![]() ![]() The presence of stepovers during the rupture of strike-slip fault zones has been associated with the initiation of supershear propagation (propagation in excess of the S-wave velocity) during earthquake rupture. This is backed up by evidence that the rupture of the 2001 Kunlun earthquake jumped more than 10 km across an extensional stepover. ![]() Numerical modelling has suggested that jumps of at least 8 km, or possibly more are feasible. For active strike-slip systems, earthquake ruptures may jump from one segment to another across the intervening stepover, if the offset is not too great. In the case of a dextral fault zone, a right-stepping offset is known as an extensional stepover as movement on the two segments leads to extensional deformation in the zone of offset, while a left-stepping offset is known as a compressional stepover. The areas between the ends of adjacent segments are known as stepovers. When strike-slip fault zones develop, they typically form as several separate fault segments that are offset from each other. Deformation styles Development of Riedel shears in a zone of dextral shear Flower structures developed along minor restraining and releasing bends on a dextral (right-lateral) strike-slip fault Stepovers Strike-slip tectonics is characteristic of several geological environments, including oceanic and continental transform faults, zones of oblique collision and the deforming foreland of zones of continental collision. Where the displacement along a zone of strike-slip deviates from parallelism with the zone itself, the style becomes either transpressional or transtensional depending on the sense of deviation. Areas of strike-slip tectonics are characterised by particular deformation styles including: stepovers, Riedel shears, flower structures and strike-slip duplexes. Where a zone of strike-slip tectonics forms the boundary between two tectonic plates, this is known as a transform or conservative plate boundary. Strike-slip tectonics or wrench tectonics is a type of tectonics that is dominated by lateral (horizontal) movements within the Earth's crust (and lithosphere). Structure and processes associated with zones of lateral displacement in the Earth's crust ![]()
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