Science for Society

Center for Coastal & Land-Margin Research

Science for Society:

Impact of tsunamis on Oregon coastal communities

Tsunami Waveforms

Tsunami waves will arrive at the coasts of the Pacific Northwest shortly after the occurrence of the earthquake. In some parts of the coast, a wave will precede the first wave crest. In other parts, the crest will arrive first. In northern Oregon, the first crest will arrive approximately half an hour (yellow line) after the earthquake. In southern Oregon, the first crest may arrive in less than fifteen minutes (red line).

Wave activity will persist for several hours. While the first wave will often be significant, it may or may not be the largest. Even when the first wave is the largest, waves of similar magnitude may in some cases arrive more than 6-8 hours after the earthquake.

The waveforms shown above correspond to positions at about 5m of depth, near the identified towns or estuaries, for Scenario 4. Waveforms at positions relatively close to those shown may exhibit rather distinctive behavior. Also, different scenarios lead to distinctive behavior at fixed positions. The marked variability of tsunami waves with space, time, and excitation characteristics will constitute a major challenge for coastal planners.