New explosive-effusive activity at Nishinoshima volcano, Japan

A new explosive-effusive activity is taking place at the Japanese Nishinoshima volcano in the Izu-Bonin Volcanic Arch. Thermal anomalies were detected by satellites and confirmed by Japanese coastguard overflight on December 6. 

The explosions are currently located at the main cone. A new vent that opened at the northeastern base of the cone is producing spattering and lava flows.

Nishinoshima erupting on December 6, 2019. Credit: Japan Coast Guard

Originally the above-water part of the ridge of an underwater caldera, Nishinoshima was first enlarged in 1974 after a series of eruptions created a new section of the island. Another eruption that began in November 2013 further enlarged the island and attracted worldwide attention.

Shortwave infrared image acquired on December 24, 2013. Image credit: NASA / Earth Observatory (ALI – EO-1)

Acquired on December 24, 2013. Image credit: NASA / Earth Observatory (ALI – EO-1).

Acquired on December 8, 2013. Image credit: NASA / Earth Observatory (ALI – EO-1).

A volcanic cone soon formed, raising to an estimated height of 142 m (466 feet) by July 2016. The eruptions ceased by November 2015, though emissions of volcanic gases continued for several months afterward.

As of 2016, the island is about 2.7 km² (667.18 acres) in size and evinces the return of various plants and animal species

New eruptions at the island were reported from April to June 2017 and July 2018.

Geological summary

The small island of Nishinoshima was enlarged when several new islands coalesced during an eruption in 1973-74. Another eruption that began offshore in 2013 completely covered the previously exposed surface and enlarged the island again. Water discoloration has been observed on several occasions since.

The island is the summit of a massive submarine volcano that has prominent satellitic peaks to the S, W, and NE. The summit of the southern cone rises to within 214 m (702 feet) of the sea surface 9 km (5.6 miles) SSE. (GVP)

Featured image: Nishinoshima erupting on December 6, 2019. Credit: Japan Coast Guard