D.L. Williams 1976 <p>Geothermal energy-from heat deep inside the Earth- is a vast potential source of power. This article is the second part of a series on geothermal energy, the first part of which was in volume 8, number 1, of the&nbsp;<i>Earthquake Information Bulletin</i> (January-February 1976). Part 1 of this series described the categories of the geothermal resource base.&nbsp;</p> application/pdf en U.S Geological Survey Geothermal energy in the United States; Part II, Assessment of resources article