GREAT EARTHQUAKES AND TSUNAMIS ALONG THE CASCADIA SUBDUCTION ZONE AND THEIR IMPACTS ON INDIGENOUS COMMUNITIES: ARCHAEOLOGY AND ORAL TRADITIONS

Humans have inhabited the coastline along the Cascadia Subduction Zone since the Late Pleistocene. Most indigenous groups in this region were heavily dependent upon coastal resources such as fish and shellfish, and most settlements were located proximate to the shoreline. The archaeological record of this region shows that large earthquakes, and the coastal subsidence and tsunamis they generated, were serious hazards for indigenous communities. Habitation sites along the margins of estuaries have been found in subsided soils covered with tsunami deposits, and some long-term coastal sites appear to have been abandoned at intervals corresponding with those of great earthquakes. Earthquakes, tsunamis, and subsidence also likely impacted coastal ecosystems, but the extent and duration of such impacts remain unclear. Problems plaguing research on the impacts of these events of past indigenous communities include issues with the chronology of the archaeological record, which often lacks the acuity necessary for precisely understanding the occupation history of sites. Accounts of earthquakes and tsunamis have been recorded by ethnographers working with nearly all indigenous language groups living along the Cascadia Subduction Zone. Some of these oral traditions appear to refer to the AD 1700 event, while others have less clear ties to geologically-known events. Tsunamis are described as over-running villages in some accounts, while in others are responsible for the complete destruction of previous human populations. In other cases the stories refer to reoccupation of flooded portions of the landscape. For some groups, earthquakes in particular are described as animate characters whose actions are intentional.