The 7.5-magnitude quake and wall of water that tore through the city on Sulawesi island on September 28 killed more than 2,000 and left thousands more missing, presumed dead.
Entire villages were sucked into the earth at hard-hit areas like Balaroa, when soil turned to mush under the force of the quake.
Rescue teams scoured the wreckage for a fortnight before calling off the search for the dead, acknowledging as many as 5,000 missing people would never be found.
"For those who have lost their family members, their friends, I want to express my deep condolences. Our hearts are broken by what has happened, but we are in full solidarity with Sulawesi and with Indonesia," Kalla said.
In a separate Twitter post, accompanied by an image of Guterres surveying a vista of destruction, he said: "Your strength and resilience are remarkable."
Guterres and Kalla also spoke with officials running the recovery effort, and survivors being treated at an outdoor tent hospital and evacuation centre.
"I have been living in this shelter for two weeks, ever since that night," 53-year-old Sarina told AFP as Guterres and Kalla inspected an evacuation centre. Many Indonesian go by one name.
"I hope the government can provide us a place to live, because I can't go home. My house, my belongings, are all gone. I only have the clothes on my back."
Nearly 90,000 people were displaced by the quake, forcing them into evacuation centres across the rubble-strewn city.
Officials said it could be two years before all the homeless are found permanent accommodation.
Donations have begun pouring into the coastal city of 350,000 after a slow start which saw Indonesia criticised for stalling the flow of relief supplies.
The focus has shifted to the recovery effort. But the memory of the dead and missing remains raw.
Many families never found their loves ones.
Rescuers struggled to retrieve the dead, the grim job compounded as mud hardened and bodies decomposed in the tropical heat.
The government had declared that the worst-hit areas would be sealed off, effectively becoming mass graves.
Monuments and parks are planned to remember untold numbers of victims buried by soil and rubble in Palu.
But in a debris-strewn clearing by Palu Bay, thousands gathered Friday before sundown for an emotional prayer service to remember those lost.
Just a fortnight earlier, an 11-metre wave roared into the bay at the very same spot, obliterating the foreshore and crashing onward into the city.
"I prayed that this disaster will end soon," said Rostin Timaloto, a 58-year-old woman. "Only by the grace of God can this ordeal end.
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