<p><em>You basically asked the same question over on Worldbuilding. I'm copying <a href="https://worldbuilding.stackexchange.com/a/209161/40609">my answer to that question</a> here. This answer does not specifically address the strength of the magnetic pulse because whether or not that strength has any affect is dependent on far too many variables to give you a simple answer (e.g., ground conductivity, ground charge, age of the power grid, availability of discharge protection, material used for the wires, climatological conditions, time of day... just to name a very, very, very few). However, it appears you're still looking for a reasonably &quot;real life&quot; justification for damaging personal electronics without blowing the power grid, so the answer is fundamentally the same.</em></p>
<hr>
<p><strong>You can screw up wireless coms, but nothing else without destroying the power grid first</strong></p>
<p>The nature of the stellar event doesn't matter. In fact, the source of what's causing the power grids to black out is irrelevant.</p>
<p>What's happening to your earth is a massive magnetic pulse, similar to a nuclear EMP. What's happening is exactly what happens with a generator: a changing magnetic field induces electrical flow in a long length of wire. The long length of wire isn't just important — it's critical. As the wire gets shorter, the strength of the magnetic field must get stronger to induce the same electrical current. The induced current must be enough to either screw up computation (very unlikely) or to blow the device's circuitry (much more likely).</p>
<p>And there's your problem. An electromagnetic (EM) event strong enough to knock out a single piece of electronic equipment would literally cause the wires in the power grid (above ground or underground, unless it was incredibly and therefore impractically deep underground) to vaporize.</p>
<p>OK, so I'm an electrical engineer, but let's not take my education's word for it. Let me give you a practical example. My family used to live in Texas, and one evening lightning struck near our house (yes, this really happened!). The thunder shook the whole house. But what happened electrically?</p>
<ul>
<li><p>A phone line (very thin, very long wire) in the corner of the house nearest the strike <em>vaporized.</em> I had to run a new phone cable. <em><strong>All other phone cables in the house were unharmed.</strong></em></p>
</li>
<li><p>An electrical wire in the wall closest to the strike heated to the point of melting the insulation, which caused it to short out and throw a breaker. I had to pull that and run a new one. <em><strong>All other electrical wires in the house were unharmed.</strong></em> Gratefully, this didn't start a fire, demonstrating the value of sheetrock and uninflammable insulation.</p>
</li>
<li><p>My computer and printer were connected using a 6-foot Centronics-style 36-wire parallel cable. It was just barely long enough to couple enough energy to blow the input port on the printer. <em><strong>The computer was unharmed</strong></em> What this really meant was that the electrostatic discharge (ESD) protection on the printer <em><strong>sucked.</strong></em> Walking across the floor and touching the input port directly would have blown it. I was very disappointed, but back then ESD protection in consumer electronics was only just coming into regular use.</p>
</li>
</ul>
<p><strong>What does this mean for you?</strong></p>
<p>It's impossible to electromagnetically (EM) damage equipment on a global scale without <em><strong>incredible</strong></em> damage to the power grid. All those really long, easy-to-induce-current-into wires make it simply impossible.</p>
<p>However, a strong global EM event could devastate wireless communications while leaving the power infrastructure intact.</p>

CC BY-SA 4.0
2021-08-01T18:02:27.563Z
2021-08-01T18:02:27.563Z
JBH
<p>After reading the <a href="https://en.wikipedia.org/wiki/Geomagnetic_storm#Occurrences" rel="nofollow noreferrer">Wikipedia article on geomagnetic storms</a>, I'm curious about what the effects of a -400-nanotesla-minimum geomagnetic storm would be on modern military and consumer electronics.</p>
<p>The <a href="https://en.wikipedia.org/wiki/March_1989_geomagnetic_storm" rel="nofollow noreferrer">March 1989 geomagnetic storm</a>, with a minimum of -589 nT, shut down Quebec's power grid, but the <a href="https://en.wikipedia.org/wiki/Bastille_Day_event" rel="nofollow noreferrer">Bastille Day event</a>, with a minimum of -301 nT, apparently didn't do much, at least to power grids. However, I cannot find information on how either effected military/consumer electronics.</p>
<p>What would a -400 nT storm cause, and how could it be shielded against?</p>

