What is the biggest fault in the world.

THE PACIFIC NORTHWEST: The biggest earthquakes in the country are not in California. A much greater hazard, at least in terms of sheer magnitude, exists to the north of the San Andreas Fault where the ocean crust is being forced beneath the North American continent.Oct 20, 2008

The San Andreas fault.
Hope this helps~!
~{Isle of flightless birds}

Answerfur trade;