Indonesia tsunami caused by collapse of volcano

Expert confirmation comes as officials say country needs new tsunami early warning system


Lisa Martin and Naaman Zhou

Mon 24 Dec 2018 


The deadly tsunami in Indonesia was triggered by a chunk of the Anak Krakatau volcano slipping into the ocean, officials have confirmed, amid calls for a new early warning system that can detect volcanic eruptions.








 

Mount Anak Krakatau erupts. Photograph: Nurul Hidayat/AP. Indonesia tsunami caused by collapse of volcano | 

World news | The Guardian


 

인니 순다해협 쓰나미, 앞바다 화산섬 경사면 붕괴로 발생 분석


화산 남서쪽 경사면 쓰나미 발생 전 대규모 붕괴

현재까지 373명 사망


  인도네시아 순다해협에서 발생한 쓰나미가 앞바다에 있는 화산섬의 경사면 붕괴로 유발됐다는 분석이 제기됐다. 


25일 트리뷴뉴스 등 현지 언론에 따르면 인도네시아 기상기후지질청(BMKG)의 드위코리타 카르나와티 청장은 전날 기자회견을 통해 "아낙 크라카타우 화산 남서쪽 경사면에서 쓰나미 발생 전 대규모 붕괴가 일어났다"고 밝혔다. 




그는 "위성사진 분석 결과 붕괴 면적은 64헥타르(0.64㎢)에 이르렀다. 이는 규모(magnitude) 3.4의 진동을 발생시켰다.


그로부터 약 24분 뒤 주변 해안에 쓰나미가 닥쳤다"고 말했다. 순다해협에 위치한 작은 화산섬인 아낙 크라카타우는 쓰나미 발생 당일인 22일 오후 5시 22분쯤 비교적 큰 분화를 일으켜 정상에서 1500m 높이까지 연기를 뿜어낸 후 9시 3분에도 재차 분화했다. 


순다해협 주변 해안에 최고 3m 높이의 쓰나미가 닥친 것은 같은 날 오후 9시 27분쯤이였다.


 

tsunami graphic Presentational white space/BBC.com


이번 쓰나미는 태양, 지구, 달이 일직선상에 있는 대조기(사리)를 맞아 만조 수위가 높아진 상황에서 발생한 데다, 지진이 아닌 화산섬의 경사면 붕괴가 원인이 된 탓에 조기경보가 이뤄지지 못해 피해가 더욱 컸다는 분석이다. 


인도네시아 재난 당국은 24일 오후 5시까지 파악된 사망자 수가 373명에 달한다고 밝혔다. 부상자는 1459명이고 실종자는 128명이다. 이재민의 수는 5600여명으로 집계됐다. 

[디지털뉴스국] 매일경제


edited by kcontents


At least 373 people were killed and many buildings were heavily damaged when the tsunami struck, almost without warning, along the rim of the Sunda Strait between Java and Sumatra islands late on Saturday.




Anak Krakatau had been spewing ash and lava for months before a 64-hectare (158-acre) section of its south-west side collapsed, an Indonesian official said. “This caused an underwater landslide and eventually caused the tsunami,” said Dwikorita Karnawati, the head of the meteorological agency.


Images captured by the European Space Agency’s Sentinel-1 satellite showed a large portion of the southern flank of the volcano had slid off into the ocean, scientists said.


The fact that the tsunami was triggered by a volcano rather than an earthquake meant no tsunami warning was triggered, scientists said. Coastal residents reported not seeing or feeling any warning signs before waves of up to three metres high surged in.


Hundreds of military personnel and volunteers spent Monday scouring beaches strewn with debris in search of survivors. At least 1,459 people were injured and more than 600 homes, 60 shops and 420 vessels damaged when the tsunami struck.




Sutopo Purwo Nugroho, the chief spokesman for the Indonesian disaster agency, said the country had no early warning system for landslides or volcanic eruptions. “The current early warning system is for earthquake activity,” he wrote on Twitter.


“Indonesia must build an early warning system for tsunamis that are generated by underwater landslides and volcanic eruptions … Landslides triggered the 1992 Maumere tsunami and the Palu 2018 tsunami.”


Residents search through debris in Tanjung Lesung, Banten province on December 24./Radio NZ

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He also said Indonesia’s tsunami buoy network had not been operational since 2012. “Vandalism, a limited budget and technical damage mean there were no tsunami buoys at this time,” Sutopo said. “They need to be rebuilt to strengthen the Indonesian tsunami early warning system.




“Anak Krakatau has been erupting since June 2018 until now. Yesterday’s eruption was not the biggest. The October-November 2018 period had a larger eruption.”


The death toll is expected to rise as 128 people were still missing on Monday. At least 1,600 people have also been displaced. Dody Ruswandi, a senior official at the disaster agency, added that the rescue effort was likely to last a week.


 


Sutopo warned locals to stay away from the coast. “People should not carry out activities on the beach and stay away from the coast for a while,” he told reporters.


The University of Queensland volcanologist Teresa Ubide said Anak Krakatau had been erupting for the past few months, which was not unusual. “It seems like the volcano is active at the moment and it may happen again,” Ubide said.




“The volcano is very close to the shoreline so … there wouldn’t be much time to warn because it’s close and the tsunamis can travel very fast.” The lack of seismic activity that would accompany an earthquake was also significant, she added.


Richard Teeuw of the University of Portsmouth said sonar surveys were needed to map the seafloor around the volcano, but that work usually took months. “The likelihood of further tsunamis in the Sunda Strait will remain high while Anak Krakatau volcano is going through its current active phase, because that might trigger further submarine landslides,” he said.


Kathy Mueller from the International Federation of Red Cross and Red Crescent Societies said aid workers were helping evacuate injured people, bring in clean water and tarpaulins, and provide shelter.


She said the group was preparing for the possibility of diseases breaking out in the tsunami zone, adding: “The situation, and the death toll, will remain fluid over the next days and even weeks.”


The water washed away an outdoor stage where a local rock band, Seventeen, were performing, killing their bassist and manager. Other people who had been watching the band on the beach were missing.


 


Azki Kurniawan, 16, said his first warning about the tsunami was when people burst into the lobby of the Patra Comfort hotel shouting: “Sea water rising.”


Kurniawan, who was undergoing vocational training with a group of 30 other students, said he was confused because he had not felt a big earthquake. He said he ran to the car park to try to reach his motorbike but discovered it was already flooded.




“Suddenly, a one-metre wave hit me,” he said, his eyes red and swollen from crying. “I was thrown into the fence of a building about 30 metres from the beach and held on to the fence as strong as I could, trying to resist the water, which felt like it would drag me back into the sea. I cried in fear ... ‘This is a tsunami?’ I was afraid I would die.”


Agence France-Presse and Associated Press contributed to this report

https://www.theguardian.com/world/2018/dec/24/sunda-strait-tsunami-volcano-indonesia




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