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The area inside and around the church of Kapnikarea in Athens (Greece), was explored by means of electrical resistivity tomography (ERT).'Flat base'electrodes were used exclusively because the survey had to be fully non-destructive.The performance of 'flat base'electrodeswas satisfactory, leading to inversions of small root mean square (RMS) errors and reliable subsurface images, which were checked against existing borehole logs. High-resistivity anomalies were observed beneath the floor ofthe church.Theyare attributed topossiblevoids, remainsofancient wells, orother man-made structures concealed under the floor of the church. The results show that 'flat base' electrodes provided the advantage of fully non-destructive geoelectrical measurements. They also show that the use of the non-destructive ERT method offersa seriousalternative anda complementarymethod to groundpenetrating radar surveys inside existing monuments.

The Mw = 6.4 July 26, 2001 Skyros (North Aegean, Greece) earthquake struck the submarine western end of Northern Aegean Sea causing damage in the nearby Skyros Island. It occurred on a left‐lateral NW‐SE trending strike slip fault, oriented transverse to the dominant dextral strike‐slip faults that are present in the area, appearing to mark the boundary between them and the E‐W trending normal faults of the Greek mainland. Foreshock activity started 5 days before the mainshock, and intense aftershock activity followed on the main rupture plane and off fault. The seismogenic structure consists of three clusters with different orientation, independent from the known normal and dextral strike‐slip faults. Theoretical static stress changes from the main shock suggests off‐fault aftershock triggering, providing a tool for assessing the seismic hazard ensuing from strong aftershocks far from the main rupture.

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