Flores aftershock tally hits 15,722 as seismic activity begins to decay

Flores — Indonesia’s meteorology agency has recorded 15,722 aftershocks in the 30 days following the magnitude 7.7 earthquake that struck Flores on 15 August 2026, most too small to be felt, while 190 were reported felt by residents according to the agency.

In a press briefing in Jakarta on 15 September, the Meteorology, Climatology and Geophysics Agency (BMKG) said aftershock activity in Flores and surrounding districts has entered a clear decay phase, with the frequency of daily and weekly quakes now falling compared with the first days after the mainshock.

BMKG’s acting deputy for geophysics, Ardhasena Sopaheluwakan, said that as of 15 September 2026 at 05:00 Western Indonesian Time, monitoring networks had detected 15,722 aftershocks with magnitudes between 0.9 and 6.2, of which 190 events were strong enough to be felt by communities.

He added that analysis of recent data shows a downward trend in aftershock activity, indicating that the sequence is entering a phase of significant decay. However, the agency continues to warn that further aftershocks remain possible and calls on residents and local governments to maintain preparedness and follow official information channels.

BMKG has repeatedly urged people in Flores and other parts of East Nusa Tenggara to avoid damaged or cracked buildings, particularly structures whose integrity may have been weakened by the initial quake and subsequent shaking. Residents are advised to check building conditions and stay clear of structures that show signs of structural damage.

In a series of updates since mid-August, BMKG officials have stressed that while the number and strength of aftershocks are decreasing, the Flores region remains part of a wider seismically active zone in eastern Indonesia. The agency has also reminded communities to remain calm, not be influenced by unverified rumours, and rely on official bulletins for information on earthquakes and any tsunami warnings.

BMKG’s field surveys between 15 and 25 August documented impacts across at least seven districts, including West Manggarai, Manggarai, East Manggarai, Ngada, Nagekeo, Ende and Sikka. According to the agency, maximum shaking during the main quake reached intensity VII on the Modified Mercalli scale in several locations in West Manggarai, Manggarai, East Manggarai, Nagekeo and Sikka, with indications of liquefaction, including sand boils, reported in parts of Nagekeo.

Authorities say these field observations are being used as a basis for ongoing disaster mitigation, rehabilitation and reconstruction planning in the affected areas, alongside continued seismic monitoring.

BMKG and national media reporting have noted that no aftershocks above magnitude 5 were recorded in the week leading up to 15 September. Officials interpret this as further evidence that the largest aftershocks have tapered off, even as lower-magnitude quakes continue.

The agency is encouraging residents, travellers and businesses in Flores and nearby islands to stay informed through BMKG’s official channels and to observe local disaster management guidance as rebuilding progresses.

Sources

• BMKG
• NU Online
• Bloomberg Technoz
• Kupang Tribunnews