So, some of you may have found my tones regarding the spreading disinformation on #Krakatau somewhat annoying, for which I am sorry. What is far more annoying, though, is that people create and start divulging false and alarmist information ...
... which, especially in our current situation, is not doing anything good for anybody. Volcanologists (as scientists working in many other disciplines) have to fight a constant battle about uncorrect or plainly false information. Unfortunately ...
... once false "news" starts circulating, there's hardly a way to stop it, and immense work is required to rectify and spread the correct information. Why is that? Because false information is not only misleading but often intended to create anguish and deflect from other issues.
Now, in the specific case of #Krakatau, we have here a volcano that is particularly notorious, because of its infamous, deadly eruption in 1883. Some sources of the latest false information state that it has not erupted since, and that is enormously wrong.
After its self-destruction in 1883, when a large portion of the original volcanic island vanished, the volcano lay silent for some 44 years and then reawoke in 1927. The initial activity was under the sea, in the huge collapse depression (caldera) left after the 1883 eruption.
This new activity created a new cone, which grew from the bottom of the sea and eventually pierced the sea level, building into a little island, which was named "Anak Krakatau" - the Son of Krakatau. Still, for several decades, the crater of this volcano was below sea level.
This was because the cone was growing on a steep submarine slope, and erupted materials preferably accumulated on the side above the slope, whereas on the other side, it continued sliding down that slopw. Only by the early 1960s, the vent was entirely sealed from the sea.
The activity now became "magmatic", which means, there was no further interaction with external water as before. There were now lava flows, and the explosive activity was of a very typical style, called "Strombolian" after the famous volcano north of Sicily, Stromboli.
Every now and then there were some more powerful explosions (these are called "Vulcanian", after another volcano on the Aeolian Islands north of Sicily, Vulcano), and at other times modest lava fountains like those often seen at Etna, Pacaya, Villarrica and some other volcanoes.
Anak Krakatau was active through most of the 1970s, in 1980-1981, 1988, and then nearly always from 1992 on, with breaks between main eruptive phases rarely lasting more than one or two years. This activity built the cone of Anak to a height of well more than 300 m.
Problem was, this beautiful, aesthecially appealing cone with its hauntingly spectacular activity still rested on that old, steep submarine slope, and its continued growth made it more and more unstable and prone to disastrous collapse. That collapse occurred on 22 December 2018.
The collapse was accompanied by violent explosive activity, partly due to interaction of the conduit that was suddenly exposed again to sea water, in part to instantaneous decompression of the magma that was in the conduit at that moment (it had been erupting for a while then).
Following the 22 December 2018 collapse, Anak Krakatau looked very much like it had done during its early stages (1920s through 1950s), the vent was again below sea level, and the activity was typical for magma-water interaction.
But gradually, the eruptions continuing intermittently through 2019 built up a new rim around the crater, which was then filled by a lake, and the explosions broke through the lake, whose bottom gradually became shallower by accumulation of the new eruptive products.
At the end of 2019, a new cone started emerging from the lake in the crater, and some of the sporadically occurring explosions showed again a magmatic character, indicating that magma-water interaction was diminishing. But eruptions have been rare in the past few months.
The activity that started on 10 April 2020 apparently started once more with magma-water interaction but then became fully magmatic, with Strombolian explosions and lava fountains. This is the type of activity needed to rebuild the cone lost in December 2018.
So to make it clear, currently Anak Krakatau does *not* have that beautiful, symmetrical cone that you see in many of the Tweets and other messages circulating on the Internet since yesterday. That cone ceased to exist on 22 December 2018.
Obviously, having followed me through this long thread, you are well aware, that Krakatau - represented by its post-1883 cone, Anak Krakatau - has been erupting very, very frequently for the past nearly 100 years, so the info saying it's not been erupting for 140 yr is ... crap.
The current activity is, from what can be understood, pretty much of the same character as various moments of Krakatau's activity between 1927 and 2019, and nothing really new for this volcano, and certainly no threat except for its immediate surroundings.
Having already collapsed catastrophically in December 2018 and being virtually absent since, the cone will very likely not undergo major collapse for some time to come, but rather grow to its pre-2018 size and possibly beyond, before it might collapse again.
Finally, a word about the name of this volcano. Its Indonesian name has forever been Krakatau. For some obscure reason, while redacting the report of the British scientific commission on the 1883 eruption, the name "Krakatau" was replaced in the manuscript by "Krakatoa".
Which means: though Indonesia at the time was not a British but a Dutch colony, this introduction of a false name was a clear act of colonialism, which unfortunately has never been thoroughly corrected. Now volcanoes and other geographic features all over the world ...
... are getting their original, indigenous, pre-colonialism names back - such as Taranaki (ex Mt Egmont) and Whakaari (ex White Island) in NZ, Denali (ex Mt McKinley in Alaska), so I guess it's about time that everybody honors Krakatau using its true, original name.
That was my long-overdue rant. Thank all of you who have followed through to here 🤗, and those who, unintendendly by diffusing the false information of yesterday, have stimulated discussions and finally this thread of mine. Now let's return to Etna ... and more of my music 😊
