The fault of Agia Paraskevi is one of the largest and most impressive tectonic structures of Lesvos. The fault that affects the volcanic rocks of the area is easily recognized by its smooth mirror surface, the surface created by the action of the fault that broke the rocks. The mirror surface of the fault is visible along the ring road of Agia Paraskevi.
The fault of Agia Paraskevi is a large dextral fault of horizontal displacement, which runs through the central part of the island, from North to South. The fault is linked to the devastating earthquake of 1867, with a magnitude of 6.8 R.
On the mirror surface of the fault, impressive slip lines appear, which are witnesses to the movement of the fault. The horizontal slip lines, which appear as striations, were created by the friction of hard grains during the opposing movement of the two blocks. The successive families of lines on the surface of the fault reveal that the fault has been activated several times by successive earthquakes that occurred in the same area.