Indonesia's main airport serving eastern Nusa Tenggara province was reported operating normally on Saturday after a powerful magnitude-7.7 earthquake struck off Flores Island, though airlines cancelled a handful of flights to the hardest-hit areas as authorities assessed the damage.

The quake struck at 5:58 a.m. local time, with its epicenter about 68 kilometers north-northwest of the city of Ende in East Nusa Tenggara province, at a depth of 10 kilometers, according to the United States Geological Survey. Three aftershocks followed within half an hour, measuring magnitudes 5.9, 5.6, and 6.1.

At least 20 people have died, according to the latest tally. Indonesia's national disaster mitigation agency, BNPB, said it evacuated about 2,000 residents in Nagekeo Regency and reported damage to houses, warehouses, and government facilities. Rescue teams around the port town of Maumere reported the bulk of the fatalities and several people still trapped under rubble.

A tsunami warning was issued shortly after the quake and later lifted. Tsunami waves of less than a metre were recorded in several areas.

On the aviation side, El Tari International Airport in Kupang—the region's main air hub—was reported operating normally as of Saturday, according to Indonesian outlet Kompas. However, low-cost carrier Wings Air filed cancellations for two flights on the Kupang-Ende route, numbers IW 1831 and IW 1957, affecting a total of 126 passengers, whom the airline said would be refunded. Airport operator Angkasa Pura Indonesia said it was continuing to monitor conditions and coordinate with Indonesia's meteorological agency (BMKG), airlines, and other stakeholders to ensure the safety and smooth running of flight operations.

Flores' airports have a history of vulnerability to natural hazards—Komodo International Airport in Labuan Bajo and several smaller Flores airfields, including those at Ende, Maumere, and Ruteng, have been repeatedly closed in the past two years due to eruptions of nearby Mount Lewotobi Laki-Laki. So far, reports indicate the earthquake did not cause runway or terminal damage at those airports, though official inspection updates had not been published in English-language coverage as of this writing.

Indonesia sits on the Pacific "Ring of Fire," an arc of intense seismic activity stretching from Japan through Southeast Asia and across the Pacific basin, making it and neighboring countries prone to frequent earthquakes.

Sources: Reuters/Al Jazeera/NBC News