The customer has provided the following information about "Seismic Reaction" at the ATFE site :

"This is according to a Norwegian Standard NS 3491-12.  For a return
period in 475 years, the zone map show a peak value for "acceleration of
soil (earth)" = 0.55 m/s2  (= 1.804 ft/s2)."

Is the above statement enough information for you to do your
calculations?  If not, please let me know and I will try to get the
additional information you need.
