NOTE CONCERNING NON-DOUBLE-COUPLE SOURCE COMPONENTS FROM SLIP ALONG SURFACES OF REVOLUTION

One suggested explanation for the origin of deviatoric, non-double-couple earthquake sources is that there is slip along curved fault surfaces. Here the moment tensor components are computed for earthquakes along idealized faults which are surfaces of revolution. The calculations show that when the slip direction is around the axis of revolution, the earthquakes may possess purely double-couple sources, or purely compensated linear vector dipole (CLVD) sources, depending on the geometry of the fault and the slip. However, a surprising result is that the CLVD component is always zero for unidirectional slip along surfaces having a suitable degree of symmetry. Thus, slip along a large variety of simple and plausible curved fault geometries produces a purely double-couple source. -Author