Paleoseismology of the western Sürgü–Misis fault system: East Anatolian Fault, Turkey

Abstract

The East Anatolian fault bifurcates into a north strand and a south strand near the City of Çelikhan, Turkey. The northern strand is referred to as the Sürgü–Misis fault (SMF) system, which is divided into a number of distinct fault segments based on geological and geomorphological characteristics. However, no paleoseismological data regarding the movement history of the SMF system previously have been reported. We excavated seven trenches across four segments of the SMF system to evaluate the paleoseismological history of these fault zones. These trenches exposed structural and sedimentological evidence of paleoseismic events that had primarily strike-slip displacements with secondary normal and reverse components of motion. Geochronological dating of the trench stratigraphy and event horizons provide the time elapsed since the last event and confirmed the Holocene activity of the faults. These fault segments are individually capable of producing surfacerupturing earthquakes, but may also rupture together generating large, complex, multi–segment ruptures. However, the SMF system has not produced surface-rupturing earthquakes in the last millennia, and therefore is accumulating strain. In light of our findings, we suggest that about 1.7 m of strain has accumulated across the Karataş and Yumurtalık fault segments, which is sufficient to produce moderate to large earthquakes when released seismically. The surrounding Gulf of İskenderun is a highly industrialized district in the Eastern Mediterranean. Therefore, the data obtained from this paleoseismological investigation will contribute to a better understanding of the earthquake hazards in the region.

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Mediterranean Geoscience Reviews (2020) 2:411–437
https://doi.org/10.1007/s42990-020-00041-6
ORIGINAL PAPER
Paleoseismology ofthewestern Sürgü–Misis fault system: East
Anatolian Fault, Turkey
TamerY.Duman1 · HasanElmacı2· SelimÖzalp2· AkınKürçer2· MeryemKara3· ErsinÖzdemir2·
AyhanYavuzoğlu4· ÇağılUygunGüldoğan5
Received: 6 August 2020 / Revised: 25 October 2020 / Accepted: 28 October 2020 / Published online: 8 November 2020
© Springer Nature Switzerland AG 2020
Abstract
The East Anatolian fault bifurcates into a north strand and a south strand near the City of Çelikhan, Turkey. The northern
strand is referred to as the Sürgü–Misis fault (SMF) system, which is divided into a number of distinct fault segments based
on geological and geomorphological characteristics. However, no paleoseismological data regarding the movement history
of the SMF system previously have been reported. We excavated seven trenches across four segments of the SMF system to
evaluate the paleoseismological history of these fault zones. These trenches exposed structural and sedimentological evi-
dence of paleoseismic events that had primarily strike-slip displacements with secondary normal and reverse components
of motion. Geochronological dating of the trench stratigraphy and event horizons provide the time elapsed since the last
event and confirmed the Holocene activity of the faults. These fault segments are individually capable of producing surface-
rupturing earthquakes, but may also rupture together generating large, complex, multi–segment ruptures. However, the SMF
system has not produced surface-rupturing earthquakes in the last millennia, and therefore is accumulating strain. In light
of our findings, we suggest that about 1.7m of strain has accumulated across the Karataş and Yumurtalık fault segments,
which is sufficient to produce moderate to large earthquakes when released seismically. The surrounding Gulf of İskenderun
is a highly industrialized district in the Eastern Mediterranean. Therefore, the data obtained from this paleoseismological
investigation will contribute to a better understanding of the earthquake hazards in the region.
Keywords Sürgü–Misis fault· Gulf of İskenderun· Paleoseismology· Earthquake hazard
1 Introduction
The Anatolian microplate initiated its westward movement
about 4Ma ago as a result of lateral extrusion (Şengör
etal. 1985) or tectonic escape from the apex of the Ara-
bian–Eurasian plate collision (Şengör and Kidd 1979; Burke
and Şengör 1986; Koçyiğit and Beyhan 1998). Beginning
in late Pliocene time, the westward “escape” and rotation
of the microplate created a fundamentally new kinematic
system in the Eastern Mediterranean region (e.g. Bozkurt
2001; Le Pichon and Kreemer 2010; Şengör etal. 1985)
(Fig.1). In this new kinematic system, the East Anatolian
fault (EAF) became a regionally significant plate boundary
structure (e.g. Herece 2008; Şaroğlu etal. 1992; Westaway
1994). It is an approximately 500km-long left-lateral strike-
slip fault zone. The EAF has a slip rate of about 10mm a−1
(e.g. Reilinger etal. 2006). From Karlıova to Çelikhan the
EAF is characterized as a relatively simple fault trace with
an overall trend of N60E (Fig.1). However, at Çelikhan, the
* Tamer Y. Duman
t.duman@fugro.com
1 FUGRO–SIAL Geosciences Consulting andEngineering,
Ankara, Turkey
2 Department ofGeological Research, General Directorate
ofMineral Research andExploration (MTA), 06800Ankara,
Turkey
3 Directorate ofEastern Mediterranean Region, General
Directorate ofMineral Research andExploration (MTA),
Adana, Turkey
4 Department ofMarine Research, General Directorate
ofMineral Research andExploration (MTA), 06800Ankara,
Turkey
5 Department ofEnergy Raw Material Research
andExploration, General Directorate ofMineral Research
andExploration (MTA), 06800Ankara, Turkey
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