Originally published 2018-10-04.
On the evening of 28 September 2018, a magnitude 7.5 earthquake struck central Sulawesi, Indonesia, and sent tsunami waves into the narrow bay of Palu within minutes. Together with landslides and ground liquefaction, it killed 4,340 people, left 667 missing and injured more than 10,000. A week later, when this report was first written, the official toll stood at 1,407, aid was struggling to reach survivors, and a volcano in the north of the island had just erupted.
A man stands amid tsunami debris beside a boat thrown inland in Palu. Waves of several metres swept fishing boats, cars and buildings far from the shore.
What happened on 28 September 2018
The main shock hit at 18:02 local time, centred in Donggala Regency about 70 kilometres from Palu, the provincial capital of Central Sulawesi. A magnitude 6.1 foreshock had shaken the area about three hours earlier. The quake ruptured roughly 150 kilometres of the Palu-Koro fault, a strike-slip fault where two blocks of crust slide past each other sideways.
Strike-slip earthquakes do not usually produce large tsunamis, which is part of why this one surprised scientists. Palu lies at the end of a long, narrow bay that funnels and amplifies incoming waves. Researchers have linked the size of the tsunami to underwater landslides along the bay's steep slopes, together with some uplift of the seafloor. Waves reached around 5 to 6 metres in Palu, and some estimates for parts of Donggala were higher still.
The warning system also came under criticism. Indonesia's meteorological agency issued a tsunami alert within minutes, but its estimate for Palu was a wave of under half a metre, and the warning was lifted about half an hour after the quake. Monitoring equipment in the area was damaged or not working, and many people near the shore had little chance to escape.
Al Jazeera's map of the disaster shows the epicentre north of Palu, the fault line running down the bay and estimated tsunami arrival times along the coast. Graphic: Al Jazeera.
The first week: a toll that kept rising
Reports during an emergency change daily as rescuers reach new areas. On 3 October 2018, Sutopo Purwo Nugroho, spokesman for Indonesia's national disaster agency (BNPB), put the death toll at 1,407, with 519 victims already buried. Thousands were injured, more than 70,000 people had been displaced, and over 66,000 homes were reported destroyed or damaged. The United Nations humanitarian office estimated that about 200,000 people needed urgent help, many of them children.
Because of the heat and the risk of disease, many identified victims were buried quickly in mass graves outside the city. The search went on at a handful of critical sites: a collapsed hotel, a restaurant, a shopping mall and the neighbourhoods where the ground itself had given way.
Volunteers and soldiers dig through mud and debris in Petobo, one of the Palu neighbourhoods destroyed by liquefaction, as the search for victims continued days after the quake. Photo: Ted Regencia / Al Jazeera.
A flattened landscape in Palu, where homes were reduced to debris. Tens of thousands of houses across the region were destroyed or damaged by the shaking, the tsunami and liquefaction. Photo: Ted Regencia / Al Jazeera.
When the ground turned to liquid
Some of the most terrifying scenes came not from the sea but from the land. In Petobo, Balaroa and Jono Oge, waterlogged soil lost its strength during the shaking and behaved like a thick liquid, a process called liquefaction. Whole neighbourhoods slid, sank or were churned into mud. In Jono Oge, parts of the village were carried as far as about three kilometres.
In Balaroa, most of the area's roughly 1,700 houses sank into the ground. Around 600 of its approximately 2,000 residents are known to have died, and more than 1,000 people there were never found. In Petobo, thousands of residents were feared buried by the mudflow. These areas are a stark reminder that earthquake risk depends not only on the strength of shaking but also on what lies beneath a city.
The ruins of the eight-storey Hotel Roa-Roa in Palu. Its owner, Denny Liem, told Al Jazeera that around 30 people were believed trapped, including a South Korean member of a paragliding team in town for a festival. Photo: Ted Regencia / Al Jazeera.
At the Hotel Roa-Roa, estimates of how many people lay buried ranged from about 30 to as many as 60. President Joko Widodo, wearing an orange hard hat, visited the site on his second trip to the disaster zone and called for more personnel and heavy equipment to speed up the search.
President Joko Widodo surrounded by reporters and officials during his second visit to Palu on 3 October 2018. Photo: Tatan Syuflana / AP.
The yellow arch of the Ponulele Bridge (Palu IV Bridge), a city landmark across the mouth of the Palu river, lies twisted and collapsed in the water after the earthquake and tsunami. Photo: Ted Regencia / Al Jazeera.
