I do not believe the damage to the city and the reason the inhabitants left was earthquakes only.
Much of the damage looks to be damage from the uplifting to the city caused when the magma chamber of the volcano started to fill. this could have
started years before the final eruption.
Major earthquakes would have destroyed the walls completely
and some of the damage looks to be twisting and repair.
I believe the inhabitants just could not keep up with repairs and finely slowly abandoned the town as the ground lifted and twisted.
I also believe it was months to years before the town was buried.