Building Performance and Geotechnical Failures in 7.5M Palu Earthquake and Tsunami 28 September 2018

On 28 September 2018, a 7.5 magnitude earthquake and subsequent tsunami hit Palu and Donggala in Central Sulawesi, Indonesia killing at least 2,245 people. Thousands of people were missing and over 10,000 were injured, of whom over 4,000 were with severe injuries. Nearly 75,000 were displaced in the three most affected areas: Donggala, Palu City, and Sigi. This paper discusses the performance of reinforced concrete buildings, bridges, port facilities, and lifelines in the Palu Earthquake. It was observed that a number of residential and commercial buildings were partially or fully collapsed and many sustained significant structural damages. The iconic twin steel arch cable-suspended Palu Bridge IV over the Palu River was collapsed. Lateral spreading induced by liquefaction resulted in huge housing damages and farm fields. It was seen from field investigations that possible reasons for building failure include the lack of confinement bars, improper confinement in beam and column joints, Ssrong beams weak columns and presence of soft story in multi-story buildings.