Intra-basinal water movements induced by faulting: the August 17, 1999, Golcuk (Izmit Bay) earthquake (M-W=7.4)

A strong earthquake (M-w = 7.4) occurred near the town of Golcuk, Izmit Bay , Western Turkey, at 00:01 GMT on August 17, 1999. Izmit Bay is a E-W trend ing pull-apart basin with a surface area of about 300 km(2) along the North Anatolian Fault Zone (NAF), in the eastern extension of the Sea of Marmara . The earthquake was caused by a westerly movement of the Anatolian plate a long NAF and was accompanied by isolated, chaotic water movements along the northern and southern shores of the bay. At localities along the shoreline a sudden drop in sea level, and a subsequent rise was prominent. The mode of observed sealevel movements rules out the occurrence of a basin-wide tsu nami, sensu stricto. Instead, the water movements are attributed to localiz ed sudden dip-slip movements of fault blocks in this pull-apart basin. (C) 2000 Elsevier Science B.V. All rights reserved.