Magnitude 7.7 Indonesia earthquake damages Flores as tsunami waves hit coast and warning is lifted

A powerful magnitude 7.7 earthquake struck off Indonesia’s Flores Island early on August 15, 2026, damaging buildings, sending residents fleeing towards higher ground and triggering tsunami warnings across parts of East Nusa Tenggara, West Nusa Tenggara, South Sulawesi and Southeast Sulawesi. Indonesia’s Meteorology, Climatology and Geophysics Agency, or BMKG, subsequently ended the tsunami warning after coastal monitoring recorded waves of less than one metre in several locations.

BMKG said the earthquake occurred at 04:58:24 WIB, equivalent to 05:58:24 in Flores under Central Indonesia Time, and revised its initial magnitude 7.0 estimate upward to 7.7. The agency placed the epicentre in the Flores Sea around 30 kilometres northeast of Mbay in Nagekeo Regency at a shallow depth of 15 kilometres. The United States Geological Survey also measured the earthquake at magnitude 7.7, using a depth estimate of approximately 10 kilometres and locating it about 68 kilometres north-northwest of Ende.

Initial assessments did not indicate a major loss of life, but evidence of structural damage emerged quickly. Video verified by Reuters showed part of a building at Maumere port collapsing as people ran from the area, while Associated Press reporting described damage to homes and public facilities across parts of Flores. At Ritapiret Seminary in Sikka, part of an assembly-hall roof collapsed during morning Mass and a priest suffered a broken leg after jumping from the second floor of a building.

Hospitals also began taking precautions. Television footage showed patients being moved outside a hospital in Ende, while residents across Flores described intense shaking and rushed from buildings. Indonesia’s national disaster agency said the earthquake was felt strongly for around a minute in areas including Nagekeo and Bima. Several aftershocks followed the main earthquake, keeping authorities focused on the possibility that already weakened structures could suffer further damage.

Where exactly did the magnitude 7.7 Flores earthquake strike and how strong was the shaking?

BMKG’s revised epicentre was at 8.41 degrees south and 121.39 degrees east, approximately 30 kilometres northeast of Mbay in Nagekeo, East Nusa Tenggara. The agency put the depth at only 15 kilometres, making this a relatively shallow earthquake capable of producing stronger ground motion close to the source than a comparably sized earthquake occurring much deeper underground.

BMKG’s preliminary shaking map placed Aesesa in Nagekeo, Riung in Ngada and Mbay at intensity VII on the Modified Mercalli Intensity scale. At that level, people generally rush outdoors and some well-constructed buildings can sustain light damage, while weaker structures can experience substantially greater effects. Wolowae and Bajawa were estimated at intensity VI, while Ende, Borong and Ruteng were around intensity V.

The intensity estimates fit reports emerging from communities across Flores. The collapse captured at Maumere port and damage reported at homes and institutional buildings demonstrate that this was not simply a large earthquake detected offshore without meaningful consequences on land. The full structural impact remained unclear early on August 15 because assessment teams were still collecting information from communities across the island.

The distinction between magnitude and intensity is important. Magnitude measures the total energy released by the earthquake, while intensity describes how strongly the ground shook at particular locations and how people and structures were affected. The magnitude remains one number for the event, but the intensity can vary considerably depending on distance, geology and construction quality.

Why did Indonesia issue a tsunami warning after the August 15 earthquake near Flores?

The combination of a very large magnitude, an offshore epicentre and a shallow source immediately raised concern that seafloor displacement could generate tsunami waves.

BMKG initially issued its first tsunami warning slightly more than two minutes after the earthquake, at 05:00:39 WIB. A second updated warning followed at 05:09:56 WIB after the agency revised the magnitude to 7.7 and refined the earthquake’s location and depth.

The agency’s modelling placed several coastlines under its Siaga alert category, corresponding to anticipated tsunami heights of roughly 0.5 to 3 metres. Those areas included northern sections of Manggarai, Ngada, West Manggarai, Ende and Sikka in East Nusa Tenggara, along with Selayar, Jeneponto and Bantaeng in South Sulawesi. Residents in Siaga areas were instructed to evacuate.

A wider group of areas received the lower Waspada warning, indicating a modelled wave of less than 0.5 metres. Those locations included parts of Flores, Bima and Dompu in West Nusa Tenggara and coastal areas of South and Southeast Sulawesi. Residents there were instructed to stay away from beaches and riverbanks.

Reuters subsequently reported that tsunami waves below one metre were recorded in several areas. BMKG later declared the tsunami warning ended, allowing communities to follow local disaster-management guidance on returning from evacuation areas.

How much tsunami activity was actually recorded after the Indonesia earthquake?

The observed tsunami was substantially smaller than the upper end of BMKG’s initial modelled scenario.

