King County water quality monitors record effects of tsunami from Japanese earthquake

The effects of the catastrophic earthquake and subsequent tsunami that struck Japan March 11 have been felt around the world in many ways - even in Vashon Island’s Quartermaster Harbor, where King County maintains an automated water quality data collection system that recorded a rise in water depth.

“While the rise in water depth in Quartermaster Harbor was not a threat to safety or structures, our sensors clearly noted a repeated rise and fall of almost four inches in the harbor’s water depth, as well as a ‘sloshing’ effect as the unusually high water came into this sheltered water body,” said Kim Stark, Marine Monitoring Project Manager with the King County Department of Natural Resources and Parks’ Water and Lands Resources Division.

The tsunami’s biggest impacts on North America occurred along the California and Oregon coasts. However, a small portion of that energy entered into the Strait of Juan de Fuca and worked its way through Puget Sound.

The Washington Department of Ecology automated monitoring systems on the coast picked up the tsunami signal, and two and a half hours later the effect was recorded in Quartermaster Harbor. Wave energy generated by the initial tsunami and aftershocks could be seen for three days before normal conditions returned.

King County currently has four automated, high-frequency, water quality data collection systems in Puget Sound that collect physical, chemical, and biological water quality measurements every 15 minutes. The data generated by these systems allow users to characterize temporal and spatial variability for multiple parameters over numerous scales – for example, daily, seasonally, annually or inter-annually.

The data can also be used to establish baseline conditions, populate numerical models, and provide data for management decisions. The sensors collect depth, temperature, salinity, dissolved oxygen, turbidity, and chlorophyll data.

Learn more about King County’s automated mooring data at http://green.kingcounty.gov/marine-buoy/.

Related informaton

King County Water and Lands Resources Division