Rulebook says: "... Thereafter, this event causes all three cultures to suffer a decimation (D2) in addition to its normal effects."
Which kind of decimation? There are 3.
Under D2. Decimations, it states there are three causes of Decimation. But there is only one Decimation: "To decimate, remove at least half your unassigned hunter cubes ..., and exactly one elder (of your choice, if you have any)."