two low-gain, long-period seismometers be established in each of the two Alaskan seismic gaps.

Additional important research areas were identified by the research planning group. They include the fundamental dynamics of long, weakly nonlinear, three-dimensional waves; refraction-diffraction and other nonlinear transformations of long waves in the near-shore region; run-up, run-down, and overland flow; interaction of waves and engineered structures; and basic research pertaining to tsunami warning systems.

Tsunami research involves a number of different government agencies and encourages, even demands, international cooperation. The warning systems that alert population centers around the Pacific Ocean basin of potential and approaching tsunamis are a model for international disaster-mitigation efforts. The tsunami warning system involves three levels of alert. First, it notes the occurrence of an earthquake strong enough to trigger a dedicated alarm located in Honolulu, in the center of the Pacific. Second, if the epicenter is found to be in an area of the Pacific basin capable of generating a tsunami—under or near the ocean—a tsunami watch is established, and communication with areas around the epicenter is attempted to verify the existence of a wave. Finally, if a tsunami has been witnessed, the Honolulu station issues a formal warning along with estimated arrival times for specific locations. Once the formal warnings have been made, individual government agencies proceed with appropriate action.

This system worked quite well for the Alaskan earthquake on March 28, 1964, except for two problems. First, the earthquake damage was so severe in the immediate vicinity of the epicenter that all communication systems were knocked out. Honolulu knew an earthquake had occurred that was large enough to set off the alarm, but the location was not established until an hour later. After another hour the first tsunami report arrived from Kodiak Island, 650 km from the epicenter. Kodiak Island reported two more crests, and a full warning with estimated times of arrival was issued by the Honolulu station. The second problem came from the public response. In Crescent City, California, citizens left their homes when alerted, but they grew impatient and returned before the third wave moved through. Seven people died. In San Francisco and San Diego only the weakness of the waves when they arrived averted disaster. Thousands of people headed down to the beach to watch the big waves, proving, once again, that all the wisdom in the world cannot save those who choose to ignore it.

Volcanic Hazards

The energy of a major volcanic eruption is well beyond what can reasonably be expected to be controlled by engineering. Consequently, volcanic phenomena can best be adapted to by accurately predicting the occurrence and the likely results of an eruption. Fortunately, volcanic eruptions have many precursory phenomena (Figure 5.17) that can readily be detected with modern instrumentation and techniques.

The reduction of volcanic risk over the next decade or two will involve three distinctly different efforts: basic volcanological research, monitoring of high-risk sites coupled with public education, and study of volcanic effects on climate. Basic research is required on how volcanoes function; particularly needed are investigations into the mechanisms that trigger eruptions and better determinations of the average time spans between explosive eruptions of large magnitude. The research on recurrence intervals should consider both global and regional frequencies of eruption. This basic research could lead to accurate assessment of specific risks. Known techniques must be expanded, and new ones developed, for assessing volcanic hazards and monitoring active and potentially active volcanoes. A high-priority must be given to public education; as with earthquake and tsunami warnings, a fine line must be followed between offering correct information about probability and risk and diluting the importance of a warning by false—or misunderstood—alarms.

A better understanding of the interaction of volcanic emissions with the atmosphere and hydrosphere is necessary. Historical records show that some volcanic events dramatically modified climate for several years following eruption by introducing large volumes of dust and gas into the atmosphere. Recent research has presented evidence that large submarine eruptions along ocean ridges may alter ocean temperatures. This mechanism has even been suggested to play a part in the short-term El Niño sea-warming condition with its subsequent implications for climatic variations that fluctuate over periods of a few years. Understanding these correlations with climate will depend on global monitoring of volcanism, most likely through satellite-based remote sensing. These new data will yield a better theoretical understanding of climatic response to heat and mass transfer from the interior into the hydrosphere and atmosphere.

Deciphering the workings of volcanoes is an eclectic challenge, involving contributions from



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