Slope Base Study Site (PN1A)

Moorings off the Oregon Margin

The Northeast Pacific is one of the most biologically productive regions within the world's oceans.

Coastal Upwelling

The coastal oceans and associated ecosystems off of the Pacific Northwest are strongly impacted by wind-driven upwelling in the spring and summer of deep, nutrient-rich water. Satellite images highlight blooms of chlorophyll associated with these events that typically last 2-20 days.

Location: 44.6ºN  125.4ºW         Water Depth: 2906-2909 meters

The Slope Base study site (Primary Node PN1A) is located near the foot of the continental slope about 60 miles (100 km) west of Newport, Oregon. This site is just west of the Cascadia Subduction Zone, where mega-earthquakes have occurred, producing tsunamis that impacted both NW coastal commmunities, as well as those along the east coast of Japan. The last magnitude 9 earthquake occurred in 1700. Just to the east, is the steep, continental slope that may result in strong topographic forcing effects on ocean currents.

The coastal region of the Pacific Northwest is a classic wind-driven upwelling system where nutrient-rich deep waters rise to replace warmer surface waters. The result is a large increase in marine productivity that ranges from phytoplankton to fish to marine mammals. Near bottom fauna are periodically negatively impacted by flow of deep waters with very low oxygen concentrations (hypoxia events), and upwelling of corrosive, acidified waters onto the continental shelf.

When coupled with other RSN and Endurance Array installations off the central Oregon coast, the Slope Base site will provide a wide variety of opportunities for seismic and coastal studies, including cross-shelf and along-shelf variability.

During the VISIONS'13 Expedition, a medium powered junction box (MJ01A) and pressure sensor were installed at this site and fully tested, as well as caisson for follow-on deployment of a broadband seismometer. In 2014, the complete geophysical array will be installed, as well as two full-water column moored profilers that host a wide variety of chemical and biological sensors.

Infrastructure and instruments to be installed at the Slope Base (PN1A) include: