We summarize our major findings of studying earthquakes and volcanoes using geodetic and remote sensing data. In terms of earthquake cycle study, we combine 20 years InSAR data with GPS data to obtain a high spatial and temporal coverage of ground deformation of the north San Francisco Bay Area. We observe the detailed spatial variations of strain accumulation and creep on major faults in the North Bay. We generate a complete 3D coseismic displacement map of the 2016 Mw 7.8 Kaikoura earthquake, New Zealand. The complex ground deformation around the Papatea fault is successfully explained by slip on a simple fault geometry, without appealing to off-fault anelastic deformation. The rupture process across multiple faults likely resulted from a triggering cascade between crustal faults, and slip on the subduction interface is not required to link the rupture. We perform a joint slip inversion of postseismic GPS and InSAR data to better understand the distribution of aftershocks associated with the 2015 Mw 8.4 Illapel earthquake. We find that aseismic afterslip on the subduction thrust surrounding the coseismic rupture is an important triggering mechanism of aftershocks. In the study of volcanos, we focus on our study of active volcanos in the southern Red Sea spreading center. Through analysis of a series of high-resolution optical images and InSAR data covering two eruptions in the Zubair archipelago (Red Sea) in 2011 and 2013, we find that the eruptions were fed by dikes much larger than the small size of the new islands might suggest. Using similar methods, we infer the shape and orientation of the conduits feeding the 2017 Erta Ale eruption and storing magma during the correspondent pre-eruptive inflation phase. We show that the magma system of Erta Ale is interconnected. Together with several seismic swarms, these recent eruptions indicate that the southern Red Sea spreading center has been experiencing a rifting episode with multiple diking events and meter-scale extension and show that this plate boundary is more active than previously thought.