ausblenden:
Schlagwörter:
Strike-slip fault · Stress-fault angle · Analogue model · Near-field stress reorientation · Fault activation
Zusammenfassung:
The evolution of the local stress field of faults under tectonic stresses is crucial to predict earthquakes. In this study, we investigated
the stress sensitivity of an analogue fault model with dimensions of 2 m × 1 m × 1 m, prepared from cement, gypsum, river
sand, putty powder, and borax mixture. The angle between the fault strike and the maximum stress direction was varied, and the
variation in the stress near the analogue fault (area 1200 × 400 mm; width 5 mm) was determined. The crack growth law of the
analogue fault was found to be consistent with a simple Riedel shear model. A main strike-displacement zone was formed, and
its direction was parallel to that of the analogue fault. Fault development was described by three stages based on stress–strain
relationships: a nucleus stage, a stable growth, and an unstable growth stage. The deflection angle (the deflection angle of the
local principal stresses) range of the local stress field was (− 45°, 45°), and it varied most significantly in the nucleus stage. The
closer to the fault, the greater the variation range in the deflection angle. The variation range was greater in the fault compression
quadrants than in the dilatation quadrants. The correlation between the deflection angle and the relative deformation velocity of
the fault was stronger in the stable growth stage than in the other stages. In this stage, the angle–deformation–velocity correlation
could be well fitted using a logistic trend model. These findings can be of importance to better understand the nucleation and
mechanisms of fault slip-induced earthquakes under varying fault-strike-stress conditions.
