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The Sulawesi earthquake with a moment magnitude of Mw 7.5 struck the Central Sulawesi region of the Sulawesi Island, Indonesia, on September 28, 2018. The epicenter of the earthquake was located in the mountainous region of Donggala Regency, in the neck of the Minahasa Peninsula in the Central Sulawesi Province of Indonesia. Although the epicenter was located in Donggala Regency, the greatest devastating effects were observed about 70 km south of the epicenter in the Palu Valley. The event was the first of its kind to cause large-scale flowslides simultaneously at four key locations such as Balaroa, Petobo, Jono Oge, and Sibalaya with extensive ground displacements ranging from several hundred meters to more than 1 km. This article reviews the field observations of geotechnical failures and infrastructure damage caused by liquefaction resulting from the shallow strike-slip earthquake at Palu City, Donggala Regency, and Sigi Regency. A geo-spatial analysis was performed on data collected from aerial drone imagery, along with portable dynamic cone penetration testing (PDCPT) in the field. The investigation revealed a highly stratified ground with alternating soil layers of varying permeability and very low bearing resistance at shallow depths. The investigation also helped in assessing the extent of damage caused by geotechnical failure to the residential infrastructures, irrigation structures, and roads. Graphical Abstract

This study proposes to develop a low cost damping scheme using soil and waste tyre crumb mixture for low to moderate rise buildings. The proposed study consists of two parts, first characterizing soil and waste tyre mixtures and finding out the optimal size of tyre crumbs. The second part is to design the isolation system for low to moderate rise buildings and determine optimum dimension of the system. In the first part, a series of Unconsolidated Undrained triaxial test and large scale direct shear test have been carried out to select the optimum size of tyre crumbs from seven different crumb sizes. The Rubber Soil Mixtures (RSM) sample that provides higher shear strength, energy absorption capacity and stiffness is considered as the optimal size and further used in numerical simulations. In the second part, to analyze the damping effect of RSM, extensive numerical simulations have been carried out on the soil-foundation-structure system with varying thickness of RSM around isolated footing, varying percentage of rubber in RSM and input time history. The reduction in shaking level in terms of acceleration and inter storey drift, at different floor level with the use of RSM can be reduced by 40 to 50%.

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