1 Introduction

Most part of Turkey lies on the Anatolian Plate, which is being forced westwards as a natural response to the collision between the Arabian Plate and the Eurasian Plate. This westward movement is accommodated by two large strike-slip fault zones, the west–east-trending right-lateral North Anatolian Fault Zone (NAFZ) in the north and the SW–NE-trending left- lateral East Anatolian Fault Zone (EAFZ) in the southeast. Movement along the two fault zones has been responsible for many large and damaging high-magnitude historical and instrumental earthquakes (Fig. 1). The most recent strong earthquakes on the EAFZ prior to last devastating earthquake in 2020 are the May 1, 2003 Bingöl Earthquake (M: 6.4) and the March 8, 2010 Elazığ earthquake (M: 6.0).

Fig. 1
figure 1

a DEM map showing regional structural elements of Turkey and surroundings (Taymaz et al. 2007), b active fault map between Lake Hazar and Çelikhan (Duman and Emre 2013) showing (the shaded rectangle) the ruptured segment of East Anatolian Fault Zone. The faults are from Duman et al. (2012) and Emre et al.2012)

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At 20:55:11 local time (17:55 UTC) on the evening of Friday, 24 January 2020, an earthquake of magnitude Mw = 6.8 and a depth of about 8.06 km hit Elazığ province (eastern Turkey). The epicenter of the earthquake given by different centers falls to the northeast of Çevrimtaş near the village of Kalaba close to the town of Sivrice in Elazığ. The duration of the earthquake was reported as 20.4 s (AFAD). The earthquake was followed by numerous aftershocks, the strongest of which with a magnitude of 5.0 Mw. The focal mechanism, epicentral location and distribution of afterschocks are all consistent with the activity caused by movement along the main strand of the East Anatolian Fault Zone.

After the earthquake, field observations were made by many researchers in the region as brief note. Gökçeoğlu et al. (2020) stated that surface deformations are observed along the East Anatolian Fault Zone (DAFZ) on the alluvial deposits on the coast of Hazar Lake in Sivrice. According to these researchers, in addition to poor quality of structural materials, construction and workmanship, another important reason of severe damage to masonry buildings and infrastructure in Çevrimtaş and nearby villages is the observed surface rupture in the area.

According to the first findings, no significant and continuous surface rupture occurred in the earthquake area instead cracks, ground run-offs caused by vibration and gravity, and many landslides are common in some sections along the fault zone. It has been stated that not all earthquakes with this magnitude results in prominent and persistent surface rupture, and it can be explained by the authors with an aseismic creep occurring in shallow crust (İTÜ 2020). In the preliminary evaluation report by Boğaziçi University Kandilli Observatory and Earthquake Research Institute (KOERI 2020), the magnitude of the earthquake is Mw = 6.5 and the estimated length of surface rupture varies between 20 and 30 km, and that the earthquake is the result of movement along the Pütürge segment of the East Anatolian Fault Zone.

In a MTA report (Kürçer et al. 2020), surface deformation features (Riedel shear fractures, en-échelon tension cracks and surface fractures) are observed along approximately 48-km-long segment of the EAFZ in the area between Lake Hazar and Pütürge. The length of individual fracture, which continue in an en-échelon pattern, usually vary from a few meters to several hundred meters. No obvious lateral displacements are observed. Two paleoseismological trenches were also excavated on the surface rupture in Ilıncakbaşı locality, 500 m south of Ilıncak Village (Sivrice–Elazığ). Accordingly, at least three paleo-earthquakes are identified. These authors suggest, based on field observations and the distribution of January 24, 2020 earthquake aftershocks that two sub-segments of the Pütürge segment were broken. They also claim that the earthquake source fault might be inclined to the northwest, because more damage occurred in areas northwest of the Pütürge segment, and the aftershocks are mostly concentrated on the northwestern block of the earthquake fault very close to the Pütürge segment. For the first time in this study, aligned gas degassing on the water surface of the Karakaya Dam Lake is recorded and photographed; the alignment is interpreted to locate the trace of surface rupture within the dam lake.

Despite the fact that there is considerable amount of preliminary reports available about the Sivrice (Elazığ)–Doğanyol (Malatya) earthquake, none presents a detailed account of earthquake-induced surface deformation features and discusses their significance. To fill this gap, we mapped and classified the seismo-gravitational and seismotectonic structures in the earthquake area, and compared them with the surface ruptures formed during the last hundred years in Turkey.

A summary of seismotectonic setting of the study area and seismogenic source of the earthquake will be given in the following section. Detailed description of mapped surface deformation features and their classification in relation to seismo-gravitational or seismotectonic behavior forms the subject of third section. After that, we focus on interferometric data for comparison with the field-based data. Finally, we present a table that summarizes information about earthquakes occurred on different active faults in Turkey during the last century. This table aims to explore if there is any relationship between earthquake magnitude, fault type, duration of the earthquake and formation surface rupture. Our results confirm the intimate relationship between earthquake magnitude, fault type and occurrence of surface rupture.

