New York City is Sinking!
Dr. Jesse Reimink: [00:00:00]
Welcome to Planet Geo, the podcast where we talk about our amazing planet, how it works, and why it matters to you.
Chris Bolhuis: Hey, how you doing? Jesse Reimink, Dr. Jesse
Dr. Jesse Reimink: yeah. Yeah. Get it right. Get it right. I'm doing well. How are you?
Chris Bolhuis: I'm great. I'm great. Hey, do you got your radio voice on Kermit?
Dr. Jesse Reimink: I'm feeling particularly carmody today. I'm getting over a cold, so [00:00:30] I'm probably like a more extreme version of Kermit? right now. Super nasally. Kermit over here,
Chris Bolhuis: That's the best
kind.
Dr. Jesse Reimink: Well there we go. You got me? You got me. I'm here baby. Um, So, Chris, before we get going today, we had an update that I think everybody will be interested in. We got another email from Joyce.
did.
you see this? We
did
Chris Bolhuis: not.
Dr. Jesse Reimink: You always miss the emails from your mom to our, to our podcast email.
So she, um, she just said that she's [00:01:00] enjoying the, the good humored, silly banter. And, uh, she really likes Biffs because she likes to pick up the pretty ones. So there we
Chris Bolhuis: That's true. Good, I have no idea when my mom emails you like, or us, I should say. I, I just didn't look, I had a very busy day yesterday, you know, stump grinding. my whole other rest of the day was occupied doing track stuff, and so I, I didn't get to it. No,
Dr. Jesse Reimink: Yeah.
you didn't get to it, so Apologize to your mom.
Chris Bolhuis: I'm sorry,
mom.
Dr. Jesse Reimink: it's always a nice email. It's always nice getting listener emails and it's particularly nice from [00:01:30] Joyce. I really enjoy those ones. So, Chris, today we're talking about really, uh, a research publication that that made its way into the science news article space and on the CNN and all sorts of stuff, but It's,
really about New York City sinking under its own weight. And you are the one who pinged this to me. Where, where did you come across it?
Chris Bolhuis: That's a funny story, at least to me. It's funny. I got a text from my son and he says, Hey dad, I was listening to this podcast and they were interviewing these guys from the U [00:02:00] S G S about New York City sinking. And he said, what do you think about that? Well, I had a lot of mixed emotions about that one.
My heart was warmed instantly that my son was listening to a, a podcast that involved science. I was, I was like, oh, I love that boy. but then I sent a, a text back that did not like depict that emotion.
Dr. Jesse Reimink: no, you probably didn't compliment em. You're probably like, what? What'd you
do?
Chris Bolhuis: not. I said, Hey, you took my [00:02:30] Geology class. You tell me what you think about that.
And then he gives me some snarky response back, like me being a nerd or
something like that. And
Dr. Jesse Reimink: Oh, dad.
Chris Bolhuis: back with something, even, you know, the one up 'em. But where the idea came from, is from my son,
so,
Dr. Jesse Reimink: Oh, hey, there we go. Your son is, is paying attention to the geoscience news world. That's, uh, that's
amazing. Good work.
Chris Bolhuis: it actually is. And he does a good job of keeping up with our podcast, which, like, kill asked me questions. I was [00:03:00] just out there visiting him a couple weeks ago and, and he's like, Hey, dad. Um, he brings up these scientific Geology things, these questions that he has, and every time it catches me off guard, like I, he should listen to our podcast because he's my boy, but, it warms the heart to know that he actually does, which is more than I can say for my daughter.
You know, she doesn't, she doesn't say anything but her friends listen to the podcast. so, I'm, doing a shout out to Bella's friends for listening to the [00:03:30] podcast. Keep it going. It's awesome. Um, and you, you, you all need to do a better job of shaming Bella for not listening.
