Amirullah, 55, was having a late afternoon nap in his home on Palu bay when the earthquake shook him awake. In the lounge his seven-year-old granddaughter was watching cartoons. She was so close to the screen that the 7.5-magnitude quake caused the television set to crash down on her head.

“I told my wife to grab her and run first, and that I would stay and help my cousin,” said Amirullah, recounting the disasters that hit Palu, on Sulawesi island in Indonesia, last Friday. His cousin, 70, who was experiencing an episode of gout, needed his help.

Facebook Twitter Pinterest Amirullah, who survived the tsunami by escaping to the roof of his home. Photograph: Kate Lamb/The Guardian

As the ground continued to shake they managed to reach the car, but it would not start. That was when the first tsunami struck – just five to 10 minutes after the quake hit – sending them up the street in a powerful whoosh and then back toward the house as the water receded into the next massive wave.

Amirullah, tall and fit, grabbed hold of his roof on the slide back and yanked himself and his cousin up on to the tiles.

Maruni, his wife, had jumped into the car of a fleeing stranger, while his 12-year-old nephew, Riswan, who had been praying at Arqam mosque, survived by clinging on to a coconut tree.

Each personal experience would be shared two days later when the family was reunited, but while on the roof Amirullah thought he would never see them again.

He chose the roof because he thought that if he died it would be easier for his wife to find him, rather than “washed up by a tsunami, God knows where”.

Facebook Twitter Pinterest A damaged mosque near Talise beach. Photograph: Hotli Simanjuta/EPA-EFE

From there he had a clear view over the sea, to the left the Donggala regency and to the right, Talise beach in Palu. He stood in horror and awe as tsunami waves from each side met in the middle, and twice more smashed down.

The first of three waves was clear, but the second and most powerful one was muddy. Amirullah estimates that it reached six metres in height; Indonesia’s disaster agency said it could have been traveling at 250mph (400km / h).

When movement in the Palu Koro fault caused last Friday’s quake, there was no official warning on the ground that a tsunami could follow. Straddling multiple tectonic plates, earthquakes are common in Indonesia. But residents in Palu say they are shocked a tsunami hit their bay, first smashing into Donggala on the western tip and then barrelling into Palu’s usually calm waters.

“I never believed there could be a tsunami here. Palu is on a bay, not open sea,” says Maruni,shaking her head and fighting back tears.

The 50-year-old returned to her house for the first time on Friday morning, a week after the quake and tsunami flattened parts of the coastline, killing more than 1,571 people. Less than a mile from her home the Ponulele Bridge lies semi-submerged; left and right the view is one of devastation.

“It’s just crazy. Crazy,” says Maruni, as she searches through the rubble of her home for important documents – land titles, school certificates, family photos.

Driving along the coastline the seemingly fickle nature of the damage is striking, swaths are flattened, while some buildings stand untouched.

Sutopo Purwo Nugroho, the disaster agency spokesman, said high-resolution satellite data showed how Palu’s topography dictated how far the tsunami penetrated inland.

Facebook Twitter Pinterest The remains of Ponulele Bridge. Photograph: Hariandi Hafid/Sopa Images/Rex/Shutterstock

When the wave met rivers, he said, it reached a mile and a half inland. In other areas, blocked by hills, it only reached as far as 2,000ft.

But everywhere you go in Palu there are stories of loss and survival, each with their own set of dramatic and strange details.

In the village of Loli Dongo on Donggala’s coast, Suriyani was knocked to the floor by the earthquake while she was praying. She ran up the hill behind her when she saw the sea was bubbling, and then watched as the tsunami hit her house below. Descending in the morning, she noticed the trail of beached tropical fish on top of the rubble.

On Talise beach, the annual Palu Nomoni cultural festival was meant to be in full swing last Friday night.

Facebook Twitter Pinterest A solitary tree on the tsunami-devastated Talise beach. Photograph: Hotli Simanjuntak/EPA

In an attempt to explain the incomprehensible destruction, some have blamed the traditional animist rituals, such as throwing a live goat and flowers into the water to appease the sea gods, that residents say were a part of the festival. They believe God is punishing them for diverging from Islam, the dominant religion in Indonesia.

Last year, the festival was followed by a devastating storm; at the time, local Islamic leaders said the event should have been banned. This year, the festival is a marker for devastating loss.

Facebook Twitter Pinterest A woman cries as she attends a mass prayer for Palu at Talise beach a week on from the earthquake and tsunami. Photograph: Beawiharta/Reuters

A week after the disaster, a few angry signs haand appeared around a horse statue on Talise beach that allude to the perceived wrath from above. Scrawled on one in big silver letters is “we reject Satan worshippers”.

When the earthquake and tsunami hit, a group of dancers from the festival were performing, swallowing fire and swirling around to a quick drum beat, said Setyo Wibowo, a nearby shop owner.

On Friday, Setyo was still searching for his daughter and daughter in-law who were on the beach for the festival. All the dancers, he noted, are also missing.