let us quickly discuss Iceland. The area around Grimsvötn and Bardarbunga is 45km deep, the oceanic crust is 5km at this spot. So, from the deepest eruptive spot to the top of Bardarbunga it is 40km.
This means that the crust has been pushed down 40km by the volcanoes on top of the area. Now someone will scream that I used the word plural, but the same goes for Hawaii.
The centrist view
Now, there is a final option in the chase of the tallest volcano on the planet. And that is to measure from the centre of the planet itself. I much prefer this way since we are after all talking about the tallest volcano ‘on the planet’.
Most people do not ponder that the planet is not a perfect sphere. It is shaped more like a tangerine, squashed at the poles. It is therefore correct to say that you are travelling down if you are travelling towards the north on the northern hemisphere.
So, which active volcano peak is the longest distance from the centre of the planet? Before I answer that one, we need to acknowledge how tall the spot is. It is not only the tallest active volcano, it is the tallest mountain on the face of the planet, however you count.
It outpaces Anatahan, Mauna Kea and Mount Everest.
Without further ramblings on my part, say hello to the unexpected winner of Chimborazo in Ecuador. It is situated on the Cordillera Occidental in the Andes. The last eruption was 150BC, but it has fumarolic activity and has suffered from historic intrusions.
How tall is it? Well, it is 2 163 metres taller than Mount Everest.
There is actually another and far better way to measure how tall a volcano is and I would like to propose that one. For natural reasons I could not find out which volcano would fit the record bill, but that volcano would be the winner from a volcanic standpoint.
It would be to measure the volcanic system height. For a couple of Icelandic volcanoes, it would put them at 45km. And many subduction volcanoes would come up towards 180km, measured from the Benioff zone.
Because in the end a volcanic edifice is just the boring top end of what is interesting. It is in the bowels things are interesting, so why not measure the height of the bowel system to give the true measure of how tall it is?
If we count it this way, we come up with two probable winners. In the subduction class the likely winner is the Altiplano-Puna Volcanic Center, and in the hotspot class we end up with Ol Doinyo Lengai. And to be quite honest, APVC is not a single volcano.
So without further ramblings, I hereby crown Ol Doinyo Lengai as the tallest volcano on the planet.