1. The relationship between kinematics and fault geometry for surface coseismic ruptures on across-strike faults: New observations of slip vectors and displacements along the Pisia and Skinos faults from the 1981 Eastern Gulf of Corinth, Greece earthquakes.
- Author
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Mitchell, Sam, Roberts, Gerald P., Faure Walker, Joanna P., Iezzi, Francesco, Sgambato, Claudia, Robertson, Jennifer, Mildon, Zoë K., Ganas, Athanassios, Papanikolaou, Ioannis D., and Rugen, Elias J.
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SURFACE geometry , *GEOMETRIC surfaces , *KINEMATICS , *EARTHQUAKES , *COLLUVIUM , *BEDROCK - Abstract
The relationships between kinematics and fault geometry for the coseismic ruptures from the 24th and February 25, 1981 earthquake sequence in the eastern Gulf of Corinth (Ms 6.7 and 6.4) are analysed. The two earthquakes ruptured faults located across strike rather than along strike as typifies other earthquake sequences. In detail, surface ruptures formed on the sub-parallel Pisia and Skinos Faults, with an 8 km along-strike overlap zone, separated across strike by < 2 km. The largest coseismic offsets occurred in the overlap zone. The 41-year-old ruptures are still well preserved as bedrock fault plane lichen-free stripes and colluvial ruptures, allowing detailed structural mapping at 213 rupture localities. A comparison between our measurements and Jackson et al. (1982) showed no overall consistent signal of post-seismic slip as some of our measurements were greater and some smaller than those recorded in 1981. The ruptures produced a single maximum asymmetric profile (Pisia: maximum throw of 223 cm) and a double maxima profile (Skinos: maximum throw of 109 cm and 130 cm). The shapes of the profiles differed in previous earthquakes on these faults, as evidenced by an older lichen-free stripe, implying non-characteristic earthquakes. Summing the two overlapping throw profiles across-strike reveals a single maximum symmetric bell-like profile. Using the above observations on coseismic offsets, kinematic information, and the geometry of faults, a rupture scenario has been proposed in terms of fault bends and corrugation orientations which suggests that parts of each fault may have ruptured in each earthquake. • Fault geometry and slip kinematic observations help understand the rupture style formed during Greece's 1981 earthquakes. • The across-strike Pisia and Skinos Faults appear to interact based on their combined surface slip distributions. • The Pisia and Skinos Faults exhibit no resolvable post-seismic slip in 41 years since the earthquakes. • The Pisia and Skinos Faults produce non-characteristic earthquakes. • Slip vector convergence and divergence toward the hangingwall may reveal the presence of major fault bends. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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