Abstract
The tragic collapse of the Champlain South Condominium Tower in Surfside, Miami Beach, Florida motivated the examining of the building's stability and coastal subsidence along the South Flroida coast using InSAR. The 2016-2021 Sentinel-1 InSAR data reveal several subsidence hotspots with subsidence rate of up to 1 cm/yr velocity in the radar line-of-sight (LOS) direction (corresponding to 1.4 cm/yr vertical velocity). The subsidence is centered on newly constructed high-rise buildings that suggests the construction could have been the causative factor. Two major subsidence hotspots are: (1) the Surf Club Hotel and (2) the Oceana condominium complex. For the Surf Club Hotel, the temporal correlation of subsidence with nearby construction activity indicates that the subsidence could have been related to the construction of the foundation. For the Oceana complex, the differential displacement of 3.5 mm/yr has not been stopped by 2022. Another interesting finding is the lack of subsidence beneath the Fendi condominium complex that was also built in 2016. Using the geotechnical reports for these buildings and the history of soil's condition before construction, we can compare the major differences between these sites that could have caused the diversity in the InSAR signal. We also aim to model the consolidation and secondary compression (creep) of South Florida's young limestone under building loads and other construction activities such as pile-driving to understand the observed pattern of subsidence. Defining the causes of subsidence in the South Florida's coral rocks is important for the mitigation of possible hazards and providing better guidelines for future construction projects.