2026 Flores earthquake
Earthquake in Indonesia
From Wikipedia, the free encyclopedia
On 15 August 2026, at 05:58 WITA, a Mw 7.7 earthquake struck off the coast of the island of Flores in East Nusa Tenggara, Indonesia. At least 70 people were killed and 1,182 others were injured. The earthquake also generated tsunamis that reached up to 1.61 m (5 ft 3 in) in height.
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A collapsed building in East Manggarai Regency | |
  Location within Indonesia | |
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| Magnitude |
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| Depth |
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| Epicenter | 8.310°S 121.352°E |
| Fault | Flores back-arc thrust fault |
| Type | Thrust |
| Areas affected | Flores, Sumbawa and South Sulawesi, Indonesia |
| Max. intensity | MMI VIII (Severe)[1] |
| Peak acceleration | 0.635 g[1] |
| Peak velocity | 46.9 cm (18.5 in)/s[1] |
| Tsunami | 1.61 m (5.3 ft) |
| Foreshocks | mb 4.6 on 2 August 2026 |
| Aftershocks | 1,576+ (46 felt), largest mb 6.1 |
| Casualties | 70 dead, 1,182 injured (mainshock) 2 dead (17 August aftershock) |
Tectonic setting
Indonesia lies on the Pacific Ring of Fire, an area of significant volcanic and tectonic activity. The archipelago is located between the Eurasian, Pacific and Australian tectonic plates.[2] The Flores area in particular contains both strike-slip faults and thrust faults.[3] The Flores backthrust (FBAT) is north of the island arc of Indonesia, and is formed by the subduction of the Indo-Australian plate underneath the Eurasian plate west of Lombok while being formed by the Australian plate and Banda Arc south of Rote Island.[4] It is characterized by intermediate-depth down-dip subduction.[5] It is a part of the larger backthrust of the back-arc region of Indonesia. Earlier marine geophysical studies have suggested that the back-arc backthrust consists of two regions: the Wetar thrust and the FBAT. However, newer research suggests that the whole thrust is continuous, spanning a distance of about 2,000 km (1,200 mi).[4] The Sunda and Australian plates converge at a rate of 80 mm (3.1 in) per year, in which the Sunda megathrust takes 70 mm (2.8 in) per year of the movement. The remaining 10 mm (0.39 in) per year rate is accommodated by the FBAT. It runs off the north coast of the Lesser Sunda Islands, in the Banda Sea.[6]
The area is seismically active, with 79 earthquakes larger than Mw 6.0 recorded in the area between 1900 and 2022. Eleven of those quakes generated tsunamis.[7] In addition, the area has generated at least six tsunamigenic quakes of ≥Ms 6.5 since 1800.[8] There exists substantial tsunami risk associated with the back-arc thrust of Indonesia.[8] The lesser-studied eastern part of Indonesia has been hit by more tsunamis than the more-studied western part.[9] Despite back-arc thrust tsunamis not being as common as megathrust tsunamis, they can still inflict severe damage. The eastern segment of the FBAT ruptured in the 1992 Flores earthquake, while the western segment has remained unruptured.[10] Corresponding segments of the FBAT in Bali and Lombok were responsible for very destructive earthquakes in 1815, 1857, 1917, 1979 and 2018.[8][11]
Earthquake
The earthquake occurred at 05:58 WITA. The USGS measured it at Mww 7.7 at a depth of 10.0 km (6.2 mi) with an epicenter off the northern coast of East Nusa Tenggara, 68 km (42 mi) north-northwest of Ende. It had a focal mechanism corresponding to shallow thrust faulting on an east-striking fault dipping at a shallow angle to the south.[12] Germany's GFZ Helmholtz Centre for Geosciences reported the event at Mw 7.61 and its depth at 25 km (16 mi).[13] The United States Geological Survey (USGS) estimated that the earthquake had a rupture size of 90 by 45 km (56 by 28 mi).[12] Wijayanto, the director of the Meteorology, Climatology, and Geophysical Agency (BMKG), said the earthquake was caused by movement of the FBAT. The segment that ruptured had been previously evaluated by geologists to generate a maximum possible magnitude of 7.8 to 7.9.[14]
Aftershocks
As of 17 August, the BMKG recorded more than 1,576 aftershocks[15] with magnitudes ranging from 1.9 to 6.2. Sixteen aftershocks had a magnitude greater than 5.0, and 46 of the aftershocks were felt.[16][17] At least 41 aftershocks exceeding Mw 4.0 were recorded by the USGS,[18] the largest measuring mb 6.1.[19] The BMKG said a high rate of aftershocks is expected to continue for the next two or three weeks after the mainshock before it gradually decays. Faisal Fathani, the head of the BMKG, said it is typical for damaging earthquakes around the North Maluku region to be followed by many aftershocks.[20]
Fault model
