Ross at Ambrym

Re-posted, from January 24, 2014

Mike Ross up late working at the rim of Marum cone at Ambrym[

Our dear Mike Ross is currently (that was written 5 years ago – editor) at the volcano on Ambrym Island in Vanuatu photographing a documentary. Apparently Ambrym means “Here are yams” in the local tongue.

Mike wearing the latest fashion in volcanic face wear

The volcano is a large shield volcano constructed by alternating layers of pyroclastic deposits and basalt. Around the year 50 AD the volcano had its last large explosive eruption that came short just below a VEI-7 with approximately 65 cubic kilometers of Dense Rock Equivalent being ejected.

The caldera that formed is 12 by 8 kilometers and within it are two large volcanic edifices called Marum and Benbow.

During the last century more cones formed at the highly active volcano. In 1953 Mbuelesi formed, in 1988 Niri (New) Taten formed and in 1989 Niri Mbuelesi formed and Taten reactivated. All of these cones have erupted several times up until now. Ambrym has become famous for its persistent lava lake formations.

Michael Ross dwarfed by the gas cloud and rim of Marum Crater. Photograph by Bradley Ambrose

The current eruption at Marum has formed a lava lake and Mike Ross is there together with Geoff Mackley to recreate Mackleys famous video of the boiling lava lakes, but this time in extreme high definition movie quality.

I think I will just let the images speak for themselves and I know that I speak for everyone when I say that we are looking forward to the finished movie. A

Helicopter delivering the crew up on Marum. Mike with the movie camera. Photograph taken by Bradley Ambrose

Living quarters in hellish light for the fireman. Not the ordinary man’s campaign ground

No words needed really

radley Ambrose hard at work with the RED Dragon 6K movie camera. Photograph by Geoff Mackley

Down the hole

Mike Ross & Carl

Addendum: the famous lava lakes emptied during the 2018 eruption. On the image, the fresh lava flows to the southeast were fed through a rift from the lakes. The lava did not reach the coast. The image (taken last week) shows no current activity in the craters.

Ambrym, 3 Nov 2019, Sentinel.

Addendum: and here are some videos of the Ambrym lava lake

24 thoughts on “Ross at Ambrym

  1. Among Subduction Zone Volcanoes, Ambrym probaly haves the hottest subduction zone magma?

    Ambrym is really hot and fluid ( magma rises fast from the source ) viscosity is low.
    Masaya and Villaricca haves similar fluid Subduction Zone basalts.

    The 3 to 4 lava lakes in Ambrym are sadly gone

    • Yes, they sprung a leak and were gone. It does show that the magma supply rates of Ambrym had been grossly overestimated. Very burpy lava though.

      • Ambrym togther with Villaricca and Masaya is the hottest among Subduction Zone basalts right?

        • I don’t know about the temperature ( ask Mike..) but it is sitting on an unusually warm mantle. But if we look at how much heat a volcano produces in total, Ambrym is close to the top. This list dates from 2014 (which is why Bardarbunga rates so high: that was the holuhraun eruption).

        • Albert thats the thermal emissions ( ammounts of hot surface exposed to radiate into space ) and not lava temperature right?

          Bardarbunga and Kilaueas huge 2014 and 2018 eruptions had huge ammounts of thermal radiation in energy released into the atmosphere.
          Bardarbunga is high on that list because of Holuhrauns huge thermal emission

          Kilauea and Nyiragongo also often haves very large permanent lava lakes that release lots of heat.

        • Ambrym is probaly around 1100 C
          Really hot among Subduction Zone Volcanoes

          The Ambrym viscosity is very low and fluid.
          But a little bit higher than Hawaii and Erta Ale.

          Holuhraun was hotter ( 1180 C ) but seemed to have just the same viscosity as Ambrym.. ( looking at lava and crust textures )

          • Holuhraun lava was measured as 1082 to 1128 °C at the flow front, and 1147 to 1200 °C at the vent. Crystalization in the lava gave a temperature of around 1185 °C before it erupted. Yes, it was toasty. I don’t know numbers for Ambrym.

          • Holuhraun was toasty indeed.
            In vent something like
            1190 or 1185 C yes.
            Making it in the vent extremely fluid.

            This is the hottest Icelandic eruption since you and I was born.

            Holuhraun was 100 C to 160 C hotter than any previous Icelandic lava flow in my lifetime so far.

