Dynamics of Rupture Barriers on Oceanic Transform Faults: Insights From the Westernmost Gofar Transform Fault

Abstract Oceanic transform faults (OTFs) accommodate plate motion largely by aseismic slip, with creeping patches arresting rupture of neighboring patches that have recurring moment magnitude 5.5–7.1 earthquakes. The structure and fault‐zone conditions of these barriers remain poorly constrained due to scarce offshore observations, leaving their role in the seismic cycle elusive. Here we use ocean‐bottom seismometer data and a machine‐learning‐enabled workflow to build two 1‐year microearthquake catalogs for the rupture barrier at the westernmost Gofar transform segment (G3) spanning December 2019 to March 2022, totaling more than 150,000 relocated earthquakes. The catalogs resolve four distinct seismicity patches on the barrier and reveal spatially variable fault zone architecture. Frequent, episodic swarms contain compact, migrating earthquake bursts, with some migrations following diffusion‐type time‐distance trends with apparent diffusivities of 2–10 /s. However, seismic burst migration speed scales with burst duration , , which is inconsistent with pure fluid‐diffusion or simple creep transients, implicating an interplay between both processes. Dilatancy likely regulates both creep transients and abundant microearthquakes during the interseismic period on damaged and fluid‐saturated barriers. In addition, dilatancy strengthening may halt large ruptures on adjacent asperities, maintaining a persistent barrier zone. The observed barrier dynamics provide a hydromechanical mechanism that may apply to other aseismic OTF segments globally, distinct from continental faults.