Geomorphological, sedimentological and structural signals of deformation in a silent subduction zone: an investigation of the Makran (Iran)

Abstract

The Makran subduction zone of southeastern Iran has not experienced a megathrust earthquake in recent history, yet, the presence of uplifted coastal morphologies indicate that the margin is still tectonically active. In this work, we study three types of geological signals of deformation that might be linked to the occurrence of large earthquakes in this region. Makran marine terraces have unique morphologies and sedimentary successions. Their mapping and dating allowed us to calculate Late Pleistocene uplift rate variations along the coast. Recent vertical displacements associated with large earthquakes are investigated into the sedimentary succession of low-lying Holocene bay beaches. Finally, we speculate that the normal faults observed along the coast, in an apparently compressive tectonic context, might be linked to post-seismic relaxation following great subduction earthquakes. Although the western Makran is seemingly aseismic for the last 500 years, geological evidences suggests that large events might have happened in the past