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Krakatoa awakes

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Krakatoa awakes

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Old 23rd Dec 2018, 11:40
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TWT
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Krakatoa awakes

You have to have sympathy for the Indonesians bearing the brunt of so many natural disasters. Many killed and missing due to an unheralded tsunami at night.

https://www.bbc.com/news/world-asia-46663158

For a reminder about the massive eruption of 1883

https://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa
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Old 23rd Dec 2018, 11:49
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No one expects the unheralded tsunami.

What happened to all that improved,expanded undersea sensor thing after the last one?
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Old 23rd Dec 2018, 12:04
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Originally Posted by meadowrun View Post
No one expects the unheralded tsunami.

What happened to all that improved,expanded undersea sensor thing after the last one?
Not sure exactly which last one you mean, but it is probably not too relevant anyway.

Firstly, Indonesia has way too much coast-line to think that coverage would ever be adequate.
And secondly, I doubt that the system support / maintenance budget would ever be adequate to ensure the system reliability that you or I might desire.
It is the way of the region.

But finally, with Pulau Krakatoa being a very short distance from the Banten coast I doubt that any system will provide a useful warning in that area.
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Old 23rd Dec 2018, 13:16
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Only a few days off the anniversary of the 2004 tsunami (26 Dec)
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Old 23rd Dec 2018, 13:18
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Vulcanic eruptions:

Bigger isn‘t always better.
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Old 23rd Dec 2018, 14:10
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I think it will blow before the Yellowstone supervolcano .
Volcanic winter to follow ,
The further acidification of the oceans , fish stock decline . Starvation and riots in overpopulated parts of the planet reliant on cheap and plentiful seafood.
Mass migration from a starving overpopulated countries like India , China and Pakistan to convert low yeild African farms into high yeild farms using cheap slave or prison labour .
Good Times to follow .
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Old 23rd Dec 2018, 14:23
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The tsunami was most likely caused by an underwater flank landslide, rather than any surface eruption, and there was no significant earthquake trigger or warning.

Anak Krakatoa has been growing for the last hundred years, so its not quite true to say it has just awakened.
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Old 23rd Dec 2018, 17:17
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so its not quite true to say it has just awakened
Given that it's erupting then it is 'awake' . I didn't say it had 'just' awakened as if it's been dormant for 100 years.
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Last edited by TWT; 23rd Dec 2018 at 17:58.
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Old 23rd Dec 2018, 22:42
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The next "biggie may well be like most other "biggies".
Previously unheard of and totally unexpected.
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Old 23rd Dec 2018, 22:47
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Not Krakatoa - translation equates to "Little Krakatoa."

Rob
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Old 23rd Dec 2018, 23:13
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Originally Posted by PPRuNe Towers View Post
Not Krakatoa - translation equates to "Little Krakatoa."

Rob
Sorry again, but you ned to be careful with the translation and what you're referring to.
As I remember from a past visit to the area (fishing), Krakatoa Kecil refers to the vestigial island segment (non-active) lyiing to the ENE of the current active caldera.
Anak Krakatoa is a generalised term referring to all the vestiges of old Krakatoa and including the new active caldera - this translates as "Child of Krakatoa" or "Krakatoa's Child, if you prefer.
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Old 24th Dec 2018, 06:01
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This eruption brings back many memories for me. I lived in Jakarta during the 80s and used to spend weekends at a resort on Carita Beach, on the west coast of Java, looking out over the Sunda Strait towards Anak Krakatau*. I also went on a Boeing hydrofoil, leased from the Indonesian Navy, to view the volcano at close range.

As WingNut60 pointed out, the areas affected by the tsunami are only short distances from the volcano - ranging from 30 to 70 km - so there is very little chance of setting up an effective warning system. On top of that, since this tsunami was triggered by a submarine landslide, there would have been no initial withdrawal of the sea, which is a feature of tsunamis triggered by deep sea earthquakes, prior to the arrival of the first wave.

Here is a map of the Krakatau islands, before and after the 1883 eruption. Verlatan is now Sertung, Lang is Krakatau Kecil and Rakata is Krakatau:



The main island, Rakata, had three volcanic cones, with the southern most one being the highest. After the 1883 eruption, most of Rakata had disappeared and in its place, was a new caldera that was seven km in diameter and nearly 300 m deep. The southern edge of the caldera cut through the middle of the southern cone of Rakata. When I visited there in the 80s, it looked exactly like a textbook cross-section through a volcano.

