Upon breaking apart 4 million years ago, the Juan De Fuca plate continued moving northeast at 26 mm/year (1 in/year) while the Explorer plate's velocity changed, stalling or moving slowly north up to 20 mm/year.
[5] The Sovanco fracture zone originated as a spreading center offset more than 7 million years ago which shows southward movement from the influence of the Explorer ridge and results in uneven spreading eastward unto the Explorer plate.
[5] The subducted portion of the plate extends downward to more than 300 km (186 mi) depth, and laterally as far as mainland Canada.
[11] The Explorer plate is the most seismically active area of Canada, but is anomalous as a subduction zone since most of the seismic activity occurs around the plate's perimeter rather than at the subduction interface.
[8] Events are generally centered around the southern and north-western areas where the borders of the plate are in contact with other plates; however, the newer ocean crust created at Explorer ridge and Juan de Fuca ridge reduces the rigidity of the region and contributes to the low magnitude of events in the region.