Former Federal Reserve Chairman Alan Greenspan told Congress in prepared testimony Thursday that the current global financial crisis is a "once in a century credit tsunami" that policymakers did not anticipate.

Greenspan was to be the leadoff witness at a House hearing lawmakers called to question past key financial players about what they felt caused the most grave financial crisis since the 1930s. The witnesses were also expected to be asked how they thought the government would deliver the nation from the economic turmoil.

Greenspan was the chairman of the Federal Reserve for 18 1/2 years. In testimony prepared for the House Government Oversight and Reform Committee, he voiced shock over the present turn of events and called conditions deplorable.

He said that he and others who believed lending institutions would do a good job of protecting their shareholders are in a "state of shocked disbelief." And Greenspan also blamed the problems on heavy demand for securities backed by subprime mortgages by investors who did not worry that the boom in home prices might come to a crashing halt.