9月28日、中国の杭州市を流れる銭塘江（せんとうこう）で波が上流へと逆流する「海嘯（かいしょう）」が発生。台風の影響で例年でも高波となる中で、レッドブルが主催するサーフィン大会が開催された。
この日の決勝では中国、アメリカ、オーストラリアの選手が参加。通常の大会とは異なって、選手はモーターボートで高波の前方に移動してスタートした。約25kmのコースを1時間かけて遡上した。
海嘯は満潮の際、河口に入る潮波の前面が垂直の高い壁状になり、砕けながら川上に進む現象。ブラジルのアマゾン川では「ポロロッカ」が有名。銭塘江では毎年、中秋の名月に合わせて発生するという。
CCTVによると、台風21号の影響で銭塘江の水位は30mも上昇。海嘯の見物客は、安全な場所に留まるように気象当局が警告していた。英紙インディペンデントによると、今回の海嘯で負傷者はいなかったが、2013年に台風と同時に起きた際には、約20人が流されてけがをしたという。
銭塘江の「海嘯」
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(01 of26)
HANGZHOU, CHINA - SEPTEMBER 01: (CHINA OUT) Spectators run away from huge waves while watching tides of Qiantang River at on September 1, 2015 in Hangzhou, China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(02 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) Waves of Qiantang River tide rush to the people on the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(03 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) Waves of Qiantang River tide rush to the people on the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(04 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) People run away from the waves of Qiantang River tide rushing to the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(05 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) Waves of Qiantang River tide rush to the people on the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(06 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) A man runs away from the waves of Qiantang River tide rushing to the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(07 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) Waves of Qiantang River tide rush to the people on the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(08 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) Waves of Qiantang River tide rush to the people on the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(09 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) People watch the waves of Qiantang River tide rushing to the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(10 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) A man runs away from the waves of Qiantang River tide rushing to the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(11 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) Waves of Qiantang River tide rush to the people on the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
High Waves Of Qiantang River Tide Rush Onto Shore In Hangzhou(12 of26)
HANGZHOU, CHINA - AUGUST 31: (CHINA OUT) People watch the waves of Qiantang River tide rushing to the shore on August 31, 2015 in Hangzhou, Zhejiang Province of China. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
Qiantang Rive Tidal Bore Draws Crowds In Hangzhou(13 of26)
HANGZHOU, CHINA - SEPTEMBER 15: (CHINA OUT) Tourists run to escape the Giant tidal Bore on Qiantang River near Qige village on September 15, 2015 in Hangzhou, Zhejiang Province of China. Renowned as the mighty silver dragon, the Qiantang Rive Tidal Bore is one of the world\'s largest tidal bores. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
Qiantang Rive Tidal Bore Draws Crowds In Hangzhou(14 of26)
HANGZHOU, CHINA - SEPTEMBER 15: (CHINA OUT) Tourists run to escape the Giant tidal Bore on Qiantang River near Qige village on September 15, 2015 in Hangzhou, Zhejiang Province of China. Renowned as the mighty silver dragon, the Qiantang Rive Tidal Bore is one of the world\'s largest tidal bores. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
Qiantang Rive Tidal Bore Draws Crowds In Hangzhou(15 of26)
HANGZHOU, CHINA - SEPTEMBER 15: (CHINA OUT) Tourists run to escape the Giant tidal Bore on Qiantang River near Qige village on September 15, 2015 in Hangzhou, Zhejiang Province of China. Renowned as the mighty silver dragon, the Qiantang Rive Tidal Bore is one of the world\'s largest tidal bores. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images) (credit:ChinaFotoPress via Getty Images)
CHINA-ENVIRONMENT-TIDE(16 of26)
A wave from a tidal bore surge hits the banks of the Qiantang River in Hangzhou, in eastern China on September 29, 2015. The levee on the Qiantang River river mouth in Zhejiang province is well known as a dangerous area for huge tides, which have reached as high as 3.5 metres (11.5 feet) in the past. The tides there have attracted spectators for the past two millennia, and it is the scene of an annual Tide-Watching Festival in late summer. AFP PHOTO / JOHANNES EISELE (Photo credit should read JOHANNES EISELE/AFP/Getty Images) (credit:JOHANNES EISELE via Getty Images)
CHINA-ENVIRONMENT-TIDE(17 of26)
