Erupting Volcano Anak Krakatau (APOD 2009 July 13)

[neufer]

http://apod.nasa.gov/apod/ap090713.html

<<Before the 1883 eruption, Krakatoa comprised three main islands: Lang ("long", now called Rakata Kecil or Panjang) and Verlaten ("forsaken" or "deserted", now Sertung), which were edge remnants of a previous very large caldera-forming eruption; and Krakatoa itself, an island 9 km (5.6 mi) long by 5 km (3.1 mi) wide. Also there was a tree-covered islet near Lang named Poolsche Hoed ("Polish hat", apparently because it looked like one from the sea) and several small rocks or banks between Krakatoa and Verlaten. There were three volcanic cones on Krakatoa: Rakata, (820 m/2,700 ft) to the south; Danan, (450 m/1,500 ft) to the north; and Perboewatan, (120 m/390 ft) to the north (Danan may have been a twin volcano).

http://earthobservatory.nasa.gov/IOTD/view.php?id=3844

Verbeek, in his report on the eruption, predicted that any new activity would manifest itself in the region which had been between Perboewatan and Danan. This prediction came true on 29 December 1927, when evidence of a submarine eruption was seen in this area (an earlier event in the same area had been reported in June 1927). A few days later, a new island volcano, named Anak Krakatau ("Child of Krakatoa"), broke water. Initially, the eruptions were of pumice and ash, and it (and two later islands) was quickly eroded away by the sea; but eventually Anak Krakatau #4 (broke water in August 1930) produced lava flows faster than the waves could erode them. Of considerable interest to volcanologists, this has been the subject of extensive study.

Since the 1950s, Anak Krakatau has grown at an average rate of five inches (13 cm) per week. The island is still active, with its most recent eruptive episode having begun in 1994. Since then, quiet periods of a few days have alternated with almost continuous Strombolian eruptions, with occasional much larger explosions. The most recent eruption began in April 2008, when hot gases, rocks, and lava were released. Scientists monitoring the volcano have warned people to stay out of a 3 km zone around the island.

http://earthobservatory.nasa.gov/IOTD/view.php?id=5638

There are two generally accepted modern spellings, Krakatau and Krakatoa, although it must be mentioned that Krakatau is frequently misstated as Krakatoa and Krakatau is the only official name. This is most likely caused by a British journalist (the result of a typographical error: the journalist swapped the 'a' and 'o' of the Portuguese spelling) who reported on the massive eruption of 1883. Also, like Egypt a couple of decades earlier, Polynesia (South Pacific) was in vogue in the late 19th century, and the Polynesian-like suffix -oa (as in Samoa) may have caught on as a result. While Krakatoa is more common in the English-speaking world, the Indonesian Krakatau tends to be favored by others, including geologists. Verbeek seems to have started the modern convention of using Krakatau for the island proper and reserving Rakata for the main cone.>>

[ta152h0]

I am taken by the artistry of the image where not only stars are in focus but also nearby vegetation. Was a pinhole cameara used ???

[Chris Peterson]

I am taken by the artistry of the image where not only stars are in focus but also nearby vegetation. Was a pinhole cameara used ???

No, it appears to have been an ordinary digital camera. The depth of focus is consistent with a short focal length (wide angle) lens.

[apodman]

Krakatoa, East of Java (1969) is a movie starring Maximilian Schell and Brian Keith ... Krakatoa is, in fact, west of Java.

[neufer]

Krakatoa, East of Java (1969) is a movie starring Maximilian Schell and Brian Keith ... Krakatoa is, in fact, west of Java.

1) Krakatoa is east of the western most tip of Java
2) Krakatoa is still 39,000 km east of Java
3) Krakatoa may oscillate from being west to being east of Java
in some sort of Kwazy Quasi-Quantum Kwakatoa Oscillation.

The discovery of the Quasi Biennial Oscillation (QBO)

<<In 1908, westerly winds were observed at about 15 km (100–150 hPa) using weather balloons launched near Lake Victoria in Africa. These westerly winds provided a conundrum: dust from the Krakatau volcano (6°S, 105°E) eruption on August 27th 1883 had traveled in a westward direction, taking 13 days to circle the equator. To resolve this conundrum, the notion of "Krakatoa easterlies" at around 30 km (10 hPa) and "Berson westerlies" around 20 km (50 hPa) was proposed.

Improved insight on the behavior of the lower stratospheric winds came in 1961, when Reed and others used time series of radiosonde data to demonstrate that the stratospheric and upper tropospheric zonal winds above the equator oscillate. Further research showed that the alternating easterly and westerly wind regimes and associated temperature anomaly descend with time and that these variations are also present in total ozone. Since this oscillation had a period between 26-28 months, it was dubbed the “quasi-biennial oscillation” or QBO.>>

<<The Krakatoa, East of Java (1969) producers learned of the geographic error only after all of the advertising and publicity materials had been prepared. It was deemed too costly to re-do these materials, and possibly delay the release, for the sake of simple geographic accuracy.>>

[oolioo]

re: APOD 7/13/09
How does an island "grow at an average rate of 2 cm per day"?

[bystander]

How does an island "grow at an average rate of 2 cm per day"?

I can only assume they are referring to average diameter or radius. It does seem odd to use a linear measure when a measure of area (cm²) would seem more appropriate. Even the wiki article Art mentioned uses linear measure when talking about growth rate.

[Chris Peterson]

re: APOD 7/13/09
How does an island "grow at an average rate of 2 cm per day"?

It means that the height of the island is increasing at this rate.

[neufer]

How does an island "grow at an average rate of 2 cm per day"?

I can only assume they are referring to average diameter or radius. It does seem odd to use a linear measure when a measure of area (cm²) would seem more appropriate. Even the wiki article Art mentioned uses linear measure when talking about growth rate.

Mountain growth is generally given in terms of altitude:

Eruptions at the volcano since 1927 have built a new island in the same location, named Anak Krakatau (Indonesian: "Child of Krakatoa"). This island currently has a radius of roughly 2 kilometres (1.2 mi) and a high point around 300 metres (980 ft) above sea level, growing 5 metres (16 ft) each year.

[bystander]

Mountain growth is generally given in terms of altitude:

Eruptions at the volcano since 1927 have built a new island in the same location, named Anak Krakatau (Indonesian: "Child of Krakatoa"). This island currently has a radius of roughly 2 kilometres (1.2 mi) and a high point around 300 metres (980 ft) above sea level, growing 5 metres (16 ft) each year.

...

Since the 1950s, Anak Krakatau has grown at an average rate of five inches (13 cm) per week.

... the emerging volcanic island continues to grow at an average rate of 2 cm per day ...

OK, that makes sense, and brings these various estimates into agreement.