The tectonic plate that influences the Pacific Coast is the Pacific Plate.

The Pacific Plate, one of the Earth’s largest tectonic plates, significantly influences the geology and seismic activity along the Pacific Coast. Its movement against the North American Plate along the San Andreas Fault is responsible for frequent earthquakes in California and surrounding areas. The plate’s subduction under the North American Plate, particularly in the Pacific Northwest, forms volcanic arcs like the Cascade Range and contributes to the region's complex landscape, including mountain ranges and oceanic trenches. The Pacific Plate’s interactions shape the coastal region, impacting natural features, climate patterns, and even the ecology of the Pacific Coast.