Seismic fluids and percolation theory

Abstract

Presents a first attempt at a quantitative assessment of seismic fluid flux. It is assumed that during an earthquake, slipped regions experience transient high permeability, high porosity, and high pressure gradients, which rapidly redistribute fluid. Percolation theory is used to model the size distribution of such slip planes. Interseismic fluid migration along background pressure gradients is ignored. To render the problem tractable, a number of assumptions are made regarding fluid movement: fluid is transported from a well supplied reservoir across the fault plane to an efficient sink; the system reaches steady state with a linear fluid concentration function across the fault. Using probability methods, we obtain a simple relation between fluid flux, slip rate, and fracture porosity. It is then a straightforward matter to calculate the total seismic fluid throughput for a region. Such estimates agree well with water/rock ratio and other data. -Authors