It is the second natural disaster to hit the area in just over 24 hours after a 4.6 magnitude quake struck 122km from East Java on Tuesday.
The death toll from the powerful tremor and subsequent sea wave on 28 September stands at more than 2,000, with 680 people officially still missing.
Rescuers had struggled to find remains in the twisted wreckage, a job made worse as mud hardened and bodies decomposed in the tropical heat.
Authorities say the official search and rescue effort will end Thursday with mass prayers in areas such as Balaroa and Petobo, where the force of the quake liquefied soft soil and tore apart neighborhoods.
Parks and monuments are planned at three of the worst-hit areas to commemorate those who may never be found.
Possibly 5,000 people were buried in places where the quake caused liquefaction, a phenomenon where wet soil weakens and collapses, becoming mud that sucks houses and everything else into the ground in a quicksand-like effect. "We just have to accept it", he told AFP.
"We hope the families understand that there's very little hope at this point", said search volunteer Hadrianos Poliamar.
Sulawesi is one of Indonesia's five main islands.
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Almost 88,000 people have been displaced and many are living in crude shelters in the hills around Palu.
United Nations Secretary General Antonio Guterres will tour the disaster zone with Indonesian Vice President Jusuf Kalla on Friday.
Humanitarian assistance has poured into the disaster-ravaged city but the recovery ever been criticised as moving too slowly.
Four days after the disaster, once the picture became clearer, President Joko Widodo reluctantly agreed to allow in overseas aid.
Some foreign rescue teams were prevented from deploying quickly to the ground to assist in the search for the dead and missing. "People were sleeping but got woken up by it", Tonny Akbar Mahendro told AFP.
A string of earthquakes in Lombok that started in early August killed more than 550 people.
People in the eastern part of Java, Madura and Bali islands also reported they felt the natural disaster.
An natural disaster measuring 6.0 on the Richter scale struck Bali early Thursday, reportedly killing three people and damaging buildings as the popular tourist island prepared to host the inaugural ASEAN Leaders' Gathering.