Seismic moment seismic moment tensor formula_8 (a symmetric tensor, but not necessarily a double couple tensor), the seismic moment is Seismic moment Seismic moment is a quantity used by seismologists to measure the size of an earthquake. The scalar seismic moment formula_1 is defined by the equation formula_2, where formula_1 thus has dimensions of torque, measured in newton meters. The connection between seismic moment and a torque is natural in the representation of seismic sources as a pair of force couples. Seismic moment is not a measure of energy. The relations between seismic moment, potential energy drop and radiated energy are indirect
Passive seismic have been also applied in another planets. For instance, during Apollo missions, the Passive Seismic Experiment sensors were deployed that detected lunar "moonquakes" and provided information about the internal structure of the Moon. Passive seismic is much less expensive than well drilling. It is also cheaper and more environmentally friendly than active seismic, which requires a strong source of the seismic waves (like an underground explosion) to predict the structure. In some cases it may be the only method for which land access is granted by the land owner. Despite the method having been successfully applied in many parts of