Name
PACSAFE LEG2: Investigating Seismicity of the Queen Charlotte Fault Offshore Haida Gwaii Using a Year-Long OBS Deployment
Date & Time
Tuesday, May 26, 2026, 11:30 AM - 11:45 AM
Description
The Pacific Coast Seismic Assessment for Faults and Earthquakes (PACSAFE) multi-year OBS program aims to investigate the earthquake hazards offshore BC, with the goal of improving the characterization of seismicity and fault structure in the region. This study examines data from the second leg of the PACSAFE program (LEG2), in which 23 OBS were deployed in the northern segment of the Queen Charlotte Triple Junction, mainly covering the region between the Revere–Dellwood Fault Extension (RDFE) and the south end of the Queen Charlotte Fault (QCF/paleo-QCF), for a year-period (July 2024–Aug 2025). We applied OBSTransformer, a deep learning–based phase picker and only retained high-quality picks (probability ≥ 0.3) for phase association, yielding 17,500 events. We subsequently conducted both absolute and relative earthquake relocations, producing a final seismicity catalog containing over 14,000 relocated events with depths predominantly shallower than 20 km, but extending to ~40 km offshore southern Haida Gwaii. The abundance of earthquakes with high-resolution locations clearly delineates the detailed active fault structure of the region. Lineated seismicity is observed along the RDFE rather than the QCF or paleo-QCF, with a major conjugate shear zone connecting the RDFE to the QCF/paleo-QCF that accommodates most earthquakes observed during the study period, including the aftershocks of the recent 2024 M 6.5 earthquake, whose mainshock hypocenter is located at the intersection of the Tuzo–Wilson Volcanic Field and the QCF. Through further seismological analyses and multidisciplinary integration, the research team anticipates gaining a better understanding of deformation mechanisms and associated seismic hazards in the region.
Location Name
Marion McCaine - Ondaatje Hall
Full Address
Dalhousie University
Halifax NS
Canada
Halifax NS
Canada
Session Type
Oral Presentation
Abstract ID
271
Speaker Organization
Dalhouise University
Session Name
S2 (1 of 2)
Co-authors
Adnan Barkat1, Miao Zhang1, Mladen Nedimović1, Alexandre Plourde2, Andrew J Schaeffer3, Tiegan E Hobbs4, Tianhaozhe Sun3, Graeme Cairns1, Katie Bosman1, John Thibodeau1, Michael G Bostock5, Edwin Nissen6, Simon Peacock5, Honn Kao3, Kelin Wang3, Kristin Rohr3, Gwyn Lintern3
1Department of Earth and Environmental Sciences, Dalhousie University, Halifax, Canada
2Natural Resources Canada / GSC-Atlantic
3Natural Resources Canada / GSC-Pacific
4Natural Resources Canada / GSC-Vancouver
5Earth, Ocean and Atmospheric Sciences, University of British Columbia
6School of Earth and Ocean Sciences, University of Victoria
Presenting Author
Adnan Barkat, Earth and Environmental Sciences, Dalhouise Univeristy