Hariklia Skilodimou

This study proposes a fusion approach to enhancing urban remote sensing applications by integrating SAR (Sentinel-1) and optical (Landsat-8) satellite datasets. The fusion technique combines feature-based fusion and simple layer stacking (SLS) to improve the accuracy of urban impervious surface (UIS) extraction. SAR textures and modified indices are used for feature extraction, and classification is performed using the XGBoost machine learning algorithm in Python and Google Earth Engine. The study focuses on four global cities (New York, Paris, Tokyo, and London) with heterogeneous climatic zones and urban dynamics. The proposed method showed significant results. The accuracy assessment using random validation points shows an overall accuracy of 86% for UIS classification with the SLS method, outperforming single-data classification. The proposed approach achieves higher accuracy (86%) compared to three global products (ESA, ESRI, and Dynamic World). New York exhibits the highest overall accuracy at 88%. This fusion approach with the XGBoost classifier holds potential for new applications and insights into UIS mapping, with implications for environmental factors such as land surface temperature, the urban heat island effect, and urban pluvial flooding.

This paper focuses on the study of the Quaternary morphotectonic evolution of the Lefkas Island using morphological and tectonic data. Based on our mainly morphological studies, two principal tectonic structures have been distinguished: (i) the Nydri-Vasiliki Fault Zone (NVF) and (ii) the Ionian Zone overthrust onto the Paxos Zone, which both divide the island into three morphotectonic units of Karya (KMTU), Maradochori (MMTU) and Athani (AMTU). Paleogeographically, it has been suggested that the broader Lefkas area was dominated by a NE–SW to ENE–WSW compressional regime since the early Pliocene that continuous in our days, resulting in the uplift of the southwestern part of the island and the submergence of the northeastern part of the island. This deformation is characterized by principal fault structures of a N110°–130° strike. These structures, combined with a fault system of N40°–60° strike representing an older Miocene fault zone, control the main morphological characteristics such as watersheds and streams and are responsible for the KMTU formation producing a northeastward plunging monoclinal en-echelon structure. During the Early Pleistocene, a shift of the compressional regime towards the east was responsible for the formation of a N70°–90° strike fault system. These faults had a morphotectonic effect throughout the island, controlling the watersheds and stream evolution. The continuous compressional regime recorded in our days results in the formation of fault structures, striking N20°–40° and N170°–190° that bound almost exclusively the coastal area of the island.