This chapter is to provide fundamentals about earthquakes and the induced structural and geotechnical hazards, as well as some seismology tectonics theory, propagations of earthquake waves, earthquake faults, elastic rebound theory, earthquake intensity and magnitude, basic earthquake signal process and seismic ground motion parameters including amplitude, frequency content and duration, and some local site effects on seismic ground motions. This chapter also discussed some fundamentals of seismic hazard analysis and seismic hazard models, including deterministic seismic hazard analysis (DSHA), probabilistic seismic hazard analysis (PSHA) including how to interpretate seismic sources from seismic hazard analysis, and risk-targeted seismic hazard ground motions as well. The aim of this chapter is to provide a broad but relatively in-depth discussion on some seismology and earthquake engineering fundamentals that are associated with structural engineering for structural engineers and structural engineering practitioners to better understand these essential principles and concepts to guide their better practices in seismic design of building structures.