Agung again: the eruption of 1963

There was a lot going in the 1960’s. This was the time of the generation battle, where the children who had grown up in a time of austerity and a cold war, rebelled and looked for something different – exploring, ignoring the boundaries but never quite finding what they were looking for. Martin Luther King and John F. Kennedy were shaping the future, and paying dearly. East and West were fighting, from Cuba to Vietnam. Europe suffered through the terrible winter of 1963. Who cared about a volcano no one had ever heard about? Even if it was one of the largest eruptions of the 20th century?

Bali is different. This island of 4 million people has its own culture, and in fact was an independent kingdom until 1906, with a distinct culture. The island is not large: 150 km by 110 km. Most here is volcanic in origin, and those volcanoes, as elsewhere in Indonesia, are alive and active. Several are over 2 km tall. The highest is Gunung Agung, at just over 3 kilometer. The climate is monsoon, with a very wet December to April but little rain from May to September. Tourism is big business, and at times it seems most of Australia is here. It seems paradisiac. But when the fertile soil of paradise comes from volcanic ash, life is never totally secure. The eruption of 1963, little recognised in the rest of the world, brought devastation.

Three volcanoes are located in close proximity to each other. Furthest east is Seraya, deeply eroded with no intention of every erupting again. In the middle is sacred Agung, with Bali’s largest temple, Pura Besakih; the climb to the top takes about four hours from there. West of Agung is Gunung Batur, 2150 meter high, with its enormous, 25,000 year old caldera. Visible further to the east, beyond Bali, is Rinjani, site of the enormous 1257 eruption, showing that this area has history. Batur and Agung both are quite able to erupt. But while Batur does frequent but minor, Agung does dangerous. Its 1963 eruption was a particularly bad one.


Although there had been fumarole activity in the crater of Agung, the mountain had not erupted since 1843. On 16 Feb 1963, with Europe shivering in its worst winter for two centuries, earthquakes began to be felt in Bali, although not strong enough to do any damage. Two day later, 18 Feb 1963, explosive activity began, minor at first. Lava flows were first seen on 19 Feb, one day after the first explosion, flowing through a gap on the northern rim. The lava had probably first appeared together with the explosions the dat before, but this had not been seen. On 20 Feb, a pyroclastic flow which reached one village. These were the first casualties. Rain caused some lahars over the next days.

A video of the early days of the eruption is available on this icon of the 2010’s, youtube:

Over the next four weeks the lava kept flowing although the amounts were not huge. The lava flow reached a length of 7 kilometer. It was 1 kilometer wide and over 50 meter thick; the volume over the next three weeks is estimated at 0.05-0.1 km3. The explosions now began to strengthen, and ash was rising as high as 3 kilometer above the peak of the volcano. From March 8, explosions were becoming severe.

From Self & Rampino

And so the main event began. At 5:30am on 18 March, major explosions began, lasting for 3.5 hours. The ash fell as far as 1000 kilometer away, in Jakarta. One of my secondary school teachers once told me that while he lived in Jakarta, he had experienced volcanic ash – and I think that may have been this eruption. Pyroclastic flows came over the rim of the caldera. Rain coming after the eruption caused lahars. These flows even reached the coast, destroyed villages and caused many casualties.

Besakih temple, threatened by Agung’s eruption

This event took some of the pressure off. The source of the lava flow was cut off after it, and the lava flow slowly came to a halt. Lava refilled part of the crater but it did not overtop the rim again. After 18 March the explosions, although continuing, lessened in intensity and by the middle of May, the eruption seemed to be subsiding. But this was deceptive. On 16 May, there was another major explosion, lasting 4 hours. Again the pyroclastic flows came, and again there was major destruction, now mainly around the foot of the mountain. Two days later there was a larger earthquake, and more explosive events although not of the same size. The lava now stopped completely. After the end of May, the explosions became less, and although the eruption continued until 1964, from here on it was a minor one. But when the rainy season started, in November, the ash soaked up the rain, became unstable and started to move. This again lead to devastating lahars, and even more casualties. And near the end, Batur joined in with its own, unrelated eruption.

By the end of the eruption, over 1100 people had died and the economy of Bali had been devastated.


