Book excerpt: This book is intended to, firstly evaluate the present relative seismicity of various parts of the earth, and secondly to discuss the geography and the geological character of the zones and areas of seismic activity. This includes correlation with alignments of active volcanoes and gravity anomalies, and with oceanic deeps, mountain structures, and other topographic features. Mechanism is discussed, particularly with reference to the crust folding and block faulting.