Geophysical monitoring for geologic carbon storage This monograph covers the state of the art geophysical techniques for monitoring CO2 storage within subsurface geologic formations such as oil fields gas fields saline formations unmineable coal seams and saline filled basalt formations. Geophysical monitoring techniques exploit geophysical signals from CO2 reservoirs or target monitoring regions such as potential leakage paths to inform where the CO2 plume is and how the integrity of cap rock seals are. These signals can be from passive sources or active sources. Geophysical monitoring employs sensors in boreholes or on the Earths surface or above the Earths surface to acquire geophysical signals. Geophysical monitoring is to use these information to infer the movement and the fate of injected CO2 within three dimensional subsurface. Most geophysical monitoring techniques are non invasive and are to detect subsurface changes caused by CO2 movement in kilometers away from the sensors. High resolution and high fidelity geophysical monitoring techniques are necessary to ensure safe and long term geologic carbon storage. In addition this monograph also provides some applications of geophysical monitoring techniques at a number of large scale field demonstration projects. These applications demonstrate the practical capabilities of geophysical monitoring techniques.