Dozens of High Rises are Sinking in Florida

Results from a new study were just released that found that there are almost three dozen luxury skyscrapers along the beach in southern Florida that are sinking and settling into the earth. Most of these buildings are less than 10 years old and some of these buildings have already sunk three inches just in the past couple of years alone. New research highlights 35 buildings along South Florida's coastline that are, according to the study, sinking. The study follows the collapse of a condo tower in Surfside, Florida in 2021, where 98 people were killed. A new study found that dozens of beachfront condos and hotels in Miami-Dade are sinking into the ground at unexpected rates. Why is this happening to high rises in South Florida in particular? The regions impacted so far are Miami Beach, Surfside, Sunny Isle Beach, and Bell Harbor, but scientists are already forecasting similar issues to arise up the coast in areas like Palm Beach. Sinking skyscrapers, you guys. This topic is no joke, like we're talking what could be potentially the beginning of billions of dollars worth of damages. Not to mention, there could be lives at stake here too. When you look at the Surfside condo tower collapse, or if you look at the Millennium Tower in San Francisco, which has been progressively leaning more and more for years, no matter how many millions of dollars they throw at the problem, you start to really appreciate the work of a good civil and structural engineer when building something that's going to stand 30 plus stories tall. In today's episode, let's take a closer look at what's happening with these buildings in Florida, why it's happening, and whether or not there's really any way to stop it. So this whole discussion started when the University of Miami conducted a study that found that 35 buildings along the Miami area coast are sinking. They've dropped anywhere from an eighth of an inch to three inches over the course of the last eight years or so. Just a couple of the impacted buildings include Trump Tower 3, the Porsche Design Tower, and the Faina Hotel. Gregor Eberle, a co-author of the study, says the goal of the report was to see how stable Florida's ground on the coastline is. The way they were able to measure that this was happening was interesting. They actually studied hundreds of satellite images that were able to basically map out the ground displacement over time. One thing that's super important to acknowledge here is that building subsidence is somewhat normal. Subsidence is something that occurs when the ground beneath a property sinks. Architects, engineers, and builders are thinking about these things before they even stick a shovel in the ground on a new project. The idea is that a little bit of movement is to be expected when you're adding so much weight onto such a small footprint. This is a very normal process. If you put load on something, it starts to compact a bit. You just need to account for that movement during the design phase. The lead author of this study, though, said that the extent of subsidence hotspots under these buildings along the South Florida coastline was unexpected. The study underscores the need for ongoing monitoring and a deeper understanding of the long-term implications for these structures. I'm going to break out my old Jenga tower again. I feel like I've been using this thing a lot lately, but I want to use this just kind of to show the three thought processes that are being talked about in all these articles and comments and conversations around what's happening in Florida. The first thing that people are considering is whether or not these buildings are sinking literally just directly underneath their footprint, so the buildings are kind of sinking into themselves. Thought process number two, though, is that the entire landmass is sinking under the weight of all of the buildings in this area. And then, of course, there's people who are bringing the whole sea level rising topic into this conversation, asking whether or not the buildings themselves are sinking or the buildings are staying put and sea levels are going like this. To answer this question, we need to look a little bit closer at the study here. And in the case of the 35 buildings studied in South Florida, researchers are specifically talking about the limestone under the beach, which is interspersed with layers of sand. It looks like what we see in our data that some buildings or some areas subside more than others, indicating that we have a bit of heterogeneous distribution of the sand layers in the subsurface. What they're finding is that this sand can shift under the weight of all of these high-rise buildings, especially when there's a bunch of vibration happening as new high-rises are being built in the area. Projects as far as 1,000 feet away are contributing to the settling of these buildings. It's not like these buildings will go like an elevator down into the subsurface, but actually it's more like if you would put a big package on a sofa, it would make a slight depression that goes under. So the street and all the things around it, they go also a bit down. And what we measured is actually the ground around the buildings, how it is subsiding over time. It's really interesting for me to hear that these buildings are not making direct contact with like one solid layer of bedrock because of the limestone being interspersed with all of this sand. I mean, I've never built a skyscraper, but my understanding is that you've got really two options when building the foundation under one of these things. The first is a pile foundation. Piles are long cylindrical structures that