<p>I did not find any Richter-scale numbers for Io, probably since there are no direct measurements yet, or how <a href="https://astronomy.stackexchange.com/users/1203/atmosphericprisonescape">atmosphericprisonescape</a> puts it:</p>
<blockquote>
<p>Nobody put a seismometer on Io yet, so we don't know. The only other bodies except for Earth, where seismometers have been placed so far are the Moon and Mars.</p>
</blockquote>
<p>But I found some interesting comparison at on NASA's SpacePlace: <a href="https://spaceplace.nasa.gov/io-tides/en/" rel="nofollow noreferrer">High Tideo on Io!</a></p>
<blockquote>
<p>On planet Jupiter's moon Io (&quot;EYE-oh&quot;), the ground itself moves up and down like an elevator taking people to the top and bottom of a 30-story building!</p>
</blockquote>
<p>This would mean amplitudes for the tidal waves (and therefore also for regular Io-quakes) of <span class="math-container">${\rm 60 \dots 90 m}$</span>! I am not sure though where that number comes from, but it compares with <span class="math-container">${\rm 0.2m}$</span> tidal waves of the Earth's solid crust which is not really measurable on Earth, except with interferometers like e.g. <a href="https://en.wikipedia.org/wiki/GEO600" rel="nofollow noreferrer">GEO600</a>.</p>
<h3>References</h3>
<ul>
<li><a href="https://en.wikipedia.org/wiki/Tidal_heating_of_Io" rel="nofollow noreferrer">Wikipedia on Tital Heating of Io</a></li>
<li><a href="https://astronomy.stackexchange.com/questions/40316/">Are planet-destroying quakes possible or observable?</a></li>
</ul>

CC BY-SA 4.0
2021-03-04T10:49:22.627Z
@ConnorGarcia [You mentioned](https://astronomy.stackexchange.com/a/40331/37191) an equation $\log E=5.24+1.44M$ to relate energy $E$  to magnitude $M$, but is that universal? Could we somehow get from wave high to Io-quake magnitude?
B--rian
CC BY-SA 4.0
2021-03-04T10:54:14.560Z
These kind of equations come from the definition of the seismic moment. Often the magnitude as defined by Richter is used so that the moment matches in Californian earthquakes (thus shallow strike-slip quakes). Energy then comes from the energy of a seismic shear wave with the amplitudes as-is. https://en.wikipedia.org/wiki/Moment_magnitude_scale
planetmaker
CC BY-SA 4.0
2021-03-04T11:01:51.883Z
@planetmaker I do not fully understand your comment, but I understand that there are multiple ways of definining magnitude. If we ignore magnitude for a minute: Do you agree with my idea that we could in general estimate the energy of the tidal "quakes" on Io, given the wavelength (and some assumptions)?
B--rian
CC BY-SA 4.0
2021-03-04T11:33:33.537Z
Yes, you need the wavelength, the amplitude and some physical properties like young's modulus, poisson number and compression modulus. These can reasonably be estimated given roughly known chemistry
planetmaker
CC BY-SA 4.0
2021-03-04T16:48:24.697Z
Amplitude is half the crest to trough, so it might be 30-45 meter amplitude.  But is this difference from Io-quakes (plate slip/shifts) or pure tidal compression?  The original Richter scale is just $M_L=\log_{10}(A)$ where $A$ is the quake amplitude (I don't know the amplitude units).  The modern formula, as planetmaker points out, require more physical properties to evaluate.
Connor Garcia
CC BY-SA 4.0
2021-03-04T10:47:54.590Z
2021-03-07T17:24:56.013Z
2021-03-07T17:24:56.013Z
B--rian
<p>Jupiter's moon Io is the most geologically active celestial body in our system. It has the strongest volcanoes and quakes. Of course in practice these quakes wouldn't be as dangerous as on Earth for someone on the surface due to Io's low surface gravity (0.183 g). Let's ignore that however, do we know some of the strongest Ioquakes, what would be their magnitude on the Richter scale?</p>

CC BY-SA 4.0
2020-02-15T16:50:39.343Z
Nobody put a seismometer on Io yet, so we don't know. The only other bodies except for Earth, where seismometers have been placed so far are the Moon and Mars.
AtmosphericPrisonEscape
CC BY-SA 4.0
2020-02-15T16:52:28.023Z
@AtmosphericPrisonEscape Probes could measure a quake from outer space.
user30007
CC BY-SA 4.0
2020-02-15T16:59:39.907Z
How do you propose to do that? To my knowledge no mission has done so. On Earth, for exceptionally strong earthquakes we can detect density disturbances propagating from the quake into the upper atmosphere, but that is only possible due to dedicated instruments on the dedicated Earth monitoring fleets by ESA and NASA. None of those factors are given on Io.
AtmosphericPrisonEscape
CC BY-SA 4.0
2020-02-15T17:02:13.077Z
@AtmosphericPrisonEscape Couldn't the Juno probe measure the seismologic activity with a laser or something? Since we know that Io has very strong quakes we can kind of make assumptions, right?
user30007
CC BY-SA 4.0
2020-02-15T17:07:35.937Z
"With a laser or something" - very vague proposal. No, Juno doesn't have any geological mapping tools. Furthermore Juno is a mission dedicated to infer Jupiter's interior structure. To achieve this, it has a high-precision radio antenna on board which has to point at specific angles between Jupiter and Earth. There is no space there for much Io science, even if the instrument were there.
AtmosphericPrisonEscape
CC BY-SA 4.0
2020-02-15T17:16:45.933Z
@AtmosphericPrisonEscape It's not a proposal, it's an option. I'm no geologist.
user30007
CC BY-SA 4.0
2020-02-16T03:22:58.997Z
This is a good question, but for now the only possible answer is "we don't know." Moreover, we won't know for at least another decade-plus because (1) as noted in other comments, a seismometer is needed, (2) missions that far out  require over a decade of planning, development, and operation, and (2) there are no proposed Io lander missions in this decade.
David Hammen
CC BY-SA 4.0
2020-07-19T16:56:01.577Z
Perhaps the Io Volcanic Observer or FIRE will give some insight. https://en.wikipedia.org/wiki/Io_Volcano_Observer https://en.wikipedia.org/wiki/Flyby_of_Io_with_Repeat_Encounters
Ioannes
<geology><io><galilean-moons><quake>
How strong are the strongest Ioquakes?
user30007
# How strong are the strongest Ioquakes?

