Dissertation Research
“Will a Cascadia earthquake cause damage where I live?”
My dissertation research evaluates the use of lake sediments as paleoseismic recorders of ground motion from a Cascadia earthquake. I hope my work will eventually lead to a better understanding of shaking intensity and duration throughout the Pacific Northwest, especially for inland locations where most people live. My dissertation has three components:
1) Observations of similarities in timing and frequency of event deposits from lake sediments and the marine record of Cascadia earthquakes (Morey et al., 2013 and 2011 conference poster).
2) Do southern Cascadia lakes contain disturbances from Cascadia earthquakes? If so, are they different from the deposits from other types of events such as floods? What mechanisms and lake processes are involved in deposition?
3) Development of a southern Cascadia earthquake chronology (in prep). Is there an influence from sediment supply? Do lakes near the California/Oregon border contain evidence of earthquakes on the San Andreas fault?
The timing and frequency of disturbances recorded in the sedimentary records from southern Oregon and northern California lakes suggest a link to Cascadia earthquakes.
Morey et al., 2013, describe disturbance event sequences from southern Cascadia lakes, and compare event timing and frequency to the marine record of Cascadia earthquakes. The locations of the sedimentary sequences used in this study are shown in Figure 1 (shown to the right). Three of the lakes, Bolan, Sanger and Upper Squaw Lakes, are located in the Klamath Mountains near the California/Oregon border.
Fig 1. Lake and marine core locations used in this study. Modified from Fig. 1 of Morey et al., 2013.
Conclusions
“The similarities between downcore magnetic susceptibility and associated radiocarbon data from both lake and marine cores over great distances and multiple depositional environments supports synchroneity and therefore earthquake triggering. Lithologic characteristics of the disturbance event deposits suggest instantaneous deposition, and include many of the features of turbidites found in the marine record with some differences based on sediment supply and setting. The presence of earthquake-triggered deposits in forearc lakes may provide important information useful for hazard assessment from the coast inland to more populated areas. In addition, the analysis of these deposits from lakes throughout Cascadia may provide insight as to subduction zone characteristics, such as rupture lengths and segmentation.”
NEW! Draft of my third dissertation chapter can be found here:
LINK
Links to posters I’ve presented at annual conferences since 2011:
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