CC BY-SA 4.0
2021-07-31T21:25:08.013Z
This specific question about phenomenon on Earth might be good to ask in [Electronics SE](https://electronics.stackexchange.com/) or perhaps better yet [Earth Science SE](https://earthscience.stackexchange.com/) but it's not about Astronomy. I think you can do a quick search in both those sites and get an idea where it will be best received and where the best answers are likely to be posted.
uhoh
CC BY-SA 4.0
2021-07-31T21:26:24.717Z
I’m voting to close this *interesting and well-researched question* because it's not about Astronomy. It's a good question and it can probably be better asked on other sites like Electronics SE and Earth Science SE as mentioned above.
uhoh
CC BY-SA 4.0
2021-07-31T21:26:46.157Z
@uhoh Well, there are questions on here (https://astronomy.stackexchange.com/questions/87/what-are-the-main-differences-between-solar-flares-and-coronal-mass-ejections?rq=1) about solar flares and coronal mass ejections, so I figured that this might be one of many good sources of information regarding this, and, unfortunately, I can only post one time per 40 minutes.
KEY_ABRADE
CC BY-SA 4.0
2021-07-31T21:28:37.610Z
I know you may need/want/like a speedy answer; have a look through those other two sights and see if there is any helpful information. For this question I'd recommend you either wait to see what others think, or go along with the close reason so that a moderator can assist and migrate your question for your.
uhoh
CC BY-SA 4.0
2021-07-31T21:31:44.510Z
@uhoh I'm really going more for "maximum possible number of perspectives on this", so I'll wait. I don't particularly expect anyone to answer questions quickly online.
KEY_ABRADE
CC BY-SA 4.0
2021-07-31T21:48:03.500Z
Power grids are shut down because they present large conducting loops; thousands of square kilometers. [Electromagnetic induction](https://en.wikipedia.org/wiki/Electromagnetic_induction) or EMF is proportional to $A dB/dt$ where $A$ is the area of the loop and $dB/dt$ is the *rate of change* of the average magnetic field in the loop (that would be Teslas per second). Military and consumer electronics are not thousands of square kilometers, they are small, well-shielded boxes. The only effect would be if their batteries didn't work when the mains power shuts off.
uhoh
CC BY-SA 4.0
2021-07-31T21:50:02.267Z
It's nothing like an [electromagnetic pulse](https://en.wikipedia.org/wiki/Electromagnetic_pulse) or EMP which happen extremely fast and are quite local phenomenon, usually due to a certain kind of nuclear explosion or a carefully crafted EMP weapon. Is it possible that you are getting the two mixed up? If there's a geomagnetic storm then the circuit breakers on the power grid trigger and your lights go out. If you have a gas generator, or something that runs on batteries, generally you're in the clear.
uhoh
CC BY-SA 4.0
2021-07-31T21:51:46.013Z
@uhoh I wasn't familiar with why they messed power grids up, so I figured that it just applied to all electronics. Apparently not.
KEY_ABRADE
CC BY-SA 4.0
2021-07-31T21:55:07.603Z
You can ask in Electronics SE or in World Building SE if there is any mechanism at all by which a geomagnetic storm could damage personal electronics or communications devices for example. It can mess with GPS signal timing and accuracy slightly and perhaps cause time bases to be off by tens of nanoseconds, and one's access to the internet might go down, but really most hard line and wireless like 4G will probably be unaffected since cell towers and internet distribution systems have battery backup for when the power goes out.
uhoh
CC BY-SA 4.0
2021-07-31T21:57:08.970Z
@uhoh I've asked those boards already. I'll let this one sit and close it if asked.
KEY_ABRADE
CC BY-SA 4.0
2021-07-31T21:57:17.213Z
Also check out [Does a geomagnetic storm visibly deflect a compass?](https://earthscience.stackexchange.com/q/19303/6031)
uhoh
<the-sun><stellar-astrophysics><coronal-mass-ejection><electromagnetic-spectrum>
What would be the effects of a -400 nanotesla geomagnetic storm on modern electronics?
KEY_ABRADE
# What would be the effects of a -400 nanotesla geomagnetic storm on modern electronics?

(Asked by: username_0 on 2021-07-31)

After reading the [Wikipedia article on geomagnetic storms](https://en.wikipedia.org/wiki/Geomagnetic_storm#Occurrences), I'm curious about what the effects of a -400-nanotesla-minimum geomagnetic storm would be on modern military and consumer electronics.

The [March 1989 geomagnetic storm](https://en.wikipedia.org/wiki/March_1989_geomagnetic_storm), with a minimum of -589 nT, shut down Quebec's power grid, but the [Bastille Day event](https://en.wikipedia.org/wiki/Bastille_Day_event), with a minimum of -301 nT, apparently didn't do much, at least to power grids. However, I cannot find information on how either effected military/consumer electronics.

What would a -400 nT storm cause, and how could it be shielded against?