2 Seismotectonics

It is generally accepted that, in eastern Anatolia where the Sivrice (Elazığ)–Doğanyol (Malatya) earthquake occurred, the collision between Arabian and Eurasian plates took place at the end of Middle Miocene, and that late Miocene is the time of consequent contractional tectonics in the region (Şengör and Yılmaz 1981; Şengör et al. 1985; Yılmaz et al. 1993; Westaway and Arger 2001). The ca. N–S compressional deformation and consequent shortening has eventually resulted in the initiation of North Anatolian and East Anatolian transform fault zones (NAFZ and EAFZ, respectively); the associated ca. E–W extension has resulted in the formation of open fractures, many of which have served as pathways for volcanic activity in the region (cf. Yılmaz et al. 1987). The transform nature of the EAFZ was first recognized by Arpat and Şaroğlu (1972) and its importance for the regional seismicity and active tectonics during Quaternary–Holocene time has been investigated by numerous researchers (McKenzie 1978; Arpat and Şaroğlu 1975; Dewey et al. 1986; Ambraseys 1988; Taymaz et al. 1991; Westaway and Arger 1996; Westaway 2003). The time of initiation of the EAFZ is proposed as Late Pliocene (Şaroğlu et al. 1987; Westaway and Arger 2001) or close to the latest Pliocene–Pleistocene boundary (Herece 2008).

2.1 The East Anatolian Fault Zone

The East Anatolian Fault Zone (EAFZ), which forms the seismic source of the Sivrice (Elazığ)–Doğanyol (Malatya) earthquake, is a major sinistral strike-slip fault zone in Turkey. It starts at the Karlıova triple junction, where the EAFZ meets the North Anatolian Fault Zone, in the northeast and runs southwestward for about 600 km through Bingöl, Palu, Hazar Lake, Pütürge, Sincik, Narlı, Türkoğlu regions and extends up to the İskenderun Bay in the Mediterranean Sea area (e.g., Arpat and Şaroğlu 1972; Hempton and Dunne 1984; Aksoy et al. 2007; Emre et al. 2013; Khalifa et al. 2018)(Fig. 2a and b). The fault zone comprises several short left-lateral fault segments and associated strike-slip basins; Lake Hazar is one of those basins. Hazar Lake is a NE–SW-trending transtensional basin in the central parts of the EAFZ in the area between Sivrice to the SW and Gezin to the NE (Fig. 2b).

Fig. 2
figure 2

modified from Koçyiğit et al. 2003; Çolak et al. 2012)

a Simplified map showing major neotectonic structures of Turkey. EAFZ—East Anatolian Fault Zone; DAFZ—Dead Sea Fault Zone; NAFZ—North Anatolian Fault Zone. b Geological map of the East Anatolian Fault Zone in the area between Yarpuzlu (Adıyaman) and Bingöl (

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A detailed account of the fault geometry and segment structure of the East Anatolian Fault Zone, based on 1:25,000-scale re-mapping of active faults, available seismological and palaeoseismological data, is well documented in Duman and Emre (2013). The main fault runs as single main fault trace of a narrow deformation zone in the area between Karlıova and Çelikhan. To the west of Çelikhan, the fault branches off two strands as southern and northern; the latter is termed the Sürgü-Misis fault system. These strands are further divided, based on the stepovers, bends and abrupt changes in the general strike, into several fault segments with variable lengths and strikes. The main strand comprises, from northeast to southwest, Karlıova, Ilıca, Palu, Pütürge, Erkenek, Pazarcık and Amanos segments (see Fig. 2 in Duman and Emre 2013). Each segment comprises several sections as well. Several morphotectonic features confirm the Holocene activity of these segments.

The Palu segment occurs in the area between Palu and Gezin (Maden, Elazığ) districts to the northeast of the Lake Hazar, whereas the Pütürge segment is located in the area between southwestern margin of the Lake Hazar and Yarpuzlu district (Sincik, Adıyaman). Pütürge segment controls linear stream valleys in a mountainous terrain along most of its trace, where the faults cut into the basement rocks (Precambrian–Mesozoic Pütürge metamorphics, Cenonian Guleman-Kömürhan ophiolites and Eocene Maden Complex) (e.g., Hempton 1985; Herece and Akay 1992; Herece 2008; Duman and Emre 2013). The measured sinistral offset of the basement rocks and morphological features in the Fırat (Euphrates) River valley vary from 9 to 22 km (Arpat and Şaroğlu 1975; Hempton 1985; Herece and Akay 1992; Westaway and Arger 2001; Westaway 2003; Herece 2008; Çelik 2008; Duman and Emre 2013). Whereas the Fırat River valley itself is offset sinistrally by about 11 km along the Hazar-Şiro fault of the Pütürge segment (Duman and Emre 2013). Holocene fault scarps are common along the Pütürge segment; there is, however, no solid evidence about the formation of surface rupture as a result of latest seismic activity.

Left-lateral displacement along the EAFZ is also confirmed by seismological observations (Örgülü et al. 2003; Türkelli et al. 2003). Bulut et al. (2012) investigated the seismic activity along the EAFZ and fault kinematics based on recordings from a densified regional seismic network. The distribution of hypocenters suggests that the EAFZ is characterized by NE–SW and E–W oriented sub-segments that are sub-parallel to the overall trend of the fault zone. Faulting mechanisms are predominantly left-lateral strike-slip and thus in good correlation with the deformation pattern derived from regional GPS data.

