Objective:

To investigate the role of naturally occurring graphene oxide in reducing friction along the Atotsugawa Fault System.

Key Findings:

• Graphene oxide was identified as a potential ultra-low-friction phase in the fault gouge.
• The fault gouge contained graphene oxide-like carbonaceous material rather than graphite alone.
• Oxygen-bearing functional groups, particularly hydroxyl groups, were abundant in the material.
• Single-layer graphene oxide was confirmed in microcracks of the gouge.
• Graphene oxide has a lower friction coefficient than graphite or most rock-forming minerals.

Interpretation:

The presence of graphene oxide may explain the low seismicity and aseismic creep observed in the Atotsugawa Fault System.

Limitations:

Conclusion:

The formation of graphene oxide in faults could provide insights into earthquake behavior and fault evolution.