How can you model the earthquake for piping protect in caesar?

Go to classic piping input element specific data there you will find options like uniform loads, wind waves, seismic loading. 

Select seismic loading being in proper elements in nodal specific data for pipe which perhaps experience seismic loads. This data of seismic loading automatically will be copied to the next element modify it if the follwing piping part doesn't experience seismic loading perhaps. 

For more info on seismic loading in CAESAR-II, Press F1 being in seismic loading option.

Well, you need to refer the structural design basis for that. Hopefully that will have all the seismological info required for design.