Complex sentence: The prominent rotunda suffered some significant damage in the 1991 earthquake to which the state responded in 1993 with a major overhaul that included an initial phase of seismic upgrades to prevent future degradation in a similar event.
Split into simpler sentences: The prominent rotunda suffered some significant damage in the 1991 earthquake. The state responded in 1993 invoking a major overhaul that included an initial phase of seismic upgrades to prevent future degradation in a similar event.