Mendocino Fracture Zone facts for kids
The Mendocino Fracture Zone is a very long line in the Earth's crust, stretching over 4,000 kilometers (2,500 miles) in the Pacific Ocean. It starts near Cape Mendocino in northern California. This zone is a special kind of boundary where two huge pieces of the Earth's crust, called tectonic plates, slide past each other.
It runs west from a spot where three important geological features meet: the San Andreas Fault, the Cascadia subduction zone, and the Mendocino Fracture Zone itself. This meeting point is called the Mendocino Triple Junction. The fracture zone continues even further west as an old, inactive part.
While "fracture zone" usually means an inactive break, this one has an active part. Many scientists call the active part the Mendocino Fault or Mendocino fault zone. This active fault marks the edge between the Pacific Plate, which is moving northwest, and the Gorda Plate, which is moving east. The Gorda Plate is actually sliding *under* the North American Plate right off the coast of Cape Mendocino.
Scientists studying tsunamis have noticed that the Mendocino Fracture Zone can focus tsunami energy. This means that tsunami waves can become taller in areas around the zone, like Crescent City, California. In these studies, the zone is sometimes called the Mendocino Escarpment because of its steep, cliff-like shape on the ocean floor.
How the Mendocino Zone Formed
In 1965, a scientist named Robert W. Pease suggested that the Mendocino Fault once stretched all the way to the land. He thought it connected to a line of geological features that included Mount Lassen and the Walker Lane in Nevada.
This line forms the boundary between different land regions, like the Modoc Plateau and the Columbia Plateau with the Great Basin. Where it meets the Honey Lake Fault, it bends and goes northeast across the northwest part of Nevada. It follows a natural dip in the land that forms the Black Rock Desert. This shows how the Earth's crust has moved and changed over millions of years.
