$!!!!$ Discuss the engineering principles and seismic retrofitting techniques employed to enhance the resilience of existing structures against earthquake hazards. Analyze common retrofitting methods, including base isolation, structural reinforcement, and damping systems, and their effectiveness in reducing seismic vulnerability and improving structural performance. Describe the integration of seismic retrofitting strategies into building codes, standards, and retrofit programs, considering regional seismic risk profiles, structural typologies, and economic considerations, to promote seismic resilience and community safety in earthquake$-$prone regions.