Environment

Volcanic Eruption Creates New Island Off Japanese Coast

February 29, 2016 | by Robin Andrews

Photo credit: The island continues to rise from the depths, as shown in this image taken in November 2015. Japan Coast Guard

A once-hidden Japanese volcano is rising up out of the Pacific Ocean. A new study in the journal Geology has outlined the remarkable evolution of one of the world’s youngest islands, revealing how it formed in two incredibly explosive phases.

Roughly 1,000 kilometers (620 miles) south of Tokyo lies the island of Nishinoshima, a volcanic island that was first seen erupting in 1973. This piece of rock is the tip of a much larger underwater volcano, one that is about 3 kilometers (1.86 miles) high and perhaps 94 kilometers (58.4 miles) in circumference at its base.

In November 2013, explosive volcanic activity was observed to the southeast of the island; huge lava outflows were seen rising up to the surface of the ocean, and within a month the new island rose 25 meters (82 feet) above sea level. By the end of the year, the new volcano and the older, larger Nishinoshima had fused in a fiery embrace.

After observing the island’s birth, the authors of this new study have revealed that its formation occurred in two main stages. The first involved the sudden release of hot, broiling lava into the shallow, cold water. An envelope of steam rapidly formed along the margins of the lava, before explosively expanding into the water and dramatically propelling glassy molten blobs high into the air.

 

 

This is known as a “Surtseyan” eruption, named after the Icelandic island that formed in precisely the same way back in 1963. Within three days of discovering the island, the Japanese Maritime Self-Defense Force noticed that the eruption style changed.

The island was now breaching the surface, and water could no longer fall into the lava-filled vent. “Dry” slugs of gas were now suddenly bursting up from the miniature mountain. This “Strombolian” eruption phase produced spectacular fire fountains, and allowed the lava to build up on the pre-existing rock.

Instead of taking a direct path from the vent of the volcano down into the sea, the lava took a far stranger route. As older lava cooled, it formed peculiar twists, bumps, tubes and grooves at the surface, so newer lava was forced down these natural helter-skelters before reaching the water and cooling.

The bizarre surface tubes and grooves of the new Nishinoshima. Maeno et al./Geology

The conjoined islands remain volcanically active in 2016; lava is still being sporadically erupted onto the surface and creating new land. In fact, since the eruption began, about 80 Olympic-sized swimming pools’ worth of lava has been produced every single day.  

Importantly, volcanic land is extremely favorable to life. As the olive groves around Mount Etna and the dense forests around Mount Fuji show, complex biology can be supported on the flanks of these beasts. The new Nishinoshima is no exception to this, and birds are already fertilizing it – somewhat unceremoniously – with their poop and vomit.

So it’s not only volcanologists that are enthralled: Biologists are waiting to see what type of life first colonizes this ever-growing natural laboratory. This assumes, however, that the volcano will still grow fast enough to stop it being eroded by the waves crashing onto its newly-birthed land.

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