Monitoring Tsunami Threats

Many countries around the Pacific cooperate in monitoring the generation and movement of tsunamis. The seismic sea wave warning system was established and became operational after the great 1946

tsunami that devastated Hilo, Hawaii, parts of Japan, and many other circum-Pacific coastlines. The seismic sea wave warning system and other tsunami warning systems generally operate by monitoring seismograms to detect potentially seismogeneic earthquakes, then monitor tide gauges to determine if a tsunami has been generated. Warnings are issued if a tsunami is detected, and special attention is paid to areas that have greater potential for being inundated by the waves.

It takes several different specialists to be able to warn the public of impending tsunami danger and reduce the threat from tsunamis. First, seismologists are needed to monitor and quickly interpret the earthquakes and determine which ones are potentially dangerous for tsunami generation. Second, oceanographers are needed to predict the travel characteristics of the tsunami. Coastal geo-morphologists must interpret the shape of coastlines and submarine topography to determine which areas may be the most prone to being hit by tsunamis, and geologists are needed to search for any possible ancient tsunami deposits to see what the history of tsunami run-up is along specific coastlines. Finally, engineers are needed to try to modify coastlines to reduce the risk from tsunamis. Features such as sea walls and breakwaters can be built, and buildings can be sited in places that are outside of reasonable tsunami striking distance. Loss control engineers typically work with insurance underwriters to identify areas and buildings that are particularly prone to tsunami-related flooding.

several detailed reports have described areas that are particularly prone to repeated tsunami hazards. The United States Army Engineer Waterways Experiment Station has produced several of these reports useful for city planners, the Federal Insurance Administration, and state and local governments.

The National Oceanic and Atmospheric Administration (NOAA) has been operating tsunami gauges in the deep ocean since 1986. These instruments must be placed on the deep seafloor (typically up to 1,500-2,000 feet [1,000 m] depth) and recovered and redeployed each year. Cables send the recordings from these instruments back to shore. The information derived from these tsunami gauges is used for tsunami warning systems and also used for planning coastal development, since the pressure changes associated with tsunami can be accurately recorded over long periods of time, and the history of tsunami heights in given areas assessed before coastal zones are further developed.

The NoAA runs Pacific Tsunami Warning Center in Honolulu. The United States Geological Survey also has been actively engaged in mapping tsunami hazard areas and establishing ancient tsunami run-up heights on coastlines prone to tsunamis, to help in predicting future behavior in individual areas. The results from these mapping programs are routinely presented to local government planning boards, to help in protecting people in coastal areas and assigning risks to development in areas prone to tsunamis.

Continue reading here: Predicting Tsunamis

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