The shallow undersea earthquake struck off East Nusa Tenggara on 15 August, prompting authorities to issue a tsunami warning and order residents of vulnerable coastal areas to move to higher ground. The warning was lifted about three hours later after monitoring showed that waves generated by the earthquake did not pose a major continuing threat.
Indonesia’s Meteorology, Climatology and Geophysics Agency, BMKG, placed the epicentre about 30 kilometres north-east of Nagekeo in East Nusa Tenggara. Its updated assessment measured the earthquake at magnitude 7.7 and placed the focus at a depth of 15 kilometres. The agency recorded the main shock shortly before 5am local time and reported further seismic activity afterwards.
Casualties were reported particularly around Maumere, the principal town of Sikka Regency on Flores. Rescue personnel had recovered at least 20 bodies and reported six injured people, while others remained trapped or missing as searches continued through collapsed structures and landslide debris.
The full scale of the disaster remained unclear because emergency teams were having difficulty reaching Nagekeo, the area closest to the epicentre. Landslides blocked road access while telecommunications were disrupted, complicating efforts to collect casualty and damage figures from affected settlements. Rescue teams were attempting alternative approaches, including movement by sea.
About 2,000 residents were evacuated in Nagekeo. Houses, warehouses and government facilities sustained damage, while parts of the regency were affected by electricity outages and severe traffic disruption. Strong shaking was reported across East Nusa Tenggara and West Nusa Tenggara and was also felt in parts of South Sulawesi.
Landslides emerged as another significant threat. Debris blocked transport routes in parts of Flores and complicated the movement of rescue vehicles. Buildings were damaged or collapsed in several districts, while hospitals moved patients outdoors because of concern that further aftershocks could weaken structures.
Residents described intense shaking that forced families from their homes in darkness. Images from Maumere showed damaged structures and debris around the port area, while emergency personnel searched through collapsed sections of buildings. The combination of shallow depth and proximity to populated parts of Flores amplified the destructive effects of the tremor.
The earthquake also generated small tsunami waves, with recorded heights below one metre in several locations. Coastal communities had initially been advised to evacuate as a precaution. Authorities subsequently ended the alert after evaluating sea-level measurements, while Australia’s tsunami warning authorities determined that there was no threat to the Australian mainland, islands or territories.
Differences remained between casualty counts issued by rescue officials and figures being compiled through Indonesia’s national disaster-management system. Such discrepancies are common during the first hours of a major earthquake when communications are damaged and reports arrive separately from isolated districts. The confirmed toll could therefore change as teams gain access to Nagekeo and other hard-hit areas.
Flores, home to roughly two million people, has experienced destructive earthquakes before. A magnitude-7.5 earthquake struck the same broad region in 1992, producing extensive destruction and a deadly tsunami. BMKG cited that event while assessing Saturday’s earthquake and its tsunami potential.
Indonesia lies along the Pacific Ring of Fire, where several tectonic plates interact and generate frequent earthquakes and volcanic activity. The Flores area is particularly complex, with active thrust and fault systems capable of producing large shallow earthquakes and tsunamis.
