The denser oceanic plates are converging with North America and subducting beneath the western edge of the continent. “Understanding these processes will certainly provide new insights on how subduction zones may have initiated in the past and how oceans start to close,” Duarte says. Subduction occurs at a convergent plate boundary. The Pacific Northwest is home to the Cascadia Subduction Zone, a 1,300 km-long tectonic boundary between the Juan de Fuca and Gorda oceanic plates to the west and the North America continental plate to the east (Fig. Even at this early phase the site will yield data that is crucial to refining the geodynamic models. The findings provide a unique opportunity to observe a passive margin becoming active-a process that will take around 20 million years.

The Iberian subduction will gradually pull Iberia towards the United States over approximately 220 million years. This break-up and reformation of supercontinents has happened at least three times, over more than four billion years, on Earth. The incipient subduction in the Iberian zone could signal the start of a new phase of the Wilson Cycle-where plate movements break up supercontinents, like Pangaea, and open oceans stabilize and then form new subduction zones that close the oceans and bring the scattered continents back together.

For the first time, we have been able to provide not only evidences that this is indeed the case, but also a consistent driving mechanism.” “Significant earthquake activity, including the 1755 quake which devastated Lisbon, indicated that there might be convergent tectonic movement in the area. (Credit: NASA Goddard Photo and Video/Flickr)

Subduction boundary