The Seismic History of the Pisia Fault (Eastern Corinth Rift, Greece) From Fault Plane Weathering Features and Cosmogenic 36Cl Dating. Issue 5 (12th May 2018)

• Record Type: Journal Article
• Authors: Mechernich, Silke; Schneiderwind, Sascha; Mason, Jack; Papanikolaou, Ioannis D.; Deligiannakis, Georgios; Pallikarakis, Aggelos; Binnie, Steven A.; Dunai, Tibor J.; Reicherter, Klaus
• Is Part Of: Journal of geophysical research. Volume 123:Issue 5(2018)
• Page Start: 4266
• Page End: 4284
• Publication Date: 2018-05-12
• Subjects: bedrock normal fault -- fault scarp analyses -- active fault -- terrestrial laser scanning -- slip rate; Geomagnetism -- Periodicals; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 551.1
• DOI: 10.1029/2017JB014600
• Languages: English
• ISSNs: 2169-9313

Abstract

Abstract: The deformation of the eastern Corinth rift (Greece) is distributed along several E‐W trending active normal faults. Here the 25‐km‐long Pisia fault experienced up to 150 cm of coseismic displacement during the 1981 Alkyonides earthquake sequence ( M = 6.7, 6.4, 6.3). Using terrestrial laser scanning, coupled with analyses of color changes, lichen colonization, and karstic features, we identify differentially weathered horizontal stripes on the exposed Pisia fault plane. The stripe boundaries occur at scarp heights of 1.10, 2.05, 2.85, 3.60, 4.15, and 5.15 m, with two additional possible boundaries at 3.10 and 4.65 m (~±0.1 m, respectively). This indicates that six to eight paleoearthquakes have exhumed the fault plane in a series of distinct coseismic slip events. A vertical profile of cosmogenic 36 Cl measurements is used to constrain age models of the exhumation. The results imply that, in addition to the last earthquake of 1981 (EQ1), exhumation events occurred at ~2.0 kyr (EQ2), ~3.1 kyr (EQ3), ~4.5 kyr (EQ4/4a, b), ~6.0 kyr (EQ5), and ~7.3 kyr (EQ6/6a, b), with modeled age uncertainties of ~0.7 kyr. Bayesian modeling provides a middle and late Holocene slip rate of 0.5–0.6 mm/yr (last 7.3 ± 0.7 kyr), while the upper part of the 8.45‐m‐high fault plane was exhumed at a higher rate of 0.8–2.3 mm/yr (7.3 ± 0.7 kyr to 10.2 ± 1.9 kyr). This slip rate variability suggests an increased seismicity or larger slip events during the early Holocene. Key Points: Several earthquake horizons are revealed by mapping visual weathering features and terrestrial laser scanning (TLS) analysis At least six events with 25–110 cm of coseismic displacement ( M w 6.2–6.7) ruptured the Pisia fault within the last 7.3 ± 0.7 kyr The Holocene slip rate decreased from 0.8–2.3 mm/yr (early Holocene) to 0.5–0.6 mm/yr (middle and late Holocene)