Salt Lake City lies at the eastern boundary of the Basin and Range Province. The major active fault zone is the normal Wasatch Fault that throws down to the west. The footwall (upthrown part) is formed by the Wasatch Range with part of the Great Basin lying in the hanging-wall (downthrown part), at one time filled by Lake Bonneville, with the Great Salt Lake forming the largest remnant. The fault zone is broken up into six segments that appear to rupture separately. Paleoseismic investigations indicate that 19 major earthquakes have occurred in the last 6,000 years along the fault system.