Reuters reported that waves of less than one metre were detected at several monitoring points after the earthquake. That outcome is significant because BMKG’s Siaga category had initially allowed for the possibility of local waves between 0.5 and 3 metres in some exposed coastal areas.

Tsunami forecasts issued immediately after a major earthquake intentionally deal with uncertainty. Authorities have only minutes to decide whether coastal populations should evacuate, and the exact amount of seafloor displacement, rupture geometry and resulting wave behaviour may not yet be fully known. Tide gauges and other observation systems then provide direct evidence allowing warnings to be adjusted or cancelled.

Australia’s tsunami warning authorities concluded that the earthquake posed no tsunami threat to the Australian mainland, islands or territories. Indonesia remained the main area of concern because communities across Flores and surrounding islands were much closer to the earthquake source.

Ending the tsunami warning does not mean the earthquake emergency itself is over. Aftershocks, unstable buildings, damaged infrastructure and local landslide risks can persist after the immediate coastal threat has passed.

What damage has been reported in Maumere, Ende and other parts of Flores?

Maumere produced some of the clearest early evidence of physical damage. Video verified by Reuters showed part of a building collapsing at the port as dust spread across the area and residents ran away. AP separately reported that the waiting room at the Pelni port terminal had collapsed.

Damage was also reported at Ritapiret Seminary in Sikka Regency. Students and nuns attending morning Mass evacuated as part of a roof collapsed, while the seminary rector said one priest suffered a broken leg after jumping from the second floor during the earthquake.

In Ende, hospital patients were moved outdoors as a precaution following the strong shaking. This is a standard but important emergency response because subsequent earthquakes can pose serious risks to patients and medical personnel if a hospital building has suffered structural damage that is not immediately visible.

AP reported damage to homes and public facilities across Flores but said authorities had not yet produced a comprehensive count of affected buildings. There were no immediate reports of deaths in the initial hours after the earthquake. That figure should remain provisional while disaster teams reach more communities and inspect damaged areas.

Why does the 1992 Flores earthquake make the August 15 tsunami warning especially serious?

Flores has direct experience with a devastating earthquake and tsunami.

In December 1992, a major earthquake struck the region and generated a destructive tsunami that killed around 2,500 people, according to AP. Maumere and surrounding coastal communities were among the areas devastated by that disaster.

That history helps explain why an August 15 tsunami warning would trigger immediate evacuations even before officials knew how large the waves might become. Coastal residents in earthquake-prone regions are generally encouraged not to wait for visual confirmation of a tsunami after severe or prolonged shaking because waves generated close to shore can arrive quickly.

The 2026 earthquake is not simply a repeat of the 1992 disaster. Earthquakes of similar headline magnitude can produce very different tsunami outcomes depending on the precise fault motion, depth, direction of rupture and amount of vertical seabed displacement. The relatively small waves observed on August 15 demonstrate why magnitude alone cannot predict the eventual tsunami impact.

The comparison nevertheless remains relevant from a preparedness perspective. A powerful shallow earthquake in the Flores Sea occurs in a region where historical evidence demonstrates that damaging tsunamis are possible, making rapid evacuation appropriate even when the final waves prove much smaller than feared.

Why is Flores one of Indonesia’s most earthquake-prone regions?

Indonesia lies within an exceptionally complex tectonic zone where several major plates and smaller crustal blocks interact. The archipelago forms part of the Pacific Ring of Fire and experiences frequent earthquakes and volcanic eruptions as tectonic plates converge around its long island chains.

Flores sits within this active eastern Indonesian environment. The region includes major thrust and fault systems created by compression associated with the convergence of the Australian plate and the Sunda-Banda island arc. These structures are capable of producing large shallow earthquakes, some of which can displace the seabed and generate tsunamis.

Indonesia has experienced several major earthquakes already in 2026. A magnitude 7.6 event in the Northern Molucca Sea in April produced tsunami waves of up to 0.75 metres and killed one person after falling debris struck in Manado. A magnitude 6.7 earthquake near Palu in June also caused casualties and damage.

The August 15 Flores earthquake is therefore another reminder that Indonesia’s seismic risk is distributed across several different tectonic environments rather than being confined to one fault or one section of the country.

How dangerous are the aftershocks following a magnitude 7.7 earthquake?

Several aftershocks were recorded after the main earthquake, according to BMKG and AP. Large earthquakes almost always redistribute stress along nearby faults and are typically followed by a sequence of smaller earthquakes that can continue for days, weeks or considerably longer.

Most aftershocks will be weaker than the magnitude 7.7 mainshock, but that does not make them harmless. Buildings cracked or partially weakened during the initial shaking may be more vulnerable to collapse during a subsequent event that would otherwise have caused limited damage.

BMKG therefore urged residents to avoid cracked or damaged buildings and to rely on verified information from official agencies rather than rumours circulating after the earthquake.

