Open University Uranium-Series Laboratory  
Earth and Environmental Sciences, The Open University, Milton Keynes, UK  

Geological Hazard
Use of corals to estimate earthquake frequencies  
Marine terraces that have been raised by fault activity in central Greece have been dated using corals. In the study area 10 (magnitude 6.0) earthquakes have occurred in the last century, but the frequency of earthquakes is poorly constrained due to the lack of data on rates of fault-slip.
As an example, in 2003, a geomorphic paleoshoreline model combined with 234U-230Th coral dates constraining the Psathopyrgos fault at the western end of the Gulf of Corinth were published (Houghton et al. 2003). The Psathopyrgos fault is the only major active normal fault, reported on published maps controlling the downthrown Rio Straits at the western end of the Gulf of Corinth. An uplift rate of ~0.7-0.8 mm/yr was derived for the western end of the Gulf of Corinth, Greece. In this area of high (15-22 mm/yr) extension rates measured with GPS, the ratio of uplift rate to extensional GPS velocity is 0.025-0.035, much lower than values of 0.15-0.25 found further east in the gulf. These low values imply that if GPS extension rates are correct then mechanical/kinematic models developed for the eastern and central gulf may not be applicable to the western gulf.
Multiple and accurate dates on terraces from central Greece are of great significance in the evaluation of deformation rates both locally and regionally and for assessing the changing intensity of differential uplift throughout the Gulf of Corinth. They are pivotal in testing the hypothesis of Morewood and Roberts (1999) concerning styles and rates of fault slip.

|More information on the uplift that is associated with fault activity in this are can be found at: Perachora uplift


Marine terraces at the western tip of the South Alkyonides Fault System on the Perachora Peninsula, central Greece © Sarah Houghton.    

Houghton et al., 2003. Geophysical Research Letters, 30(19), 2013.
Morewood and Roberts, 1999, J. Structural Geology, 21, 635-652

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© Peter van Calsteren
Last updated: 23 December, 2011 11:38