Accurate Three Dimensional Calculations for Advancing Slip Zones in the Earth's Crust

将一种精确、有效的弹性固体裂纹三维分析方法应用于地壳准静力推进滑动带的研究。计算是为了确定应力和地表变形，这是由于剪切断层进入或围绕锁定或更有抵抗力的浅层地壳部分而造成的。特别令人感兴趣的是前进锋面的非均匀性不稳定的条件，因为它们会引起滑动的快速自发传播，以及可以区分小地震和大地震的条件。这些计算也使得将地表变形的测量与地震活动性的增加联系起来成为可能，地震活动性可能是由伴随滑动带前进的应力升高引起的。其他考虑的影响是在自由表面爆发的可能性，以及由于自由表面的存在而产生的法向应力和剪应力的耦合。最初的研究将是走滑几何，以便可能应用于南加州帕克菲尔德地区，但该方法的多功能性也允许研究逆冲断层。

An accurate and efficient method for the three-dimensional analysis of cracks in elastic solids is applied to the study of quasi-statically advancing slip zones in the earth's crust. Calculations are done to determine stresses and surface deformations due to the advance of shear faults into and around locked, or more resistant, portions of the shallow crust. Of particular interest are conditions for which non-uniformities in the advancing front are unstable, in the sense that they give rise to rapid spontaneous propagation of slip, and conditions that may distinguish small from large earthquakes. These calculations also make it possible to relate measurements of surface deformation to increases in seismicity that may be triggered by the elevation of stresses that accompanies slip zone advance. Other effects considered are the possibility of breakout at the free surface and the coupling of normal and shear stress due to the presence of the free surface. Initial studies will be for strike-slip geometries for possible application to the Parkfield region of southern California, but the versatility of the method allows study of thrust-faults, as well.