The USGS published a preliminary finite fault rupture model with the primary slip patch having a dimension of 150 by 40 km (93 by 25 mi) and a total rupture duration of about 51 seconds. The fault is oriented east-northeast and dips to the south at 32°. Slip propagated bilaterally but most of the displacement occurred around the hypocenter, down-dip and west of it. The shallower (>10 km (6.2 mi)) parts of the fault up-dip and northwest of the hypocenter experienced the greatest slip of 3.8653 m (12.681 ft). The primary slip zone propagated to the seafloor while extending to depths of 30 km (19 mi) within the crust. There is also an isolated slip patch at 20 km (12 mi) depth east-southeast of the hypocenter where the slip peaked at 1.0318 m (3 ft 4.62 in).[12]
Ground motion
Seismic observations at BMKG reported a maximum Modified Mercalli intensity of VIII (Severe) in Manggarai Regency and VII (Very strong) in West Manggarai Regency and Bima Regency. In the epicenter areas of Ngada, Nagekeo and Sikka, and further west in Sumbawa, the intensity was VI (Strong). Intensity V (Moderate) was recorded in East Sumba, East Flores and III–IV (Weak–Light) in some regencies of southern Sulawesi. A maximum peak ground acceleration of 0.635 g was recorded at Kuwus district in West Manggarai, while a peak ground velocity of 46.9 cm (18.5 in) per second was recorded by a seismic station at Ruteng.[1]
Tsunami
The BMKG issued a tsunami warning for South Sulawesi, Southeast Sulawesi, East Nusa Tenggara, and West Nusa Tenggara[21] two minutes and sixteen seconds after the earthquake.[22][23] Evacuation orders were issued because of the warning. The BMKG later declared these warnings over at 07:30 WIB.[24][25] A tsunami with a maximum height of 1.61 m (5 ft 3 in) was reported in Reok, Manggarai Regency.[22] A 0.94 m (3 ft 1 in) tsunami was recorded at Maurole District in Ende Regency[26] while at Labuan Bajo in East Nusa Tenggara, a 30 cm (12 in) tsunami was recorded.[27] A 0.17 m (6.7 in) tsunami occurred in Dompu.[28]
Authorities said the tsunami struck ten locations across East Nusa Tenggara and South Sulawesi provinces.[29] On Buton, South Sulawesi, the tsunami flooded a beach and village in Siontapina Sub-District.[30]
Impact
According to the National Agency for Disaster Countermeasure (BNPB), at least 70 people were killed and 1,182 others were injured.[31][32] It is the deadliest earthquake to hit Indonesia since the 2022 West Java earthquake.[33] At least 40,040 people were displaced.[34] East Nusa Tenggara governor Emanuel Melkiades Laka Lena said most of the victims died while they were asleep as rubble fell onto them.[35] Manggarai and East Manggarai regencies recorded 26 and 25 deaths, respectively; 8 deaths were reported in Nagekeo, and the remaining 10 deaths were from Sikka, Ende, Ngada and West Manggarai.[32] A total of 19,297 homes were damaged, of which 6,463 were severely damaged, 2,481 were moderately damaged and 12,006 were slightly damaged. At least 658 educational facilities, 172 health facilities, 172 places of worship, 187 offices and 89 public facilities were also affected.[32] Twenty of 52 petrol stations in Flores were closed due to earthquake damage. Three roads were blocked by landslides.[36] Around 566,797 people lost electricity.[37]
Initial power outages made sharing information about the earthquake damage difficult.[38] At least eight people died in Reok District of Manggarai.[39] Two people were killed and five others were injured in Maumere. A maritime passenger terminal in the city collapsed, causing hundreds of passengers inside to be struck by falling debris.[40] Also at the terminal, some people fell into the sea after a gangway to an inter-island ferry collapsed as they were boarding.[35] Among the injured were two Chinese tourists at a hotel in Labuan Bajo who were fleeing in panic.[41] In Padar Island, 986 tourists were stranded after maritime port services were suspended.[42]
Authorities said more than 150 homes and many other facilities including schools, hospitals and offices were damaged.[35] Many buildings were damaged in Ruteng while at Frans Sales Lega Airport, the ceiling partially collapsed.[43][44] Damage also occurred in a campus building of a university in Ruteng.[45] At the district's hospital, its operating theatre and clinic ceilings collapsed.[46] Buildings were also damaged in Borong.[47] In the remote areas of the regency, many homes collapsed and several bridges were damaged. Many residents fled to hilly areas due to fears of a tsunami.[45] Multiple roads were impassable, such as between Ende and Nagekeo, and Ende and Maumere.[48] In Mbay, Nagekeo Regency, at least five or six homes were reportedly damaged.[49] In Labuan Bajo, buildings were damaged in several locations, including a hotel and Komodo International Airport.[50][51] Many homes and buildings were damaged or destroyed in West Manggarai Regency.[44] The Umbu Mehang Kunda Airport in East Sumba Regency and Soa Airport in Bajawa were also affected.[51]
