Rupture processes of the 1999 August 17 Izmit and November 12 Düzce (Turkey) earthquakes

Abstract

We derive the rupture history of the 1999 August 17 Izmit (Mw=7.4) and 1999 November 12 Düzce (Mw=7.1) earthquakes in Turkey from teleseismic body waves using broad‐band data of the Global Seismograph Network, aftershock locations and mapped surface breaks. The centroid solutions indicate strike‐slip mechanisms for both events. The Izmit earthquake was characterized by rupture propagating predominantly eastwards. It consisted of a main rupture lasting about 25 s followed within 1 min by two more events of Mw=6.9 and Mw=7.0. With the teleseismic data, we could not resolve the westward extent of rupture into the Marmara Sea. However, an upper bound of the seismic moment release west of the epicentre of the Izmit event is estimated to be 1.9×1019 N m. The Düzce earthquake lasted about 14 s and was characterized by a bilateral mode of rupture, in excellent agreement with mapped surface breaks and aftershock locations.