Active crustal straining and fault reactivation at Valles Marineris.

Seismic evidence shows that inherited faults in Valles Marineris on Mars can be reactivated after billions of years, involving strike-slip faulting in the deep crust.

• Why it matters: Understanding whether ancient tectonic fabrics can still generate seismic failure under current stress is crucial for insights into Mars's geological activity and planetary evolution.
• What they did: The study analyzed a marsquake detected by InSight in the western hemisphere, using the focal mechanism to infer stress orientation and fault reactivation in Valles Marineris.
• The result: Findings suggest that pre-existing fault systems remain mechanically favorable for reactivation over billion-year timescales, indicating long-term strain release via slip on deeply rooted faults.