During the instrumental period, the westward motion of Anatolian platelet along the NAFZ is about 2.5 cm/year, while it is about 1 cm/year along the EAFZ (Reilinger et al. 2006; Özener et al. 2010). The rate of motion along the EAFZ is variable between 4 and 10 mm/year. Westaway (2003) suggested for 4.0–4.6 mm/year which is consistent with GPS data reported in McClusky et al. (2000). Özener et al. (2010) argued for 10 mm/year, while Duman et al. (2017) proposed a rate of 7 mm/year for the Pütürge segment. In a more recent study, Aktuğ et al. (2016) collected and analyzed new survey-type GPS data, and homogeneously combined published velocities from other studies, and this forms the most complete GPS data set covering the EAFZ. Their results show that while the slip rate of the EAFZ is nearly constant (~ 10 mm/year) to the North of Türkoğlu, it decreases to 4.5 mm/year in the south. The results also confirm two well-known seismic gaps across the EAFZ, Palu-Sincik and Çelikhan-Türkoğlu segments. These segments have slip deficits of 1.5 m and 5.2 m and have the potential to produce earthquakes with magnitudes of M: 7.4 and M: 7.7, respectively.

2.2 Earthquake activity during historical and instrumental periods

The Eastern Anatolian Fault Zone (EAFZ) is interpreted as the source of a series of major destructive earthquakes especially during the nineteenth and twentieth centuries (Ambraseys 1988). In particular, the Pütürge segment was described as a seismic gap that can produce a near future destructive earthquake (Duman and Emre 2013). In this regard, Lake Hazar and its surroundings were considered as seismically highly active region. Statistical analysis of microseismic study reveal a daily average of five events with magnitudes less than 3.0 in the Lake Hazar area (Çetin et al. 2003). In addition to all, historical records and paleoseismological studies clearly show that earthquakes with magnitudes greater than 7.0 have occurred in this region (Ergin et al. 1967; Ambraseys 1988; Eyidoğan et al. 1991; Ambrassey and Finkel 1995; Ambrassey and Jackson 1998; Tan et al. 2008; Baştürk et al. 2017; Köküm and Özçelik 2020); the 1874, 1875 and 1971 events in the Lake Hazar, Palu and Bingöl are the most well-known earthquakes. In May 1874, Ms = 7.1 earthquake severely damaged the Lake Hazar and its immediate surroundings. There is also evidence for deformed (folded) river terraces along Şiro river valley (Aktimur and Oral 1981 in Duman and Emre 2013).

There are limited number of research on the paleoseismic activity of different segments of the Eastern Anatolian Fault Zone (Çetin et al. 2003; Karabacak et al. 2011). Most trenches are opened along the Palu, Pazarcık and Amanos segments (Çetin et al. 2003; Karabacak et al. 2011; Yönlü et al. 2017). Çetin et al. (2003) excavated two exploratory trenches on the two main strands (Gezin fault and Hazar fault) of the Palu-Lake Hazar segment; they also made detailed field observations. The authors interpreted the results of trenching to suggest that there are two major surface rupturing earthquakes: 1874 (Ms = 7.1) and 1875 (Ms = 6.7). Some claims that 1875 surface rupturing event (Ambraseys and Jackson 1998) has occurred along the Pütürge segment (Nalbant et al. 2002; Herece 2008). The historical earthquakes (Ambraseys and Jackson 1998) and results of the paleoseismologic study (Güneyli 2002; Çetin et al. 2003) are interpreted to suggest that 1875 event occurred along Lake Hazar releasing bend. Accordingly, the recurrence interval of a major (M > 7) earthquakes along Palu segment is estimated as minimum 100 ± 35 and maximum 360 years (Çetin et al. 2003) or as 350–400 years (Duman and Emre 2013). Thus, the time elapsed since 1789 Palu earthquake is about 230 years.

The slip deficits on the Karlıova and Palu segments for the latest major earthquakes are estimated as 1.46 and 1.40 m, respectively (Duman and Emre 2013). These authors also argued for the lack of data about the recurrence interval for major earthquakes on the Pütürge segment. Considering the interpretation of Ambrasey (1988) that the 1905 (M 6.8) earthquake may have occurred on the Yarpuzlu bend at the western tip of the Pütürge segment, Duman and Emre (2013) considered the ca. 100-km-long Pütürge segment as one of several seismic gaps along the main strand of the EAFZ.

