Devastating tsunami strikes Indonesia

222 fatalities have occurred in Indonesia after a tsunami struck the country on 22 December. 164 fatalities occurred in Pandeglang, 11 in Serang, 48 in Lampun and 1 in Tanggamus according to the Indonesian Red Cross Society. The death toll is expected to rise over the next few days as the full scale of the disaster is assessed.

843 people have been injured and 28 are missing according to the most recent official government report. 556 homes, 9 hotels, 60 restaurants or food stalls and 350 ships/boats have been damaged or destroyed. Approximately 5000 people were initially evacuated after the tsunami.

The tsunami waves, measuring a maximum 0.9 metres in height (approximately 3 feet) swept the coastal towns of Sunda Strait at approximately 21:27hrs local time. Pandeglang is reported to be the worst impacted, where 624 have been injured and widespread damaged has occurred. Shocking footage have been circulating on social media and news sites showing the impact and scale of the tsunami.

The Indonesian government and organisations such as the Indonesian Red Cross Society (Palang Merah Indonesia - PMI) have been responding and providing support and aid to the affected population. Rescuers have been looking through the debris to find signs of survivors. The graphic by OCHA below shows the numerous responding organisations.

(Source: OCHA)

It is believed that the tsunami was generated by edifice collapse of the southwest flank of Anak Krakatau (Child of Krakatua). Although satellite images have confirmed the collapse, the actual mechanism of the tsunami is yet to be determined and is awaiting further investigation. So far there has only been speculations. What is clear is that the tsunami was not generated by an earthquake since no significant seismic activity was recorded. 

Sentinel-1 image of Anak Krakatua collapse

Sentinel-1 image of Anak Krakatua before the collapse

Close up comparison showing the difference before and after the flank collapse

Although 81% of tsunamis are generated by earthquakes, 6% are generated by volcanoes and 3% by landslides. 21% of volcano fatalities have been a result of volcanogenic tsunamis!

The video below demonstrates how a volcanogenic tsunami triggered by a landslide is generated.

After the devastating 2004 tsunami which claimed over 220,000 lives, a tsunami warning system (based on seismic waves), was set up in the Indian Ocean consisting of 28 member states including Indonesia. Over the years, vandalism and increasing cost of maintenance and equipment has meant that numerous buoys and equipment are not functioning. In Indonesia, the buoys have not been functioning since 2012. Even with a functioning warning system in place, it would have been unlikely that enough lead time would have been provided to the population due to the nature of the generation and the distance from the volcano.

You can find more information on the Indian Ocean Tsunami Center by following this link.

Tsunamis are not rare in Indonesia, however, the majority are generated by earthquakes. On 28 September 2018, a tsunami generated by a magnitude 7.5 earthquake resulted in over 2,100 fatalities of which the majority were in Palu. The estimated wave height ranged from 4 to 7 metres (13 to 23 feet).

Research carried out by T. Giachetti R. Paris, K. Kelfoun and B. Ontowirjo in 2012 looked into tsunamis generated by a flank collapse of Anak Krakatua. You can access paper titled ‘Tsunami hazard related to a flank collapse of Anak Krakatau Volcano, Sunda Strait, Indonesia’ here.  

Study by T. Giachetti R. et al showing simulated propagation of a tsunami generated by a landslide at Anak Krakatua (Source: T. Giachetti R. et al).

Updated figures: On 24 December, the number of fatalities have increased to 373, 1,459 have been injured, 128 are missing and 11687 have been displaced. 611 homes, 69 hotels, 60 stalls and 420 boats have been damaged or destroyed. 5,665 have also been evacuated.

On 25 December, the number of fatalities have increased to 429, 1,485 injuries, 154 missing and 16,082 have been displaced. 882 homes, 73 hotels and villas, 60 stalls, 434 boats and 65 vehicles have been damaged or destroyed. The graphic from OCHA breaks down the details for the districts affected. The figures are expected to continue to rise, as rescue and response efforts continue in the affected area.

(Source: OCHA)

To view the most up to date situation report from the Indonesian Red Cross, follow this link.

There are fears of further activity at Anak Krakatua could generate another tsunami and the population has been warned to stay within a safe distance from the beach. Anak Krakatua continues to erupt. The volcano has been showing signs of activity since September. Information on the volcanic activity will be provided separately.

Further updates will follow.

Official information sources:

You can find official and reliable reports and updates from:

·         Meteorology, Climatology, and Geophysics Agency (BMKG) Twitter account: ​@infoBMKG

·         Indonesian Disaster Management Agency (BNPB), Twitter: ​@BNPB_Indonesia or for  Sutopo Purwo Nugroho: @Sutopo_PN, Facebook page  

·       Centre of Volcanology and Geological DisasterMitigation)  (PVMBG) Facebook page, ​ Twitter: ​@vulkanologi_mbg 

·      Reliefweb

·       Indonesian Red Cross Society or follow their Twitter account: @palangmerah, Facebook page

·        For information on Anak Krakatua: Global Volcanism Program

·        For ash advisory: Darwin Volcanic Ash Advisories

Numerous scientists including volcanologists have been providing details and information on the event on Twitter.

Videos and images below show the scale and devastation caused by the tsunami. 

(Source: Reuters)

(Source: Antara Foto/Reuters)

(Source: AP)

(Source: EPA)

(Source: Reuters)

(Source: Dian Triyuli/EPA)

(Source: AFP/Getty Images)

(Source: AP)

(Source: AP)

(Source: AP)

(Source: AP)

(Source: AFP/Getty Images)

(Source: AFP/Getty Images)

(Source: EPA)

(Source: EPA)

(Source: EPA)

(Source: EPA)

(Source: Reuters)