Two months after Alan Greenspan inherited the Federal Reserve Bank chair, “Black Monday” wreaked havoc on America’s stock markets. On Oct. 19, 1987, the Dow lost 20 percent of its value, the largest crash since the Great Depression. Greenspan successfully survived the quake; the Fed flooded the market with money, stocks stabilized, and Greenspan became a hero.

Nearly 20 years later, the new Fed chairman, Ben Bernanke, may be about to face a “Black Monday” of his own.

Wild gyrations in global stock markets and rising volatility readings are making some wonder if a crash isn’t on its way. The unstable atmosphere is also providing Chairman Bernanke with his biggest test yet.

Stock markets plunged worldwide early Friday, as shock waves from the U.S. mortgage crisis hit across the globe.

The recent shake-up came after France’s largest bank, bnp Paribas, announced that it was freezing three funds that invested in U.S. subprime mortgages. Earlier in the week, German banks had been forced to pool efforts to rescue ikb from its U.S. mortgage investments gone bad.

For the first time since 9/11, U.S., European and Japanese central banks acted in concert to inject vast amounts of money into the financial markets. The Australian, Hong Kong and Canadian central banks also joined in the effort to stabilize the markets.

On Friday, the European Central Bank injected $83.9 billion into the financial system; this was in addition to the $130.8 billion it provided the previous day. Thursday’s injection was the bank’s largest infusion ever.

The U.S Federal Reserve Bank also added a larger-than-normal $24 billion into the U.S. banking system on Thursday. On Friday morning, it released $19 billion, then, in an unusual act, it added another $16 billion by noon.

Over the space of 48 hours, central banks injected more than $373 billion to prevent the system from spinning into a global credit crunch. On Monday, the European Central Bank injected an additional $65.06 billion into the money market.

In the Fed’s statement following Friday’s market operation, the Reserve said it would pump as much money as needed into the U.S. financial system to “facilitate the orderly functioning of financial markets.”

The last two times the central bank made similar statements were following Sept. 11, 2001, and after “Black Monday” in 1987.

Judging by market reactions, central bank efforts have yet to settle market tremors.

In Asian markets on Friday, Tokyo dropped 2.37 percent, and Korea fell 4.2 percent. Hong Kong’s Hang Seng Index was down 3 percent by midday, and Singapore’s Straits Times Index was down 2.89 percent. Australia’s major markets showed a 3.7 percent loss, and the benchmark index in the Philippines was off 3 percent.

In Europe, France dropped 3.1 percent, while Germany fell 1.5 percent. The UK and Ireland were among the worst European performers, tumbling 3.7 and 4.2 percent respectively.

If U.S. mortgage woes are creating such trouble in the world’s financial markets, one wonders how severe the credit-tightening fallout will be at its epicenter, inside America.

Ben Bernanke is directing an economy vastly more precarious than Greenspan’s in 1987. A billowing national debt load, rising oil prices, and a war in Iraq only complicate the delicate balancing act of managing the opposing forces of a popping housing bubble and a falling dollar.

Bernanke’s shoes may soon become the least-coveted in America.