I'm inclined to think it didn't happen so soon, because in PSII Motavia looks the same until the end of the game. Who knows how long it took the group to explore Dezolis; I think it took a while to complete their exploration since they had to do so much travel on foot. This, however, is purely speculation on my part.
Anyway, is there a clearer source for this information? Also, in PSIV it says this:
Then a series of disasters struck.
The system-wide managment system, 'Mother Brain,' was destroyed.
So was the first planet, Parma.
Over 90% of the system's population died, and the advanced technological
culture was lost.
For some reason I always thought what was meant by that was that of the remaining system's population--not including those that perished during Palma's destruction--over 90% died. I might be misunderstanding this, however. Does the over 90% include the ones that died on Palma?
The Compendium translation says this about The Great Collapse:
Term referring to the destruction of Mother Brain and the annihilation of Parma by the fall of the artificial satellite Gaila in AW 1284. Due to these events, more than 90% of the total population was killed, and civilization was thrust into a rapid decline.
So... I'm thinking "of the total population" refers to the ones lost on Palma as well. Maybe?
When do you think Motavia was hit by a Palma fragment?