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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.