During the first four weeks of the eruption, lava flows and explosive activity occurred at the same time from within the caldera. It seems problematic that these came from the same location; more likely is that there were several vents in the caldera, some giving phreatic explosions and one or more expelling lava. But no observations were made within the caldera. It was, after all, during the peak of the rainy season.

The ash of the 17 March eruption was blown to the west, covering all of Java. On the slopes of Agung, the layer was up to 50 cm thick, and it reached 0.1 cm in Jakarta. The ash of the 16 May was less widespread, and was blown mainly the the north where the layer reached 40 cm in depth. Much was blown out to sea, and some fell 175 km away on the island of Sempanjang. Pyroclastic deposits are found in the valleys on the slopes of the volcano but it appears they did not reach much into the low lands. Instead, the major damage was mostly done by the lahars, which was partly due to the fact that the main event occurred during the rainy season. In a way, this was a foreshadowing of what would happen later at Pinatubo, where the eruption coincided with a typhoon.

So how much did this 1963 eruption erupt? The ash layers are fairly well mapped, and summing everything up suggest that the 17 March event caused 0.4 km3 of ash. The 16 May event is less accurately mapped, but it is estimated at 0.3km3. This is fresh ash: the dense-rock-equivalent (the hole in the crater it left) is less, and this is estimated at 0.28 km3 in total. Adding the lava makes the total eruption 0.4 km3 DRE.

The precise cause of the event is not known, hampered by a lack of observations. The deposits show that two lava types mixed in the eruption. Self & Rampino suggest that older, andesite magma was already present, and that in Feburary 1963, new basaltic magma was injected into this reservoir. This resulted in lava filling the crater and causing the highly viscous lava flow. A second pulse of fresh magma high in volatiles caused the 17 March explosion. The magma became capped, but in May this cap broke because of the pressure from below, and a new explosion occurred.

Although the ash cloud was only reported to be 10 km high, it likely was much higher than this. The eruption rate makes it likely that it reached twice as high, 18-20 km. In fact, a year later a plane measured some ash from this eruption at 20 km altitude. Not only had the plume reached the stratosphere, some of the ash there stayed aloft for a long time.

After 1964, Agung went back to sleep, and the people returned to the local villages. The mountain would sleep for over 50 years. But now, a prince has come and kissed the sleeping beauty awake. A new injection of magma has taken place, and since a week there is explosive activity. I today’s event, like in 1963, the ash is reaching some 3 kilometer above the mountain, 6 kilometer above sea level. And again it has started close to the rainy season.

It is difficult to predict how this will evolve: If it remains similar to 1963, the next step will involve lava, which may be viscous and slow moving. However, eruptions rarely do copy each other. There are lessons, though, and they show that the biggest danger is not from the lava, and not even the pyroclastics. Once the rains come, the biggest danger is from lahars, coming down the river valleys. Following those valleys, they can reach far beyond the mountain.

Agung has history, and the history shows that this sacred mountain should not be taken for granted. The current eruption may end without much more activity: volcanoes do as they please and if we are lucky, the gods have now ben satisfied, the prince giving his marching orders, and the mountain allowed to fall asleep again. However, if it behaves as in 1963, this may just be the beginning and we could be in for a dangerous few months. Only time will tell.

Lahars covering a village, March 1963


Main reference source:

Self, S., & Rampino, M. R. (2012). The 1963-1964 eruption of Agung volcano (Bali, Indonesia). Bulletin of Volcanology, 74(6), 1521-1536.

389 thoughts on “Agung again: the eruption of 1963

    • As a general rule links to images have to end in some image extension like jpg or gif or png… any thing else denotes scripting or a server fed image. Those tend to fail since WP is at the whim of whatever the 3rd party site does and will give up on trying to retrieve the supposed image due to security concerns for the person reading the page. (no logical reason to pass on what could be malicious activity from 3rd party site) With a proper image extension, the WP server knows what it is supposed to receive and if it’s different than what’s expected, it can see that.

  1. As JuleP pointed out, a very strong continuous sieismogram signal that lasted for 45 minutes and then slowly faded out. Tremor or passing lahar? Now seismic signal back to low noise line. The ash emission seems weaker..

