and most of the festival attendees did not realize that there was a possibility of a tsunami. Eyewitnesses even stated that some people were still strolling on the beach when the tsunami struck. It was estimated that hundreds were caught off guard and swept away by the waves. The Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) later admitted that the tsunami detectors in Palu were damaged in the earthquake. The shaking was violent enough to damage the tsunami detectors in Palu, as further examination revealed that none of the detectors were able to send signals to alert residents. As Palu was located at the end of a narrow bay, the tsunami's force was intensified when the waters entered. Officials confirmed that the waves that struck Palu had actually reached a height of 5 metres, with some as nearly as high as 6 metres. The size of the tsunami surprised geologists. It was expected to be at a low height, no more than about 2 metres, since the earthquake was a strike-slip earthquake, which usually do not have enough vertical movement to create large tsunamis. One explanation is that the earthquake triggered underwater landslides, causing the tsunami. A study of coastal liquefaction has suggested that 84% of the tsunami amplitude was a result of the combined effect of coastal and submarine landslides, based on an analysis of tide gauge records at Pantoloan. A 2019 research suggests the earthquake created about 1.5 meters of vertical seafloor movement, which, combined with a very fast rupture speed, could have produced the tsunami, regardless of any landslides. Damage More than 70,000 houses are reported to be damaged, forcing tens of thousands of people to live in shelters and tents. In Palu, the capital of Central Sulawesi, 1 mosque and a major section of the Antapura Hospital collapsed. Palu's Tatura Mall, one of the oldest shopping centres in Palu, collapsed, trapping dozens of people. An eight-story hotel, identified as the Roa-Roa Hotel, had also collapsed, trapping numerous hotel guests, several of whom were participants of the Palu's annual paragliding festival. At the time of the earthquake, 76 of the 80 bedrooms of the hotel were occupied. Palu's Mutiara SIS Al-Jufrie Airport was forced to close as large cracks, one of which was 500 meters long, had been formed on the runway. Airport officials confirmed that the navigation system was damaged and the control tower of