A great example...

...of a Risk that nearly qualifies as unknown unknown status. Full paper can be downloaded here. With new systems (electronic data as "money") comes new vulnerabilities, new risks, and new implications therefrom.

...This potentially hazardous power of the sun comes in the form of super solar storms. Super solar storms hitting earth could possibly wipe out significant parts of electricity grids around the world.

Furthermore, our current electronic money system is particularly vulnerable. Most of today’s money is purely electronic money, depending on electricity and on fine electronics. In addition to this existence in the virtual world, since the exit from the Gold Standard in the early 1970s, there is no longer anything physical behind our money, like gold. Most of today’s money is merely numbers in computers; it is simply a large machine-operated accounting system. But yes a very important accounting system indeed. According to the Federal Reserve about 69% of all money (USD) were electronic in 1991.2 The rest of the assets were in the form of paper bills and coins. That is nearly 20 years ago, and due to enormous growth in use of computers and electronic money since then, there are reasons to believe that electronic money now is a much bigger percentage of the total money supply, if I am guessing more than 90% of the total money supply, I am probably not that far off. With electronic money we normally think of bank deposits, prepaid cards, debit cards and credit cards. This could be broadened to also include electronic securities. Today almost all financial assets like stocks and bonds are just electronic numbers in computers. In its broadest sense electronic money is any transaction or potential transaction that dose not involve physical cash (coins and bills). A very large coronal mass ejection from the sun that could cause a super solar storm if it should hit the earth might wipe out the global money system within minutes from impact. Stock exchanges would not operate, banking systems would not function, and both credit cards and ATM machines would stop working. We could find ourselves without the use of our modern electronic forms of money for months and possibly years. And yet, even in a catastrophic scenario where water pumps, power plants, public transportation, and other infrastructural assets that are essential to contemporary life had failed, some type of functioning money system would be required to keep the basic necessities, such as food and medical supplies flowing without too much friction.