Surface Horizontal Displacement Research Articles

A dislocation model for the Fairview Peak, Nevada, earthquake

abstract Maruyama's equations have been used to calculate both vertical and horizontal surface displacements for a Volterra dislocation in a uniform half space. The shape of the dislocation surface is assumed to be a plane rectangle. A least-squares procedure has been used to determine the dislocation surface which best fits the geodetic data for the Fairview Peak, Nevada, earthquake of December 16, 1954. The best model strikes N9°E, has a total length of 50 km, a width of 8. ± 2. km, a dip of 57° ± 6°, and a fault displacement of 2.3 ± 0.4 m normal dip slip and 2.9 ± 0.4 m dextral strike slip. The width of the model is probably somewhat less than the true width of the fault, but the other parameters appear to be quite reasonable. The N9°E strike of the model is thought to be more realistic than the N4°W to N11°W strikes indicated by nodal-plane solutions. It appears that the Dixie Valley earthquake of December 16, 1954 was associated with normal slip on a fault plane parallel to, but offset from, the fault plane of the Fairview Peak earthquake.

Exact transient solution of the buried line source problem

The disturbance due to a line source buried within an elastic, homogeneous and isotropic half-space represents a most interesting problem of theoretical seismology. Exact formal solutions have been published by a number of investigators, but the integrals which appeared in their solutions could be evaluated only approximately at large distances from the source. As a result, the behaviour at intermediate distances or close to the epicentre could not be investigated analytically. This paper discusses a different approach to the problem. It is shown that the use of Laplace transform techniques and of a suitable contour in the complex plane reduce the complexity of the problem to a point where no integration is required. The surface displacements as a function of time and position are found to be expressible in terms of algebraic functions in closed form. The case of a source displacement consisting of a sudden rise followed by a gradual recovery is considered in detail. Graphs are presented which show the vertical and horizontal surface displacement as a function of time, at different distances from the epicentre and for different values of Poisson’s ratio.