Effects of Improved Production Rates and Statistical Treatment of Cosmogenic Dates on California fault slip rates

Veronica B. Prush, & Michael E. Oskin

Published August 15, 2017, SCEC Contribution #7858, 2017 SCEC Annual Meeting Poster #137

Terrestrial cosmogenic nuclides (TCNs), such as Beryllium-10, are commonly used in fault slip-rate studies to determine the ages of offset surfaces. Two recent advances in the treatment of TCN ages necessitate reinterpretation of previously published datasets: (1) refinement and calibration of physics-based models of TCN production [Phillips et al., 2014]; and (2) a new mechanistic model for TCN clast age populations based on landslide recurrence [Prush and Oskin, submitted]. We find that the impacts of these new models lead to opposing outcomes. New production rates are slower, increasing individual clast ages. However, our new clast-age population model tends to reduce overall surface ages, despite increased individual clast ages. This occurs due to the assignment of the scatter of ages to the interplay of landslides and background erosion, rather than as a result of post-depositional modification of the target surface. The net effect of these models on slip rate varies on a site-by-site basis. In most cases, our preliminary results suggest that the net effect on fault slip rate estimates throughout California will be limited.

Citation
Prush, V. B., & Oskin, M. E. (2017, 08). Effects of Improved Production Rates and Statistical Treatment of Cosmogenic Dates on California fault slip rates . Poster Presentation at 2017 SCEC Annual Meeting.

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Earthquake Geology