A. Pınar, D. Kalafat, C. Zülfikar

Kandilli Observatory and Earthquake Research Institute

To obtain the source characteristics of the mainshock and the aftershocks of the October 23, 2011 Eastern Turkey earthquake (Mw=7.2)

To understand how the crust staying directly on the hot astenosphere (no mantle lithosphere) responds to the ongoing compression

Improve our knowledge on the convergent boundary tectonics in Eastern Turkey

We use the local broadband waveform records at stations operated by Kandilli Observatory to retrieve CMT solutions for 377 aftershocks (Mw>3.5) using the Kuge (2003) algorithm,

We use the IRIS GSN data to obtain a slip model for the mainshock using the Kikuchi & Kanamori (2003) method,

We use the ZMAP program to investigate spatio-temporal evolution of the stress field.

Şengör et al. (2003), GRL

Red contours display the lithospheric mantle thickness in km

Blue dashed lines are the northern and southern border of the Eastern Anatolian Accretionary Complex (EAAC)

Eastern Anatolia

Slab steepening and breakoff beneath a subduction-accretion complex (Keskin, 2003)

Instrumental Period (Albini et al. 2012)

(1) October 23, 2011 Mw=7.2, Van

(2) November 24, 1976 Mw=7.3 Çaldıran

(3) May 6, 1930 Mw=7.1 Salmas (Iran)

(4) April 28, 1903 Muş-Malazgirt, Mw=7.0

Historical Period:

1275, 1646, 1696

Fault rupture on NNW-dipping fault plane (surface deformation and aftershock distribution) Simple teleseismic waveforms

Kocyigit (2011)

Slip vector of the fault plane strike,dip, rake: 248, 36, 62

Slip vector of the fault plane strike,dip, rake: 248, 36, 62

Coseismic slip distribution based on the teleseismic data

COSMO co-seismic interferogramAtzori et al (2011)

Ercek Lake

ITU field observations

Kocyigit (2011)

1) The Lack of large aftershocks in the area of large co-seismic slip is noticable, 2) To the NE and SW part of the ruptured area predominantly strike-slip mechanisms take place, 3) In the western part of the source area reverse faulting dominates,

Variance of stress tensor at each node &orientation of 1

Faulting type &orientation of 1

Slip Distribution

Stress Tensorall aftershocks

70<Rake<110

88 aftershocks

35<Rake<145

177 aftershocks

35<rake<145

compressive177 aftershocks

35>rake>145

noncompressive200 aftershocks

Foot wall

Hanging wall

Hanging wall

Foot wall

Two subevents Complex waveforms

Seismic reflection profile (sp-13) crossing Lake Van E-W(Toker and Şengör, 2011)

Seismic reflection profile (sp-10) crossing Lake Van NE-SW(Toker and Şengör, 2011)

Although the maximum compressive stress axis Hmax is perpendicular to the strike of the north dipping fault plane the slip vector deviates about 30 degree from the Hmax direction, suggesting lateral escape

The lack of large aftershocks in the area of large co-seismic slip is noticable,

To the NE and SW part of the ruptured area predominantly strike-slip mechanisms take place,

In the western part of the source area reverse faulting dominates,

Some aftershocks show predominantly normal faulting mechanism,

In the area of high co-seismic slip the stress field is heterogenuous,

Clockwise and counterclockwise rotations of 1 axes are observed from the fault plane solutions of the aftershocks.