The island of Bougainville in Papua New Guinea is home to three impressively large volcanoes, of which Mount Bagana, pictured here, is extremely active.
Ever since scientists discovered this volcano in 1840, its activity has continued uninterrupted, as evidenced by the steady lava flows down the slopes of the volcano. Over the past 300 to 500 years, these have caused Mount Bagana to grow to an impressive 1,850 meters – making it one of the youngest and at the same time most active volcanoes in the South Pacific.
This NASA satellite image of the volcano from May 28, 2022 shows a strong eruptive phase in the last twenty years: Recent lava flows appear dark brown in the image and partly extend into the surrounding dark green forest. The vegetation in the light brown areas was probably destroyed by flying rocks and toxic gases. In contrast, lava flows from longer ago have already been recaptured by the flora of Papua New Guinea and appear in a light green.
Mount Bagana not only emits large amounts of lava, but also emits thousands of tons of sulfur dioxide per day – more than any other volcano without a lava lake in the world. The Bagana owes its sustained volcanic activity to its geological location on a particularly active plate boundary, because in the Southwest Pacific two continental plates are moving towards each other at a speed of around eleven centimeters per year.
This slow-motion collision causes one plate to slide under the other. The associated forces have created a deep sea trench on the lower plate, while the magma rising at this interface of the earth has formed volcanoes on the upper plate. The Pacific and Australian plates have been in this so-called subduction process for millions of years, which led to the volcanic rocks of Bougainville Island and later the formation of the Bagana volcano.