In the Sunda Strait in Indonesia, a tsunami hit both the west coast of Java, facing the volcano Krakatau, and the east coast of Sumatra on December 22 in the evening.
A first announcement is made by Oystein Lund Andersen at 21:15 BST, in vacation at the hotel Anyer. He was busy photographing the erupting Krakatau when he saw a big wave coming ... he ran away, while the wave was passing the beach and engulfed in the land for about twenty meters. A second wave followed, entering the hotel and sweeping cars. He took refuge with his family on the heights by forest roads, and are all safe and sound.
Anak Krakatau 22.12.2018 / 19:03 local, about two hours before the tsunami - photo Oystein Lund Andersen
These devastating waves were not attributed to a tsunami at first, in the absence of characterized seismic signals.
The event is large and the number of victims recorded is growing: at the time of writing, there are at least 168 dead, 30 missing and 745 injured (Sutopo Purwo Nugroho / BNPB); the material balance is also heavy, with more than 500 homes damaged, and roads cut.
The hypothesis of a flank collapse or submarine slide of the Krakatau at the origin of the tsunami must be verified.
A premonitory tweet of March 2018 by Simon Carn warned of the potential danger in connection with the constant erection of the Anak Krakatau on the edge of the caldera formed by the eruption of 1883.
Anak Krakatau - location of its edification on the edge of tne 1883's caldera - Doc. Attached to Simon Carn's tweet in March of this year
Images from the Himawari 8 satellite show that ash reached 12-14 km after the eruption; other sources mention a height of 16 km.
A pronounced "cool spot" was observed on infra-red satellite images above the volcano, indicating very high clouds, and a large post-eruptive pyrocumulonimbus.
An update upon receipt of clarification.
To be continued ...
Sunda Strait - IR image of the Himawari 8 satellite on 23.12.2018 / 00h - to pick up the "cool spot" above the Krakatau
A notice from VAAC Darwin this morning
DTG: 20181223 / 0545Z
VOLCANO: KRAKATAU 262000
PSN: S0606 E10525
SUMMIT ELEV: 813M
ADVISORY NR: 2018/368
SOURCE INFO: HIMAWARI-8
AVIATION COLOR CODE: RED
At 16h WIB, the BNPB revised the tsunami report to the rise: 222 dead, 843 wounded, 28 missing - 556 homes and 9 hotels, 60 food stands and 350 boats damaged.
Sutopo Nugroho warns of the potential threat of another tsunami, with notice in place until Monday. It is important not to be on the beaches around the Sunda Strait, especially during high tides during the full moon.
Testimony of Tsunami Violence - Indonesian band Seventeen was in concert on Tanjung Lesung beach when the tsunami swept the site, killing the manager and the bass player; four other members of the group are reported missing.
Update - 2
The hypothesis of a collapse of the Krakatau is clear:
A radar image of the Sentinel-1 satellite appears to confirm a partial collapse of the Krakatau cone (and shows concentric waves coming out of the caldera) - via R.Natsuaki / Simon Carn / Twitter.
An aerial photo of Susi Air / Twitter comes in support.
Anak Krakatau - image Sentinel-1 from 22.12.2018 / 22:33 UTC - via R.Natsuaki / Simon Carn / Twitter. - one click to enlarge