    • I think, It can be lahar/flood, if it passed near the seismic station. TMKS is the only one of eleven stations around the Agung and we don’t know how it impacts on over seismograms.
      This tremor is not visible in JAGI seismogram (150 km west of Agung). I remember M2,5 – 3 Agung events shown on Jagi seismogram.

      • I think the entire Vatnajökul area is interesting. There is the swarm at Herðubreið and Askja. Then we have a pattern of quakes between Bárðarbunga and Kverkfjöll that reminds me a bit of pre Holuhraun activity. The last week we have also seen a batch of very deep quakes and quite a lot of activity along the Holuhraun dike. Then there is of course Öræfajökull, where the activity keeps on going. In the middle of it all, Grímsvötn seems to be holding its breath, waiting…

        I think we are in for interesting times in Iceland.

  2. If you are a new of infrequent commenter, you may find that your comment does not appear here immediately after it is submitted. What happens is that our protector quarantines such comments, and puts them in a ‘to be approved’ queue. The comment has to wait for an admin, and that may take anywhere from minutes to hours. Once a comment is approved, the protector gets the message and tends to leave future comments alone. We ask for your patience!

    • Apologies for an inappropriate and probably offensive comment the other day. Must have swallowed placebos instead of my common sense pills.

      • That is fine, and thanks for the apology. These things happen. I am happy to accept corrections where errors were made – and typos are rather common in posts that were written late at night and in a hurry!

  3. Some more pondering from me. It has been suggested that the night time bukit asah camera is in IR mode rather than low light, i’m not so sure. Looking at the images last night, the glow looked to me to be reflective. If the camera was picking up true incandescent material then i would assume the entire ash column would be glowing, not just the right hand side as seen from that cam? Now watching it in twilight (cloud free hurrah!) to see if there is any colouration apparent in daylight mode before the switch over to night mode.

    • I think the operator of that cam read this and decided to play a little trick on you. Just after your comment was posted, the camera was turned away from the mountain 😉

    • Just as i go to look, someone is manually moving the camera about and have just been given a 360 panoramic tour (18.45 their time) – this may be helpful in locating the cams actual position.

      • Bukit Asah as on google earth is actually a very good fit to that 360 degree tour we have just had, unable to spot the actual pylons however. This puts the cam at 19km from the summit and the lights/settlements in the foreground are much further out than i assumed, which is a good thing really.

      • It seems both cameras are now frozen !
        There’s a growing danger of me actually getting some work done….. This can’t be a good thing.

        • Eruptions come in bursts – lots of activity, followed by days of inactivity, followed by a new burst or by turning off. Just like us, really.

        • work?? i even regret having to get up and make coffee.. 😉 (kidding! just got thu Thanksgiving which is really busy here and the Grandkids on the computer works as a natural control for me 🙂 )

    • Some red colouration was evident in the plume as darkness descended, switch over was at 18.57 and the night cam glow was much more extensive. Still not entirely sure if the glow is reflective or inherent to the plume, from what i’ve seen, especially the red colouration this evening id err towards it being inherent to the plume. It’s possible with there being more than one plume source that there is mixing between hotter (ash) material and cooler (steam) thus an uneven appearance if the camera is recording in IR?

    • 12.05pm: Larger eruption may be “imminent”

      The latest BNPB statement said: “Continuing plumes of smoke are occasionally accompanied by explosive eruptions and the sound of weak blasts that can be heard up to 12 km (seven miles) from the peak.

      “Rays of fire are increasingly visible from night to the following day. This indicates the potential for a larger eruption is imminent.”

      • 12.25pm: Explosions throw out molten rock and ash

        David Pyle, a volcano expert at the University of Oxford, said: “It remains possible that the eruptive crisis could continue for some time.”

        He added: “What we are seeing at the moment are small explosions, throwing out hot gases and fragments of molten rock, or ash.”

      • I think this report was from yesterday. Things are quieter today and ‘imminent’ may mean next month!

    • Ok, so if I read the translated Indonesian article correctly, the tremor was recorded at 11 different points around the mountain. Then I think it is safe to rule out a lahar local to the one station available to the public. I still wonder about the spectrogram signature. Why is it not showing any lower frequencies?