Emergency teams will also need to inspect bridges, roads, port facilities, schools, hospitals and other infrastructure before normal activity fully resumes. Damage hidden inside structural components can be more significant than visible surface cracks suggest, particularly following intense shaking measured around VI to VII MMI.

Does the lifting of Indonesia’s tsunami warning mean residents can safely return home?

The end of the tsunami warning removes the immediate official expectation of dangerous tsunami activity, but it is not a blanket declaration that every building and neighbourhood is safe.

People evacuated specifically because of the tsunami alert can follow instructions from local authorities about returning from higher ground. BMKG’s warning system now states that the tsunami threat from the magnitude 7.7 earthquake has ended.

Residents whose homes suffered visible structural damage face a different issue. BMKG specifically advised people to stay away from buildings that had cracked or been damaged by the earthquake. Aftershocks can exploit weaknesses created by the mainshock, making professional inspection particularly important for seriously affected structures.

Coastal communities should also distinguish between this cancelled warning and future earthquakes. A new sufficiently powerful offshore aftershock could produce a new assessment and potentially another tsunami alert. The cancellation applies to the threat generated by the event authorities were monitoring, not to every possible seismic development that could follow.

What are the key takeaways from Indonesia’s magnitude 7.7 earthquake off Flores on August 15?

• Indonesia’s BMKG revised the August 15 Flores earthquake from an initial magnitude 7.0 to magnitude 7.7 and placed the epicentre approximately 30 kilometres northeast of Mbay in Nagekeo at a depth of 15 kilometres.
• The earthquake struck at 04:58 WIB, equivalent to approximately 05:58 in Flores, and produced strong shaking across East Nusa Tenggara, with BMKG estimating intensity VII MMI around Aesesa, Riung and Mbay.
• BMKG issued a tsunami warning within minutes and initially modelled possible waves of 0.5 to 3 metres for several coastal areas in East Nusa Tenggara and South Sulawesi, prompting evacuations to higher ground.
• Tsunami waves below one metre were subsequently recorded in several areas, and BMKG has now declared the tsunami warning ended. Australia’s tsunami authorities said there was no threat to Australian territory.
• Structural damage has been confirmed in Flores, including a building collapse at Maumere port and damage at homes and public facilities. A priest at Ritapiret Seminary suffered a broken leg during the evacuation.
• Hospital patients were moved outside in Ende, while residents across affected districts fled buildings after strong shaking that Indonesia’s disaster agency said lasted around a minute in some locations.
• There were no immediate reports of deaths in the first assessments, but the casualty and damage picture remains preliminary while officials inspect communities across Flores and surrounding areas.
• Several aftershocks followed the main earthquake, and BMKG has warned residents to avoid cracked or damaged buildings even though the immediate tsunami warning has been cancelled.

Why the first few hours suggest Flores avoided the worst tsunami scenario but the earthquake story is far from over

The most encouraging development from Indonesia’s magnitude 7.7 earthquake is that the tsunami observed so far was considerably smaller than the most dangerous scenario contained in the initial warning. BMKG’s modelling allowed for waves between 0.5 and 3 metres in several exposed areas, while subsequent monitoring detected waves below one metre and the agency eventually ended the warning.

That is particularly important for Flores because the island carries the memory of the devastating 1992 earthquake and tsunami. A repeat of that kind of coastal disaster was the central fear immediately after such a large, shallow offshore earthquake struck before sunrise. Early evacuation therefore appears to have been a prudent response rather than an overreaction, even though the wave heights ultimately remained much lower than the maximum forecast.

The damage emerging on land prevents the event from being dismissed as a near miss. Maumere has already recorded a building collapse at its port, institutional buildings have been damaged, hospital patients were moved outside in Ende and communities across Flores experienced sufficiently strong shaking for BMKG to estimate intensity VI and VII conditions in several districts.

The next phase will depend on damage assessments rather than tsunami modelling. Authorities need to determine how many homes and public buildings were affected, whether roads and bridges remain structurally sound and whether remote communities closer to the epicentre suffered damage that has not yet been communicated.

Aftershocks remain the other major uncertainty. A magnitude 7.7 earthquake releases enormous energy, and a prolonged aftershock sequence would be normal. Each additional significant tremor increases the risk to buildings already weakened by the first shock and can send residents back into open areas even after the tsunami threat has passed.

The early picture on August 15 is therefore cautiously better than the scale of the initial warning suggested. Indonesia experienced a major shallow earthquake, tsunami waves were generated and buildings were damaged, but there was no immediate indication of the catastrophic tsunami or mass casualty event that residents of Flores understandably feared.

That assessment can still change as daylight inspections reach more communities. For now, the central story has shifted from whether a large tsunami is approaching to how much damage the magnitude 7.7 earthquake itself caused across Flores and whether its aftershocks create a second wave of structural danger.