The eruption triggered a locally devastating tsunami measuring 25 m (82 ft).

German zoologist and anthropologist Dr. Adolf Bernhard Meyer, an eyewitness to the eruption described Ruang as a conical island rising above the sea.

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.