Reactivation potential of inherited structures on southwestern Grand Banks, Newfoundland, Canada

Abstract

The November 18, 1929, M 7.2 Grand Banks earthquake occurred in the Laurentian Channel near the crest of the continental slope off the eastern coast of Canada. This seismic event, followed by a tsunamigenic landslide, is the largest instrumentally recorded earthquake that has occurred in the region. The event led to 28 confirmed casualties and significant destruction of critical commercial infrastructure and operations, including trans-Atlantic telecommunications cables and coastal facilities serving communities in southern Newfoundland. Despite the significance of this event, there is a limited understanding of the structural setting and neotectonics of the region. Imaging deep structures where the earthquake likely occurred is challenging, but shallow rift-related structures, influenced by deeper faults through structural inheritance, offer valuable insights into this deeper system. Here, we apply this concept through the analysis and interpretation of key regional faults on two-dimensional offshore seismic reflection data. Then, using slip tendency analysis, the reactivation potential of these structures under the present-day stress field was calculated. The analysis shows that regional NW-SE-striking normal faults, dipping at 40°– 60°, have high slip tendency values, offering insights into potentially active fault locations and geometries that support seismic hazard assessment and earthquake scenario modeling to assess impacts on populations and assets in southern Newfoundland.