Ritter Island is a small crescent-shaped volcanic island 100 kilometres northeast of New Guinea, situated between Umboi Island and Sakar Island.

There are several recorded eruptions of this basaltic-andesitic stratovolcano, the most spectacular of which took place in 1888. Prior to that eruption, it was a circular conical island 780 metres high, but the explosive phreatic eruption triggered a flank collapse which caused most of the subaerial portion of the volcano to slide into the sea.^[1] Tsunamis 12-15 metres high were generated by the collapse and devastated nearby islands and the adjacent New Guinea coast killing around 3000 people.^[2] Basalt Basalt is a common gray to black volcanic rock. ... A sample of andesite (dark groundmass) with amygdaloidal vesicules filled with zeolite. ... A stratovolcano is a tall, conical mountain (volcano) composed of both hardened lava and volcanic ash. ... Phreatic eruption at the summit of Mount St. ... The tsunami that struck Malé in the Maldives on December 26, 2004. ...

The collapse left a 140 metre high 1900 metre long crescent-shaped island with a steep west-facing enscarpment. Two small eruptions have occurred offshore since 1888, one in 1972 and another in 1974.

References

1. ^ Ritter Island at the Smithsoniam Global Volcano Program
2. ^ Ritter Island at Volcano World