Spectacular aerial video of Anak Krakatoa now with crater lake
- The crater area has closed to become a lake which showed steaming (no explosions have been recorded since yesterday, as the activity has continued to calm down, perhaps only temporarily).
- The forest on the island is completely destroyed by ash fall and surges, but still visible.
Rakata Island (Krakatoa): beach destroyed by tsunami waves
The entire beach and the slightly higher, up to 50 m wide forested platform behind it, separating it from the cliff, have been washed away and/or collapsed in landslides following the receding wave.
Surviving fishermen who were in the caldera at the time of the event reported seeing massive waves sweeping over the entire, lower island of Sertung (west of Anak Krakatau), estimating them to be about 25 m in height.
Video was taken by a friend and local guide Black from Carita who also confirmed that the forest and beach of Anak Krakatau are gone as well...
Reconstruction of recent events: collapse, tsunami and regrowth of the Anak Krakatau island
Comparing the morphology of the island as seen on the pictures, a plausible reconstruction of events would be as follows:
22 Dec: part of the lava flow terrace that forms the western shores of Anak Krakatau collapse, probably involving a significant underwater volume. This caused the tsunami that hit the Java west coast around 21:30 local time.
23-24 Dec: additional collapses (but involving much less volume each) in combination with violent explosions remove more material from the island, eating away until the whole summit cone is gone (3rd picture).
25 Dec: heavy and very wet water-lava explosions deposit meters of fresh, wet ash and blocks all over the island, along with sea current that wash the muddy material to shores. This way, the crescent-shaped island seen on the 27 Dec (and later) pictures with the open crater bay is formed. Significant land addition has extended the island's eastern shores (compare the satellite overlay image posted earlier).
Radial erosion gullies formed quickly as result of torrents of water carving down the loose material now covering the island. This water is both from a) heavy rains as well as b) ejected liquid and b) condensation of steam from the water-rich explosions.
Source: Teka Teki Gunung Anak Krakatau (Dongeng Geologi)
Krakatoa volcano (Sunda Strait, Indonesia): extraordinary footage showing intense explosions of water with lava
Even though it is from 40 km away, it shows the activity in amazing detail. It takes place at the island of Anak Krakatau, hidden from view now behind Panjang island seen in the foreground. The active vent is now under water and lets sea water interact violently with the rising magma: the result is so-called Surtseyan activity, a type of volcanic eruption that takes place in shallow seas or lakes, named after the island of Surtsey which appeared off the southern coast of Iceland and had this activity in 1963.
In this video, very powerful explosions can be seen generating jets of ash, debris, steam and water to several hundred meters ("rooster tails") radially from the explosion point.
In addition, large surges (horizontally expanding hot clouds of steam mixed with ash) can be seen sometimes engulfing the whole island of Panjang, which is hiding the view of Anak Krakatau itself.
Be sure to watch to the end, at times, the explosions tend to be bigger and bigger throughout the video.
The video was generously granted for display here by local resident and videographer Doni Janskulo, who lost most of his equipment during the 22 Dec 2018 tsunami that devastated Java's west coast.
If you want to support him, subscribe to his youtube channel or embed this video.
Links / Sources:
Krakatoa volcano (Sunda Strait, Indonesia): ash plume reported to 35-40,000 ft altitude
Seismic activity is still relatively low, but has picked up again after a phase of near absence at the end of 2018.