**3. Geological settings**

Lake Van is the largest soda lake of the world which has 607 km3 volume and 451 metres depth (Kempe et al., 1978). The lake was formed at least 500 kyr ago (Litt et al., 2009). Lake Van Basin exist at Eastern Anatolia Plateau as the product of Middle Miocene collision of Eurasia and Arabian plates (Şengör & Kidd, 1979; Şengör & Ylmaz, 1981; Keskin et al., 1998) (Fig. 1).

Fig. 1. Simplified geological map showing the active faults (Modified from Kurtman et al., 1978; Bozkurt, 2001; Koçyiğit et al., 2001).

Neotectonic period was started in Pliocene for the Eastern Anatolia Plateau and Lake Van Basin (Koçyiğit et al., 2001). This period is represented by N-S compressional regime. That compressional regime creates NW-SE trending dextral and NE-SW trending sinistral strikeslip faults (Şaroğlu & Ylmaz, 1986; Bozkurt, 2001; Koçyiğit et al., 2001) (Fig. 1). The region has a number of active faults that create earthquakes (M≥5). The Çaldran Earthquake (1976) is the most known among these with their impact (Ms= 7.2) (Table 1).

Lake Van Basin stays on basement units which are Bitlis Metamorphic Complex, Upper Cretaceous Ophiolites and Oligocene-Miocene turbidites (Van formation). The basin fill

Van Basin exist at Eastern Anatolia Plateau as the product of Middle Miocene collision of Eurasia and Arabian plates (Şengör & Kidd, 1979; Şengör & Ylmaz, 1981; Keskin et al., 1998)

Fig. 1. Simplified geological map showing the active faults (Modified from Kurtman et al.,

Neotectonic period was started in Pliocene for the Eastern Anatolia Plateau and Lake Van Basin (Koçyiğit et al., 2001). This period is represented by N-S compressional regime. That compressional regime creates NW-SE trending dextral and NE-SW trending sinistral strikeslip faults (Şaroğlu & Ylmaz, 1986; Bozkurt, 2001; Koçyiğit et al., 2001) (Fig. 1). The region has a number of active faults that create earthquakes (M≥5). The Çaldran Earthquake (1976)

Lake Van Basin stays on basement units which are Bitlis Metamorphic Complex, Upper Cretaceous Ophiolites and Oligocene-Miocene turbidites (Van formation). The basin fill

is the most known among these with their impact (Ms= 7.2) (Table 1).

1978; Bozkurt, 2001; Koçyiğit et al., 2001).

(Fig. 1).

consists of Quaternary volcanic rocks (from Nemrut and Süphan volcanoes), contemporaneous lacustrine deposits, Late Quaternary travertines and alluvium (Fig. 2). Generally, lacustrine sediments locate in east and north of Lake Van (Fig.1). These sediments were deposited during the period of highest lake level (+105 m) in 115000 years ago (Kuzucuoğlu et al. 2010). The deformation structures (seismites) are observed in these lacustrine deposits.


Fig. 2. Generalized stratigraphic columnar section of the study area (from Aksoy, 1988; Acarlar et al., 1991).


Table 1. Earthquake records with magnitude 5 and higher occured in the study area (from Utkucu, 2006; KOERI, 2009), (Lat. = Latitude, Long. = Longitude, Mag. = Magnitude)

#### **4. Deformation structures (Seismites)**

Soft sediment deformation structures are observed in horizontally bedded, sandy, silty and clayey lacustrine deposits of Lake Van. Deformation structures exist in different levels of these shallow water deposits with the other sedimentary structures as cross-beds and wave ripples. Soft sediment deformation structures are classified differently according to morphologic properties or occurrence processes of the structure (Rossetti, 1999; Dramis & Blumetti, 2005; Neuwerth et al., 2006; Taşgn & Türkmen, 2009).

In this study, soft sediment deformation structures, observed in lacustrine deposits of Lake Van, were classified as contorted structures (simple-complex convolute bedding and ballpillow structures), load structures (flame structures) and water escape structures (dish and pillar structures).
