Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 13, 2441-2463, 2013
https://doi.org/10.5194/nhess-13-2441-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
09 Oct 2013
Are great Cascadia earthquakes recorded in the sedimentary records from small forearc lakes?
A. E. Morey1, C. Goldfinger1, C. E. Briles2, D. G. Gavin3, D. Colombaroli4,5, and J. E. Kusler3 1College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA
2School of Geography and Environmental Science, Monash University, Melbourne, VIC, Australia
3Department of Geography, University of Oregon, Eugene, Oregon, USA
4Institute of Plant Sciences, University of Bern, Bern, Switzerland
5Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
Abstract. Here we investigate sedimentary records from four small inland lakes located in the southern Cascadia forearc region for evidence of earthquakes. Three of these lakes are in the Klamath Mountains near the Oregon–California border, and one is in the central Oregon Coast range. The sedimentary sequences recovered from these lakes are composed of normal lake sediment interbedded with disturbance event layers. The thickest of these layers are graded, and appear to be turbidites or linked debrites (turbidites with a basal debris-flow deposit), suggesting rapid deposition. Variations in particle size and organic content of these layers are reflected in the density and magnetic susceptibility data. The frequency and timing of these events, based on radiocarbon ages from detrital organics, is similar to the offshore seismogenic turbidite record from trench and slope basin cores along the Cascadia margin. Stratigraphic correlation of these anomalous deposits based on radiocarbon ages, down-core density, and magnetic susceptibility data between lake and offshore records suggest synchronous triggering. The areal extent and multiple depositional environments over which these events appear to correlate suggest that these deposits were most likely caused by shaking during great Cascadia earthquakes.

Citation: Morey, A. E., Goldfinger, C., Briles, C. E., Gavin, D. G., Colombaroli, D., and Kusler, J. E.: Are great Cascadia earthquakes recorded in the sedimentary records from small forearc lakes?, Nat. Hazards Earth Syst. Sci., 13, 2441-2463, https://doi.org/10.5194/nhess-13-2441-2013, 2013.
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