Referring to ASCE7 seismic maps, specifically ASCE7-10 figure 22-7. Are these maps based on a 1% exceedance in 50years (5,000 yr return)? I'm trying to understand the difference between the variable "PGA" when referenced in ASCE7 vs AASHTO and I beleive the difference is the return period, but the probability is not listed on these figures. I assume they are the same as others, but I might off entirely.

ASCE7 PGA = mapped MCE (Maximum considered earthquake) peak ground acceleration (not sure what the return period is)

AASHTO PGA = Horizontal peak ground acceleration coefficient (with 7% probability of exceedance in 75 yr, 1000year return)

In general the ASCE7 PGA is higher than AASHTO which would make sense if the return period is 5,000 years.

Thanks

EIT
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