Solar Flares
Solar flares could disrupt the radio communications and power distribution systems. There was a solar flare which hit the earth on 1859 caused Telegraph offices to explode and caused other damage.

Suppose one hits the Earth in the near future (White House prepares for this).

Could solar flares damage digital data stored in any medium such as HDD, SSD etc? (Which are not connected to a power source in any way, but simply kept on my table)?

If they can, how can I protect my precious data? (Please don't tell me to backup my data. :p)

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    Backing up your data is exactly how you would prepare for possible data loss. Commented Dec 16, 2015 at 13:04
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    @ChrisInEdmonton Even if I do so, where do I keep the back-up drive or how? (Actually, thats exactly the question)
    – RogUE
    Commented Dec 16, 2015 at 13:07
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    I suggest putting your hard disk inside of a Faraday cage. These days, most PC cases are Faraday cages already.
    – Aron
    Commented Dec 17, 2015 at 3:09
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    Keep your backup off-site. Your house burning down is probably more likely than data being damaged by a solar flare. A backup that's in the same house as the computer you're backing up is no backup. If you really value your data find a service that will continuously backup your data offsite. Commented Dec 21, 2015 at 20:02
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    Using a redundant storage method for backups (e.g. specialized filesystem, RAID5, or even encrypted archives with recovery information) would largely mitigate any possible effects on the backups themselves. Another option would be to generate recovery information directly as parchives (e.g. using QuickPAR), although as mentioned it's also important to use a robust filesystem that is resistant or can easily recover bit errors. Commented Dec 23, 2015 at 6:41

6 Answers 6


The problem with a geomagnetic storm is that it will induce currents in conducting objects, such as power lines.

A geomagnetic storm shares some properties with, but it is not, an EMP. Or better: what we think of as an EMP is a very localized phenomenon, which at relatively close range has energies orders of magnitude above the ones of a CMU that happened 150 million kilometers away from the Earth.

So an EMP like STARFISH PRIME's would trash your equipment if it happened within a few (tens of?) kilometers, depending on shielding. A geomagnetic storm will induce currents that are proportional to the length of the conductor coil. While this is very bad if you're a power station connected to a 500 km set of wires, it is next to harmless if you're a home PC no wider than a few tens of inches.

But telluric current protection is in effect on most power lines since the bad period in the 1990's, and hard disks and the like are lightly shielded against everyday magnetic interference.

Only the severest magnetic storms are able to pierce Earth's magnetosphere, in which your hard disk lives immersed. It follows that only rarely a magnetic storm will develop local strengths of more than, say, five times Earth's magnetic field, which is around 0.50 Gauss.

And hard disks (and consumer electronic equipment in general) are largely immune to fields up to six hundred times that.

For example, in RAID disks, you'll have DISK 2 which is spinning very close to disks 1 and 3, which come equipped with very powerful rare earth magnets. From 2's point of views, those two magnets are an interference and a harassment, yet RAID disks perform flawlessly for years.

Additionally, desktop PC are usually encased in a steel or iron case which is not only antistatic (a Faraday cage) since it is metallic, but it is also antimagnetic since it's made of ferrous alloy. Laptop PCs have lighter alloy cases (from most to least expensive, titanium, magnesium, aluminum and plastic) which are not antimagnetic (plastic is not even antistatic - or not very much even when the inside is surface treated with conductive paint).

However, there are magnetic shielding cloths that will increase your equipment's resistance to solar flares by anywhere from 2 to 7 orders of magnitude; I remember seeing an antistatic/antimagnetic/RFID-proof case for Mac Air on Amazon, so I'm pretty sure they should exist for other models too.

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    Or alternatively put your PC electronics inside of a metal case...if only PC manufacturers did that already for you....
    – Aron
    Commented Dec 17, 2015 at 3:10
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    "RAID disks perform flawlessly for years" except for bit-rot, which I believe is induced by these same magnetic forces.
    – enorl76
    Commented Dec 17, 2015 at 18:02
  • @Aron : very good point. I was thinking of my laptop, which is plastic with a copper (ish) insulation that's good against electric fields, not magnetic disturbances. Desktop PC cases, yes, are mostly made of magnetic steel or iron sheet - a magnet will stick to them - and should be proof against an Armageddon flare.
    – LSerni
    Commented Dec 17, 2015 at 20:09
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    Earth's magentic field strength seems to be 0.5 Gauss. Commented Dec 18, 2015 at 11:10
  • Well spotted, @PeterA.Schneider . Botched the conversion from T. Fixed that. Also integrated Aron's comment.
    – LSerni
    Commented Dec 18, 2015 at 11:17

You have time to prepare

As you can read in the Wikipedia article about the Carrington event, 2 days before the solar storm, a lot of sunspots were detected. This, in combination with warnings from the NOAA forecast of M and X GOES class solar flare events give you a bit of time to prepare.

Events much less severe as the Carrington event

There are two basic strategies here:

  1. As you can see in the EMP simulator, not the entire earth is directly affected by a solar flare. So distributing your data over the globe is a good strategy. Several cloud storage services deliver such services.

  2. Grounding and shielding your electronic equipment could shield your data by diverting the EMP to the ground instead of meshing up your data. Shielding is best achieved with a Faraday cage. Wrap your electronics in several layers of well conducting material (aluminium foil, tin litter can, etc.), separated by non-conducting materials (plastic or PVC will do fine). In the most optimal case, ground the outer layer with the ground water or a large body of water, so the cage can discharge. A more elaborate description can be found here.

