Long-term fault growth involves the dynamic evolution of fault zone architecture, structural maturity, and physical properties. Accurate characterization of these features is essential for improved understanding of fault mechanics, rupture dynamics and earthquake hazard. Fault structural maturity has traditionally been quantified via analysis of geological features. Nonetheless, the manifestations of an incipient fault are still poorly known, partly due to a lack of fault outcrops and limited diagnostic characteristics of this type of fault. In this study, we integrate coseismic and postseismic geodetic (InSAR/GPS) observations, relocated aftershocks, optical satellite imagery, and field measurements to characterize the fault kinematics of the May 21 2001 Mw7.4 Maduo earthquake, which occurred on an immature fault. Using relocated aftershocks, we determine the fault damage zone thickness and damage density decay at a comparable resolution with field geological investigations. We analyze surface inelastic strain along the rupture using both InSAR and optical images. We construct a buried slip model and refine the coseismic slip distribution to determine a shallow slip deficit, which we attribute to off-fault deformation. We also examine the afterslip distribution and moment release following the earthquake to probe its relationship with coseismic rupture. All pieces of evidence point to the dominant role of immaturity of the fault hosting the Maduo earthquake. Our study demonstrates that the combined analysis of seismological data, geodetic observations and field measurements helps to comprehensively characterize fault structural maturity and to better understand the role of single earthquakes in the long-term fault zone evolution.