BMKG Logs 15,722 Aftershocks in Flores in First Month After M7.7 Quake

Labuan Bajo — Indonesia’s meteorology agency has recorded tens of thousands of aftershocks in the Flores region of East Nusa Tenggara in the month since the 15 August 2026 magnitude 7.7 earthquake, with the latest official count reaching 15,722 events ranging from magnitude 0.9 to 6.2 according to BMKG and local media reports.

BMKG, the Meteorology, Climatology and Geophysics Agency, says this sequence remains active but shows a clear downward trend, while disaster officials report that the number of people displaced by the earthquake has fallen sharply to 46,461.

Aftershock totals and magnitudes

In an update summarising field survey results and seismic monitoring, BMKG’s acting deputy for geophysics, Ardhasena Sopaheluwakan, said that up to 30 days after the main shock — calculated to 15 September 2026 at 05:00 WIB — the agency had recorded 15,722 aftershocks in the Flores sequence.

According to that BMKG report, the events ranged from magnitude 0.9 to 6.2, and 190 were felt by residents. An English-language summary carried by a local outlet reports the same figures and timeframe, describing 15,722 aftershocks “ranging from magnitude 0.9 to 6.2 in the 30 days following the magnitude 7.7 earthquake”.

Earlier BMKG releases traced how the sequence built up. On 15 August, BMKG reported 37 aftershocks between magnitudes 3.6 and 6.2 in the hours after the main event. By 17 August, the agency reported 1,624 aftershocks with magnitudes between 1.3 and 6.2, and by 19 August the count had risen to 2,768 aftershocks between magnitudes 1.1 and 6.2.

Routine BMKG earthquake information pages for individual aftershocks also characterise later moderate tremors, such as a magnitude 5.0 quake near Ende on 26 August and a magnitude 5.5 event near Manggarai Timur on 31 August, as part of the same aftershock sequence. Those entries state that 7,914 and 10,386 aftershocks respectively had been recorded by those dates, each with a maximum magnitude of 6.2.

Trend over time, not a forecast

The BMKG 30‑day summary emphasises that the Flores sequence is meluruh, or subsiding, and provides a breakdown of aftershocks by week. A separate English-language report based on BMKG data notes that 5,011 aftershocks were recorded in the first week after the main shock, declining to 4,267 in the second week, 3,158 in the third week, and 2,421 in the fourth week, with 864 events from the fifth week through 15 September.

These figures describe earthquakes that have already occurred. BMKG’s communications and media summaries make clear that an aftershock count is not a prediction of a larger earthquake, nor a guarantee that the sequence has ended. BMKG continues to urge residents and travellers to follow official information channels and remain cautious around damaged buildings.

Displacement and damage

While BMKG monitors seismic activity, Indonesia’s National Disaster Management Agency (BNPB) tracks impacts on communities. In a 15 September briefing, BNPB officials said the number of people displaced by the Flores and NTT earthquakes had dropped from more than 150,000 to 46,461 evacuees.

An Indonesian-language report citing BNPB data states that, one month after the earthquake, 142 people had died, 1,603 were injured, and about 46,461 residents were still living away from their homes because of serious damage.

The displacement figures measure people, not seismic events. They should not be conflated with the BMKG aftershock totals, which refer to recorded earthquakes regardless of whether they caused additional damage or were felt by the public.

Implications for residents and travellers

BMKG’s data shows that the Flores aftershock sequence remains active but is declining, with most events too small to be felt and a limited number reaching magnitudes that can cause shaking.

For residents and visitors, the practical implication is that earthquake activity is still present in Flores and parts of East Nusa Tenggara, and authorities continue to monitor the situation. BMKG and BNPB consistently advise the public to stay informed via official channels, exercise caution near damaged structures, and follow any local instructions on safety, evacuation routes and access to affected areas.

Sources

• BMKG – Gempa Flores Meluruh, BMKG Ungkap Hasil Survei Lapangan sebagai Basis Mitigasi dan Rekonstruksi
• Tempo.co (English) – 15,722 Aftershocks Recorded in 30 Days After Flores Earthquake
• The World Now – NTT Quake Evacuees Drop to 46,461 as Aftershocks Decline for Earthquakes Today
• Metro TV News – BNPB: Pengungsi Gempa NTT Turun, Tersisa 46.461 Jiwa