Events similar or bigger than the Carrington event

The best solution is to store your data in non-electronic format. CD/DVD's should work fine (source: The Official CHFI Study Guide). If you want something more safe than regular or archive quality CD's/DVD's, you could put all your data on an M-Disk.

M-DISC is an archival-quality storage solution that preserves photos, videos, music, and documents for 1,000 years or more. Unlike hard drives, flash drives, and other writable media, that can lose data, M-DISC has been designed to protect your information from degradation and loss for centuries.

Also printing your documents and photo's is a way to keep a non-electronic copy. After the cataclysm, you could re-digitize your photo's and documents.

As Lloyds predicts, the impact will be severe, and electricity will be down for a long time (the Lloyds report mentions weeks and even months). Without power, daily life will soon become chaotic and your lost photo's is probably the least of your worries.

Theoretically, if your Faraday cage is good enough (enough layers, thick enough conducting layers), it might pull it off. But I'm not sure if that will work with such violent events.

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    Very good point - upvoting that! - on the time to prepare. However a Faraday cage won't do much, for the main effect is inductive (as I said, this is not exactly the same thing as an EMP). The recommendation is still good, except you need an antimagnetic cage. A soft-iron cupboard or turned-off oven will do nicely. Or thin magnetic steel foils glued to a large enough wooden box; that would double up as a reasonable Faraday cage.
    – LSerni
    Commented Dec 16, 2015 at 15:36
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    "Without power, daily life will soon become chaotic and your lost photo's is probably the least of your worries". This, very much so. Odds are that you will be dead by the time power is restored as food and water supplies will be severely disrupted. Commented Dec 18, 2015 at 16:32
  • @BrianKnoblauch: you optimist! ;-p
    – agtoever
    Commented Dec 18, 2015 at 17:04
  • Quick warning about the "EMP Simulator" - domain is hijacked and is now malicious.
    – Orphans
    Commented May 10, 2021 at 8:31

Since I have a hard time taking this question seriously, I'm going to suggest you use core memory for the most important data:

enter image description here

the Space Shuttle flight computers initially used core memory, which preserved the contents even through the Challenger's disintegration and subsequent plunge into the sea in 1986.

Now that's robustness!

Seriously, read the article you linked to carefully. White House is not preparing for data damage. They prepare to handle the loss of satellites, telecom equipment, power grids, radiation hazards etc.

A flare powerful enough to overwrite your HDD will alter Earth's magnetic field badly enough to let solar radiation through. So before you even start worrying about data integrity, you should build a solenoid which would provide magnetic field around your house (or in your basement), and an electric generator to power it.


It would depend on the size of the event. The event causes a huge magnet wave, which could induce current to flow in any electrical carriers. That means the power grid, phone lines etc. But it would also de-gauss magnetic storage if strong enough. A faraday cage under your basement is likely the best option for an individual.

For extreme protection you would build a shielded bunker and place it near to the equator where the wave would be felt the least.

Realistically though you wouldn't care. No power, no water, no communications. Food shortages after a few months. Losing a few JPGs would be the least of your worries.

NB: Physics/Electrical Engineering could give a much more technical answer than my laymans summation here.

  • Would the flares affect SSD and Optical media?
    – RogUE
    Commented Dec 16, 2015 at 13:25
  • CD/DVDs are non conductive ceramic so they should be fine. NAND I'm not sure, but flash is a bad long term storage device as the cells can lose charge over time leaving undefined bits.
    – Linef4ult
    Commented Dec 16, 2015 at 13:29
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    Don't forget you'll need a long ladder (or rope) to get down to the bunker...
    – Kinnectus
    Commented Dec 16, 2015 at 13:48
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    @Linef4ult While the disk itself is plastic, the data is in a metallic layer Commented Dec 16, 2015 at 19:11
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    @Linef4ult you are incorrect. The magnetic fields are STRONGEST at the magnetic poles sand thats why the Auroras can be seen in both places.
    – Keltari
    Commented Dec 16, 2015 at 20:11

Print out all your data on a holerinth punch card array.

960 bits per card 2tb hard drive would be 1.6e+13 bits

50000000000/3 punch cards.

While this could be a bit bulky,at lease your data is safe.

In an 8 bit format,of course..might loose some detail on your family photos,but it will look very "retro and stylish" good luck.

Source: https://stackoverflow.com/questions/12290483/how-many-bytes-is-a-hollerith-card


You will have to use a non-magnetic form of storage.

Optical media will work, but since the life of optical media is limited, you will need to refresh every few years or ideally, months. As with any good backup plan, you should never depend on one copy in one location - e.g. treat a 100-stack of discs as 25 x 4 copies each and make sure all are in separate locations as spread-out as possible.

You could also use paper for small amounts of really significant data.

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    A geomagnetic storm powerful enough to erase a hard drive will be accompanied by a CME powerful enough to strip the atmosphere off the Earth.
    – Mark
    Commented Dec 16, 2015 at 22:15
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    @Mark can you give source on that? Commented Jan 14, 2018 at 12:54
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    @JanŚwięcki, no source, just a general understanding of the scales involved. In order to cause magnetic effects on a hard drive, you'd need a magnetic field at least 100,000 times more powerful than the one that accompanied the 1989 geomagnetic storm
    – Mark
    Commented Jan 14, 2018 at 20:47

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