Seismic acceleration, big discrepancy between Canada code and ASCE7?

[leeStruct]

I am not quite familiar with Canada building code. Recently I found Canada building code divide its territory into 7 seismic zones (from 0 to 6), what confused me is that its biggest seismic acceleration (corresponding to the fundamental period of 0.2 sec.) at seismic zone 6 is only 0.32g from its seismic zoning map, while looking at ASCE7 Figure 22-1 the maximum 0.2 sec spectral response acceleration can be come to 200%g to 300%g (i.e. 2g to 3g). Can anybody help to explain it to me why there is such a large discrepancy for the biggest seismic acceleration between these two Codes. By the way I believe the highest intensity of earthquake in Canada and in USA are similar.

Thank you for your help.

 

[leeStruct]

Here is the link to the seismic zoning map for canada, which shows its maximum seismic acceleration (corresponding to the fundamental period of 0.2 sec.) at seismic zone 6 is only 0.32g.

While in ASCE7 the maximum seismic acceleration (corresponding to the fundamental period of 0.2 sec.) is 2g to 3g. That means the maximum seismic acceleration in US is nearly 10 times larger than the maximum seismic acceleration in Canada. That does not make sense.

Am I missing something?

http://commons.bcit.ca/civil/students/earthquakes/unit1_02.htm