This dissertation focuses on observations and modeling of fault creep in California aiming to understand the relationship between creep and earthquakes and assess the earthquake hazards in California. Chapter 1 gives an introduction of fault creep research in California, geodetic methods used to measure fault creep, and mechanism of fault creep. Chapter 2 documents an investigate on a creep event on the Supersitition Hills Fault in Southern California and the spatial and temporal variations in slip history between 1992 and 2008 using ERS, and Envisat Satellite data confirming that the fault creep is confined within the sediments layer and is probably due to the low normal stress in unconsolidated sediments. Chapter 3 presents a study on triggered slip on faults in the Salton Trough by the 2010 El Mayor-Cucapah Mw 7.2 earthquake. Chapter 4 compiles geodetic data and investigates the relationship between shallow stress accumulating rate and creep rate. Chapter 5 and 6 explores two technical projects related to fault creep observations in California. Chapter 5 analyzes decorrelation of L-band and C-band interferograms in California with implications for future fault creep study. Chapter 6 proposes an optimal way to combine GPS and InSAR to measure interseismic deformation, including fault creep. The proposed method is compared with other method and the improvements are observed. Chapter 7 presents the conclusions of the previous six chapters. Chapter 8 presents my work in the first two years in graduate school, which is not related to fault creep. We compute global maps of surface minus basal heat flow that show qualitative agreement with heat flow based on the inverse square root of age relation. In the beginning of each chapter, I provide you an earthquake safety tip. I borrowed them from an interesting website for your safety and interests. Hopefully it could be one more motivation to read through my thesis. I didn't bother to invent them, as Ralph Waldo Emerson noted "All my best thoughts were stolen by the ancients."