can be driven deep into the ground. Some are made of concrete. They also can be made of steel, but they can be driven down like as far as 100 feet deep. Then you've got caissons though as another option. These are similar to piles, but they're formed by drilling big diameter holes into the ground and then filling those holes with concrete. The idea here is to get the caisson deep enough to reach a stable layer of rock. And once you have the pile or the caisson system into the ground, you build a reinforced concrete slab on top, which is engineered to ensure the weight of the building is transferred evenly and safely into the ground. The other thing that we observed is that when construction will go on and they put the piling down to make the structures of the building actually safe, that in these cases we see a bit enhanced of subsidence because the sand with the vibration of the pilings when they're driven into the subsurface, it settles a bit and it makes the whole area subsided. The point is we kind of have this process down by now. I mean, we've been building big skyscrapers all around the United States for well over a hundred years now. And even in Miami, we've been building these things forever too. The six-story Burdine's department store was built in 1912. The McAllister Hotel was built in 1919. The Freedom Tower was built in 1925. So yeah, it's not like we're experimenting with some new concept by building skyscrapers in this region of Florida. Obviously, what has changed is the quantity of buildings. When you look at the coastline, there's a lot of weight sitting on this land nowadays compared to back in the early 1900s. And this map here shows us that the entire Florida peninsula is lined by limestone. There are some other materials here like clay and peat and rocks underground that can reduce vulnerabilities with shifting. But yeah, all that yellow on this map feels a little alarming after hearing the news that we're talking about today. Even though this study only closely looked at 35 buildings, one of the researchers made a statement to CBS that almost all the buildings at the coast itself are affected here. And another one of them, a professor of civil engineering, said that this is probably a much larger problem than we even know at this point. So it's safe to say that a ton of more research is needed before we jump to any conclusions about the future of these buildings in this part of Florida. As I was researching today's video, I was actually kind of surprised to learn that there are several other areas that are experiencing similar sinking issues around the world. It's not just South Florida facing this sinking feeling. Scientists last year found New York City sinking at a rate of 1 to 4 millimeters per year. They suggest the weight of all those buildings may be speeding up the sinking. New Orleans is sinking, with human activity being the major cause. The city is sinking at the rate of 6.4 millimeters per year on average. Venice is also sinking. It has been sinking for centuries due to the lack of effective land support systems. Although out here, their ground level is only sinking about 1 to 2 millimeters per year. Mexico City is sinking due to excessive groundwater extraction. This city is sinking as much as 20 inches per year in some areas. Then there's other cities like Houston and Ho Chi Minh and Charleston and Virginia Beach and Bangkok that are all sinking at rates that are concerning to say the least. The situation is so bad that the World Economic Forum published a piece in 2019 that said 11 of these cities could disappear completely by the year 2100. Not surprisingly, even back in 2019, Miami was on this list, with the author saying that there's virtually no scenario under which you can imagine Miami still existing at the end of the century. Although, to be clear, this study was more related to sea levels rising than skyscrapers actually weighing down the earth below them. And if I've learned anything from the videos that I've done on this topic in the past, it's that we're not all exactly on the same page about this whole sea level rising situation. Back to the original story though and to kind of round this video out, here's the deal. I don't personally think that we should be overly surprised by what was discovered with these buildings in Florida. I mean skyscrapers weigh a lot. Obviously it's going to depend on the size of materials used, but just looking at the Empire State Building as an example, that tower alone is estimated to weigh around 350,000 tons. The study's absolute worst finding was an instance of a building sinking 3 inches over the course of about 7 years, so what is that, less than a half of an inch of sink per year? That means that if we just do nothing and let these buildings sink at the rate that they have been, over the course of the next 100 years, they'll sink by about 3.5 feet in total. That's probably not even enough to put their lobbies underwater, but it is enough to cause significant problems with the mechanical, electrical, and plumbing systems in these buildings, not to mention the stresses that this movement could put on other areas like doors and windows. So yeah, hopefully we see some further research on this completed soon. I'll be watching closely, and if there's anything interesting that unfolds in the future, we can revisit this thing. I'll see you guys next week. Kobe Carp says there are at least six inspectors on any high-rise development to ensure its safety and that it is settled on the ground it's built on. I personally feel very, very comfortable with the structural integrity and structural systems in the building that were mentioned in the report.