Showing papers by "Donald J. Weidner published in 1978"
TL;DR: In this article, the elastic constants of orthoenstatite have been determined from Brillouin-scattering measurements, and they are c 11 = 2.247, c 22 = 1.527, c 31 = 0.541 and c 12 = 0.724 Mbar.
167 citations
01 Aug 1978
TL;DR: The elastic constants of andalusite and sillimanite have been determined using the technique of Brillouin scattering as discussed by the authors, and they are characterized by chains of edge-linked coordination octahedra extending parallel to the crystallographic c direction, crosslinked by polyhedra of lower coordination.
Abstract: The nine elastic constants of andalusite and sillimanite have been determined, using the technique of Brillouin scattering. They are, in megabars, for andalusite: c11=2.334, c22=2.890, c33=3.801, c44=0.995, c55=0.878, c66=1.123, c23=0.977, c13=1.162, c12=0.814; for sillimanite: c11=2.873, c22=2.319, c33=3.884, c44=1.224, c55=0.807, c66=0.893, c23=1.586, c13=0.834, c12=0.947. Both structures are characterized by chains of edge-linked coordination octahedra extending parallel to the crystallographic c direction, cross-linked by polyhedra of lower coordination. In each structure the stiffness measured parallel to c is greater than that measured normal to c. The shear moduli can be directly correlated with the relative rigidity of the cross-linking structures.
131 citations
TL;DR: In this paper, the focal mechanism and depth of a small intra-Caribbean plate earthquake have been determined using observed Rayleigh wave signals, which yields the best fit to both the surface wave data and the body wave data, with the compression axis trending approximately NW-SE.
Abstract: The focal mechanism and depth of a small yet tectonically important, intra-Caribbean plate earthquake have been determined using observed Rayleigh wave signals. This earthquake occurred on August 14, 1972 and is believed to be the first known hypocenter in this area of the Caribbean Sea; about 330 kilometers from any previous event. Thus, the source mechanism of this earthquake should yield important information about the stresses in the interior of the Caribbean plate. Only about 5 reliable P-wave first motions were recorded at WWSSN stations, due to the low magnitude (M b = 4.7) of this earthquake. Therefore, the focal mechanism of this event can not be determined from the body wave data alone. Nonetheless, coherent surface wave trains were recorded as far away as 7,000 kilometers. The deduced mechanism is obtained from a comparison of the observed Rayleigh wave phase from this earthquake with that of a master event (September 13, 1971: M b = 5.7) located along the northern boundary of the Caribbean plate. The mechanism which yields the best fit to both the surface wave data and the body wave data is of the strike–slip type, with the compression axis trending approximately NW–SE.
2 citations