Low spectral response value Ss yielding small seismic forces in Hawaii

[SoCalSE]

Under the IBC 2003, seismic base shears are based on maximum considered earthquake ground motion for one-second and short spectral responses, S1 and Ss. Typically in Southern California, Ss is on the order of 1.4. In Hawaii the value is 0.178, resulting in a base shear of only 4% gravity. This seems ridiculously low. Can anyone confirm a similar design value for a Hawaii job?

Many thanks.

 

[Taro]

Depends where you are. Ss values can be 2.67 near the active volcanoes on the island of Hawaii. A value of 0.19 would apply at Barking Sands on Kauai.

 

[SoCalSE]

Thank you. I did a comparison to the UBC, which yields 6% gravity for the base shear. I did not realize that parts of Hawaii had the equivalent of a UBC Zone 1 seismicity.