Abstract: On the importance of isotopic dating and related uncertainties in paleoseismology
Institut de Physique du Globe de Strasbourg, France
Paleoseismology is a relatively young method of earthquake studies at the interface between geology and seismology. Paleoseismic investigations have enriched the fault rupture database in some active zones (e.g., California, Turkey, Italy) and contribute to a significant progress in the concept of earthquake cycle and seismic hazard assessment. The increasing number of paleoseismic studies in the last decades was dedicated primarily to the major continental faults that experienced large earthquakes (M>7). The validity of paleoseismic results were tested in regions with long historical catalogues and well documented past earthquake ruptures.
The dating of past earthquakes is a critical step in paleoseismic studies. In trenches, the relative chronology of sedimentary units is often complemented by isotopic dating and other methods. For this presentation, I will show examples of paleoseismic studies of active and seismogenic faults from diverse tectonic zones. In particular, I will focus on the use of the isotopic analyses (mainly radiocarbon and OSL-TL methods) that help us to bracket past faulting-seismic events from collected samples in paleoseismic trenches. The constraint of uncertainties in the dating of samples is tested to the well known record of historical and archeoseismic earthquakes along major continental faults in the Middle East (Jordan, Syria and Turkey).