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The 1999 Izmit, Turkey Earthquake: A 3D Dynamic Stress Transfer Model of Intraearthquake Triggering

Ruth A. Harris, James F. Dolan, Ross Hartleb, & Steven M. Day

Published February 2002, SCEC Contribution #595

Before the August 1999 Izmit (Kocaeli), Turkey earthquake theoretical studies of earthquake ruptures and geological observations had provided estimates of how far an earthquake might jump to get to a neighboring fault. Both numerical simulations and geological observations suggested that 5 km might be the upper limit if there were not any transfer faults. The Izmit earthquake appears to have followed these expectations. It did not jump across any stepover wider than 5 km and was instead stopped by a narrower stepover at its eastern end, and possibly by a stress shadow due to a historic large earthquake at its western end. Our three-dimensional spontaneous rupture simulations of the 1999 Izmit earthquake provide two new insights. One, the west to east striking fault segments of this part of the North Anatolian fault are oriented so as to be low stress faults, and two, the easternmost segment involved in the 1999 August rupture may be dipping. An interesting feature of the Izmit earthquake is that a 5-km-long gap in surface rupture and an adjacent 25 degree restraining bend in the fault zone did not stop the earthquake. The latter observation is a warning that significant fault bends in strike-slip faults may not arrest future earthquakes.

Harris, R. A., Dolan, J. F., Hartleb, R., & Day, S. M. (2002). The 1999 Izmit, Turkey Earthquake: A 3D Dynamic Stress Transfer Model of Intraearthquake Triggering. Bulletin of the Seismological Society of America, 92(1), 245-255. doi: 10.1785/0120000825.