Households’ expected and actual preparation times in tsunami evacuation drills

Near-field tsunamis pose a serious threat to life safety in the Cascadia Subduction Zone’s (CSZ’s) coastal communities. These communities face critical challenges in making timely decisions and evacuating from the inundation within 15–20 min after the end of earthquake shaking. The objective of this paper is to examine the ability of coastal residents to successfully evacuate from such tsunamis by answering two questions: (1) Is there a significant difference between the coastal residents’ expected evacuation preparation times (EPT) and their actual evacuation preparation times (APT)? (2) What variables are correlated with EPT and APT? To address these questions, an in-home evacuation preparation drill was conducted to record both variables. Following the drill, participants completed a questionnaire that contained items addressing five categories of variables expected to predict EPT and APT. These are tsunami hazard awareness, expected actions before evacuating, prior preparedness actions, relationship to a local emergency preparedness organization, and demographic characteristics. The results indicate that 56.3% of respondents underestimate their evacuation preparation times. For a quarter of respondents, their calculated inundation zone clearance times exceed the scientifically estimated first wave arrival times, meaning that these people are at risk of being caught by a tsunami wave. Additional analyses examined the correlations of EPT and APT with the five categories of potential predictor variables. EPT and APT had significant positive correlations with tsunami hazard awareness and APT had significant negative correlations with prior preparedness actions. Surprisingly, EPT and APT both had nonsignificant correlations with expected actions before evacuating. This research fills a critical knowledge gap in the validation of evacuation preparation time estimates and contributes to the management of response to rapid-onset hazards.