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.
Red contours display the lithospheric mantle thickness in km
Eastern Anatolia
Slab steepening and breakoff beneath a subduction-accretion
complex (Keskin, 2003)
Blue dashed lines are the northern and southern border of the
Eastern Anatolian Accretionary Complex (EAAC)
Şengör et al. (2003), GRL
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 MuşMalazgirt, Mw=7.0
Historical Period:
1275, 1646, 1696
Kocyigit (2011)
Fault rupture on NNWdipping fault plane (surface
deformation and aftershock
Simple teleseismic waveforms
distribution)
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
COSMO co-seismic interferogram
data
Atzori et al (2011)
Ercek
Lake
ITU field observations
Kocyigit (2011)
1)
2)
3)
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,
Slip
Distribution
Stress Tensor
all aftershocks
Variance of stress
tensor at each node &
orientation of 1
Faulting type &
orientation of 1
70<Rake<110
88 aftershocks
35<Rake<145
177 aftershocks
35<rake<145
compressive
177 aftershocks
Hanging wall
35>rake>145
noncompressive
200 aftershocks
Foot wall
Two subevents
Complex waveforms
Seismic reflection profile (sp13) crossing Lake Van E-W
(Toker and Şengör, 2011)
Seismic reflection profile (sp10) 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.