1 THE TSUNAMI EVACUATION AT HAWAII DUE TO THE 2012

THE TSUNAMI EVACUATION AT HAWAII DUE TO THE 2012 HAIDA
GWAII TSUNAMI
Angela Santos (1), Rita Cunha (2)
(1) Environmental Hazard and Risk Assessment and Management, Centro de Estudos Geográficos,
Instituto de Geografia e Ordenamento do Território da Universidade de Lisboa, Portugal. Email:
[email protected]
(2) Portugal Enviromental Agency, Portugal. Email: [email protected]
Oral presentation
Sub-theme 8: Geomorphological processes, risks and evolution of landscape
(Sub-tema 8. Processos geomorfológicos, riscos e evolução da paisagem)
Abstract
On the October 28, 2012, at 3:04 (UTC) an earthquake has occurred offshore Haida
Gwaii, in the western British Columbia, Canada, with 7.8 magnitude (USGS). The
earthquake generated a tsunami, and the Pacific Tsunami Warning Center issued a
tsunami warning to Hawaii, 2 hours after the earthquake has occurred.
Since Hawaii has been hit by more than 10 tsunamis in the past (Santos and Cunha,
2013), spatial planning authorities and emergency agents are in urgent need of
operational tools that would provide accurate tsunami forecast as guidance for rapid,
critical decisions in which lives and property are at stake. One of the main concerns was
to quickly confirm potentially destructive tsunamis and reduce false alarms (Bernard,
2005), since false evacuations are costly both in terms of dollar expenses and credibility.
Moreover, the state of Hawaii has been improving the tsunami preparedness, by
updating tsunami hazard maps and organizing regular siren exercises. These exercises
also include the local populations.
The objectives of this paper are to show that tsunami numerical models are an effective
tool to forecast far-field tsunamis, and to understand tsunami preparedness in Hawaii.
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The tsunami numerical model results show the tsunami reached Hawaii 5 hours and 30
minutes after the earthquake. The maximum water level shows that the energy is mainly
focused slightly northward of Hawaii, and not towards the islands. Furthermore, the
maximum water level is about 1 m, decreasing from the tsunami source location.
In addition, the witnesses’ accounts were compiled by the media. Hawaiians and
tourists respond well to the evacuation. But the majority evacuated by car causing heavy
traffic. Some car accidents were also reported. Other witnesses questioned if the
evacuation was really necessary; other witnesses were complaining that could not return
home. Therefore, the “always evacuate” idea is not straightforward.
The tsunami warning issued by the Pacific Tsunami Warning Center to Hawaii was in
fact a false evacuation because no major threat hit Hawaii. Therefore, stakeholders
should use all the available tools before considering issuing any warning: real time data
and tsunami numerical model.
Keywords: Tsunami numerical model, tsunami evacuation, tsunami preparedness,
Hawaii.
(Palavras-chave: modelação numérica de tsunamis, evacuação de tsunami, preparação
de tsunami, Hawaii)
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