(Asked by: username_0 on 2020-02-15)

Jupiter's moon Io is the most geologically active celestial body in our system. It has the strongest volcanoes and quakes. Of course in practice these quakes wouldn't be as dangerous as on Earth for someone on the surface due to Io's low surface gravity (0.183 g). Let's ignore that however, do we know some of the strongest Ioquakes, what would be their magnitude on the Richter scale?

**Tags:** geology, io, galilean-moons, quake

> **Comments:**
> **username_1**: Nobody put a seismometer on Io yet, so we don't know. The only other bodies except for Earth, where seismometers have been placed so far are the Moon and Mars.  
> **username_0**: @username_1 Probes could measure a quake from outer space.  
> **username_1**: How do you propose to do that? To my knowledge no mission has done so. On Earth, for exceptionally strong earthquakes we can detect density disturbances propagating from the quake into the upper atmosphere, but that is only possible due to dedicated instruments on the dedicated Earth monitoring fleets by ESA and NASA. None of those factors are given on Io.  
> **username_0**: @username_1 Couldn't the Juno probe measure the seismologic activity with a laser or something? Since we know that Io has very strong quakes we can kind of make assumptions, right?  
> **username_1**: "With a laser or something" - very vague proposal. No, Juno doesn't have any geological mapping tools. Furthermore Juno is a mission dedicated to infer Jupiter's interior structure. To achieve this, it has a high-precision radio antenna on board which has to point at specific angles between Jupiter and Earth. There is no space there for much Io science, even if the instrument were there.  
> **username_0**: @username_1 It's not a proposal, it's an option. I'm no geologist.  
> **username_2**: This is a good question, but for now the only possible answer is "we don't know." Moreover, we won't know for at least another decade-plus because (1) as noted in other comments, a seismometer is needed, (2) missions that far out  require over a decade of planning, development, and operation, and (2) there are no proposed Io lander missions in this decade.  
> **username_3**: Perhaps the Io Volcanic Observer or FIRE will give some insight. https://en.wikipedia.org/wiki/Io_Volcano_Observer https://en.wikipedia.org/wiki/Flyby_of_Io_with_Repeat_Encounters  

---

## 1 answers

### Answer by username_4 on 2021-03-04. Score: 1

I did not find any Richter-scale numbers for Io, probably since there are no direct measurements yet, or how [username_1](https://astronomy.stackexchange.com/users/1203/username_1) puts it:

> Nobody put a seismometer on Io yet, so we don't know. The only other bodies except for Earth, where seismometers have been placed so far are the Moon and Mars.

But I found some interesting comparison at on NASA's SpacePlace: [High Tideo on Io!](https://spaceplace.nasa.gov/io-tides/en/)

> On planet Jupiter's moon Io ("EYE-oh"), the ground itself moves up and down like an elevator taking people to the top and bottom of a 30-story building!

This would mean amplitudes for the tidal waves (and therefore also for regular Io-quakes) of ${\rm 60 \dots 90 m}$! I am not sure though where that number comes from, but it compares with ${\rm 0.2m}$ tidal waves of the Earth's solid crust which is not really measurable on Earth, except with interferometers like e.g. [GEO600](https://en.wikipedia.org/wiki/GEO600).

### References

* [Wikipedia on Tital Heating of Io](https://en.wikipedia.org/wiki/Tidal_heating_of_Io)
* [Are planet-destroying quakes possible or observable?](https://astronomy.stackexchange.com/questions/40316/)

> **Comments:**
> **username_4**: @username_6 [You mentioned](https://astronomy.stackexchange.com/a/40331/37191) an equation $\log E=5.24+1.44M$ to relate energy $E$  to magnitude $M$, but is that universal? Could we somehow get from wave high to Io-quake magnitude?  
> **username_5**: These kind of equations come from the definition of the seismic moment. Often the magnitude as defined by Richter is used so that the moment matches in Californian earthquakes (thus shallow strike-slip quakes). Energy then comes from the energy of a seismic shear wave with the amplitudes as-is. https://en.wikipedia.org/wiki/Moment_magnitude_scale  
> **username_4**: @username_5 I do not fully understand your comment, but I understand that there are multiple ways of definining magnitude. If we ignore magnitude for a minute: Do you agree with my idea that we could in general estimate the energy of the tidal "quakes" on Io, given the wavelength (and some assumptions)?  
> **username_5**: Yes, you need the wavelength, the amplitude and some physical properties like young's modulus, poisson number and compression modulus. These can reasonably be estimated given roughly known chemistry  
> **username_6**: Amplitude is half the crest to trough, so it might be 30-45 meter amplitude.  But is this difference from Io-quakes (plate slip/shifts) or pure tidal compression?  The original Richter scale is just $M_L=\log_{10}(A)$ where $A$ is the quake amplitude (I don't know the amplitude units).  The modern formula, as username_5 points out, require more physical properties to evaluate.  

---