      • That does not really inspire any confidence that things might settle down. Would i be correct in thinking that tremor like this may caused by fresh magma at depth starting to degas as it rises into the system?

      • I am not convinced this was volcanic tremor. Lahar activity fits the duration and signature, with a slow decline. But let’s see what the official reports say.

    • Sat in front of the screen it looks like a ghostly face, but stepping a few feet back from the screen then wow, that is a rather unnerving likeness!

      Last night after neil and macusn mentioned seeing things in the night cam – i promptly saw a dragon head/face, followed by a cartoon style sauropod and eventually a teddy bear. Obviously the night time images are of a friendlier nature.

    • From Wikipedia:

      Pareidolia is a psychological phenomenon in which the mind responds to a stimulus, usually an image or a sound, by perceiving a familiar pattern where none exists (e.g. in random data).

      Common examples are perceived images of animals, faces, or objects in cloud formations, the Man in the Moon, the Moon rabbit, hidden messages within recorded music played in reverse or at higher- or lower-than-normal speeds, and hearing indistinct voices in random noise such as that produced by air conditioners or fans.

      The word derives from the Greek words para (παρά, “beside, alongside, instead [of]” — in this context meaning something faulty or wrong) and the noun eidōlon (εἴδωλον “image, form, shape.”

      • Quick follow-up. As an example of Pareidolia, I often see Bozo the clown in Carl’s avatar. 🙂

        • I have become Bozo, the Destroyer of World’s…
          It was Lurking that originally posted that image, and for reasons regarding the post about nuclear bombs and Baekdu I found it a good fit for me.

  4. With all the scaling changes, assigning an amplitude is a bit “iffy”…but overall the seismic signal appears to be the strongest we’ve seen to date (I think). I don’t think a lahar would result in such a strong signal.

    • I think if THAT was caused by a lahar, it would be of such a scale that we would have heard news of it by now.

      • If a lahar or landslide passed by close to the seismometer it could perhaps cause such a signal. However, If the report stating that many other sensing instruments around the mountain gave similar signal amplitudes, it would be hard to explain it with a lahar/landslide..

        • Not a lahar according to a couple of articles in the Bali Tribune / Giggle translate:

          Apparently there is a continuous tremor (overscale) that occurred at 13:30 to 14:00 pm.

          Head of Disaster Mitigation Division of Volcanology and Geological Disaster Mitigation Center I Gede Suantika said during the Gunung Agung crisis, the tremor earthquake happened continuously and this phenomenon was the first time.
          According to him, conditions that occur indicate Mount Agung entering a critical phase to a larger eruption.
          “It has entered a very critical phase for a bigger eruption, as volcanic material is quite large, just this time noting an overscale tremor,” said Suantika.

          Precisely on the north side of Mount Agung.

          The rain stones shortly after the overscale tremor .
          The stone was hot to 500 degrees Celsius.
          Hotter than the crater lip.
          Head of Mitigation Division of Volcanology and Geological Hazard Mitigation I Gede Suantika, Tuesday (28/11/2017) explains the throwing of stone that begins shortly after the overscale tremor.
          “Tremor overscale was indeed followed by a stone throw,” said Suantika.
          He also added why the direction of throwing occurred in the Kubu region is more due to the crater of Mount Agung is leaning lower on the north side.

    • Ash?.. Or rain? Currently rain in the area according to my weather service.

  5. I haven’t watched the web cam frequently enough to be able to picture the layout in the dark but that glow in the middle above the electric light – is that lower down the slop or is that from the crater? It fades in and out or possible grows and diminishes.

    • They’ve recently changed the angle of the camera. That, if you mean the one that is just about squarely in the centre of the screen, is the crater.

    • It will affect the work of a great many people there…and it will affect me. I run a fair trade gift shop. A significant part of my stock is sourced from that part of Bali.

      • It shows elevation differences between two epochs. The colours together cover 2.8 cm. Where colours repeat, the difference adds up. Going from north of Agung to its summit yo can count 8 blue lines. That means that the summit has inflated by 8*2.8cm which is around 22 cm. For some reason the radar observations east of the summit didn’t give a result. Dense vegetation is a possible cause.

          • They are hard to count and you may well be right! Of course, on the far side of the summit you start counting down again..

