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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #volcanic activity

The latest assessment of the tsunami on December 24 at 19h WIB, still on the rise, mentions 281 dead, more than 1,000 wounded, 57 missing, and 11,687 displaced; the material damage concerns 611 houses, 69 hotels, 60 stalls and shops, 420 boats. (BNPB)

Tsunami report at 24.12.2018 / 22:00 WIB - Doc. BNPB

Tsunami report at 24.12.2018 / 22:00 WIB - Doc. BNPB

Return on the disaster, with the information of the moment:

A particularly violent episode took place on December 22 at 21:03 local, accompanied by an eruptive column more than 16,8 km, according to VAAC Darwin.

The two photos of Øystein Lund Andersen are accompanied by his comment: " I remember being surprised that activity had totally ceased, and Anak-krakatau wasnt even visible at all. No eruption sounds were heard. Then a few minutes passed, and the Tsunami arrived. "

Anak Krakatau - eruption on 22.12.2018 at 19:12 local - photo Øystein Lund Andersen

Anak Krakatau - eruption on 22.12.2018 at 19:12 local - photo Øystein Lund Andersen

Anak Krakatau eruptive site 22.12.2018 at 21:26 WIB - photo Øystein Lund Andersen

Anak Krakatau eruptive site 22.12.2018 at 21:26 WIB - photo Øystein Lund Andersen

The explosion / blast must have dislocated much of the island, causing an aerian collapse (and / or submarine) in the south and southwest areas, which caused the tsunami. The latter could, according to Simon Carn, have been reflected / diffracted by the remains of the caldera, resulting in complex dispersion patterns.

Note that a simulation carried out in 2012 (reference sources) indicated the coastal areas possibly affected by a tsunami following a collapse of the southern flank of Anak Krakatau ... they were actually affected by the tsunami of 22.12. 2018.

Max. waves in the simulation of Giachetti & al. The main cities or important infrastructures possibly impacted around the Strait of La Sonde are indicated by red diamonds BL: Bandar Lampung; K: Kalianda - on Sumatra - M: Merak; A: Anyer; C: Carita; L: Labuhan; P: Panimbang - on Java.

In his conclusions, "the numerical simulation shows that a partial destabilization (0.28 km3) of Anak Krakatau to the southwest could be dangerous at the local level (tourism and fishing activities around the volcano) or even at the regional scale (Sumatran and Java coasts). "

"Due to the large population, the concentration of road and industrial infrastructure along parts of the exposed java and Sumatra coasts, and the low elevation of most of these lands, the tsunami could pose a significant risk. "

"However, as the tsunami travel time is several tens of minutes between the Krakatau archipelago and the main cities along these coasts, a rapid detection of the collapse of the Volcano Observatory, coupled with a system effective warning on the coast, could prevent this hypothetical event from being fatal. "

 

A premonitory tweet of March 2018 by Simon Carn warned again of the potential danger in connection with the constant erection of Anak Krakatau on the edge of the caldera formed by the eruption of 1883.

Anak Krakatau - 23.12.2018 - black cypressoid jets and white plume of steam - Kumparan photos - by Dicky Adam Sidiq uploaded to 16h WIB
Anak Krakatau - 23.12.2018 - black cypressoid jets and white plume of steam - Kumparan photos - by Dicky Adam Sidiq uploaded to 16h WIB

Anak Krakatau - 23.12.2018 - black cypressoid jets and white plume of steam - Kumparan photos - by Dicky Adam Sidiq uploaded to 16h WIB

The eruption of Anak Krakatau continued on 23 December:

Function of the aerial images available (Kumparan - by Dicky Adam Sidiq put on line around 16h WIB), showing black cypressoïdes jets and whites plume of steam, base surges at the base, one can qualify the current phase of the surtseyan type  (see phase of the 1963 eruption that led to the emergence of the island of Surtsey) during which the magma comes out under water, shallow, with significant fragmentation.

We went from a magmatic eruption to a pheatomagmatic eruption.

Anak Krakatau - surtseyan activity from 23.12.2018 - note the collapse scar on the left of the blast on the picture above - and the collapse of the plume generating the blast on the picture below - Grand Carava Susi Air photos via BNPB
Anak Krakatau - surtseyan activity from 23.12.2018 - note the collapse scar on the left of the blast on the picture above - and the collapse of the plume generating the blast on the picture below - Grand Carava Susi Air photos via BNPB

Anak Krakatau - surtseyan activity from 23.12.2018 - note the collapse scar on the left of the blast on the picture above - and the collapse of the plume generating the blast on the picture below - Grand Carava Susi Air photos via BNPB

Vidéo Kumparan

Kompas TV video

A lot of lightning was detected by the WWLLN Lightning strike detection this December 23 : 10,856.

More than 10,000 lightning strikes recorded during the day of 23.12.2018 - Doc. WWLLN Lightning strike detection

More than 10,000 lightning strikes recorded during the day of 23.12.2018 - Doc. WWLLN Lightning strike detection

Summary of the day of December 23 in 2 images: desolation, and power released by the current eruption.

The wave submerged the entire coastline, here in Anyer on 23.12.2018. Doc. EPA-EFE / ADI WEDA

The wave submerged the entire coastline, here in Anyer on 23.12.2018. Doc. EPA-EFE / ADI WEDA

The Kompas front page of this 24.12.2018

The Kompas front page of this 24.12.2018

Sources:

- Kumparan news - https://kumparan.com/@kumparannews/foto-udara-situasi-terkini-gunung-anak-krakatau-1545561798885566899

- Tsunami hazard related to a flank collapse of Anak Krakatau Volcano, Sunda Strait, Indonesia - T. Giachetti, R. Paris, K. Kelfoun and B. Ontowirjo

Geological Society, London, Special Publications, 361, 79-90, 3 January 2012, https://doi.org/10.1144/SP361.7

http://sp.lyellcollection.org/content/361/1/79/tab-figures-data

- PVMBG & BNPB

- photos: Øystein Lund Andersen and Kumparan - by Dicky Adam Sidiq

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