Tsunami Debris Washes Ashore on the Olympic Peninsula?

By Nikolai Maximenko and Jan Hafner

Carried by ocean currents and winds, tsunami debris is expected to drift across the North Pacific from Japan toward the Northwest Coast of North America. The speed with which it drifts depends on its shape and composition. If the item is light and sticks out of the water, it will drift much faster across the Pacific. The drum that washed on the shores of the Olympic Peninsula is such a light object; the part that sticks out of the water acts like a sail, and the wind can push it much quickly than heavier objects. Researchers on the West Coast are now in the same position that our team has been for a while: verifying that the debris that has been found is indeed tsunami debris. The unknown composition of the tsunami debris makes modeling complex.

The arrival of light objects should provide a warning that heavier and possibly more dangerous debris is approaching. We have assessed the trajectories of heavy debris using our models that are based on knowledge gained through analysis of the motion of satellite-tracked drifting buoys, which have 45-foot-long, heavy drogues. According to our models such heavy debris is still far from the West Coast. See the model animations on our marine debris news page.

Only a small part of this debris will end on the North American coast. We expect the majority of heavy debris will move towards the North Pacific Garbage Patch, a convergence located between Hawaii and California that routinely collects floating objects. There it will stay until changes in the winds and currents will eject it and send that which is still floating on towards Hawaii's east-facing shores.

If the debris, reported from the West Coast, is shown to have originated from the March 11 tsunami, continuous monitoring of the coastline should provide valuable information on the composition and trajectory of the tsunami debris field.

We look forward to obtaining more information about the whereabouts of the tsunami debris as this will help us to improve our models. These science-based models can become invaluable tools for monitoring and possible recovery of marine debris from the current disaster and for mitigating the impact of this and other disasters in the future.