Subsurface investigation of a liquefaction-induced lateral spread, Thousand Springs Valley, Idaho. Final report

A subsurface investigation was made across a lateral spread that was induced by liquefaction during the 1983 Borah Peak Earthquake (MS=7.3). The lateral spread is at a site near Whiskey Springs in the Thousand Springs Valley, Idaho. The purpose of the investigation was to (a) determine whether previous liquefaction and lateral spreading had occurred; (b) measure and evaluate geologic and geotechnical properties susbsurface sediments many of which are gravels; and (c) analyze liquefaction and ground failure susceptibility. Because there are very few past case histories of liquefaction in gravel, this study provides an opportunity to further evaluate the behavior of this important matarial. The field investigations included trenching, SPT tests, CPT soundings, BDT (Becker Drill) tests, and SASW tests (Spectral-Analysis-of Surface-Waves). Radiocarbon dataing and grain-size analysis were conducted on samples collected in the field.