Is the seismic moment tensor ambiguous at a material interface?

0394892 - GFÚ 2014 RIV GB eng J - Journal Article
Vavryčuk, Václav
Is the seismic moment tensor ambiguous at a material interface?
Geophysical Journal International. Roč. 194, č. 1 (2013), s. 395-400. ISSN 0956-540X. E-ISSN 1365-246X
R&D Projects: GA ČR(CZ) GAP210/12/1491
EU Projects: European Commission(XE) 230669 - AIM
Institutional support: RVO:67985530
Keywords : earthquake dynamics * earthquake source observations * body waves * seismic anisotropy * dynamics and mechanics of faulting
Subject RIV: DC - Siesmology, Volcanology, Earth Structure
Impact factor: 2.724, year: 2013

The moment tensors are unique and describe the body force equivalents of rupture processes in any medium including faulting at a material interface, defined as the contact of two media with non-zero velocity or density contrasts. From a practical point of view, however, the moment tensor inversion of sources near or at a material interface is more involved than if the medium is smooth in the source area. First, the moment tensors of sources characterized by the same displacement discontinuity display jumps when the source crosses the interface. Consequently, the moment tensors become sensitive to the source location. If the source lies near the interface, the location into an incorrect half-space can introduce errors in the moment tensor. Second, if the source lies at the material interface, some of the spatial derivatives of the Green's function are, in general, discontinuous and the radiated wave field must be calculated using a generalized representation theorem. Third, the moment tensors are functions of averaged elastic parameters known from effective medium theory.
Permanent Link: http://hdl.handle.net/11104/0223054