Life safety and seismic hazards selecting buildings for review and questions still to answer

Los Alamos National Laboratory (LANL) is situated on the eastern flank of the Jemez Mountains in which lies the Valles Caldera, a volcanic center that erupted 1.1 to 1.5 million years ago. Los Alamos is also situated within the western margin of the Rio Grande Rift system, where there is a possibility for seismic activity. Within the Los Alamos area are numerous faults, some within a kilometer or two of LANL structures, some even closer. Many of the permanent structures within Los Alamos were designed and constructed in accordance with applicable building codes in the 1950s. These codes have now been determined to be deficient with respect to both forcing functions of seismic events and structure design. LANL, in response to a letter from the University of California dated October 29, 1990, started a Seismic Hazards Investigation Program to determine the characteristics of a probable seismic event at Los Alamos, and to determine the ability of the existing structures to withstand the forces generated by such an event. The Seismic Hazards Investigation program uses paleoseismic methods to determine seismic characterization and a systematic method to investigate existing structures, systems and components for their ability to resist seismic forces. This paper presents the methodology evolved to determine the above