In 1927, submarine eruptions in the centre of the caldera finally built up to the surface and the new island of Anak Krakatau started growing and had in recent years reached a height of over 300 m.

This website displays technical data about the current eruption:

https://www.volcanodiscovery.com/kra...i/updates.html

and this one contains interesting information about the 1883 eruption:

KRAKATOA (KRAKATAU) VOLCANO - TSUNAMIS GENERATED BY THE EXPLOSIONS AND CALDERA COLLAPSES ON AUGUST 26-27, 1883 - by Dr. George Pararas-Carayannis

Of particular interest are the tide gauge and barograph records from Batavia (Jakarta). Also there is a map of tsunami travel times which shows travel times of 25 to 40 minutes for the waves to reach the shores of Java and Sumatra.

When you drive along the coast of western Java, you can see blocks of reef limestone, weighing several hundred tonnes, which were carried inland by the 1883 tsunamis.

* Spelling: the Indonesian spelling is Krakatau whereas the anglicised version is Krakatoa. Regardless of how you spell it, it's always been west of Java!

https://en.wikipedia.org/wiki/Krakatoa,_East_of_Java
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Old 24th Dec 2018, 06:23
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For a memorable experience I recommend a sunrise visit, on a fine morning, to the rim of Gunung Bromo.
The path around the rim is little more than single file in many places, and you are looking straight down into the caldera.
Have a look on Giggle Mirth to get an idea of what it's like.

You should pick a period of low activity, of course.

The sunrise can be spectacular.
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Old 24th Dec 2018, 07:22
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WingNut,

Bromo is on my bucket list. I never got there when I lived in Jakarta.

An important piece of advice though. In spite of the fact that Java is near the equator, it gets cold up on the volcanoes ( by tropical standards) so take warm clothes. I remember shortly after I arrived in Java, some geology students were stranded overnight on a volcano (maybe Bromo) and some of them died of exposure!

When I posted the link to volcano discovery.com, I meant to point out this remarkable satellite image that might be showing a tsunami wavefront:

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Old 24th Dec 2018, 08:03
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Correct. VERY cold.
You need to travel out over the Sea of Sand to get to the base of Bromo for a relatively easy ascent (500') to the top of the rim.
When at the top you begin to realise that Bromo is only a pimple in the middle of the greater caldera; somewhat similar to the current Krakatoa
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Old 24th Dec 2018, 12:54
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Originally Posted by PPRuNe Towers View Post
Not Krakatoa - translation equates to "Little Krakatoa."

Rob

yes, "son of Krakatoa" Anak Krakatau
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Old 24th Dec 2018, 13:48
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India Four Two, your latest photo partly answers something that has been bothering me for a while now.

If the central cone collapsed or slipped down one side, surely any tidal wave would have been seriously disrupted by the three remaining islands ringing it. Did some kind of misshapen tsunami escape out through the three windows, I wonder, hitting certain sections of Sumatran coast north west, and Java coast south east of Krakatau?
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Old 24th Dec 2018, 13:55
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Originally Posted by ironbutt57 View Post
yes, "son of Krakatoa" Anak Krakatau
Sorry to be pedantic again, but Anak (alone) = "child", it is gender neutral.
Two expressions that are commonly used for child are "anak laki-laki" (boy child) or, occasionally, "putra"; putra being more Javanese than general Indonesian.
Anak Krakatoa is best translated, I believe, as Child of Krakatoa.

And so also says the lady leaning over my shoulder (SWMBO).

Last edited by WingNut60; 24th Dec 2018 at 14:10.
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Old 24th Dec 2018, 14:14
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Originally Posted by jolihokistix View Post
India Four Two, your latest photo partly answers something that has been bothering me for a while now.

If the central cone collapsed or slipped down one side, surely any tidal wave would have been seriously disrupted by the three remaining islands ringing it. Did some kind of misshapen tsunami escape out through the three windows, I wonder, hitting certain sections of Sumatran coast north west, and Java coast south east of Krakatau?
Pure speculation, but in my mind I can imagine the wave being spurted through the gaps between the islands in a cone fashion, like water from a garden hose nozzle.
Someone with a good grounding in fluid dynamics might seek to differ.

Which flank of the cone slipped would, of course have a direct impact on which way the energy release was focused.
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Old 24th Dec 2018, 14:35
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The Gods are angry , time for some sacrifices
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