Structure and Morphology of an Active Conjugate Relay Zone, Messina Strait, Southern Italy

Abstract

The Messina Strait is a narrow fault-bounded marine basin that separates the Calabrian peninsula from Sicily in southern Italy. It sits in a seismically active region where normal fault scarps and raised Quaternary marine terraces record ongoing extension driven by southeastward rollback of the Calabrian subduction zone. A review of published studies and new data shows that normal faults in the Messina Strait region define a conjugate relay zone where displacement is transferred along-strike from NW-dipping normal faults in the northeast (southern Calabria) to the SE-dipping Messina-Taormina normal fault in the southwest (offshore eastern Sicily). The narrow marine constriction of the Messina Strait is a graben undergoing active subsidence within the relay zone. Pronounced curvature of normal faults near their tips results from large strain gradients and clockwise rotations related to fault interactions. Based on regional fault geometries and published age constraints, we propose a model for northwest (oceanward) migration of normal faults in southern Calabria during the past ~2–2.5 Myr in response to rapid crustal extension at the southeast margin of the Tyrrhenian Sea.

QUIN 2.0 - new release of the QUaternary fault strain INdicators database from the Southern Apennines of Italy

“…We opted not to utilize the DISS database ( https://diss.ingv.it/ ) for QUIN host faults, as it serves different applications and lacks the requisite details for our specific purposes. We derived the age of the fault-systems’ activity from the geological literature 3 , 28 , 35 , 38 , 62 , 63 , 65 , 98 – 109 and from the evidence of earthquake activity in historical and instrumental times 27 , 110 .…”