Significant Landslide Events in the United States

The April 1983 landslide at Thistle, Utah, created a 200-ft-high (60-m-high) blockage of Spanish Fork canyon that caused disastrous flooding of the Thistle creek and Soldier Creek valleys upstream.  The flooding caused by the landslide required relocation of a major highway and railway.  An emergency spillway and diversion tunnels were constructed to drain the reservoir.  Direct costs exceeded $200 million (in 1983 USD).