Variations in population vulnerability to tectonic and landslide-related tsunami hazards in Alaska

Nathan J Wood,Jeff Peters

doi:10.1007/s11069-014-1399-6

Abstract

Effective tsunami risk reduction requires an understanding of how at-risk populations are specifically vulnerable to tsunami threats. Vulnerability assessments primarily have been based on single hazard zones, even though a coastal community may be threatened by multiple tsunami sources that vary locally in terms of inundation extents and wave arrival times. We use the Alaskan coastal communities of Cordova, Kodiak, Seward, Valdez, and Whittier (USA), as a case study to explore population vulnerability to multiple tsunami threats. We use anisotropic pedestrian evacuation models to assess variations in population exposure as a function of travel time out of hazard zones associated with tectonic and landslide-related tsunamis (based on scenarios similar to the 1964 M w 9.2 Good Friday earthquake and tsunami disaster). Results demonstrate that there are thousands of residents, employees, and business customers in tsunami hazard zones associated with tectonically generated waves, but that at-risk individuals will likely have sufficient time to evacuate to high ground before waves are estimated to arrive 30–60 min after generation. Tsunami hazard zones associated with submarine landslides initiated by a subduction zone earthquake are smaller and contain fewer people, but many at-risk individuals may not have enough time to evacuate as waves are estimated to arrive in 1–2 min and evacuations may need to occur during earthquake ground shaking. For all hazard zones, employees and customers at businesses far outnumber residents at their homes and evacuation travel times are highest on docks and along waterfronts. Results suggest that population vulnerability studies related to tsunami hazards should recognize non-residential populations and differences in wave arrival times if emergency managers are to develop realistic preparedness and outreach efforts.

Highlights

A significant element of tsunami risk reduction is educating at-risk populations about the potential for future events, how they should prepare, and what they should do if a tsunami is detected (National Research Council 2011)
To explore potential issues related to portraying multiple tsunami sources as a single hazard zone, we examine variations in population vulnerability based on multiple tsunami threats in the Alaskan coastal communities of Cordova, Kodiak, Seward, Valdez, and Whittier (Fig. 1)
For this study of multiple tsunami threats, we focus on five Alaskan coastal communities (Cordova, Kodiak, Seward, Valdez, and Whittier; Fig. 1) due to recent efforts to model tsunami threats from multiple sources in these areas, as well as the extensive damage they suffered from both earthquake- and landslide-related tsunamis during the 1964 disaster

Summary

Introduction

A significant element of tsunami risk reduction is educating at-risk populations about the potential for future events, how they should prepare, and what they should do if a tsunami is detected (National Research Council 2011). To support tsunami preparedness and education efforts, there has been considerable work in recent years to characterize population vulnerability to tsunamis, including exposure assessments (Wood 2007; Lovholt et al 2012), demographic sensitivity analyses (Wood et al 2010), pedestrian evacuation modeling (e.g., Jonkmann et al 2008; Post et al 2009; Yeh et al 2009; Wood and Schmidtlein 2012, 2013; Freire et al 2013), and vertical evacuation siting (Park et al 2012; Wood et al 2014) All of these efforts contribute to understanding whether or not at-risk populations would have sufficient time to evacuate hazard zones before tsunami waves arrive and for recognizing what landscape or demographic characteristics may hinder their ability to evacuate.

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Discussion

Conclusion