On 17 August 1999, a catastrophic magnitude 7.6 earthquake struck the Kocaeli Province of Turkey, causing monumental damage and 17,127–18,373 deaths. Named for the quake’s proximity to the northwestern city of İzmit, the earthquake is also commonly referred to as the 17 August Earthquake or the 1999 Gölcük Earthquake. The earthquake occurred at 03:01 local time (00:01 UTC) at a shallow depth of 15 km. A maximum Mercalli intensity of X (Extreme) was observed. The earthquake lasted for 37 seconds, causing seismic damage and is widely remembered as one of the deadliest natural disasters in modern Turkish history. The 1999 earthquake was part of a seismic sequence along the North Anatolian Fault that started in 1939, causing large earthquakes that moved progressively from east to west over a period of 60 years. The earthquake encouraged the establishment of a so-called earthquake tax aimed at providing assistance to the ones affected by the damages of earthquake. Tectonic setting The North Anatolian Fault Zone (NAFZ), which the quake occurred on is a dextral (right-lateral) strike-slip fault zone, expanding from the Gulf of Saros to Karlıova that formed around 13—11 million years ago in the eastern part of Anatolia and moved towards the west. The fault later reached the Marmara Sea at around 200,000 years ago, despite the shear-related movement in a rather broad zone which had already started in late Miocene. The fault zone has a diverse geomorphological structure, is seismically active and currently stands as one of the world's most major and active strike-slip fault, having an entire group of ruptures being produced as large as 8.0 on the moment magnitude scale. Since the 17th century, it has shown cyclical behavior, with century-long large earthquake cycles beginning in the east and continuing westward. Although the record is less clear for earlier times, lively seismicity could still be seen in that timespan. The 20th century earthquake record has been interpreted as where every earthquake concentrates the stress at the western tips of the ruptured areas leading to westward migration of larger earthquakes. The August 17 and November 12, 1999 events have loaded the Marmara segment of the fault, and another major, up to magnitude 7.6 event was expected in the half-century 2005-2055 with a probability of 50% on this segment. Currently, the deformation of the rocks by stress in the Marmara Sea region is asymmetric. This is conditioned by the geology of