1871 Ruang eruption and tsunami
Volcano	Mount Ruang
Start date	March 3, 1871
End date	March 14, 1871
Location	Sangihe Islands, Molucca Sea
VEI	2
Deaths	416

The 1871 Ruang eruption began on March 3, and ended on March 14 at the Ruang volcano in the Molucca Sea, Indonesia. The eruption triggered a locally devastating tsunami measuring 25 m (82 ft). It flooded many villages on nearby islands, killing some 400 people.

The eruption on March 3 began when volcanic materials began falling from the summit and into the sea. German zoologist and anthropologist Dr. Adolf Bernhard Meyer, an eyewitness to the eruption described Ruang as a conical island rising above the sea. At the time of the eruption, the island was uninhabited. The residents of nearby Tagulandang island however, owned plantations on Ruang island. A strong earthquake and loud rumbling sound occurred at 20:00 local time. Based on examining historical observations of the eruption, Pranantyo and others interpreted it as the partial collapse of the eastern volcanic flank. Simulation of a flank collapse and the triggered tsunami indicate the volume of the slide at 0.1 km³ (0.024 cu mi) best fit the historical descriptions of the tsunami heights on nearby islands.^[1] The Global Volcanism Program at the Smithsonian Institution assigned the eruption Level 2 on the volcanic explosivity index (VEI).^[2] Eruptions continued on March 9–10 and 14.^[3]

According to Dr. Meyer, the tsunami caused extreme devastation on Tagulandang island, located next to Ruang, very few homes survived the tsunami.^[4] Waves of up to 25 m (82 ft) swept into the seaside settlements, and inundated 180 m (590 ft) inland. Two additional tsunami waves struck the coast shortly after. The tsunami destroyed the village of Bahhuas; at least 75 homes were destroyed. Three homes remained at the coast but only one was safe for use; the two other homes suffered major damage. Many homes were overturned or obliterated. A church on the island with thick exterior walls was also demolished. Debris of homes were deposited all over the former settlement.^[3][5]

• 1741 eruption of Oshima–Ōshima and the Kampo tsunami
• 1888 Ritter Island eruption and tsunami
• 2018 Sunda Strait tsunami
• 2022 Hunga Tonga–Hunga Haʻapai eruption and tsunami
• List of tsunamis
• List of volcanic eruptions by death toll