Geomorphology, sedimentology, and stratigraphy of tsunami deposits at Quidico, Chile

Isabel Hong
May 2013

Research Objectives

Tsunami deposits are a good proxy for large earthquake activity and can provide information on the extent and size of an earthquake (Nanayama et al., 2003). The known magnitude and extent of the subsequent tsunami event can be used to approximate the amount of oceanic floor uplift and sea floor deformation caused by an earthquake (Plafker and Savage, 1970). Furthermore, by gaining an understanding of the location and magnitude of tsunami deposits, researchers are better able to evaluate the tsunami hazard of a local region – an area that is often far greater than that affected by an earthquake (Peters and Jaffe, 2010).

Quidico, in south-central Chile, is an ideal site for a focused paleotsunami study of fault segmentation because the region is a site of earthquake rupture overlap from the 1960 Mw 9.5 and 2010 Mw 8.8 earthquakes (Fig. 1) (Bilek, 2009; Melnick et al., 2012). Research in Quidico is especially needed because the region lacks a measured study of historical earthquakes (Bilek, 2009). I hypothesize that due to Quidico’s unique location as a site of rupture overlap there will be more, if not double, the number of tsunami deposits at Quidico compared to other sites located to the north and south. The objective of this research is to construct a paleoseismic and land-level history for Quidico by utilizing geomorphic, microfossil, sedimentological and stratigraphic analysis of tsunami deposits and interbedded deposits within and around the banks of the Quidico River. Results of this study at Quidico will be compared to a neighboring research site, Tirua, in order to assess the consistency of paleotsunami deposit preservation as well as to identify possible differences in coseismic and interseismic activity between different settings. Establishing and correlating this record with historical accounts of earthquakes and tsunamis will lead to an advancement in our understanding of potential seismic hazards in south-central Chile.

Full Thesis Proposal (PDF format)