Recommended reading: the Inside Risks column from the Communications of the ACM, and the RISKS digest. Excerpt from 2007:
“”"The 1980 four-hour ARPANET collapse (a combination of unchecked memory errors and a weak garbage-collection algorithm) and the 1990 half-day AT&T long-distance network collapse (a bug in newly installed software for autorecovery from telephone switch failures) are examples of iteratively propagating system failures. Similarly, numerous widespread power outages have occurred, notably the Northeast U.S.~blackout of November 1965, the New York State blackout in July 1977, blackout of ten western U.S. states in October 1984, separate outages in July and August 1996 that took out much of the Western U.S. (the second of which also affected parts of Canada and Baja California in Mexico), and the Northeastern U.S. again in August 2003. In each case, a single-point failure triggered a cascading effect.
Various other serious power outages include the month-long outage in Quebec in January 1998 (due to the collapse of ice-laden transmission towers) and the week-long area outages in Queens NY in July 2006 (due to fires and failures in 100-year-old wiring). In addition, many less dramatic outages have been reported, including a power failure that triggered fire alarms and evacuation of Oregon’s Portland Convention Center during the ACM OOPSLA conference on October 26, 2006, and also shut down the surrounding area including the light rail system, for almost an hour. Additional power outages were compounded by failures of backup power systems, such as the 1991 four-hour shutdown of New York City’s three airports and an ESS telephone system (due to misconfiguration of the backup power, which instead of being driven by the activated generators was running on standby batteries until they were drained).
The most recent case of a cascading power outage occurred on November 4, 2006, and affected about 10 million people in Germany, Austria, Italy, France, Spain and Portugal. Among other disruptions, 100 regional Deutsche Bahn trains were disrupted. The widespread outage began with a supposedly routine event, in which a power line over the Ems River in northern Germany was shut down to allow a ship (the Norwegian Pearl) to pass http://safely.be restored.
From “Widespread Network Failures” by Peter G. Neumann
Inside Risks 200, CACM 50, 2, February 2007