According to the USGS, the earthquake rupture was on an east northeast-west southwest fault with a right-lateral strike-slip motion.

This region of Indonesia is also not as seismically active, hence many expert seismologists did not expect a large earthquake to occur.

Videos posted on social media showed panicked residents running to higher ground to avoid the anticipated waves.

[13] The Flores region lie at the complex tectonic boundary between the Australian and Sunda plates, as well as several microplates.

The Flores Back Arc Thrust formed due to the convergence between the Sunda and Australian plates, accommodating compression.

In the early 19th-century, the Flores Back Arc Thrust Fault also produced the large earthquakes and tsunamis in 1820 and 1815.

[15][16] The Selayar and Flores islands were worst affected by the earthquake; 5,064 people were displaced, according to the Indonesian National Board for Disaster Management (BNPB).

[22][23][24] On 23 December, an elderly man with severe head injuries after being hit by falling debris died at the hospital while receiving treatment.

[26] Residents in South Sulawesi and the Flores region were told not to immediately enter their homes, but to inspect for damages first.

An official from the BMKG advised people in the affected areas to avoid approaching cliffsides or the mountains due to potential rockfall and landslide risks.