Dating an active volcano. And I don't mean metaphorically.

By Phil Plait | June 1, 2012 6:30 am

[Note: At the bottom of this post is a gallery with more awesome pictures of volcanoes from space!]

One of the best uses of space exploration is to look back on our own planet. So much of our Earth — as heavily explored as it is — is so far from human eyes that the best view is from hundreds of kilometers above.

This is certainly true in the case of the volcano Bagana, located in Papua New Guinea. Although the top of the stratovolcano reaches nearly 1800 meters high (more than a mile), it’s so far from any population centers that it’s difficult to monitor. But the Earth Observing-1 satellite doesn’t care how far humans are, and its view is of the volcano is unparalleled.

[Click to hugely encalderenate.]

This natural-color shot, taken on May 16, 2012, is very revealing. The big tongue of lava flowing up and to the right is new; it wasn’t there before March of 2011. You can tell it’s new by looking at the color: brown, the color of fresh rock. Papua new Guinea is tropical, and bare ground doesn’t last long. If you look at other flows around that volcano, you can almost guess which ones are older by how much greener they are. In fact, relative ages of flows sometimes can be found that way.

You can also see the thick plume of water vapor and gas blowing to the left (west), and scattered clouds over the volcano. The detail on this image is remarkable; the north-south extent of the new flow at the tip (where it spreads out vertically in the picture) is only about 600 meters (2000 feet)! You could fairly easily hike across it in less than an hour… assuming the terrain isn’t rugged. I’m guessing it is; Bagana is known for thick lava flows, and that generally produces aa — the solidified lava that’s rough-hewn and has rocks full of sharp edges. Those are sometimes called clinkers. I was on the La Palma volcano years ago, and the pumice rocks there would make high-pitched clinking sounds when they hit each other. The reason for the name was pretty obvious.

Image credit: NASA/Jesse Allen and Robert Simmon using EO-1 ALI data

Related Posts:

Desktop Project Part 20: Angling in on a smoking volcano
Desktop Project Part 11: Upside down volcano plume
Desktop Project Part 7: A new volcano parts the Red Sea. Kinda.
Desktop Project Part 4: Underwater volcano in teal


CATEGORIZED UNDER: Pretty pictures, Science

Comments (17)

  1. 600m in under an hour? I should hope so! Even with rough terrain. If the terrain is reasonably good, 600m should take about 10-15 minutes to hike.

  2. JB of Brisbane

    Wait on – isn’t Bagana on Bougainville? Technically, it’s part of Papua New Guinea, but not the same island. My dad spent time behind the Japanese lines on Bougainville during the war, and was there when Bagana erupted once.
    Sadly, he passed away nearly a year ago, just short of turning 93. I wish I could have showed this to him.

  3. Carter

    Looks like the satellite almost missed the volcano!

  4. Matt B.

    Speaking of dating and volcanos, I’ve always been confused by the Elvis lyric “Her lips are like a volcano that’s hot.”

    I’ve always thought: So…they’re hot, then. Because otherwise, you must mean that they’re spewing lava and ash.

  5. Actually, the terms a’a and pahoehoe are reserved for basaltic lavas like those that erupt in Hawai’i. Bagana erupts andesite lava, which has more silica than basalt, so we wouldn’t call the lava flows a’a, but rather “blocky” lava flows.

    Although these aren’t andesite lavas, here are some more examples of the landforms that blocky lavas can form, with prominent flow fronts and flow levees on the side:

  6. The Bobs

    No a’a on Bagana. A’a is a basaltic lava, Bagana produces andesitic lava, much more viscous than a’a.

  7. Trebuchet

    @#2: Just to nit-pick your nit-pick, the BA did say the volcano was IN Papua New Guinea, not on it! That would mean in the nation.

    Sorry about your dad; I know how you feel since my dad, also a WWII vet, passed away two years ago.

    Regarding the picture, if that was one of our snow-capped Pacific Northwest volcanoes I’d have assumed that lava flow to be a mudflow!

  8. Randy A.

    Phil, when you said “The big tongue of lava flowing up and to the right is new…”, you really meant to say the down and to the northeast, right?

    After all, lava, like all fluids except liquid helium, flows downhill!

    It’s a common thing to say “up” when we mean “north”, but it causes endless confusion for young people, and adults too. I recently has a student draw rain clouds on a diagram of the Earth — in the southern hemisphere the student drew rain falling toward the bottom of the page — in other words, it was raining up!

    So I encourage you to reserve “up” and “down” for directions away or toward the local center of gravity.

  9. Matt B.

    @Randy, I know what you mean. I had a classmate in high school that thought all rivers flowed south.

  10. UP North

    Sorry, Bob, both a’a and pahoehoe can form from the same lava chemistry. In some places, a pahoehoe flows can turn onto an a’a flow along the flow route due to change in gradient. (I have observed this in Hawai’i). The terms do not indicate a lava type, but the depositional form resulting from complex interplay of source volume, lava temperature and insulation of the overlying cooled layer, gradient, and atmospheric conditions during flow. Andesitic a’a and pahoehoe lavas are prevalent at Mount Garibaldi (a Cascade volcano in Cananda)

    At the risk of being yet another nit-picker on this post, you are not likely to get “pumice” resulting from any flow, pahoehoe or a’a. Pumice is formed by violent eruptions throwing liquid lava in the air which cools as the volatiles are being released, but before they can bubble out.

  11. Erik

    I have to disagree with Up North on this one. I’ve never heard of anyone refer to andesite as a’a or pahoehoe – maybe basaltic andesite, which has less silica than andesite – but not andesite. If there are andesitic a’a or pahoehoe at Garibaldi, I’d love to see evidence, but I thought Garibaldi was mostly dacite anyway.

  12. I have to agree with Erik. I haven’t been to Garibaldi, but I’ve never seen intermediate composition lavas (andesite or dacite) with what are conventionally described as a’a or pahoehoe morphologies. In my experience those morphologies are restricted to basaltic (+/- basaltic andesite) compositions. If UP North has documentation of this, I’d be very eager to see it.

  13. Randy A.

    Lava with an andesitic composition usually create flows with a “blocky” texture.

  14. NWimby

    Erik, the northerner is right about the various influences on A’a and Pahoehoe, more to do with deposition environment than chemistry. Not too familiar with Garibaldi, but it looks pretty complicated, chemistry wise:

  15. bassmanpete

    Bipedal Tetrapod, I thought the same thing for a second then realised that Phil probably meant hike across the area in the photograph in an hour.

  16. Georgijs

    For some reason I want to call volcanoes as the planets zits. When one pops, watch out!

  17. Nigel Depledge

    The BA said:

    If you look at other flows around that volcano, you can almost guess which ones are older by how much greener they are. In fact, relative ages of flows sometimes can be found that way.

    Moreover, there are some parts of the world where lava flows overlay one another so their stratigraphy (and hence relative age) is there to see. Just such a set of formations (on Sicily, IIUC) formed the first evidence that the Earth was really and truly old.

    In the 17th century (IIUC), a fellow whose name escapes my memory was walking over an old lava flow on Sicily and noticed that the lava was still in the process of being colonised by plant life, whereas other nearby lava flows possessed rich and varied plant life. He deduced that this was an indication that the lava flow upon which he walked was younger. The lava flow upon which he walked was from a documented eruption, so he could determine its age precisely. It had formed from an eruption that occurred when the Romans were invading Sicily, placing the youngest lava flow at approximately 1600 years old.

    He went on to document all the lava flows from the volcano and concluded that the Earth was probably at least 100,000 years old – far older than any previous estimate. This story is related in the book Measuring Eternity by Martin Gorst.


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