**Tags:** the-sun, stellar-astrophysics, coronal-mass-ejection, electromagnetic-spectrum

> **Comments:**
> **username_1**: This specific question about phenomenon on Earth might be good to ask in [Electronics SE](https://electronics.stackexchange.com/) or perhaps better yet [Earth Science SE](https://earthscience.stackexchange.com/) but it's not about Astronomy. I think you can do a quick search in both those sites and get an idea where it will be best received and where the best answers are likely to be posted.  
> **username_1**: I’m voting to close this *interesting and well-researched question* because it's not about Astronomy. It's a good question and it can probably be better asked on other sites like Electronics SE and Earth Science SE as mentioned above.  
> **username_0**: @username_1 Well, there are questions on here (https://astronomy.stackexchange.com/questions/87/what-are-the-main-differences-between-solar-flares-and-coronal-mass-ejections?rq=1) about solar flares and coronal mass ejections, so I figured that this might be one of many good sources of information regarding this, and, unfortunately, I can only post one time per 40 minutes.  
> **username_1**: I know you may need/want/like a speedy answer; have a look through those other two sights and see if there is any helpful information. For this question I'd recommend you either wait to see what others think, or go along with the close reason so that a moderator can assist and migrate your question for your.  
> **username_0**: @username_1 I'm really going more for "maximum possible number of perspectives on this", so I'll wait. I don't particularly expect anyone to answer questions quickly online.  
> **username_1**: Power grids are shut down because they present large conducting loops; thousands of square kilometers. [Electromagnetic induction](https://en.wikipedia.org/wiki/Electromagnetic_induction) or EMF is proportional to $A dB/dt$ where $A$ is the area of the loop and $dB/dt$ is the *rate of change* of the average magnetic field in the loop (that would be Teslas per second). Military and consumer electronics are not thousands of square kilometers, they are small, well-shielded boxes. The only effect would be if their batteries didn't work when the mains power shuts off.  
> **username_1**: It's nothing like an [electromagnetic pulse](https://en.wikipedia.org/wiki/Electromagnetic_pulse) or EMP which happen extremely fast and are quite local phenomenon, usually due to a certain kind of nuclear explosion or a carefully crafted EMP weapon. Is it possible that you are getting the two mixed up? If there's a geomagnetic storm then the circuit breakers on the power grid trigger and your lights go out. If you have a gas generator, or something that runs on batteries, generally you're in the clear.  
> **username_0**: @username_1 I wasn't familiar with why they messed power grids up, so I figured that it just applied to all electronics. Apparently not.  
> **username_1**: You can ask in Electronics SE or in World Building SE if there is any mechanism at all by which a geomagnetic storm could damage personal electronics or communications devices for example. It can mess with GPS signal timing and accuracy slightly and perhaps cause time bases to be off by tens of nanoseconds, and one's access to the internet might go down, but really most hard line and wireless like 4G will probably be unaffected since cell towers and internet distribution systems have battery backup for when the power goes out.  
> **username_0**: @username_1 I've asked those boards already. I'll let this one sit and close it if asked.  
> **username_1**: Also check out [Does a geomagnetic storm visibly deflect a compass?](https://earthscience.stackexchange.com/q/19303/6031)  

---

## 1 answers

### Answer by username_2 on 2021-08-01. Score: 1 | Accepted answer

*You basically asked the same question over on Worldbuilding. I'm copying [my answer to that question](https://worldbuilding.stackexchange.com/a/209161/40609) here. This answer does not specifically address the strength of the magnetic pulse because whether or not that strength has any affect is dependent on far too many variables to give you a simple answer (e.g., ground conductivity, ground charge, age of the power grid, availability of discharge protection, material used for the wires, climatological conditions, time of day... just to name a very, very, very few). However, it appears you're still looking for a reasonably "real life" justification for damaging personal electronics without blowing the power grid, so the answer is fundamentally the same.*

---

**You can screw up wireless coms, but nothing else without destroying the power grid first**

The nature of the stellar event doesn't matter. In fact, the source of what's causing the power grids to black out is irrelevant.

What's happening to your earth is a massive magnetic pulse, similar to a nuclear EMP. What's happening is exactly what happens with a generator: a changing magnetic field induces electrical flow in a long length of wire. The long length of wire isn't just important — it's critical. As the wire gets shorter, the strength of the magnetic field must get stronger to induce the same electrical current. The induced current must be enough to either screw up computation (very unlikely) or to blow the device's circuitry (much more likely).

And there's your problem. An electromagnetic (EM) event strong enough to knock out a single piece of electronic equipment would literally cause the wires in the power grid (above ground or underground, unless it was incredibly and therefore impractically deep underground) to vaporize.

OK, so I'm an electrical engineer, but let's not take my education's word for it. Let me give you a practical example. My family used to live in Texas, and one evening lightning struck near our house (yes, this really happened!). The thunder shook the whole house. But what happened electrically?

* A phone line (very thin, very long wire) in the corner of the house nearest the strike *vaporized.* I had to run a new phone cable. ***All other phone cables in the house were unharmed.***
* An electrical wire in the wall closest to the strike heated to the point of melting the insulation, which caused it to short out and throw a breaker. I had to pull that and run a new one. ***All other electrical wires in the house were unharmed.*** Gratefully, this didn't start a fire, demonstrating the value of sheetrock and uninflammable insulation.
* My computer and printer were connected using a 6-foot Centronics-style 36-wire parallel cable. It was just barely long enough to couple enough energy to blow the input port on the printer. ***The computer was unharmed*** What this really meant was that the electrostatic discharge (ESD) protection on the printer ***sucked.*** Walking across the floor and touching the input port directly would have blown it. I was very disappointed, but back then ESD protection in consumer electronics was only just coming into regular use.

**What does this mean for you?**

It's impossible to electromagnetically (EM) damage equipment on a global scale without ***incredible*** damage to the power grid. All those really long, easy-to-induce-current-into wires make it simply impossible.

However, a strong global EM event could devastate wireless communications while leaving the power infrastructure intact.


---

