[AusNOG] Solar flare

[Jake Anderson]

On 03/09/2012 10:10 AM, Jason Leschnik wrote:
> _Most_ (i hope) of us are prudent with backups from Disk to Tape, in
> the event of the 1859 solar flare occurring again would this put all
> our data at risk?
Shouldn't do
Its different to an EMP kinda like how say anfo is different to TNT ;->

Even an EMP *probably* wouldn't bother a hdd that was off, despite what 
Hollywood says the coercivity of most magnetic storage media is pretty 
high, wiping your credit card over a magnet generally won't bother it, 
hdd's are weaker but they aren't terrible. Most of the effects are due 
to frying of electrical circuits.
Note a magnet over a hdd when its on is going to be very different to if 
its off. The spinning is going to introduce some epic eddy currents in 
the platters, also it'll work better from the back side through the Al 
casting rather than through the steel face that'll conduct most of your 
magnetic field away.

A "geomagnetic storm" has relatively slow rates of change of flux 
(compared to an EMP), the voltage induced in a conductor is based on the 
rate of change of flux and the length of the conductor in said flux.  As 
such it will mainly bother things like power lines and pipelines with 
runs in the 100's of Km. A 1859 storm would probably start to bother 
shorter run cables, gut feeling is in the 10km range. With localised 
areas (5-10km) where its much worse where natural eddies in the field 
snap around and things like that.
The other thing is given the size of the driving forces some really 
massive currents are available to back up these voltages, there's been 
instances where thick pipes have been corroded basically by 
electroplating themselves into the surrounding dirt. Hundreds to tens of 
thousands of amps (of DC current too, transformers really don't like 
that ;->)

An emp has a much *much* more rapid flux change, inducing decent voltage 
in much shorter conductors.
Basically its pretty similar to having a nearby lightning strike that 
doesn't actually hit the power lines.
Things with long antennas (your longwave ham rig) are going to get fried 
through that at significant distances.
mobile phone antennas are pretty teensy and their longest conductors are 
going to be on the order of ~10cm or so, it'll take a pretty fair whack 
to bother them (if your phone is bothered your going to be rather more 
bothered by the nuclear bomb that just went off ;->). The mobile phone 
base stations are a different kettle of fish, expect them to be fried.
Stuff connected to power lines is going to be hit the hardest but then 
they are fairly tolerant of the nasties in the power lines. Expect to 
see bunches of fried PSU's but motherboards will probably be ok. 
Especially if they are in a steel case (specifically steel, aluminium 
will help but not as much) so put the side back on your computer ;-P

The biggest issue i see is networks, ethernet is only rated to ~400v or 
so isolation as far as I'm aware? so runs of 10's of meters will 
probably fry anything plugged into either end. (that motherboard isn't 
looking so good anymore :-<)