1888 Ritter Island eruption and tsunami

On the morning of 13 March 1888, a section of Ritter Island, a small volcanic island off the coast of New Guinea, collapsed into the sea in a sector collapse. Prior to its collapse, Ritter Island was a steeply-sloping, 780 m (2,560 ft) volcanic cone which produced eruptions in the 1690s and 1790s. The collapse in 1888 reduced its height to about 140 m (460 ft), while the remaining edifice, estimated by volcanologists to be 2.4 km³ (0.58 cu mi) or 4.2 km³ (1.0 cu mi), was deposited onto the seafloor. If the latter figure is correct, this sector collapse would be more voluminous than the 1980 eruption of Mount St. Helens. The present-day Ritter Island is a crescent-shaped remnant of the former cone and it last erupted in 1972.

The collapse triggered tsunami waves that struck nearby and distant islands such as New Guinea, Umboi, Sakar and New Britain. Some waves were as high as 15 m (49 ft) based on reading the tidemarks. It caused heavy damage and deaths in coastal settlements. While no confirmed death toll exists, it is estimated that between 1,500 and 3,000 people died. The tsunami also had far-field effects in Chile and Australia.