Armutlu

Evolution of seismicity at the western end of the 1999 Izmit rupture

A joint R&D project in collaboration with Kocaeli University  and the Kandilli earthquake observatory  Istanbul

PI: J. Zschau,
Participants:
Kocaeli Universität : M.F. Özer, S. Baris, S. Irmak
Kandilli Erdbeben Observatorium: M.K. Tuncer, C. Celik
GFZ: H. Grosser, H. Woith, B.G. Lühr, H.U. Wetzel, R. Wang, M. Motagh, T. Walter, S. Parolai

project duration: 2005-

Ten major earthquakes with magnitudes above Ms > 6.5 migrated along the North-Anatolian fault zone (NAFZ) between 1939 and 1999. The western end of the 1999 Izmit earthquake rupture is located south of Istanbul next to the northern shoreline of the Armutlu Peninsula depicted by distinct clusters of micro-seismic activity. Thus, the local seismic network ARNET (Fig. 1) had been set-up by the end of 2005 in co-operation with Kocaeli University to monitor the chronological evolution of seismicity (Fig. 2). Additionally, possible interactions between seismic waves and pore-pressure variations in geothermal systems are studied at deep wells. These activities contribute to the implementation of an Anatolian plate boundary observatory (PBO) belonging to a series of GFZ-operated Earth System Observatories to systemically study coupled Earth processes. 

Fig. 1: Stations of ARNET. Red triangles mark REFTEK systems with L4-3D seismometers (short period) and black stations mark GURALP systems (broadband). Stations with smaller signs are no longer in operation. Onshore tectonics taken from remote sensing images (H.-U. Wetzel, 2006) and offshore from Armijo et al. (2002) and Yaltirak & Alpar (2002). 

Fig. 2: Recent seismicity on the Armutlu peninsula south of Istanbul observed with the ARNET. White: September 2005 – February 2006; yellow: M=5.4 Gemlik earthquake of 24 October 2006 and its aftershocks. The red line marks the 1999 Izmit break.