Introduction to Special Section: Mechanical Involvement of Fluids in Faulting

摘要: A growing body of evidence suggests that fluids are intimately linked to a variety faulting processes. These include the long term structural and compositional evolution fault zones; creep; nucleation, propagation, arrest, recurrence earthquake ruptures. Besides widely recognized physical role fluid pressures in controlling strength crustal zones, it is also apparent can exert mechanical influence through chemical effects. The United States Geological Survey sponsored Conference on Mechanical Effects Fluids Faulting under auspices National Earthquake Hazards Reduction Program at Fish Camp, California, from June 6 10, 1993. The purpose conference was draw together evaluate disparate for involvement faulting; establish communication importance mechanics between different disciplines concerned with zone processes; help define future critical investigations, experiments, observational procedures evaluating faulting. This drew diverse group 45 scientists, expertise electrical magnetic methods, geochemistry, hydrology, ore deposits, rock mechanics, seismology, geology. Some outstanding questions addressed this workshop included following: 1. What levels within seismically active zones? Do they remain hydrostatic throughout full depth extent seismogenic regime, or generally superhydrostatic depths excess few kilometers? 2. Are zones constant an cycle, time-dependent? spatial variability pressures? 3. overall process stress accumulation, release, transfer during cycle? Through what mechanisms might pressure act control processes rupture arrest? 4. facilitating creep, including their aiding solid-state creep brittle fracture solution-transport deformation mechanisms? 5. effects aqueous constitutive response, fractional stability, long-term strength? 6. compositions properties faultfluids levels? 7. by which porosity permeability either created destroyed middle lower crust? factors rates these processes? How should be incorporated into models time-dependent transport zones? 8. roles do faults play distributing crust altering domains? In other words, when aid inhibit migration? typical fluid/rock ratios, flow rates, discharges acting as conduits? 9. present subseismogenic crust, transformation and/or shallower portions faults?