The May 22, 1971 Bingöl earthquake (Ms: 6.8) during instrumental period affected Bingöl and its immediate surroundings, and caused a great loss of life and property (Ambrasseys 1989; Ambrasseys and Jackson 1998). The records show that 81 earthquakes with magnitudes 4.0 or greater occurred in the region in the last 85 years. Three earthquakes with magnitudes 5.0 or greater have occurred in Sivrice district. Some of the other destructive earthquakes (M = 5.0 or greater) along different segments of the EAFZ include August 11, 2004, February 9, 2007, February 21, 2007, March 9, 2010 and June 23, 2011 events that affected Sivrice, Karakoçan and İçme districts (Kalafat et al. 2010, 2011; Tan et al. 2011). The June 13, 2003 (M: 5.6) and November 26, 2005 (M: 5.3) events caused considerable amount of damage in the region but fortunately there were no loss of life. More recent September 17, 2010 (M: 4.8), April 4, 2019 (M: 5.2) and December 27, 2019 (M: 5.0) earthquakes all occurred along the Pütürge segment. Thus, there is an apparent increase in the seismic activity along the Pütürge segment during last 17 years period.

The last one, a moderate size earthquake occurred at 20:55:11 local time (17:55 UTC) on Friday, January 24, 2020 in Sivrice (Elazığ) and Doğanyol (Malatya) area. Turkish Republic Ministry of Interior, The Disaster and Emergency Management Presidency of Turkey (AFAD) Earthquake Department announced magnitude of the earthquake 6.8 (Mw), focal depth as 8.06 km and epicenter as Çevrimtaş village (0.81 km south of Sivrice). According to Bogaziçi University Kandilli Observatory and Earthquake Research Institute (KOERI), the magnitude, focal depth and epicenter of the earthquake are MI: 6.6 (Mw: 6.5), 5 km and Çevrimtaş village (Sivrice). On the other hand, these parameters are 6.7, 11 km and Kalaba village (11 km NNE of Doğanyol) according to USGS (Fig. 3).

Fig. 3
figure 3

A seismotectonic map showing the distribution of main and aftershocks of the 24.02.2020 Sivrice (Elazığ)–Doğanyol (Malatya) earthquake (Mw = 6.8). The active fault map is from Emre et al. (2011)

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It is here suggested, based on the data published by both national and international institutions and organizations, fault plane solutions, personal observations on surface deformation structures that the 6.8 (Mw) magnitude Sivrice (Elâzığ)–Doğanyol (Malatya) earthquake occured along the Pütürge segment of the EAFZ.

This earthquake once again showed that Turkey is located in a geography where destructive earthquakes have frequently occurred throughout history owing to its geological features. As a result of the earthquake, it was observed that the property damages in Elâzığ city center were concentrated in different neighborhoods of the city center; in addition to the demolished buildings in Mustafapaşa and Sürsürü neighborhoods, there were also heavy damage in Abdullahpaşa district. Outside Elâzığ city center, one building was destroyed in Gezin village located near the Lake Hazar. As you go to the south-southwest, especially in the villages of Kösebayır, Doğanbağı, Kalaba, Görgülü, Duygulu, Ilıncak, and Çevrimtaş in the Karakaya Dam Lake area close to the epicenter of the earthquake, there are losses of life and property due to the collapse or severe damage of the houses. These villages occur mainly on the river banks, the old alluvial fan deposits, landslides, and loose young (Plio–Quaternary) sediments within the fault zone (Fig. 4).

Fig. 4
figure 4

HGM Küre map showing the location of surface deformation features that occurred in January 24, 2020 Sivrice (Elazığ)–Doğanyol (Malatya) earthquake. The red dots indicate the areas of the surface fracture, the yellow dots, areas where surface deformations are observed, and the blue, green and orange dots, the epicenter of the main shock given by KOERI, USGS and ERD, respectively

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3 Surface deformations of Sivrice (Elazığ)–Doğanyol (Malatya) earthquake

Surface deformations developed during and immediately after the Sivrice (Elazığ)–Doğanyol (Malatya) earthquake were examined and mapped in detail along 30 km damage zone between Gezin village and Sivrice during the 10-day field studies between January 25, 2020 and February 3, 2020. Locations of surface deformations are indicated in Fig. 4. Most of the surface deformation features are interpreted to occur due to seismic shaking and gravity that developed during or just after the main shock. In addition to these, surface deformation originating from tectonic forces has also developed due to stress distribution along the Pütürge segment. Observed surface deformation features can be evaluated as seismic geomorphological indicators of the earthquake. Seismic geomorphology examines the changes and causes of this type of deformation that occur on and/or near the earth surface during or immediately after the main seismic shock (cf. Audemard and De Santis 1991; Dramis and Blumetti 2005). Recognition and mapping of these structures are very important in revealing a region’s seismic risk analysis (Dramis and Blumetti 2005). In this study, the surface deformation features developed in relation to the Sivrive (Elâzığ)–Doğanyol (Malatya) earthquake were examined under two main classes: seismotectonic and seismo-gravitational. Seismotectonic surface deformation occurs in the form of surface fractures and cracks, ascending-collapsing and longitudinal ridges that develop due to tectonic stresses, while seismo-gravitational surface deformation features are in the form of mass movements, lateral spreading, capillary cracks and liquefaction (Table 1).

Table 1 Surface deformations developed in relation to the January 24, 2020 Sivrice (Elazığ)–Doğanyol (Malatya) earthquake
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Field observations show that seismo-gravitational structures occur along the Gezin–Sivrice–Doğanbağı line, while both seismotectonic (as surface fracture and cracks) and seismo-gravitational structures are common on the Doğanbağı–Çevrimtaş–Koldere–Ormaniçi line to the southwest.

