An earthquake is an instantly occurring and unpredictable natural event. Thepotential and effects of earthquakes and other natural disasters on power systems aresystem faults. The faults are not only limited to the physical damage of power systems, butpower quality disturbances may also take place. The Marmara Earthquake, which occurredin Turkey on Aug 17, 1999, caused death and catastrophe. After the earthquake, theTurkish Power System collapsed. This is the largest power blackout in Turkey in last twentyyears. In this study, the impact of the Marmara earthquake on the Turkish power systemare described and the Marmara Earthquake Blackout is examined in detail as regards thequalitative behavior of the power system.