 The northern coastal region of California, which includes RNSP and the adjacent offshore area, is the most seismically active in the U.S. Frequent minor earthquakes in the park and offshore under the Pacific Ocean have resulted in shifting river channels, landslides, and erosion of seaside cliffs. The North American, Pacific, and Gorda Plates are tectonic plates that all meet at the Mendocino Triple Junction, only 100 miles (160 km) southwest of the parks. During the 1990s, more than nine magnitude 6.0 earthquakes occurred along this fault zone, and there is always potential for a major earthquake. The park ensures that visitors are aware of the potential for a major earthquake through the use of pamphlets and information posted throughout the parks. The threat of a tsunami is of particular concern, and visitors to the seacoast are told to seek higher ground immediately after any significant earthquake.