          • The supply of Ambrym partly comes from spreading, the entire area from Vanuatu to New Zealand is full of rifts and back-arc basins, the graben where Ambrym is located is probably one of these rifts and I seem to remember the magma of Ambrym was MORB-like. Though subduction probably contributes.

            The temperature for late-crystallisation of Ambrym is estimated in 1090-1100 ºC.

            Ambrym had 6 lava lakes before the collapse, there is one satellite image in the global volcanism program actvity reports showing them. 2 inside Benbow, 3 in Marum (one inside Mbwelesu, another in Niri Mbwelesu and the other in an unnamed crater) and the 6th in Niri Taten Mbwelesu

          • Ambrym is a clear subduction zone look at Google Earth
            A migthy trench is just outside the Islands

          • Jesper, I think the tectonic setting there is a little more complicated than “just look at that mighty trench right at the islands”.
            I’m not convinced ambrym is purely subduction-driven. Look at all those faults visible on google earth. Also the huge graben running from ambrym over ambae to gaua island may play a role. It might be interesting to map the deep source of ambryms magma. Does anyone have an idea if thats been done?

          • Yes, I am not saying it is not subduction but that spreading probably plays a role. Ambrym is indeed in a very peculiar setting with a trench to the west (sort of blurred next to Ambrym though) it is on top of a graben, the Aoba basin, which must be extensional… And it also has a system of thrust faults to the east (incipient subduction?). There are publications on the chemistry of Ambryms magmas, probably could tell something about its origin

            Sentinel image showing the lakes though maybe the smaller ones are just strombolian actvity? not sure:

          • The image is false color by the way to show the infrared wavelengths as green and red, I colored it the same way gvp had.

          • Impressive 6 lava lakes
            ( 3 confirmed ones )
            And 3 possible lava lakes🔥

            I imagines these magma conduits being connected at depth like a chandelier to a main conduit?

            I also have read that Ambrym may have many magma chambers.

            DustDevils source saying 1100 C seems correct for Ambryms rather fluid basaltic magmas

          • This is a post-collapse image showing the changes to the summit complex of Ambrym. It was the least cloudy sentinel image of 2019 and yet it still has some clouds:

            Most of Benbow’s floor has collapsed (thecone to the left). The right cone, Marum, has had its central section drop down and the 2 craters that were previously there have coalesced, the eastern craters, Mbwelesu and Niri Mbwelesu haven’t changed much in size but are now filled with rubble, to the south Niri Taten has enlarged but it is still a small feature.

          • There are 3 diferent collapsing areas in the image which are diferent shallow magma chambers but the main storage is 4 km deep and underlies much of the larger 12km wide caldera, all the lava lakes probably feed from this one. It is probably still an oversimplification of a much intrincate plumbing

          • Ambrym is around 1100 C

            But what is the temperature of Nyiragongos superalkaline ultrabasic Nephelinite magmas?

            Nyiragongos caldera is filling up
            From lava lake overflows and from a lava spewing vent in the caldera wall. We are soon at 1977 lava levels again.

            A deeper higher magma column puts alot of pressure stress on the edifice and increasing the risk of flank intrusion and lava eruption.

            Goma is home to 2 million persons now! all living under threat of fast moving Nephelinitc flows

          • That is correct, and is one of the lessons from Ambrym, and in a way Leilani too. Lava lakes are prone to rifting which can quickly threaten distant regions.

  2. Major problem for Nyiragongo is that unlike Ambrym it has a large lava lake contained within a steep-sided stratovolcano edifice, the sort of structure which could be liable to flank collapse if overstressed. And that lava lake is, well, pretty stressful.

    • Ambryms recent lava lakes during recorded history been pretty small ( 20 to 80 meters )

      But the caldera walls in Marum and Benbow
      Haves thick thick columnar layers of cooled lava
      That where there before these historical craters formed.
      That suggest really huge ancient lava lakes since they look ponded.
      It coud also be simply thick columnar sills.
      You been there and knows exactly what I talks about : )

      • The prehistoric caldera of Marum was filled with thick rootless lava lakes, probably fissure eruptions that ponded inside the caldera, there are also many sills, dikes and lots of tephra. I think Benbow doesn’t have any exposed rootless lava lakes, its walls are made of pyroclastics, sills and dikes

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