Variation in fracture zone rigidity by dynamic effects

Abstract

The coefficient of normal rigidity of different-order fault zones was evaluated from seismic data. The crust tectonic faults were shown to be dynamic systems and nonstatic. Specifically, this is manifested in the variability of their rigidity with time. The value of the rigidity of fault zones varies in time with periods of 13–15 days, 27–32 days, and around 1 year. Here, the coefficient of normal rigidity of different-order fault zones can vary by 1.3 (semimonthly variations) 1.5 (monthly variations), and 2.5 times (annual variations), respectively. These variations are most likely governed by the rate and intensity of the transformation of matter of fault zones and, as a consequence, the variations in their mechanical properties under tidal conditions. Dynamic effects like seismoexplosive waves lead to a reduction in the rigidity of fault zones by 5–50% depending on the amplitude of the compression wave.