Dr. Jesse Reimink: Yeah. that's right. Give her a hard time. Okay, so, oh man. So the, title of the news article here and like I said, this made its way around the world in the geoscience news space and actually the real news space. You know, this was on cnn. This was discussed a lot of different places. The one we focused on and the one we looked at was a Scientific American article that the title is just New York City is sinking [00:04:00] under its own weight.
And this is really based on a journal article, which we've talked about how to read journal articles recently, Chris. So everybody should not be afraid to read a journal article, but it's, the title of this one is The Weight of New York City. Possible contributions to Substance from Anthropogenic Sources.
So, Yeah, we'll, we'll talk about the different titles here, I think maybe, but I think those are the two things we're talking about.
Chris Bolhuis: I gotta ask, you just said substance. I always say subsidence.
who's right.
Dr. Jesse Reimink: I think I've, [00:04:30] uh, maybe lost the Midwestern, uh, framing. I also don't
say, yeah, I, I also say data instead of data, which a lot of people in Michigan say data.
Chris Bolhuis: Oh yeah. Okay. So you think subsidence is the Midwest thing?
Dr. Jesse Reimink: It might be, I'm not sure.
Chris Bolhuis: Okay. I'll have to break the mold and switch it up and say
Dr. Jesse Reimink: you know, I also sometimes say basalt instead of basalt these days,
cuz I've hung around with a lot of English geologists before.
Chris Bolhuis: Oh my gosh. Do you also say methane instead of methane?
Dr. Jesse Reimink: No. Aluminum. [00:05:00] Aluminum instead of, I can never say it the way do anyways.
Chris Bolhuis: All right. Let's go. Let's jump into this. Let's get into some science,
Dr. Jesse Reimink: So I, Chris, what were your main takeaways after, after your son pinged you with this?
What was your knee-jerk reaction,
and then what was your
deep reaction?
Chris Bolhuis: okay. Yes. Good, good question. I didn't read the article I just was responding instantaneously to texts. Right. And I'm thinking, well, that makes sense. I mean, New York City has a lot of massive buildings. It's a [00:05:30] staggering amount. Actually,
Dr. Jesse Reimink: Yes. it is. And let's put some numbers on that real quick cuz this is the main contribution that this paper, the research paper did is they added all of this up. And so as of 2020, New York City had 8.8 million people roughly. So this is the most populous city in the us. It had almost 1.1 million buildings. And they added these up. They looked at the commercial use. Is it a big office building? Is it industrial building? Is it residential? And they added all that up and they said the number. [00:06:00] That is the weight of New York City, the five boroughs, 764 billion B billion kilograms, or 1.68 trillion with a T trillion pounds. That's a lot of weight.
Chris Bolhuis: That's a lot of weight. So here's where my mind went to. I didn't know the numbers, I just knew New York is big, it's got a lot of weight on it from these buildings. And I thought, alright, well that's a geologic principle. It's called iso and so this is a [00:06:30] really good opportunity for us to review
Dr. Jesse Reimink: Define that.
Define that. Cuz I don't know if we've actually really hammered ISO before in the podcast. So will
you just define it real quick, Chris?
Chris Bolhuis: I'll, I'll do my best. You're putting me on the spot, but Asasi is basically this gravitational balance. Um, let me explain it this way.
If you have two people walking on a beach on the part of the beach, that is kind of like somewhat wet and somewhat, it's not like soupy, runny or anything like that. They're gonna leave [00:07:00] footprints in the sand. You have one person that's six eight. Weighs 350 pounds and they're walking on the beach and they're walking next to somebody that's five foot tall and weighs a hundred pounds.
the bigger person is gonna have deeper footprints than the smaller person, right? It's a gravitational balance. And so geologically, we have a lot of things that can do this, you know, have this gravitational effect on the surface of the earth. For instance, glaciers.
At the height of the last ice age, you had glaciers that were, you know, [00:07:30] maybe three miles thick, right? I mean, that's a lot of weight. And that caused then that thickest part of the glacier to cause the ground below it to sink the most. it's like deep footprints, right? A lot of weight, a lot of sinking
mountains do the same thing.
