A tsunami warning was sent out - lasting just over 30 minutes - but it appears to have drastically underestimated the scale of the tsunami that would follow. So what went wrong?
A 7.5 magnitude earthquake occurred just off the island of Sulawesi at 18:03 local time (10:03 GMT) on Friday, triggering dozens of aftershocks.
Indonesia's meteorological and geophysics agency BMKG issued a tsunami warning just after the initial quake, warning of potential waves of 0.5 to three metres.
But it lifted the warning just over 30 minutes later.