A magnitude 7.7 earthquake struck off the coast of Flores Island in eastern Indonesia before dawn Saturday, killing at least 47 people and sending a tsunami warning up and down the coastline before it was lifted hours later.
Flores sits directly above the collision zone between the Indo-Australian and Sunda plates, where one slab is forced beneath the other at a rate of several centimeters a year, storing up exactly the kind of stress that a shallow rupture like Saturday's releases all at once.
Landslides Seal Off Nagekeo Regency From Rescue Crews The earthquake's most severe damage was concentrated in Nagekeo regency, but it was also the hardest area for rescuers to reach.
No tsunami-specific casualties had been confirmed as of Saturday evening, with the confirmed deaths so far attributed to building collapses rather than drowning, a distinction rescue coordinators said would matter for how search efforts are prioritized in the coming days.
A magnitude 6.9 quake at 172 kilometers releases its energy so far beneath the surface that most of it dissipates before reaching populated areas, which is almost certainly why Sumatra escaped serious damage despite the quake's substantial magnitude.
A shallow 7.7 quake off Flores Island triggered a tsunami warning and buried the main highway to the hardest-hit region under landslides, as the death toll climbed from 38 to 47 in a single day.