Geophysicists study the physical aspects of the earth using a range of methods, including gravity, magnetic, electrical, and seismic. Although many geophysicists work for extractive industries (e.g. oil and gas or mining companies which have high environmental impacts and are common sources of workers’ rights problems, especially in developing countries), there are other opportunities in more responsible roles such as research and management of natural geological hazards (e.g. volcanoes, earthquakes and landslides). Environmental consultants may use geophysical techniques to investigate sites for waste disposal, water resource management, archaeology or construction.