Surface deformation features occur along a ca. 30-km-long zone between Sivrice and Ormaniçi village and covers and area of up to 2 km in some places. This zone also forms the main part of the Pütürge segment. The 12-km left-lateral displacement of the Fırat River is also located within the central part of this deformation zone (Fig. 4).

A significant part of the surface deformation features developed in slope debris, colluvial materials and alluvial fans of Holocene age. Small-scale mass movements and capillary cracks have also been observed along the fault zone on-road cuts and stabilized/asphalt roads. In places, fossil landslides were triggered in response to ground shaking and moved down slope under the influence of gravity; they appear as semi-circular sliding surfaces in the area.

3.1 Seismo-gravitational surface deformation

Among the seismo-gravitational structures that developed along/near the fault zone, include mass movements, such as small-scale landslides and rock falls, and capillary cracks observed along roads. Small-scale lateral spreading and liquefaction structures are also common, especially in the areas of alluvial fans (delta) where they form due to interaction between Karakaya Dam Lake and streams flowing perpendicular to the fault zone.

Detailed observations around villages of Kösebayır, Kılıçkaya, Doğanbağı, Çevrimtaş and Ilıncak located to the southwest of Sivrice district (Fig. 4) reveal that most deformational structures are seismo-gravitational in origin, and that dense network of capillary cracks are common structures along the road between Kösebayır and Kalaba villages. Ground defeats up to 300 m in length developed in many sections along the road between Sivrice and Doğanbağı village. Such deformation features are particularly common on the east-southeast free slope of the road where vertical movements of up to 50 cm are observed. The ground defeats are mostly parallel to the slope direction but biased directions are also observed. These features caused the road to become unusable at many points (Figs. 5 and 6).

Fig. 5
figure 5

a GoogleEarth image showing the location of seismo-gravitational landforms around Kalaba-Kılıçkaya villages. b–d Field views illustrating ground defeats and small-scale mass movements (e.g. rock fall)

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Fig. 6
figure 6

a Google Earth image showing the location of seismo-gravitational landforms around Kösebayır village. b–d Field views illustrating ground defeats, such as capillary cracks and small-scale mass movements with down-slope surface deformation

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Lateral spreading and liquefaction structures are common in the alluvial fan-fan (delta) areas where streams flowing perpendicular to the deformation zone along the Doğanbağı–Çevrimtaş–Ilıncak line meet/interact the Karakaya Dam lake. Deformation of lateral spreading are represented by cracks normal and parallel to the fan axis, and display a step-like pattern towards the dam lake (Fig. 7). The slope debris and colluvial wedge materials stably located along high slopes were mobilized to form small-scale mass movements by sliding down the slope during shaking. Surface deformation features caused by this kind of seismo-gravitation are common especially on the slopes of Karakaya Dam Lake where the Fırat River valley is cut and displaced sinistrally by about 11 km along the Pütürge segment of the East Anatolaian Fault Zone. These features suggest that materials, which are in critical balance on high slope, slided down and flowed during or immediately after the earthquake and caused the dam lake to narrow at certain rates (Fig. 7).

Fig. 7
figure 7

a Seismo-gravitational surface deformation features that developed along the roads between Sivrice and Doğanbağı village; b lateral spreading structures formed in the alluvial fan deposits between Doğanbağı and Çevrimtaş villages

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Detailed studies on the GoogleEarth and HGM Küre images taken at different times, it is understood that a number of fossil landslides became active during or after seismic shaking (Fig. 8a, b, red arrows). A surface fracture crack, which can be traced at short intervals along the ridge axis to the south of the mass movements, was observed (see red arrows in Fig. 8d). Vertical and steep capillary cracks developed on some parts of Sivrice–Doğanbağı road. These cracks pinch out laterally and show no vertical and horizontal movement but occur as open fractures with apertures ranging between 1 and 5 cm.

Fig. 8
figure 8

a, b Field views from the undurable materials moving down slope towards Karakaya Dam Lake during seismic shaking in the east of Ilıncak village, c GoogleEarth image and d HGM KÜRE orthophoto show that the fossil landslides on the dam lake slopes were reactivated during Sivrice (Elâzığ)–Doğanyol (Malatya) earthquake

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3.2 Seismotectonic surface deformation

Seismotectonic surface deformation features are observed in the form of surface fractures and cracks, ascending-collapsing and longitudinal pressure ridges that develop due to tectonic stress. The locations of observed seismotectonic surface deformations are given in Table 2. These features are observed along a pressure ridge between Çevrimtaş and Doğanbağı villages, and a 1.5-km-long pressure ridge that extends between Topaluşağı and Doğanyol to the northwest of Ilıncak; they commonly occur as surface fractures and cracks. Similarly, en-échelon fractures are observed along a pressure ridge around Koldere and Ormaniçi villages.

