Geomechanical Aspects of the 1999 Gölcük Earthquake

ABSTRACT: Recent large-magnitude earthquakes on the North Anatolian Fault at Gölcük and Düzce in Turkey have caused widespread destruction and loss of life. Analysis of damage from these quakes is shedding light on the complex mechanical interaction that occurs between faults and local geological features. Damage resulting from the Gölcük earthquake is analyzed here, with respect to fault mechanisms, ground response and local geological conditions. Rupture length, rupture area, and surface displacement are calculated from empirical formulas and compared to values measured in the field. Activity on the North Anatolian Fault during the last 60 years is summarized, and existing seismic gaps on the fault are discussed. Liquefaction-related phenomena and resulting damage are examined in detail. Cyclic-shear stresses are calculated for soil profiles taken from the earthquake region, and used to evaluate the likelihood of liquefaction.