The 1964 Alaska earthquake and tsunami killed 120 in Alaska and the west coast of the United States. This led to the creation of the Alaska Tsunami Warning Center for local warnings in Alaska. Similar local and regional warning centres were established in Japan, USSR, Tahiti and Chile in the following decades. All of these Pacific warning centres coordinated their efforts with PTWC in Hawaii. The international effort to mitigate tsunamis continued to improve as the seismological community successfully installed a global network of instruments to detect earthquakes throughout the world. Advances in satellite communications made detecting earthquakes faster and more accurate. Unfortunately, the technology to directly measure tsunamis lagged. The warning centres became rich in seismic information while remaining poor in tsunami generation determination. Assessing the latter involves more than just determination of the location and characteristics of the earthquake (see §1a), yet the warning centres had no choice but to use the earthquake fault solutions alone to assess tsunami potential along with very limited data from coastal tide gauges. This situation led to over-warnings, i.e. warnings that were unnecessary because the observed tsunami was non-destructive. From 1949 to 2000, 75% of the warnings turned out to be unnecessary. The problem of over-warning led to credibility issues among the populations being served and to economic studies of the cost of over-warning. Following the 1986 ‘false alarm’ in Hawaii when Waikiki Beach was evacuated, the State of Hawaii estimated an economic loss of US$ 40 million due to the interruption of business and the closure of State government offices (Bernard 2005a,b). The decade of the 1990s elevated the awareness of tsunamis, as over 4800 people died from 11 destructive events. Serendipitously, the United Nations
established International Decade of Natural Disaster Reduction (1990–2000).
The tsunami science community responded by developing technology to produce inundation maps at the community level. During the decade, 73 maps were produced in nine countries (Bernard 1999). As expected, the impact of the mapping was overwhelmingly positive. The maps provided the necessary information for local communities to plan for tsunamis, including evacuation procedures and recovery plans. One small tsunami occurred in 1992 in northern California that killed no one. However, this was the first recorded earthquake on the Cascadia subduction zone, and seismologists feared that a larger tsunamigenic earthquake was imminent. In response to this concern, the US created the National Tsunami Hazard Mitigation Programme to address two concerns: (i) a Cascadia earthquake/tsunami and (ii) over-warning. By 2001, this programme had developed the technology to detect tsunamis in the deep ocean, paving the way for forecasting which reduced over-warning (see §5 for details), produced inundation maps for 130 communities in the US and introduced the concept of tsunami-resilient communities (Bernard 2005a). A special issue of Natural Hazards was published to document the accomplishments of the programme (Bernard 2005b). The 26 December 2004 Sumatra tsunami killed 232 000 and shocked the world with the impact that a destructive tsunami can have on the international community. People from 55 nations perished during the attack in the Indian Ocean. As a result, there is now demand for a global tsunami warning system. The efforts of the tsunami community since 1946 will serve as a solid foundation upon which to build the warning system of the future and will reduce the loss of life from future events (Bernard 2001).