Table 2 Locations of seismotectonic surface deformation features (see Figs. 5, 6, 9, 11, 12, 13, 14 and 15 for location)
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Surface cracks are aligned parallel to the slope of the pressure ridges and define pop-up structures. These structures are compatible with the restraining bend/overlap geometry tracked throughout the Pütürge segment. The surface cracks observed between Çevrimtaş and Doğanbağı can be traced for about 500 m along the axis of the NE–SW-trending ridge. There is no observable horizontal displacement along these the surface cracks. They rather show vertical displacements on both sides of the ridges and define pressure ridges resembling a positive flower structures (Fig. 9).

Fig. 9
figure 9

GoogleEarth image showing the location of surface cracks around Doğanbağı (a) and Çevrimtaş villages (b). Field views showing surface rupture/cracks. Note the right-stepping capillary fractures in photo right b

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Çevrimtaş is one of the villages that have been damaged by the earthquake; it consists of two separate neighbourhood, while the upper neighborhood is located on the metamorphic rocks of the Pütürge Massif, the lower neighborhood is built right on the surface fracture of the Pütürge segment. The field observations confirm that most of the houses in lower settlement were severally damaged and collapsed, while there was loss of life as well. Personal communication with the villagers confirm that the ruins on the ridge to the northeast of lower neighbourhood belong to the previous residential area of the village, and that it was destroyed by the earthquake in 1875. Local have then moved the village to the new location to southwest tip of the same ridge. It was observed that the surface fracture formed in the last earthquake also pass through the old settlement area (Fig. 10).

Fig. 10
figure 10

Field view from unmanned areal vehicle (UAV) a showing the surface fracture passing through the east-southeast of the Çevrimtaş village. Note the extension of the fracture from the old village ruins (R) to the lower neighbourhood (Aşağı Çevrimtaş) and b, c from the upper neighborhood and lower neighborhood areas. Pay attention to the abundance of houses damaged in the lower neighborhood which is located on the surface deformation zone

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To the 4.5 km northwest of Doğanyol where 1.7-km-long NE–SW-trending elongated pressure ridge occurs. There, several surface cracks are developed during the earthquake. These deformation features are observed along the Kertik Tepe as right-stepping surface cracks and laterally discontinuous small-scale surface ruptures with reverse-slip component (Fig. 11).

Fig. 11
figure 11

a GoogleEarth image showing the location of surface cracks around the Kertik Hill and Ilıncak village. b, e Close-up field views illustrating surface rupture/cracks along the Kertik Hill

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Surface deformation features are mapped in the southeast of Ormaniçi district in a N50°–60° E-trending zone of up to 500 m in length and 30 m in width (Figs. 12, 13, 14 and 15). Here, there are intermittent distances between individual fractures. The fracture network (Fig. 12a) and normal vertical displacements along individual fractures are consistent with a typical sinistral strike-slip deformation.

Fig. 12
figure 12

Structural map of fractures and GoogleEarth image showing surface deformation developing in the form of a large deformation zone to the southwest of Ormaniçi village

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Fig. 13
figure 13

Field views showing normal-slip motion along individual fractures in a deformation zone to 500 m southwest of Ormaniçi village. Vertical normal slip here reaches up to 40 cm. Views are from southwest to northeast

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Fig. 14
figure 14

Different views from surface deformation features observed in the southwest of Ormaniçi village; views are from northeast to southwest

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Fig. 15
figure 15

Different views from surface deformation features observed in the southwest of Ormaniçi village

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4 Radar interferometry data

The Sentinel-1 (S-1) mission is based on a constellation of identical C-band synthetic aperture radar (SAR) satellites, which are currently comprised of the A and B units, to provide data continuity to European Space Agency’s (ESA) (Yague-Martinez et al. 2016). The Sentinel-1 mission requirements ask for data products with different image characteristics and require implementation of four different measurement modes: Stripmap Mode, Interferometric Wideswath Mode, Extra-Wideswath Mode, and Wave Mode. The interferometric wide swath mode (IW) is a widely used in most applications as is done during this research. The Interferometric Wideswath mode will allow combining a large swath width (250 km) with a moderate geometric resolution (5 × 20 m) (Torres et al. 2012). Detecting changes in the position of the Earth’s surface requires two radar images of a selected area taken from approximately the same position at different times. Interferometry is based on processing the pair of images to map out the differences in the reflected signals over the area. Differential interferometric synthetic aperture radar (DInSAR) can detect small differences in the distance between its position and the ground as the land surface moves—whether up, down, or sideways. Especially, InSAR allows to see unrecognized faults or other potentially seismogenic subsurface structures and to better define the subsurface position of known structures (Helz 2005). DInSAR technique is based on the combination of two synthetic aperture radar (SAR) images acquired for the same area at different times from slightly different positions. The result of this combination is a new image known as interferogram, whose main phase component, after corrections for topography and earth curvature, is the ground displacement along the radar Line of Sight (LOS) (Sarychikhina and Glowacka 2015).

