Child Item 3 of 3 : Long-Period Transition Period Maps

For designing buildings and other structures to safely resist earthquakes, the 2009 NEHRP Recommended Seismic Provisions and the 2010 ASCE/SEI 7 Standard contain maps of long-period transition periods (TL.). TL is based on the modal moment magnitude obtained from the disaggregation of a 2% probability of exceedance in 50 years hazard analysis for spectral acceleration at 2-second period for the conterminous United States and Alaska, and 1-second period for Hawaii. For the U.S. territories of Puerto Rico, U.S. Virgin Islands, Guam, Northern Mariana Islands, and American Samoa, the long-period transition, TL, is 12 seconds and no maps or shapefiles are provided in this data release.