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

We derive the rupture history of the 1999 August 17 Izmit (M-w=7.4) and 199 9 November 12 Duzce (M-w=7.1) earthquakes in Turkey from teleseismic body w aves using broad-band data of the Global Seismograph Network, aftershock lo cations and mapped surface breaks. The centroid solutions indicate strike-s lip mechanisms for both events. The Izmit earthquake was characterized by r upture propagating predominantly eastwards. It consisted of a main rupture lasting about 25 s followed within 1 min by two more events of M-w=6.9 and M-w=7.0. With the teleseismic data, we could not resolve the westward exten t of rupture into the Marmara Sea. However, an upper bound of the seismic m oment release west of the epicentre of the Izmit event is estimated to be 1 .9 x 10(19) N m, The Duzce earthquake lasted about 14 s and was characteriz ed by a bilateral mode of rupture, in excellent agreement with mapped surfa ce breaks and aftershock locations.