Previous studies demonstrated the promising capability of Interferometric SAR (DInSAR) techniques for studying co-seismic deformation. Interferometric analysis using the Sentinel-1’s SAR dataset is one of the effective methods available to detect tectonic displacements associated with East Anatolian Fault Zone (EAFZ) in the January 24, 2020 Sivrice (Elazığ)—Doğanyol (Malatya) earthquake. For generating interferogram, minimum two S-1 data are required. One image is used for the master and others is the slaves (usually the new ones). The phase of SAR data represents the phase difference between the two images; the amplitude of both SARs images is multiplied. In this study, we generated co-seismic interferogram from S-1 IW data using images acquired from descending orbit (Table 3). We constructed phase and deformations images using SNAP software distributed by ESA (2020). The first step corregistration ensures that each ground target contributes to the same (range, azimuth) pixel in both the master and the slave image. Others steps are interferogram generation for removing the flat-Earth phase, deburst to merge the results of the processing from all subswaths, topographic phase removal for simulate an interferogram based on a reference DEM and subtract it from the processed interferogram, Goldstein phase filtering for reducing noise (Goldstein and Werner 1998). Another important processing step is phase unwrapping, which is necessary for displacement maps. After these steps are completed, we obtained phase interferogram and displacement maps.

Table 3 S-1 images used for this study
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The January 24, 2020 Sivrice (Elazığ)–Doğanyol (Malatya) earthquake represents the largest seismic event affecting surface ever observed with modern DinSAR techniques. Co-seismic measurements allow us to estimate vertical displacement and to prepare a deformation maps (Fig. 16). Surface deformation after the earthquake is visible in the phase map (Fig. 16a) and we find mean 10 cm uplift on NW block and maximum—6 cm subsidence on SE block (Fig. 16b). The line, which is clearly evident between the subsidence and uplift block, corresponds to the area where the surface rupture may form. The 30-km-long surface rupture starts from the SW of Sivrice and continues along the Fırat River, ends between the Pütürge and the Doğanyol (Fig. 16b). The distribution of surface deformation features, such as landslides, tension cracks, etc. caused by aftershocks, occur in a zone that reaches to length of about 50 km (Fig. 16b). In many published articles, data on horizontal deformations were obtained using optical, InSAR, and geodetic data. If we briefly talk about these studies; modelling of geodetic data by Cheloni and Akıncı (2020) obtained from the geodetic inversion shows left-lateral strike-slip with up to 2.3 m of slip. Pousse-Beltran et al. (2020) investigated horizontal surface deformation using an optical image correlation (OIC) of pre‐earthquake and post-earthquake maps. Displacement measurement uncertainties are ∼ 0.75 m in the east‐west component and ∼ 1.0 m in the north‐south component, whereas WSW of the epicenter, after slip decreases rapidly to ∼ 2–3 cm and the locking depth diminishes to near 0, indicating post-seismic surface rupturing (Pousse-Beltran et al. 2020). Jamalreyhani et al. (2020) estimated a uniform slip of 1.6 ± 0.2 m, within 68% of confidence. Melgar et al. (2020) mapped LOS displacements from InSAR showing 45-cm left-lateral sense of slip.

Fig. 16
figure 16

Co- and post-seismic interferogram maps from the descending tracks. a Phase map between 16–28/01/2002 dates and b vertical LOS displacement map between 21–27/01/2020 dates. Faults are from Duman et al. (2017); yellow star shows main shock location

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5 Discussion on surface deformation of instrumental earthquakes in Turkey

In this section, classification of surface deformations developed during the instrumental earthquakes in Turkey will be presented and their relation to co- to post-seismic events will be discussed (Table 4; Fig. 17).

Table 4 Classification of surface deformations of instrumental earthquakes in Turkey between 1939 and 2020
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Fig. 17
figure 17

a and b Relationship between surface rupture length and magnitude/co-seismic duration and c magnitude and co-seismic duration of strike slip/compressional/extensional earthquakes that developed during the last hundred years in Turkey

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As can be seen from the Table 4, ten surface rupture forming earthquakes have occurred on the North Anatolian Fault Zone during the 80-year period between 1939 and 2020. Among these catastrophic events, the maximum magnitude was Mw: 7.9 (1939 Erzincan earthquake), and the minimum magnitude, Mw: 6.8 (1992 Erzincan earthquake) with 360-km-long and 30-km-long surface ruptures, respectively. In these shallow-focus earthquakes, co-seismic earthquake duration varies between 52 and 15 s. The maximum horizontal-slip recorded is 750 cm (December 26, 1939 Erzincan earthquake) and the minimum, 30 cm (August 19, 1966 Varto earthquake). In addition, in the March 13, 1992 Erzincan earthquake, which occurred in a similar magnitude with the Varto Earthqukae, 100-cm horizontal slip and 10 cm vertical throw were measured. Considering the earthquakes that resulted in the surface faulting of the last 80 years, it is seen that there is a linear relationship between the earthquake duration and the surface rupture length. Accordingly, while the seismic shaking lasted 52 s (1939 Erzincan earthquake), a 360-km-long earthquake surface rupture developed, while 15 s seismic shaking (1992 Erzincan earthquake), a 30-km-long earthquake surface rupture developed.

