In Defence of Volcanic Pedantry

5 February 2014 by Robin Wylie, posted in General, Super Terrestrial, Uncategorized

Every day, on the island of Java, masked men risk their lungs for sulphur. At least it’s colourful work. On the hazy summit of Indonesia’s Kawah Ijen volcano, a crater lake blazes – tinted green by the noxious air. The deep gases seep from a nearby vent, burning blue after dark. It's the warmer hues, though, which lure people here.

The air, saturated with magmatic fumes, literally leaks molten sulphur. At first bright red, it solidifies to the familiar yellow of “elemental” sulphur before being lugged down the mountain in blocks by hand. To the miners it's money. But to pedantic volcanologists with smaller worries, their cash flow raises a different question: can you call liquid sulphur lava or not?!


A miner at Kawah Ijen stands in front of the flowing sulphur.

A miner at Kawah Ijen stands beside a sulphur flow. Credit: Paul Hessels.


To most people if it's red, runny and comes from a volcano, there’s only one word for it. I thought so too. But when I mentioned “sulphuric lava” on a popular microblog – I got called out.

The Oxford English Dictionary lists lava as "a stream of molten rock issuing from the crater of a volcano or from fissures in the earth". So where's the rub? The Kawah Ijen sulphur is certainly molten. It came from a volcano. But according to one commentator, it still wasn’t lava – because elemental sulphur, they said, wasn’t a rock. If it was, wouldn't other single-element material also inherit this (let's face it) slightly underwhelming title? A rock of gold? Platinum pebbles?

Either way, volcanoes like Kawah Ijen are so rare that it hardly matters beyond semantics. This example though, highlights a more pervasive problem with the L-word.    


When a volcano erupts, a mild mania descends on journalists. Most symptoms are harmless – recycling stock phrases where things are invariably “shot” or “spewed” or “spat” "[x] miles into the air". But on closer inspection there’s another, more furtive presence.

For example, here’s how major news outlets chose to describe a recent large eruption (of Mount Sinabung, in Indonesia):


"[Mount Sinabung] started spitting ... lava up to 7,000 meters in the air" 

– The Associated Press, 31 Dec 2013. (Repeated by WKYC, an NBC-affiliated TV station)


"[Sinabung] shot lava into the air nine times overnight" 

– Agence France-Presse, 31 Dec 2013. (Repeated by the Australian Broadcasting Corporation and The Straits Times)


[Sinabung] was still spitting lava as high as 4,000 meters" 

– The Daily Telegraph (UK), 05 Feb 2014


I found these in five minutes. They’re cherry-picked; but they’re certainly not rare. So what's the problem? Well, Sinabung did erupt lava. But it did not spit it 7km into the air. No lava has ever been spat 7km into the air. That was the ash.


Locals witness the onset of the (ongoing) eruption of Mount Sinabung. (Note: the stuff ominously billowing into the sky is not lava).

Locals witness the onset of the (ongoing) eruption of Mount Sinabung. (Note: the stuff ominously billowing into the sky is not lava). Credit: Flickr


More than that, what lava there was probably never made it airborne at all. Volcanoes like Sinabung emit extremely dense lava – geologically speaking, Andesite or Dacite – very different from the free-flowing basalt most people associate with eruptions. This kind tends to tumble or, at best, flow at a crawl.

But no eruption worth over-hyping can do without those four letters. The word slips in unnoticed; it’s part of the woodwork. And that’s what makes its misuse so easy to miss. It was ash which reached those fantastic heights above Sumatra – and it was astonishing. It was awe-inspiring. But it wasn't lava. In these cases and more, the urge to force in this keyword has compromised factual accuracy in important news stories.

That alone would justify this post. But it’s about more than poor journalism. These words – more than most – have weight. Just days ago, Sinabung claimed 16 lives. These people were killed by a pyroclastic flow. They could have sidestepped lava. Sadly, volcanoes don't need hyping.

4 Responses to “In Defence of Volcanic Pedantry”

  1. Boris Behncke Reply | Permalink

    Dear Robyn, thank you for the good idea to discuss the issue with the "L-word". Let me elaborate a bit further and be as pedantic as the geological terminology requires ;-)

    It is actually not an open question whether the burning sulfur at Ijen volcano can be called lava or not, it definitely is not lava. Lava is a mixture of countless chemical elements and compounds (not one single element as sulfur), which originates as molten rock (magma) and comes to the surface in a volcanic eruption. Plus, lava does NOT burn.

    The burning molten sulfur at Ijen is not being produced by an eruption, but by gas emission that is called fumarolic (or sometimes, solfataric) activity. Sulfur comes from the so-called volatile (gas) portion of a magma, and is not rock at all. Likewise, gold and silver are not rock, they constitute minor proportions of some rocks.

    Finally, the phenomenon that killed the unfortunate 16 at Sinabung was - certainly not lava, as you rightly stated, but neither was it "boiling ash", this is something that does not exist. It was a pyroclastic flow, which is a hot current of volcanic gas mixed with rock fragments that flows downslope from a volcano and kills either for its heat or its mechanical impact (imagine being struck by a hurricane heavily charged with bits of rock ranging in size from sand grains to truck-size boulders). It looks a bit like the cloud of ice dust rising from a snow avalanche, but the true pyroclastic flow is at the base of that cloud.

    • Robin Wylie Reply | Permalink

      Dear Boris,

      Thank you for your informative comment,

      I have encountered confusion in the literature about how to define the liquid sulphur at volcanoes. For example, in a 1985 Nature paper (Nature 313, 778 - 780), J. A. Naranjo refers to sulphur flows at Lastarria volcano in the North Chilean Andes as "lava". There is also an older (1970s) paper I came across which referred to the same at Mauna Loa, which I can find for you. While of course the Kawah Ijen sulphur was not "erupted" directly as a liquid - rather, as you rightly say, as a gas - at other volcanoes it has been observed to emanate directly as a liquid (i.e. it condenses below the surface). In my opinion, this could add further ambiguity. I would really welcome your further thoughts on this.

      Lastly, thank you for pointing out the incorrect statement about "boiling ash". Silly mistake. I have now changed this to "pyroclastic flow".

      Best wishes,

    • Robin Wylie Reply | Permalink

      Hi Boris, quick last thought,

      If you think that Nature reference is not representative of the current scientific consensus, then I'll happily change the article to reflect that there is NOT much of a debate : )

      Thanks again,

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