Using rate-and-state friction constitutive laws to predict seismicity rates for ice rifts on the Ross Ice Shelf in Antarctica

• Seismicity along ice rifts is modulated with oscillatory stress rate. • Rate-and-state friction law can explain tidally driven icequakes. • Maturity of ice rifts influences their seismic response to stress. • Characteristic time of seismicity increases with ice rift strength. Determining what fault characteristics and applied stress conditions modulate the occurrence of seismicity is a key question in the field of seismology. Here we analyze the seismicity measured at two ice shelf rift zones of different maturity in the Ross Ice Shelf, which are subjected to long-term dilatational stress modulated by tidal stress variations. We analyze the periodicity of the seismicity and its relationship to tidal stress variations and find that the seismicity rate at both rifts is controlled by tidal stress rate variations. We compare the observed icequake occurrence times with analytical predictions from rate-and-state friction constitutive laws that have been used to model frictional behavior on terrestrial faults. We find that seismicity rate is predicted well by an analytical model based on rate-and-state friction, confirming that it can be used to understand ice rift seismicity. We constrain for the first time the characteristic time of seismicity rate, t a , for both rifts, and find that ice rifts have a faster recovery time than continental faults, and that their responses to stress and characteristic times are age dependent. This implies that the strength of the rift changes with time and determines the amount of stress or stress rate dependency of the system. Our results can be used to understand seismicity occurrence across other ice rifts in Antarctica and Greenland and holds implications for seismicity on icy satellites.