Today’s entry: Brian, great interview today with FIU professor but I missed a KEY question: Which other properties were studied and found sinking?
Bottom Line: It’s extremely important to note, before addressing further, that the cause of the collapse hasn’t been determined though is increasingly looking like it was a structural failure, according to a 2018 engineering report on the Champlain Towers South building released by Surfside. In the report, there were several concerning items, most notably, "The failed waterproofing is causing major structural damage to the concrete structural slab below these areas. Failure to replace the waterproofing in the near future will cause the extent of the concrete deterioration to expand exponentially". That was three years ago and pretty well speaks for itself at this point.
The widely cited FIU study of the Champlain Towers South site was led by FIU’s Earth and Environment expert Dr. Shimon Wdowinski and was co-authored by the University of Padova’s Earth Sciences professor Dr. Simone Fiaschi. Though the research began in 1993, the study, referred to as Local land subsidence in Miami Beach (FL) and Norfolk (VA) and its contribution to flooding hazard in coastal communities along the U.S. Atlantic coast, was notably just published last year in the journal Ocean and Coastal Management. The findings specific to the Champlain Towers South site itself was sinking at the site of 1.9mm annually between 1993 and 1999. When backed up with the 2018 engineering report on the building, it's certainly possible the sinking was connected to “major structural damage”.
To the root of your question what other sites were observed in the 2020 study? Broadly the study showed Miami Beach sinking at the rate of 1-3mm annually during the same window in the ’90s. As FIU notes, that’s low compared to other monitored locations globally. Mexico City, which sits 7,200 feet above sea level, at a remarkable 15 inches per year! Other locations specifically cited where developments exist included Flamingo/Lummus which was monitored at a decline of 2mm annually. Another, Park View, was monitored to be sinking at a rate of 2.3mm annually between 1993-1999. In the study, they specifically cited the worst receding having occurred at sites of reclaimed wetlands. Champlain’s site wasn’t one of those.
The point being, land anywhere may be susceptible, and this isn’t as easy as thinking it’s something unique to the coast. Incidentally, in the same FIU study, Norfolk appeared to have more pervasive sinking than Miami Beach. That’s why FIU’s Dr. Shimon Wdowinski said the sinking alone wouldn’t account for the tragedy we’ve witnessed and to that end mean that a repeat is due to happen nearby as a result. Maintenance of structures is critical.
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