Prediction and observation of strain waves in the Earth

The theoretical prediction of strain waves in the Earth is one of the most significant achievements in geophysics of the last third of the 20th century. Using the strain wave theory, the physical foundations were developed for the mathematical theory of strain wave propagation, and the search for methods that could detect the strain waves in experiment and simulation has commenced. This article provides an overview of the history of the strain wave theory and describes the observation methods, the main types of geological structures generating strain waves, and the properties of strain waves. It presents the most important results of the theoretical, laboratory and field studies of slow migration of strain. Future studies based on the strain wave theory may initiate a fundamental revision of the current concepts of the seismic process.