From 2005 Penrose Conference:

Use of elasticity theory to model structures beneath Mammoth Mountain, CA
G. Hughes, D. Pollard, G. Mahood

In 1989-1990 earthquake swarms beneath Mammoth Mountain accompanied a possible dike intrusion (Hill et al 1990; Langbein et al 1993, 1995; Prejean et al 2003) and the possible activation of normal slip on a ring-like structure at depth (Prejean et al 2003). Models based on these proposed structures and constrained by geological data, were constructed in Poly3D, a modeling program based on elasticity theory, in order to investigate surface deformation resulting from dike intrusion and fault slip. Models were evaluated by a comparison of the calculated surface deformation with the 1988-1992 leveling data presented in Lanbein et al 1995.
The preliminary results of this study suggest that a 1 m width dike aligned with the plane of seismicity suggested by Prejean et al (2003) would not produce the required surface deformation. Thus a longer and shallower aseismic extension of the plane, similar to Langbein et al’s 1995 formulation might be necessary to explain surface deformation at the centimeter scale. Additionally, a model of the ring-fault showed that 1 cm of normal slip caused negligible deformation.