The taller the mountains are, the deeper their roots extend down into the mantle. and so I think about it that way so immediately, right? My mind went to, well, yeah, New York [00:08:00] City, lots of people, lots of buildings that have an unbelievable amount of mass and you just put, it was like staggering numbers on that.
Of course it's sinking. It made sense, right? It, I thought, well it's not just New York, it's every major city is gonna have kind of thing
So that's where my mind went. What about you?
Dr. Jesse Reimink: Yeah. So I kind of was like, I kind of had the similar thought through it with, a different conclusion I suppose. Cuz you know, in New York City, if you're a geologist and you've been to New York City, you probably walked [00:08:30] around Central Park and the Manhattan Shift is exposed in Central Park and this is bedrock.
So A lot of the city, or at least substantial part of it, is built right on bedrock, at least Manhattan area, where all the big skyscrapers are, that's built on bedrock. And so I was kinda like, Hmm, that's interesting. I, I, I don't know,
maybe it is sinking under, maybe it
is sinking under its way. So I was, I was, I was kind of like thinking, oh, this is interesting. I, I need to read more into this. I didn't really have, I, I thought I was curious, That's for sure. But I
didn't have a
knee jerk reaction maybe.[00:09:00]
Chris Bolhuis: really interesting because I think that's important. The, what you brought up about the shift, this is shift is bedrock and it's not very compressible.
your thinking is, well, that's really interesting, but New York City, really, at least Manhattan should not be sinking because it's sitting right on this really not compressible bedrock,
Dr. Jesse Reimink: that brings up another really interesting part of this is that the researchers who put this together, they had to consider what kind of bedrock, or what kind of land are the buildings built on? Is it sitting on the bedrock [00:09:30] like central park, the Manhattan shift, or is it sitting on glacial till there's glacial till in the of the five boroughs?
Or is it sitting on infill, which I didn't know this, that there's a lot of New York City that's built on infill that the city has just kind of expanded the land area by. Putting fill in and then building on top of that. That stuff is super compressible. And so basically let's, let's sort of back up. And what the researcher did, they compiled all this data, compiled all the numbers, looked at the underlying Geology, and then fed this into [00:10:00] substance models.
So basically models that said, how much is that weight going to compress that type of land, whether it be bedrock or others. how much is it going to compress that and then compared that to. GPS and geodetic measurements of the ground movement. So then compared that to the observed ground movement in the New York City area.
That's kind of, you know, what they did here
Chris Bolhuis: Okay. that's a really interesting thing. So basically what you're saying is the authors didn't really [00:10:30] say that New York City's sinking due to its own mass or due to the mass that we've put
Dr. Jesse Reimink: this is an, interesting exercise, Chris, because I, I think you, um, as we're putting together, especially Camp Gio, you always gimme a hard time for hedging so much. And I'm always hedging, especially on this podcast, right? I'm like, oh, yeah, yeah, it's this. But, and, uh, the authors. Of this article, reading Between the Lines, we're doing this as well because in the published article, they don't [00:11:00] really say that it's sinking under its own weight in their title of their paper.
The Weight of New York City, possible contributions to substance from anthropogenic sources. Basically, I, I think my reading of it is that their conclusion is that in these areas where, The city is built on infill. there. could be a substantial amount of substance going on, and New York City is sinking At a rate of about one to two millimeters per year. That's what we observe. in different parts of the city. Some places are sinking faster, which again, could be due [00:11:30] to this infill, but actually the whole region, meaning from New York City, all the way down to the Carolinas, is sinking at a rate of a couple millimeters per year, mostly due to glacial relaxation.
Post glacial relaxation.
Chris Bolhuis: Can I interrupt you though a second, Jesse? Because I think that's not as intuitive. Let's, let's first talk about where ISO happens geologically or where we can see this kind of going on, right? Like for instance, you look at the Hudson Bay,
why is
the Hudson Bay there?
