GOFAR
Pore fluid dynamics at Gofar quasi-periodic earthquakes transform fault system
PI: R. L. Evans (WHOI)
Postdoctoral Investigator: C. Chesley (WHOI)
Ph.D. student: B. L. Fluegel (MIT-WHOI joint program)
Collaborators: E. Attias, D. Sherman (UTIG's OCEEMlab)
Gofar's oceanic transform faults (OTFs) at the East Pacific Rise (EPR) demonstrate quasi-periodic Mw ∼6 earthquakes along two rupture segments separated by a barrier zone. This barrier zone is assumed to result from extensive fault damage, higher fluid availability, or increased pore pressure. However, previous studies of these OFTs neglected the potential contribution of processes (e.g., melt, geothermal activity) occurring adjacent to Gofar's major fault axis.
In this GOFAR project, we aim to study the evolution of stress, deformation, and pore fluid behavior along the Gofar OTF system located along the EPR. During a six-week cruise in early 2022, we collected seafloor MT/CSEM and towed receiver CSEM data along five towlines across the Gofar system. Two-dimensional CSEM inversion models will image the subsurface electrical resistivity from which we derive the porosity of the crust. By mapping porosity variations throughout the Gofar damage zone of primary seismicity and a barrier zone that inhibits rupture propagation, we can better understand the role of fluids in Gofar’s quasi-periodic seismic cycle.
PROJECT STATUS
-
The ocean-bottom electromagnetic (OBEM) receiver results were published in Chesley et al., (2025) in Science Advances.
-
Preliminary results of the deep-towed CSEM receiver data were presented at the AGU Fall Meeting 2024.
* NSF grant OCE-192252 supports this project
COLLABORATORS
GOFAR
Cruise area: Gofar Transform Fault, EPR
Cruise dates: January–March 2022 (42 days)
NSF cruise number: TN-399
Ship spec: R/V Thomas G. Thompson
Ship current location: MarineTraffic
Ship MMSI: 366345000