When within plate faults examined in Turkey, 48-km-long surface rupture was developed along the Çaldıran fault during the November 24, 1976 Çaldıran earthquake (Toksöz et al. 1977). On the other hand, there is no observed evidence of surface rupture formation during magnitude 6.3 (Mw) earthquake in 1998 along the Misis Fault (Gürsoy et al. 1998). Whereas a 10-km-long surface rupture developed along the Dodurga Fault during the June 6, 2000 Orta-Çankırı earthquake (Mw: 6.0) (Koçyiğit et al. 2001a, b). Similarly, although the 38-km-long surface rupture developed in the 1971 Bingöl earthquake (M: 5.9–6.5) on the East Anatolian Fault Zone, there is no observed evidence (except for a few places) for surface rupturing during the 24 January, 2020 Sivrice (Elazığ)–Doğanyol (Malatya); instead there is overwhelming evidence for occurrence of surface deformation features at regular intervals in approximate 30-km-long deformation zone.

Considering the earthquakes developing in the last century in the contractional tectonic setting, a 28-km-long surface rupture developed on BSZ in the September 6, 1975 Lice earthquake, which lasted for 23 s, there was, however, no significant surface ruptures in the October 23, 2011 Van earthquake, whose magnitude was 7.2 and the duration was 29 s. The absence of surface rupture(s) is attributed to the geometry of a blind thrust (Özkaymak et al. 2011).

Similar comparison is made for normal fault earthquakes occurred in western Anatolian extensional province. For example, the February 3, 2002 Çay earthquake (M = 6.0) lasted for 21 s and developed a 21-km-long surface rupture on Sultandağı Fault. In addition, during the October 1, 1995 Dinar earthquake (Mw: 6.2), which lasted 25 s, a 10-km-long surface rupture was mapped. The seismic shaking of Mw: 6.5 magnitude event lasting 28 s in the March 28, 1969 Alaşehir earthquake resulted in the development of a 36-km-long surface rupture. A 45-km-long surface rupture developed on the Gediz Fault during the March 28, 1970 Gediz earthquake with a magnitude Mw: 6.8–7.1. Accordingly, it is suggested that surface ruptures form during normal fault earthquakes with magnitudes Mw: 6.0 and larger in extensional environments.

On the other hand, surface deformations related to seismic shaking develop in all earthquakes with a magnitude larger than 6.0 and this totally depends on local ground conditions and groundwater level as being close to the surface. The mass movements triggered by the earthquake are, however, related to the lithological and structural features of the units that outcrop along the fault zone and the presence of critical slopes that are stable at a certain critical angle.

6 Conclusion

Discontinuous surface deformation features occur within an approximately 30-km-long and 200–300 m wide deformation zone during the Sivrice (Elazığ)–Doğanyol (Malatya) earthquake. The deformation zone width obtained from interferometry is, however, approximately 1 km (Fig. 18). The observed and mapped seismic geomorphological deformation and related features in the area between Gezin (Elâzığ) and Ormaniçi (Pütürge) villages are classified into two classes as seismotectonic and seismo-gravitational features. Surface rupture and cracks, uplifted and subsiding topography and elongated pressure ridges are common seismotectonic surface features while mass movements, lateral spreading and liquefaction are reported as seismo-gravitational surface features.

Fig. 18
figure 18

a DEM map showing the relationship between the surface rupture obtained with interferometric data and the previously mapped Pütürge segment. b Surface deformations obtained by field observations and interferometric rupture zone

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Although no significant strike-slip displacement was observed along the surface fractures, vertical offsets up to 40 cm were measured, especially in the southwest of Ormaniçi village. The absence of a regular surface fractures as a result of the 6.8 magnitude earthquake can be explained in different ways: (1) left-lateral strike-slip displacement was not able to reach the surface; (2) left-lateral torque movement of the fault around a vertical axis during the earthquake, (3) restraining bend nature of the Pütürge Segment, or (4) the presence of Pütürge metamorphics along the fault strike. It is also important to note that along most part of the Pütürge segment, surface deformation features are observed in areas where talus, colluvial or alluvial fan sediments are exposed. Unconsolidated and/or poorly consolidated nature of these sediments may also be counted as one of the main reason for not observing horizontal displacements on the surface. The fracture passes through the metamorphic rocks of the Pütürge Massif in the region. The earthquake increased the stress level on the soutwestern end of the Pütürtge segment and the adjacent Palu segment to the northeast. It has been observed that previously mapped Pütürge segment and field observations show a deformation pattern consistent with interferometry data (Fig. 18b).

Earthquakes with magnitudes 6.0 and larger that occurred on different active faults of Turkey in the last century are examined in terms of surface deformations. It is clearly seen that most were not associated with regular surface ruptures. Specifically, the earthquakes associated with strike-slip faulting along the North and East Anatolian Fault Zones create surface ruptures with magnitudes 6.0 and larger. It is, therefore, concluded that (1) the formation of the surface deformations varied according to the fault type and the state of regional stress in a given region, (2) the magnitude of the earthquake, (3) the duration time of the earthquake and (4) the geomorphologic feature of landscape in relation to the lithologic and structural features of the rock units located along the active fault zone.