Seismic moment 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 and approximative. The seismic moment of an earthquake is typically estimated using whatever information is available to constrain
Seismic array analyst's work. However, to obtain automatic time picks and thereby provide a slowness estimate automatically, techniques like cross-correlation or just picking of peak amplitude within a time window may be used. Because of the amount of required computations, plane wave fitting is most effective for arrays with a smaller number of sites or for subarray configurations. Current seismic arrays worldwide: YKA or Yellowknife Seismological Array is a medium size seismic array established near Yellowknife in the Northwest Territories, Canada, in 1962, in cooperative agreement between the Department of Mines and Technical Surveys (now Natural Resources Canada) and the United Kingdom