          • I too count 12 lines, it is easier to see when you filter out the green & red:

        • Quickly simple estimation based on equation of cone volume and radius 5km.

          (1/3) *3,14*5000m^2* 0,33m = 8,6 mln m^2 =0,0086 km^2 Enough for VEI 3
          But it is about only 12 days and after the main Agung seismic activity decreased.

          There is also earlier Interferogram which shows the inflation soon before the seismic unrest started. (6-18 september)

          • Yes – the pattern in the LIDAR image closely matches apparent density of vegetation as seen from satellite images.

        • How do you tell whether you should count up or count down, since blue is both at +2.8 and -2.8?

          • I always that very hard to see! I have been assuming that this was taken before the eruption. If after, some deflation was possible as well. Also, when magma goes into he final kilometer, it can cause deflation at larger distances

  6. Activity seems have dropped to very low level for now, only a slight plume from the crater. Have we reached VEI-3 yet?

    • Not official. But by my estimate → 1.0420905 x 107 cubic meters.

      • And remember, that’s just my estimate of DRE expended as ash. When the magma gets into the show, my numbers go into the toilet and only serve as an estimate of the lower bounds of what the DRE is officially tallied up to. Even at that, my estimate is a poor guess since I haven’t grabbed data from every single VAAC report. Another source of error is from the fact that Darwin VAAC is not concerned about the accuracy of the height estimate and ALWAYS errs on the side of flight safety. This could lead to overestimating plume height. We are just leaching off the free data to get our volcano fix.

  7. I think I am seeing some orange/red tint to the clouds closest to the rim.


    • Yes, significant uptick of activity over the last 30 minutes

      (Rescued from the Netherworld /Lugh)

  8. What worries me is that Agung still shows continuing inflation despite the significant venting in the last few days. Some volcanologists who are there say the decreasing activity is not a good sign.

  9. If you have yet to see this picture of a “dirty storm” (lighting on an erupting volcano) you will have to check this out. It is a 10 min exposure of Volcán Calbuco in Chile. Check out the star trails on the right side of the photo!

    “At at the Volcán Calbuco in Chile, photographer Francisco Negroni captured a stunning example of the phenomenon, winning second prize at this year’s Epson Pano awards.”


  10. The aircraft ash warning zone has shifted as the wind has moved more to the NE, now – and for the forecast up to 18 hours – the airport at Denpasar is clear. According to some reports I’ve read, over 100,000 people are stuck in Bali due to travel disruption.
    But even if the air above Denpasar is clear, I don’t know how they can work it. Presumably there will be a shortage of inbound tourists – and I’m not sure if airlines will be wanting to take the risk to fly empty aircraft in to evacuate tourists, with risk the planes could be stuck on the ground if the weather changes and/or the eruption intensifies. It seems like a logistic nightmare – let alone what insurer’s attitudes will be.
    I see a Batik Air 737 is headed to Denpasar from Perth, it’s about an hour and a half out now – on flightrader:

    • Interesting, the airport was supposed to stay closed, but all the tourists that said they were going anyway, are VERY unhappy, and lots of kids there on school break, wonder if the teenagers are leaving first?

        • Yes – looks like a change of plan – the plane’s transponder is back in range of flightradar – looks like it’s headed to Lombok – it may have been headed there anyway but flightradar had Denpasar as the destination based on flight number. The airport was supposed to have been closed.
          Some of the kids there on a school break are what the Aussies call “schoolies” – kids who have finished the end of last year of high-school, and traditionally spend time getting as drunk and obnoxious as possible – as a rite of passage into adulthood, apparently.

          • Oh wait – not it isn’t – it flew straight over Lombok at 38,000 feet, heading NE to goodness knows where.

  11. For reference… 1991 Pinatubo was about 1000 times larger, and 1815 Tambora was 16000 times larger… give or take. Eyjafjallajökull – 25 times larger in ash production. (So far)

  12. Bukit Asah cam is shaking. Wind or seismic? Cannot get to the drumplot at this time


      • There’s been another burst of strong (presumably) volcanic tremor over the past hour. Not a lot visible on the webcams – except cloud.