In Bima, West Nusa Tenggara, several homes and buildings were damaged, including a mosque and a warehouse.[52] Strong shaking was felt in Makassar, where it lasted two minutes.[53] In Selayar Islands Regency, South Sulawesi, nine homes were slightly damaged, four others were moderately damaged, and several others were affected by seawaves that entered houses in Pasilambena District. More than 50 families evacuated in hilly areas, primarily due to the trauma caused by previous incidents especially the 2021 Flores earthquake.[54] The earthquake was also felt as far as Lombok.[55]
In August 17, at 08:46 WITA, a magnitude 5.7–5.8 aftershock killed two people in Ngada Regency, including one as a result of rockfalls.[56][57]
Response
More than 2,000 people fled to higher ground after the earthquake when a tsunami warning was issued.[58] The warning was later rescinded, but local authorities advised residents not to enter damaged buildings or infrastructure because they could collapse during aftershocks. A search-and-rescue spokesperson said on 15 August that their main priority was to search for people who may be trapped beneath the rubble. Other officials were also on Flores to assess the extent of the damage.[59] Damaged homes and fear among residents forced thousands to live in shelters. There were 6,487 evacuees in Manggarai; 6,221 in Nagekeo; 5,681 in Sikka, 3,666 in Ende, and 966 in East Manggarai.[34] A field outside the Ende police station became a makeshift shelter for residents worried about returning to their homes.[60]
A 14-day state of emergency was declared in East Nusa Tenggara by governor Emanuel Melkiades Laka Lena beginning 15 August.[61] The Presidential Assistance program assisted in providing 50,000 food packages measuring 275 tonnes for affected residents.[62][63] Several other agencies including the BNPB also aided them with supplies.[62] The National Search and Rescue Agency (Basarnas) dispatched specialized teams from areas including Bali and West Nusa Tenggara to assist in rescue efforts in East Nusa Tenggara.[64] About 100 Mobile Brigade Corps personnel of the Indonesian National Police (Polri) and additional members from other specialized response divisions were sent to Flores.[65] Polri said 137 members from Java were dispatched on 15 August, and they would also send a team of police dogs to support in looking for people trapped under the rubble the following day totaling 260 personnel.[66] The Indonesian National Armed Forces (TNI) also deployed 1,267 personnel to assist in emergency operations.[67] The Indonesian Air Force mobilized three aircraft to deliver aid to Flores from El Tari Airport in Kupang.[68] The Ministry of Marine Affairs and Fisheries sent 50 metric tons of relief supplies from Kendari to Labuan Bajo aboard the surveillance vessel Orca 06.[69]
President Prabowo Subianto ordered Coordinating Minister for Human Development and Culture Pratikno, Minister of Home Affairs Tito Karnavian, Minister of Public Works Dody Hanggodo, Basarnas head Mohammad Syafii, BNPB chief Suharyanto and two deputy ministers to go to East Nusa Tenggara to assess the situation.[70] By 17 August, some 3,500 members of TNI and Polri had been dispatched in Manggarai, Maumere, and other affected regions. Cabinet secretary Teddy Indra Wijaya said a total of 27 tons of aid supplies were delivered via several flights.[71] The Ministry of Public Works was tasked with clearing roads blocked by landslides. They were able to clear major routes like the Trans-Flores road and another road near the 49KM marker in Reo District. The Perusahaan Listrik Negara (PLN) also said power was beginning to be restored in several areas.[72] To support relief efforts, the provincial disaster management office of East Java also flew in their logistics personnel and healthcare workers on 17 August.[73]
Across the island, hospitals and clinics operated outdoors because their buildings and equipment were damaged. Medical supplies were also rapidly diminishing for those injured.[74] Patients at two hospitals in Sikka and Ende regencies were evacuated.[59][75] Fifteen patients and five infants received care in a tent installed outside the Ende Regional General Hospital grounds. The hospital was evacuated as a precautionary measure in the event an aftershock causes it to collapse.[60] Many displaced residents of Sikka Regency also spent the night of 15 August at the Gelora Samador Stadium.[76] Some hospitals like the Dampek Health Centre contined to treat patients despite bring destroyed although there was only one doctor treating several hundred patients. At Lalang Health Centre, essential medical supplies from other regions only arrived on 17 August, and a doctor said that those in serious conditions were referred to the Ruteng Regional General Hospital four hours away. At the Ruteng hospital, a communications personnel said that despite news of additional assistance arriving, they have yet to receive any. For some remote communities such as Nitung Village and on Palue Island north of Flores, relief only arrived several days later.[74]