Hunger, fuel shortages and slow aid
For survivors, the first days were a struggle for food, clean water, fuel and medicine. Roads and bridges were broken, power and communications were down, and there was little heavy machinery to clear rubble. Petrol stations were damaged or emptied. People searched wrecked warehouses and shops for anything usable, from rice and canned milk to painkillers.
When an aid truck finally reached one Palu neighbourhood, residents cheered. A 63-year-old man named Heruwanto, clutching a box of noodles, told the Associated Press: "I really haven't eaten for three days." Others said aid had been announced but had not reached them yet.
(The Facebook video originally embedded here is no longer available.)
Residents wait beside rows of small green LPG cylinders to buy rationed cooking gas in Palu. Fuel of every kind was scarce in the first week. Photo: Ted Regencia / Al Jazeera.
Children eat a meal outdoors in Biromaru village, Sigi Regency. Many families slept and ate outside their homes for days, afraid that aftershocks would bring down damaged walls. Photo: Beawiharta / Reuters.
Wreckage along the shore at dusk. Aid workers warned that survivors in Donggala, closer to the epicentre and harder to reach than Palu, were desperate for food and water. Photo: Athit Perawongmetha / Reuters.
To restore order, the authorities stationed troops at markets, the airport and fuel depots, and military chief Hadi Tjahjanto said an armed soldier and an armed police officer would ride with each aid truck. Some looting of shops and a mall was at first tolerated as people sought food, before police were ordered to crack down on those taking goods other than essentials.
Indonesian soldiers detain a man accused of stealing motorcycle spare parts in Palu and confiscate the sword he was carrying. Photo: Ted Regencia / Al Jazeera.
International help and the airport lifeline
Indonesia, which often handles disasters with its own resources, accepted international help after President Widodo appealed for it at the end of September. More than 25 countries offered support. Australia pledged 50 medical professionals as part of a $3.6 million package, and the United States and China were among others offering help. In the first days, however, very little of that assistance had physically arrived.
Palu's Mutiara SIS Al-Jufrie Airport became the main lifeline. Cargo planes brought in supplies, rescue teams and volunteers, including an aircraft carrying more than 12,000 litres of fuel, while hundreds of people camped near the terminal, some receiving treatment and others waiting for a seat on an outbound flight.
Injured survivors lie on stretchers as they wait to be evacuated from Palu airport. Military and commercial flights carried thousands of people out of the city. Photo: Athit Perawongmetha / Reuters.
A soldier unloads bags of presidential aid from a truck. Getting supplies from the airport to the hardest-hit districts was one of the biggest challenges of the response. Photo: Athit Perawongmetha / Reuters.
The Soputan eruption: related or coincidence?
On 3 October 2018, Mount Soputan in North Sulawesi erupted, sending a column of ash more than 6,000 metres into the sky. Coming less than a week after the earthquake, the timing led many headlines to link the two events.
Soputan volcano sends ash high into the sky on 3 October 2018. The volcano lies in the northern arm of Sulawesi, hundreds of kilometres from Palu. Photo: Handout / BNPB via AFP.
Soputan is one of many active volcanoes in Indonesia. It lies hundreds of kilometres from the epicentre, and no direct causal link between the Palu earthquake and the eruption was established. Links between distant earthquakes and eruptions are difficult to prove, so the safest reading is that the eruption happened close in time rather than as a result of the quake.
The final toll and lessons learned
When the counting was done, the disaster had killed 4,340 people, injured 10,679 and left 667 missing. More than 70,000 people were evacuated, and a month after the quake over 206,000 were living as displaced people. Damage was estimated at about 24.6 trillion rupiah, roughly 1.7 billion US dollars.
The Palu disaster changed how scientists think about tsunami risk from strike-slip faults and narrow bays, and it exposed gaps in early warning: a reminder that a tsunami can arrive within minutes, before any official alert. For people living near coasts in earthquake zones, the most important advice remains simple. If you feel strong or long shaking near the sea, move to high ground at once without waiting for a warning, and stay there until officials say it is safe.
The people of Palu, Sigi and Donggala have spent years rebuilding. The photographs from that first week remain a record of the scale of the loss and of the ordinary people who dug, cooked, queued and carried each other through it.
Sources: Wikipedia: 2018 Sulawesi earthquake and tsunami | Al Jazeera: Indonesia earthquake and tsunami latest updates (October 2018) | Wikipedia: Soputan | Photos: Ted Regencia / Al Jazeera, Reuters (Beawiharta, Athit Perawongmetha), AP (Tatan Syuflana), BNPB via AFP; graphic: Al Jazeera
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