  13. Looks like the same harmonic tremor as yesterday has started/continued at almost the exact same time. Perhaps this is linked to precipitation during the morning/early afternoon as the clouds roll in? With the tropical storm nearby the rainfall amounts might not be so small, and could possibly help trigger steam eruptions/volatility within the crater?

    Seems too coincidental in timing and period to be random… but I am probably wrong!

    • There were reports in the local paper that the episode last night coincided with fist-sized rocks falling on a village about 4km north of the crater, so I think it’s only coincidence that another strong tremor is showing approx 24 hours later.

      • I know it’s a significant distance away, but the camera at Rendang is showing little or no wind.

        • Seems to be frozen at the mo.

          Link here for two cams that seem to be outside both the ash fall and rain storm zone at least, but still a lot of cloud about.

          • Bukit Asah cam working again. Still very murky, although it has lifted a little. Clearly raining, with ash in the rain.

    • I was assuming it was wind but the seismo has been off scale for the past ten min.

      • Yes – I’m having some difficulty connecting, presumably their server is getting hammered – but this is the latest seismo image I could get:

        • Dr Janine Krippner‏Conta verificada
          1 minHá 1 minuto
          Mais Dr Janine Krippner retweetou Elaine Brown
          Seismogram: This means that the signal is too large to be shown here, they have intentionally clipped the data so it doesn’t take up too much of the screen. Red = where they have clipped the data

  14. Hi, just found my password. Pardon, just checking in on you and Bali and I should land in the neither regions?

      • nether in the neither… Oops. Thought my mail would go to the dungeon first, giving you a chance to delete it. Did not want to irritate all with my testing.
        Had a question, but now it has embarrassed itself into thin air. Will be a good hen now until the question resurfaces.

  15. The Bukit Asah cam, and the mast that it seems attache to has been shaking for several hours and it is not more severe than before the onset of high amplitude drum signal. Not clear what causes this shaking.

    Bali tribune newpaper published today an article on yesterday seismic event. Google translate of the text makes me understand that yesterday reports on volcanic lava-bombs/stones shot from Agung are not true or could not be verified… So, it will be exciting to se what reports that comes out of this seismic event.

    • That camera is zoomed quite a way in to the volcano. It seems to be susceptible to wind movement.

  16. Drumplot line shown on some live streams (youtube) suggests that high amplitude tremor is coming and going the last hours. Interesting, Exciting, SCARY!! Let us hope the evacuations were effective and enough extended!

    • Thanks Pyter, This report suggests that the water rich matherial is already mostly lost and cannot cool down the lava anymore. Wonder if the next level will be a slow spill over or if it will go explosive?

  17. some glow showing in the clouds at 19:35. More to the right of where we have been seeing it. Could be due to the shift in the winds.


  18. This is me writing a very long sentence to test if it is linebreaks or return strokes that causes the boonfangled problem of wordpress and Edge, so let us what is happening now without a return stroke.

      • Don’t use return key strokes when using Edge and you should be fine. We will have mighty long paragraphs for a while the WP techs fix the problem.

  19. Not very is seen on this seismometer about 150 km away suggesting that the high amplitude activity on Agung may be very close to the seismometer and perhaps not as strong and dramatic as we tend to think.

  20. What’s happening in the spectrogram? Something seams to be changing…

    • seems they have made a new setting at around 2125. Low frequency signal is now up strongly compared to before. Could mean moving magma. ( Śóḿéóńé´from the expert group need to comment on this guess).

      • I think the scaling changes every single row, so that the maximum amplitude is always red. In my opinion this makes the spectrogram very hard to read.

    • Low frequency tremor almost disappeared during the continuous tremor at 14:30 – 18:30.

    • Carl says to “be nice”, so I’m not gonna say anything other than the author of that article is a dipshit. “Like Mount Agung, one of the last known super-eruptions… Yada yada yada..”

      The only thing “like” about that stuper eruption and Mt Agung is that they are both volcanic features on a rocky planet near a small yellow star. It’s like Katla being similar to Mt Ranier. Both have ice on top.

    • Thanks Ian for updated map. Iceland boils on! Will be an exciting 2018!

    • A VEI 6 eruption is at least needed to have any significant effects on global temperature. I doubt if Gunung Agung is able to do this.

    • Something seems to be heading towards the lights I just hope this area has been evacuated.

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