US–Indian space mission maps extreme subsidence in Mexico City
100 points
2 days ago
| 8 comments
| phys.org
| HN
mturmon
28 minutes ago
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Like the article hints at, some of the particular strengths of this new measurement:

- frequent revisit, so can track even sub-monthly changes

- the L-band radar is at a wavelength (24cm) that penetrates vegetation canopy, removing a confounder from the measurement

- excellent spatial resolution that is relevant to urban scenes

The data volume is exceptionally high and required a lot of engineering effort. All radars are demanding, but this one was a new high-water mark.

(https://www.earthdata.nasa.gov/news/now-that-nisar-launched-...)

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hn_throwaway_99
5 hours ago
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So, perhaps a dumb question, but the article mentions that 14 steps have been added to the base of the Angel of Independence monument, and the Wikipedia article mentions the same things:

> Originally, nine steps led to the base, but due to the sinking of the ground, an ongoing problem in Mexico City, fourteen more steps have been added.

So why didn't the monument itself also sink? Does it have piles going down to bedrock or something?

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resist_futility
4 hours ago
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thousands of wooden piles to create a foundation with the first one even failing and the foundation being reconstructed

http://www.mexicomaxico.org/ParisMex/resumen.htm

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sandworm101
4 hours ago
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Also from wikipedia: ... "The commission determined that the foundations of the monument were poorly planned, so it was decided to demolish the structure."

So yes, it has an engineered foundation, a double-engineered foundation. The roads around it almost certainly do not. So it is plausible that the monument is not sinking as quickly.

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wartywhoa23
5 hours ago
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Angels don't sink, they rise! :)
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AntiUSAbah
5 hours ago
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Depending of what stories you want to reference with this: Lucifer, Belial, Beelzebub all did not 'rise'.
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wartywhoa23
4 hours ago
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Surely The Angel Of Independence must ascend, no? :)
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sundarurfriend
3 hours ago
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I don't know the actual Christian theology, but at least in modern popular interpretations, Lucifer is the Angel of Independence, so that would suggest no!
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pcrh
5 hours ago
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The amount of subsidence is quite dramatic, up to 25 cm per year!

What are the practical consequences of this today, and what is being done to remedy this?

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mturmon
36 minutes ago
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Just as a fun fact, here are some images of the extent of subsidence (due to groundwater pumping for agriculture) in the California Central Valley: https://www.usgs.gov/centers/land-subsidence-in-california/m...

Note in particular the last one, which is a classic. Roads, buildings, and all underground infrastructure is affected. As well as anyone else who uses that groundwater, as well as future users - because come groundwater reservoirs do not recover, the compaction is permanent.

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nadermx
4 hours ago
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They are clearly not doing enough to remedy this; The only real solucion is to stop pumping the ground water, like I believe Japan did.
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Schiendelman
3 hours ago
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Miami has a similar issue, doesn't it?
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manquer
3 hours ago
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so does Jakarta and few other cities in the world.
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alephnerd
42 minutes ago
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> What are the practical consequences of this today

Infrastructure degradation. Think overpass collapses or metro rail lines being misaligned.

> what is being done to remedy this

Not enough. CDMX faces the issue of multiple political entities with varying power making management difficult.

A lot of the subsidence happens in informal settlements [0] due to a mixture of political populism (no one would dare demolish an informal settlement and piss off voters).

Beijing used to have a similar issue, but a mixture of hukou, mass evictions, and mass demolitions helped alleviate the issue.

[0] - https://penniur.upenn.edu/uploads/media/02_Gutierrez.pdf

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gurjeet
6 hours ago
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For the uninitiated, ISRO -> Indian Space Research Organization
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zx8080
3 hours ago
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Cloudflare: verification rejected. Accessing from Japan.

Thank you very much, Cloudlare.

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hactually
53 minutes ago
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same in Australia
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ani_k47
4 hours ago
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I really can't believe that an issue discovered in 1925 still isn't solved. A kind of issue which wont take a Nobel prize to be solved. This is sad.
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chrisco255
3 hours ago
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What solution? The earth is constantly moving and churning. The article states the city is built on an aquifer.
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trillic
3 hours ago
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Mexico City was built on top of a lake that was dried to facilitate the expansion of the city.
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1270018080
3 hours ago
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> What solution

The nobel prize winner hopefully figures that out

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BurningFrog
2 hours ago
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Many, many problems have good practical solutions that are politically impossible to implement.
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anigbrowl
6 hours ago
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I get that the article is primarily about the satellite capabilities, but it's rather annoying it doesn't mention what the future impact of the subsidence might be.
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greggsy
6 hours ago
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I think that it’s quite responsible not to speculate on something they’re not an expert on.

It’s exactly the sort of news bite that catastrophists glom onto.

This is responsible journalism.

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PunchyHamster
4 hours ago
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> I think that it’s quite responsible not to speculate on something they’re not an expert on.

"Recent satellite maps show Mexico City getting closer to hell at alarming rate"

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anigbrowl
5 hours ago
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They could just call a geologist and ask, or cite some published works on the topic. It's not responsible, it's lazy.
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icegreentea2
4 hours ago
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This is a phys.org "article". They're usually just rehashed press releases, and this one is particularly bad - it's literally just the NASA press release with the last 2 paragraphs chopped off. https://www.nasa.gov/missions/nisar/us-indian-space-mission-...
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AntiUSAbah
5 hours ago
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It breaks water lines which increases the water problem even faster. On one side because its expensive to fix and on the other side because small leaks lead to massive water losses you don't find fast or easy.
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robocat
3 hours ago
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Also broken mains lead to sinkholes: https://www.bbc.com/news/videos/cj9zex1r3kjo
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dhosek
2 hours ago
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There are also abandoned mines under parts of the city which also contributes to hazardous conditions.
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barney54
5 hours ago
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Nor does it say how much subsidence the satellite documented.
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barbazoo
5 hours ago
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There's this under the picture.

> New data from NISAR shows where Mexico City and its environs subsided by up to a few centimeters per month (shown in blue) between Oct. 25, 2025, and Jan. 17, 2026

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dhosek
2 hours ago
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The labels on the map were also confusing, and at first because of the relative positioning of the texts identifying the airport and the angel I thought up was East and not North, although a closer inspection made things clearer (and yes, up is North).
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gnabgib
2 hours ago
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Uh, you know, from the original source - Nasa (2 points, 2 days ago) https://news.ycombinator.com/item?id=47970672

Real shame this re-report made the SCP

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