Assessing local impacts of the 1700 CE Cascadia earthquake and tsunami using tree-ring growth histories: a case study in South Beach, Oregon, USA

Abstract. We present an investigation of the disturbance history old-growth Douglas-fir (Pseudotsuga menziesii) stand in South Beach, Oregon, for possible growth changes due to tsunami inundation caused by 1700 CE Cascadia Subduction Zone (CSZ) earthquake. A high-resolution model run-up heights at assuming “L”-sized earthquake, is also presented better estimate levels several kilometers inland site. This indicates Beach fir would have been subjected local depths from 0 10 m. Growth chronologies collected shows that trees experienced a significant reductions year relative nearby stands, consistent with estimates. The ±1–3-year timing disturbances are previously observed Washington state coastal forest ∼220 km north. Moreover, were not largest over >321-year tree chronology this location, other likely climate drivers (e.g., drought or windstorms). Our study represents first step using ground truth models providing site-specific physical evidence.