Dr. Jesse Reimink: one.
Chris Bolhuis: The [00:12:00] Hudson Bay was the zone of accumulation for continental ice sheets during the last ice age.
ice was tremendously thick, miles thick. And that's Hudson Bay is where the ice was, the thickest, that's where it was the heaviest. And so as a result, that's where the ground subsided more than anywhere else. And so it creates this natural depression, right? And so when it's gone, got invaded you know, covered with, with water.
And there you go. You got the Hudson Bay. you know, and that's. [00:12:30] This is why you get rocks that formed really, really deep in the earth, like nices and granites. How do they get exposed at the surface? This is one of the mechanisms for that.
Dr. Jesse Reimink: And so I think Chris, to explain, you described the Hudson Bay, and this is the classic one. You have this glacier weight, and as it's sitting on top of the rocks, all this three kilometers of continental scale glaciers are pushing down. Now the glaciers are gone and the crust is rebounding slower than the glaciers retreated.
So the glaciers are [00:13:00] gone and the crust is slowly rebounding up. And that makes intuitive sense. So why is the northeast of the United States sinking, subsiding? Because of glacial rebound, and I'm gonna use your analogy, I'm gonna modify your analogy. And your analogy for this is like, a shipping container ship where when it's empty, it's floating high.
When you pile stuff on top of it, it starts to float lower and lower and lower and sink down. Right now, if you take that shipping container ship, take all the containers off it, it's going to rebound up. That's like removing the glaciers. [00:13:30] Instead of that, I'm gonna take the really, really long shipping container ships Super long ones and I'm gonna put all of the weight on the back end, put all of the shipping container weight, really, really heavy stuff like we're gonna put tons of really heavy stuff right on the back and the front is gonna tip up right when you sort of sink the back of the ship. The front's gonna kind of tip up a little bit.
That's what happened. When the glaciers were in North America, when the glaciers were up north, the south and New York City and south to the Carolinas was kind of tipped [00:14:00] up. Now the glaciers are removed. We took all that stuff off and the ship is kind of. Leveling back out. right.
And so the New England area and down to the Carolinas is subsiding because of that post glacial relaxation of what's called the four bulge that the nose of the ship tipping up would be the four bulge.
And so that explains most of the regional subsidence, and I think it's an important thing to think about when we talk about sea level rise. The sea level is rising in a particular area, not just because the ocean's rising up, but the [00:14:30] land could be sinking. And these two things go hand in hand. Like the sinking of the land and the rising of the water due to climate change.
Those can make any problems with sea level rise. Much more dramatic, I guess.
Chris Bolhuis: Yeah. Hey Jesse. You nailed it. That analogy was my, that was great actually. Really, really well done on that. I, because that makes sense. I think anybody can understand that.
good job. Yeah.
That was awesome. Yeah.
Dr. Jesse Reimink: Well, I think, um, this was a Cool.
it was a cool article.
Chris Bolhuis: Catchy [00:15:00] title. Catchy title, man.
Dr. Jesse Reimink: Yeah, it is a Catchy title, It was, it was worth a
Chris Bolhuis: Yeah. and hey, once again, geoscience making news.
Dr. Jesse Reimink: So good. So cool. Excellent stuff. Hey, if you wanna learn all the basics of Geology, just like you would if you're sitting in Crisp, he's basically AP Geology class, or my intro to physical Geology at Penn State. You can go to geo.camp courses.com. It's the first link in your show notes. That's the Camp Geo all the images you need with audio discussions.
Send us an email, planet geo cast gmail.com. We love that. You can [00:15:30] go to our website, planet geo cast.com and there you can subscribe, you can support us. We really appreciate that. A couple people have done that recently. We super appreciate that. And, uh, leave us a rating and a review on your podcast platform that helps us with the algorithm
Chris Bolhuis: Cheers.
Dr. Jesse Reimink: peace.
