Your local code should have some guidelines for accelerations to be used in liquefaction analysis. Liquefaction analysis was developed mostly based on observations from lessons learned after earthquakes. In Japan we use 0.2g and 0.30g for typical and large earthquakes, respectively. The latter was based on the large Kobe earthquake in 1995. I think that the guidelines have been changing due to the last large earthquake in 2011. Bottom line, you should use whatever has been experienced during large earthquakes in your area.