The biggest volcano

News on big volcano

This past week you might have heard that a team of scientists believes it has found the largest volcano on Earth, Tamu Massif.

According to NPR,

It not only outclasses previous record holder Mauna Loa in Hawaii by about 60 times, but it’s in the same league as Olympus Mons on the planet Mars, the largest known volcano in the solar system.

Only not really…yet. Science doesn’t work that way.

This NPR story is good because it gives a link to the original paper (though you will most likely have to pay to read it), but almost everything else, except the basic fact that scientists made a discovery in the Pacific, is speculation.

At least the idea is out there now, so the rest of the scientific community can discuss it, criticize it and, hopefully, replicate the results (James Cameron, care to go deep sea diving again, collecting frozen lava samples this time?).

Only then it will be time to decide if Olympus Mons and Mauna Loa must be moved down a notch on the “biggest volcano” scale.

But what about the Ontong Java Plateau and that place in Canada?

Height

When it comes to measuring the size of volcanoes, there are all sorts of ways to do it. I’ve taken a look at the major meaurements and done some quick checking this morning. The following may not be correct (please say so in the comments, if you spot an error), it’s the best I could do.

Let’s start with elevation.

Already it’s necessary to get specific. I’m talking height: how far it is from the top of the volcano to its base.

Measured this way, Mauna Loa in Hawaii, at 10.6 miles/17 km, is way taller than Mount Everest.

Mauna Loa erupting in the 1930s (probably the first color film ever made of a volcanic eruption; it has no soundtrack, by the way):

However, the scientists’ best estimate of the height of Olympus Mons on Mars is 16 miles/25 km, so until definitively proved otherwise, Mars beats Earth when it comes to height, just as thoroughly as Mauna Loa beats Everest.

Olympus Mons flyover animation by James Pontarelli:

Area

Biggest area is what the scientists are arguing for Tamu Massif. They identify an area of oceanic plateau – 120,000 mi2/311,000 km2 – as a single volcano. Not all volcanologists agree with that.

Even though Mauna Loa makes up half of the island of Hawaii, its area of some 2000 mi2/5200 km2 looks pretty puny in comparison. However, no one has ever claimed that Mauna Loa is the volcano that has the largest area.

Here again, we’ve got to define a term: volcano. Dr. Wikipedia’s definition is a pretty good one:

A volcano is an opening, or rupture, in the surface or crust of the Earth or a planetary mass object, which allows hot lava, volcanic ash and gases to escape from the magma chamber below the surface.

Some volcanoes can be flat.

If you’ve ever visited the Portland Wilderness area along the Columbia River, you’ve seen some spectacular scenery. There’s a volcano (or volcanoes) to thank for that.

Sometimes when molten rock reaches Earth’s surface, its chemical makeup and other conditions make it runny. When there’s a lot of it, as there was a long time ago in what we now call the Pacific Northwest, you will literally have a flood of basalt, through multiple fissures, that may cover an enormous area, quite dwarfing the area suggested for Tamu Massif.

The Columbia River flood basalts, in total, “only” covered almost 6300 mi2/164,000 mi2. That wasn’t as large as the area given for Tamu, but these basalts, while spectacular, aren’t unique, and they’re not the biggest large igneous provinces (yes, LIPs) on the planet, either.

Note that some scientists say that it isn’t correct to call these igneous provinces a single volcano. However, we still don’t know for sure that Tamu Massif, the new contender for volcano bigness, is a single volcano, either.

If Tamu Massif turns out to be a flood basalt, the Deccan Traps, at an area of nearly 200,000 mi2/500,000 km2 will have it beat, but let’s check out Canada, eh?

Mackenzie_Large_Igneous_Province

Over a million years ago, north and west of what is now Hudson Bay, the Mackenzie Hotspot erupted through many fissures.

The lava has now cooled into dikes, and this swarm of dikes covers over a million square miles (2.7 million square kilometers).

Since the area of Olympus Mons is some 114 114,000 mi2/295 295,000 km2, Earth beats Mars when it comes to volcanic area (including LIPs), and on Earth, Canada beats the Ontong Java Plateau (more about this one later – you’ll see why).

Volume

Area only measures the surface a volcano covers. How about the amount of material it contains?

I haven’t read the paper on Tamu Massif (and would probably have difficulty understanding its details if I tried), but Erik Klemetti says “they never offer a total volume of erupted material.”

Mauna Loa’s volume is 19,000 mi3/80,000 km3. So…Mauna Loa wins by default?

Maybe on Earth, but Olympus Mons contains some 1.9 million cubic miles/8 million cubic kilometers of material so it definitely wins the biggest volume contest for the Solar System…

…unless we include LIPs.

Here is where the Ontong Java Plateau in the southwest Pacific Ocean comes into its own.

Canada’s Mackenzie LIP has a volume of some 120,000 mi3/500,000 km3. However, in 1997 scientists estimated the Ontong Java Plateau LIP’s volume to be as much as 106,521,000 mi3/444,000,000 km3.

Eat your heart out, Mars.

Digging Up Facts

Wait a minute! They knew that Earth’s biggest volcano was larger than Olympus Mons in 1997? How come we never heard about it?

That’s science for you.

First, there’s the whole consideration about different kinds of volcanoes. Ontong Java Plateau is a large igneous province, while Olympus Mons is a shield volcano.

Technically, it is incorrect to compare LIPs to individual volcanoes, but then, so is a lot of the speculation you may have read this week about Tamu Massif being the new “largest volcano” anywhere.

In reality, it’s all very complex and we know very little about volcanoes on the seafloor. A lot of hard work is still needed.

Also, it’s hard to make up sensational headlines with this sort of material:

You can’t take field trips to volcanoes at the bottom of the Pacific Ocean, whether you want to look at Tamu Massif or the Ontong Java Plateau. Many scientific cruises have to be made over a span of years. Multiple types of measurements are taken, but none is as reliable as a drill core.

Imagine all the cores of Ontong Java Plateau it took – not to mention all the rest of the research and interpretation of data – before this paper (PDF) could be published in 2005!

I did not see mention of the volume of the plateau in that paper. Probably the 1997 volume given was just a ballpark estimate and now that more information is available, that huge number has been thrown into question and is still unresolved.

The researchers on Tamu Massif apparently took just one drill core and came up with a solid number for the area. Maybe they’re correct, but certainly much more work needs to be done there before the current champions are unseated.

These are:

  • Olympus Mons, Solar System award for height, Mauna Loa for tallest volcano/mountain on Earth.
  • Olympus Mons, the Solar System award and Mauna Loa the Earth award with regard to area (excluding LIPs), MacKenzie Igneous Province in Canada for the double award otherwise. (corrected)
  • Olympus Mons, Solar System award for volume and Mauna Loa for Earth (excluding LIPs), otherwise, the Ontong Java Plateau for both awards, easily.

Research is still ongoing, and one thing is for sure – eventually everything on the list will change.



Categories: Sunday morning volcano, volcanoes

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