The moon may be tectonically active • Hacker News Board

Re: The moon may be tectonically active

#11

Post by tracer4201 » Thu, May 16, 2019, 7:11 AM UTC

I’m a bit out of my depth here, so someone more knowledgeable correct me if my understanding is wrong.

In the article, they’re stating they believe it’s seismic activity because it’s occurring within some distance of these fault scarps, which also appear to be where the surface displays lines in the images shown in the article?

How are they dismissing it’s not a result of material from space striking the surface? Is it that their sensors are able to disambiguate if the source is from the surface vs deeper in the moon?

Re: The moon may be tectonically active

#12

Post by flukus » Thu, May 16, 2019, 7:19 AM UTC

tracer4201 wrote: post #11

I’m a bit out of my depth here, so someone more knowledgeable correct me if my understanding is wrong. In the article, they’re stating they believe it’s seismic activity because it’s occurring within some distance of these fault scarps, which also appear to be where the surface displays lines in the images shown in the article? How are they dismissing it’s not a result of material from space striking the surface? Is…

> How are they dismissing it’s not a result of material from space striking the surface?

The earthquakes are magnitude 5.5, plugging that into an energy calculator (http://earthalabama.com/energy.html#/) gives a result of 0.2 Hiroshima bombs, which I think would be noticeable.

Re: The moon may be tectonically active

#13

Post by arethuza » Thu, May 16, 2019, 8:08 AM UTC

xaduha wrote: post #5

ryannevius wrote: post #2

The abstract from the actual study[1]: > The discovery of young thrust faults on the Moon is evidence of recent tectonic activity, but how recent is unknown. Seismometers at four Apollo landing sites recorded 28 shallow moonquakes between 1969 and 1977. Some of these shallow quakes could be associated with activity on the young faults. However, the epicentre locations of these quakes are poorly constrained. Here we p…

Didn't people believe at some point that moon landings themselves caused the Moon to vibrate or something along those lines? Always found that eyebrow-raising.

The ascent stages of the Apollo Lunar Modules were deliberately crashed onto the Moon to generate shock waves to support seismology experiments:

https://www.popsci.com/how-apollo-lunar-modules-were-smashed...

Re: The moon may be tectonically active

#14

Post by Galaxity » Thu, May 16, 2019, 8:26 AM UTC

taneq wrote: post #3

Pun intended.

I rolled my eyes, but then thought "ok, that's fair".

Re: The moon may be tectonically active

#15

Post by [deleted] » Thu, May 16, 2019, 8:44 AM UTC

tracer4201 wrote: post #11

I’m a bit out of my depth here, so someone more knowledgeable correct me if my understanding is wrong. In the article, they’re stating they believe it’s seismic activity because it’s occurring within some distance of these fault scarps, which also appear to be where the surface displays lines in the images shown in the article? How are they dismissing it’s not a result of material from space striking the surface? Is…

[deleted]

Re: The moon may be tectonically active

#16

Post by pferde » Thu, May 16, 2019, 9:38 AM UTC

Looks like Arthur C. Clarke guessed correctly in his sci-fi novel https://en.wikipedia.org/wiki/A_Fall_of_Moondust, where a moonquake causes problems to a "sand-cruiser" full of tourists.

Re: The moon may be tectonically active

#17

Post by vegasdew » Thu, May 16, 2019, 9:54 AM UTC

Maybe it is ready to hatch. [https://tardis.fandom.com/wiki/Kill_the_Moon_(TV_story)]

Re: The moon may be tectonically active

#18

Post by IanSanders » Thu, May 16, 2019, 10:05 AM UTC

flukus wrote: post #12

tracer4201 wrote: post #11

I’m a bit out of my depth here, so someone more knowledgeable correct me if my understanding is wrong. In the article, they’re stating they believe it’s seismic activity because it’s occurring within some distance of these fault scarps, which also appear to be where the surface displays lines in the images shown in the article? How are they dismissing it’s not a result of material from space striking the surface? Is…

> How are they dismissing it’s not a result of material from space striking the surface? The earthquakes are magnitude 5.5, plugging that into an energy calculator ( http://earthalabama.com/energy.html#/ ) gives a result of 0.2 Hiroshima bombs, which I think would be noticeable.

I wonder if the calculation requires correction due to moon/earth mass difference.

Re: The moon may be tectonically active

#19

Post by wallace_f » Thu, May 16, 2019, 10:12 AM UTC

arethuza wrote: post #13

xaduha wrote: post #5

Earlier quoted context omitted.

Didn't people believe at some point that moon landings themselves caused the Moon to vibrate or something along those lines? Always found that eyebrow-raising.

The ascent stages of the Apollo Lunar Modules were deliberately crashed onto the Moon to generate shock waves to support seismology experiments: https://www.popsci.com/how-apollo-lunar-modules-were-smashed...

Also, for the record this was explicitly discussed in the OP...

Re: The moon may be tectonically active

#20

Post by saagarjha » Thu, May 16, 2019, 11:19 AM UTC

IanSanders wrote: post #18

flukus wrote: post #12

Earlier quoted context omitted.

> How are they dismissing it’s not a result of material from space striking the surface? The earthquakes are magnitude 5.5, plugging that into an energy calculator ( http://earthalabama.com/energy.html#/ ) gives a result of 0.2 Hiroshima bombs, which I think would be noticeable.

I wonder if the calculation requires correction due to moon/earth mass difference.

Moment magnitude is generally supposed to be correlated to the amount of energy released, so I would tend to think that it wouldn’t need correction.