A fishing boat is pictured struggling due to a tidal bore surge along the banks of the Qiantang River in Hangzhou, in eastern China on September 29, 2015. The levee on the Qiantang River river mouth in Zhejiang province is well known as a dangerous area for huge tides, which have reached as high as 3.5 metres (11.5 feet) in the past. The tides there have attracted spectators for the past two millennia, and it is the scene of an annual Tide-Watching Festival in late summer. AFP PHOTO / JOHANNES EISELE (Photo credit should read JOHANNES EISELE/AFP/Getty Images) (credit:JOHANNES EISELE via Getty Images)
CHINA-ENVIRONMENT-TIDE(18 of26)
Waves from a tidal bore surge flood the banks along the Qiantang River in Hangzhou, in eastern China on September 29, 2015. The levee on the Qiantang River river mouth in Zhejiang province is well known as a dangerous area for huge tides, which have reached as high as 3.5 metres (11.5 feet) in the past. The tides there have attracted spectators for the past two millennia, and it is the scene of an annual Tide-Watching Festival in late summer. AFP PHOTO / JOHANNES EISELE (Photo credit should read JOHANNES EISELE/AFP/Getty Images) (credit:JOHANNES EISELE via Getty Images)
CHINA-ENVIRONMENT-TIDE(19 of26)
Waves from a tidal bore surge hit the banks of the Qiantang River in Hangzhou, in eastern China on September 29, 2015. The levee on the Qiantang River river mouth in Zhejiang province is well known as a dangerous area for huge tides, which have reached as high as 3.5 metres (11.5 feet) in the past. The tides there have attracted spectators for the past two millennia, and it is the scene of an annual Tide-Watching Festival in late summer. AFP PHOTO / JOHANNES EISELE (Photo credit should read JOHANNES EISELE/AFP/Getty Images) (credit:JOHANNES EISELE via Getty Images)
CHINA-ENVIRONMENT-TIDE(20 of26)
Waves from a tidal bore surge hit the banks of the Qiantang River in Hangzhou, in eastern China on September 29, 2015. The levee on the Qiantang River river mouth in Zhejiang province is well known as a dangerous area for huge tides, which have reached as high as 3.5 metres (11.5 feet) in the past. The tides there have attracted spectators for the past two millennia, and it is the scene of an annual Tide-Watching Festival in late summer. AFP PHOTO / JOHANNES EISELE (Photo credit should read JOHANNES EISELE/AFP/Getty Images) (credit:JOHANNES EISELE via Getty Images)
China Asia Eclipse(21 of26)
Visitors watch a tidal bore at the Qiantang River after a solar eclipse in Yanguan town, Haining City, China, Wednesday, July 22, 2009. The longest solar eclipse of the 21st century pitched a swath of Asia into near-darkness after dawn, as millions watched the once-in-a-lifetime phenomenon Wednesday. (AP Photo/Eugene Hoshiko) (credit:ASSOCIATED PRESS)
High Tide At Qiantangjiang River Injures 20(22 of26)
HAINING, CHINA - AUGUST 31: (CHINA OUT) A journalist reports huge tides of Qiantang River at a dike on August 30, 2011 in Haining, Zhejiang Province of China. More than 20 spectators were injured by strong tides as the typhoon Nanmadol approached on Wednesday. (Photo by ChinaFotoPress/Getty Images) (credit:ChinaFotoPress via Getty Images)
High Tide At Qiantangjiang River Injures 20(23 of26)
HAINING, CHINA - AUGUST 31: (CHINA OUT) Spectators are swept by huge waves while watching tides of Qiantang River at a dike on August 31, 2011 in Haining, Zhejiang Province of China. More than 20 spectators were injured by strong tides as the typhoon Nanmadol approached on Wednesday. (Photo by ChinaFotoPress/Getty Images) (credit:ChinaFotoPress via Getty Images)
High Tide At Qiantangjiang River Injures 20(24 of26)
HAINING, CHINA - AUGUST 31: (CHINA OUT) Spectators are swept by huge waves while watching tides of Qiantang River at a dike on August 31, 2011 in Haining, Zhejiang Province of China. More than 20 spectators were injured by strong tides as the typhoon Nanmadol approached on Wednesday. (Photo by ChinaFotoPress/Getty Images) (credit:ChinaFotoPress via Getty Images)
High Tide At Qiantangjiang River Injures 20(25 of26)
HAINING, CHINA - AUGUST 30: (CHINA OUT) Spectators are swept by huge waves while watching tides at a dike of Qiantang River on August 30, 2011 in Haining, Zhejiang Province of China. More than 20 spectators were injured by strong tides as the typhoon Nanmadol approached on Wednesday.(Photo by ChinaFotoPress/Getty Images) (credit:ChinaFotoPress via Getty Images)
High Tide At Qiantangjiang River Injures 20(26 of26)
HAINING, CHINA - AUGUST 31: (CHINA OUT) Spectators are swept by huge waves while watching tides of Qiantang River at a dike on August 31, 2011 in Haining, Zhejiang Province of China. More than 20 spectators were injured by strong tides as the typhoon Nanmadol approached on Wednesday. (Photo by ChinaFotoPress/Getty Images) (credit:ChinaFotoPress via Getty Images)
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