Along‐strike variation of fault slip rate of a transform plate boundary in Tierra del Fuego (South Patagonia)

Abstract

The Magallanes–Fagnano Fault is an active strike‐slip structure accommodating the relative displacement between South America and the Scotia Plate. The Chilean portion of the fault is poorly studied because most of it runs below the sea level in the Strait of Magellan. Our tectonic geomorphological study is focused on a rare onshore fault section, along which streams horizontally deflected by hundreds of metres since the last main deglaciation are compatible with a dominant left‐lateral fault kinematics and yield a slip rate of 15.7 ± 2.4 mm/year. This rate is between 2 and 3 times higher than the one estimated on the Argentinian portion of the fault over the same period. This spatial variation may be due to both glacial unloading on the fault zone and/or structural factors. These results point out the need to study strike‐slip faults on several portions to unravel behaviour changes related to internal or external forcing.