Long-period transition period, TL, for the conterminous United States, Alaska, Hawaii, Puerto Rico and United States Virgin Islands, 2009 NEHRP.
Description
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.