###### Abstract  
On 30 October 2020, an Mw = 7.0 earthquake struck the eastern Aegean Sea. It triggered earthquake environmental effects (EEEs) on Samos Island detected by field surveys, relevant questionnaires, and Interferometric Synthetic Aperture Radar (InSAR) analysis. The primary EEEs detected in the field comprise coseismic uplift imprinted on rocky coasts and port facilities around Samos and coseismic surface ruptures in northern Samos. The secondary EEEs were mainly observed in northern Samos and include slope failures, liquefaction, hydrological anomalies, and ground cracks. With the contribution of the InSAR, subsidence was detected and slope movements were also identified in inaccessible areas. Moreover, the type of the surface deformation detected by InSAR is qualitatively identical to field observations. As regards the EEE distribution, effects were generated in all fault blocks. By applying the Environmental Seismic Intensity (ESI-07) scale, the maximum intensities were observed in northern Samos. Based on the results from the applied methods, it is suggested that the northern and northwestern parts of Samos constitute an almost 30-km-long coseismic deformation zone characterized by extensive primary and secondary EEEs. The surface projection of the causative offshore northern Samos fault points to this zone, indicating a depth-surface connection and revealing a significant role in the rupture propagation. 2021 31 March 2  
was more severe in the area of Izmir, western Turkey, to the north of the seismic source. According to the final report of [14], in that area 114 fatalities and 1035 injuries were counted, 13 buildings were completely destroyed, and 3000 buildings were heavily damaged. According to preliminary reports, the earthquake also caused important effects on the natural environment of Samos, such as surface deformation and various types of ground failures [12]. Relative sea level changes [15] and a tsunami of moderate size [16] have also been reported. On 20 January 2021, a strong aftershock measuring magnitude Mw = 4.5 occurred closer to Samos Island with respect to the mainshock (Figure 1). Further uplift was reported by local people after that aftershock and, therefore, our analysis included this uplift episode as well. In this paper, we focus on the environmental effects of the earthquake and present a detailed collection, documentation, and mapping of relevant field observations acquired during post-event field surveys conducted on Samos Island immediately after the earthquake event. Additional observations were collected after our communication with local people. The studied earthquake environmental effects (EEEs) are classified into two groups. The first group concerns primary EEEs, i.e., coastal uplift and subsidence, as well as surface ruptures, which constitute the surface expression of tectonic movement in the seismogenic source. The second group of studied EEEs includes a variety of effects related to and induced by the ground shaking, such as slope failures, liquefaction in soil, ground cracks, rockfalls, and hydrological changes, all observed at several sites of the island. However, tsunami observations are not included in this study since they have already been presented elsewhere [16]. Figure 1: Map illustrating the epicenter and the focal mechanism of the 2020, Mw = 7.0, Samos (eastern Aegean Sea) earthquake from [1] along with its aftershock sequence from 30 October to 5 March 2020 from the Earthquake Catalogue of the Seismological Laboratory of the Department of Geophysics–Geothermics, Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens ([[http://www.geophysics.geol.uoa.gr/stations/gmapv3_db/index.php?lang=en](http://www.geophysics.geol.uoa.gr/stations/gmapv3_db/index.php?lang=en)]([http://www.geophysics.geol.uoa.gr/stations/gmapv3_db/index.php?lang=en](http://www.geophysics.geol.uoa.gr/stations/gmapv3_db/index.php?lang=en)) (accessed on 31 January 2021)).