Marine terraces, isostasy, earthquakes, and uplift rates

Alexander R. Simms, Helene Rouby, Kurt Lambeck, & Angela Roman

Submitted August 11, 2016, SCEC Contribution #6602, 2016 SCEC Annual Meeting Poster #083

Marine terraces line the southern California coast and have been used for decades to constrain rates of tectonic uplift. However, despite years of study two fundamental questions remain concerning their relationship to tectonic uplift. First, how accurate are previous estimates of tectonic uplift that ignore the impacts of glacio-isostatic adjustment (GIA)? Second, is that uplift slow and steady or punctuated by abrupt (co-seismic) events. In this study, we adjust uplift rates across the Pacific Coast of California for the impacts of GIA. We also present results from a shallow-marine seismic survey within a coastal lake inset into a marine terrace in Santa Barbara. We find that ignoring GIA results in uplift rates that are on average 40% too high across the California Coast. Furthermore, accounting for GIA brings uplift rates calculated from marine terraces of different ages into better agreement. Our seismic survey also reveals a seismic pattern consistent with abrupt uplift of a marine terrace near Santa Barbara. This data suggests that uplift of the marine terrace was punctuated by 4-6 co-seismic (?) events.

Key Words
tectonic uplift, sea level, co-seismic deformation

Simms, A. R., Rouby, H., Lambeck, K., & Roman, A. (2016, 08). Marine terraces, isostasy, earthquakes, and uplift rates. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology