As　a　method　of　the　information　forecasting,　commensurability　information　system　was　mainly　applied　to　studying　system　characteristics.　The　difficulty　of　commensurability　information　system　is　the　pick-up　of　commensurable　data.　This　paper　adopted　the　commensurability　as　module　for　data　partition,　and　extracted　data　by　the　different　frequency.　According　to　the　commensurability　and　time　order,　there　are　M≥8　earthquakes　in　Chinese　Mainland　and　M≥7　earthquakes　in　California.　The　two　methods　reached　the　same　goal　by　different　routes.　The　results　show　that　the　series　of　M≥8　earthquakes　in　Chinese　Mainland　and　M≥7　earthquakes　in　California　are　in　a　sense　rather　than　fully　stochastic.