According to the US Geological Survey (USGS) and the Indonesian government, this earthquake triggered a tsunami warning and caused hundreds of people to evacuate.
The epicenter of the earthquake was off the north coast of Flores Island, about 68km northwest of Ende, according to USGS.
After the first 7.7 magnitude earthquake, strong aftershocks also occurred in the same area, including a 6.1 magnitude aftershock.
Suddenly it started shaking and I panicked. The patient also ran away from the hospital, the shaking was very strong. I saw some walls cracking" - Lukas Lotar, 31, a customer service staff member of a hospital, told AFP.
The Indonesian Meteorological, Climate and Geophysical Agency (BMKG) warned that there is a possibility of tsunamis appearing after this earthquake.
Tsunami simulation results show that this earthquake is likely to create tsunamis in the East Nusa Tenggara, South Sulawesi and Western Nusa Tenggara provinces," said BMKG's Director of Seismology and Tsunami Department Wijayanto.
Warnings have been issued with the risk of waves from 0.5-3m high.
An AFP reporter witnessed people in Maumere town on Flores Island, about 2,400km from the epicenter, evacuating to higher ground. The reporter said sea levels in the area are receding - a common phenomenon before tsunamis.
Images broadcast on Indonesian television show hundreds of people in nearby Nagekeo district evacuating from the area. Buildings here were damaged after the strong earthquake.
Authorities have not reported any casualties, but noted that waves caused by the earthquake were detected at a height of 19 to 30cm.
Indonesia and neighboring countries often record earthquakes due to being located in the Pacific "Fire Belt" - a strong seismic activity arc stretching from Japan across Southeast Asia and throughout the Pacific basin.
Historically there have been earthquakes that have caused heavy casualties to Indonesia, including the devastating 9.1-magnitude earthquake in 2004 off Sumatra, which caused a tsunami that killed 220,000 people throughout the region, including about 170,000 people in Indonesia.
This tragedy is one of the deadliest natural disasters in history.
In 2018, a strong earthquake shook Lombok Island and many other aftershocks continued to occur in the following weeks, killing more than 550 people on the island and neighboring Sumbawa Island.
Later that year, a magnitude 7.5 earthquake and subsequent tsunami in Palu on Sulawesi Island killed or missing more than 4,300 people.
