Phreatomagmatic eruption

About Phreatomagmatic eruption

• A new island near Japan's Ogasawara island chain was formed by a phreatomagmatic eruption.
• It is an eruption that involves both magma and water.
• It typically interacts explosively leading to concurrent ejection of steam and pyroclastic fragments.
• Phreatomagmatic ash is formed by the same mechanism over a wide range of basic and acidic compositions.
• A blocky and uniform crust with low vesicle content is formed.
• Deposits from phreatomagmatic eruptions are thought to be better classified and finer-grained than those from magmatic eruptions.
• This is the result of higher fragmentation of phreatomagmatic eruptions.

Key facts about Ogasawara Islands

• The Ogasawara Islands are located in the North-Western Pacific Ocean.
• It is also known as the Bonin Islands.
• It is a volcanic arc comprising more than 30 islands and islets. 
• The landscape is dominated by subtropical forest types and sclerophyllous shrublands surrounded by steep cliffs. 
• It is one of the famous UNESCO World Heritage sites of Japan.

Q1) What is a volcano?

A volcano is a geological formation on the Earth's surface that occurs when magma, volcanic ash, and gases escape from below the Earth's crust through an opening called a vent. Volcanoes can take various forms, ranging from stratovolcanoes (composite volcanoes) to shield volcanoes and cinder cone volcanoes.

Source: New island is born in Japan after undersea volcanic eruption