Hydraulic Fracturing

In hydraulic fracturing, better known to the public as “fracking,” a mix of water, proponents, and chemicals is injected at high pressures into subsurface rocks containing hydrocarbons, with the aim of creating small fractures to facilitate the extraction of gas or oil. Within the last few years, hydraulic fracturing has become an increasingly important topic discussed by the media, politicians, and scientists. This interest is not only due to the economic benefit of extracting natural resources from previously inaccessible geological formations, but also to its huge environmental impacts. The injection of water into the subsurface changes fluid pressure and stress at depth, and it can cause the surface to deform and sometimes induces earthquakes. Other impacts include the emission of greenhouse gases measurable even years after depletion of a well. This chapter gives an overview of hydraulic fracturing, its environmental consequences, and how remote sensing methods can be used to contribute to monitoring and hazard mitigation. The purpose of the present chapter is neither to discuss the advantages and disadvantages of hydraulic fracturing, nor is it meant to give a rating of the technique. Instead, it serves as an overview of the possible environmental impacts of hydraulic fracturing and how remote sensing techniques can be used to monitor and assess those impacts and the associated geological hazards.