Characterizing Geometry, Kinematics, and Fracturing of a Wavy Fault Surface, Arkitsa, Greece

The Arkitsa fault is a high angle normal fault within the Gulf of Evvia rift system of central Greece. Quarrying of hanging wall sediments has exposed a 600 m length of a wavy footwall fault surface within Triassic/Jurassic platform carbonates. This excellent exposure enables examination of fault damage zone processes up to hundred meter scale. Using a robotic reflectorless total station we create a virtual fault surface with 1-m spatial resolution and sub-cm precision that extends over a length of 250 m and a vertical height of 60 m. Zones of extreme curvature (antiforms and synforms) parallel the average slip direction with approximately 7-m peak-to-peak spacing and thereby define the wavy fault surface. Detailed field measurements across the base of the scanned surface further characterize the fault orientation, slip, and footwall fractures. Fault strike varies over 75° with a mean of 291° while dip varies over 29° with a mean of 63°(n=165). The trend of slip indicators (surface grooves and slickenlines) varies over 57° with a mean of 342° while the plunge varies over 22° with a mean of 56° (n=162). Fracture density and orientation, measured at 24 circular scanlines, varies across the studied exposure and has little correlation to fault dip direction (P > 0.30). Open through-going fractures are oriented at a high angle to the observed slip direction with a mean strike of 59° and dip of 42° (n=317). The virtual fault surface and field measurements are integrated using sub- cm resolution digital orthophotos within a geographic information system (GIS). The integrated data allows for exploration of possible interactions among fault shape, fault slip, and footwall fractures.