Seismicity trends and detachment fault structure at 13°N, Mid-Atlantic Ridge

Research output: Contribution to journalArticlepeer-review

Authors

  • R. Parnell-Turner
  • R. A. Sohn
  • C. Peirce
  • C. J. MacLeod
  • R. C. Searle
  • N. M. Simão

Colleges, School and Institutes

External organisations

  • Scripps Institution of Oceanography
  • Woods Hole Oceanographic Institution
  • Durham University
  • Cardiff University

Abstract

At slow-spreading ridges, plate separation is commonly partly accommodated by slip on long-lived detachment faults, exposing upper mantle and lower crustal rocks on the seafloor. However, the mechanics of this process, the subsurface structure, and the interaction of these faults remain largely unknown. We report the results of a network of 56 ocean-bottom seismographs (OBSs), deployed in 2016 at the Mid-Atlantic Ridge near 13°N, that provided dense spatial coverage of two adjacent detachment faults and the intervening ridge axis. Although both detachments exhibited high levels of seismicity, they are separated by an ∼8-km-wide aseismic zone, indicating that they are mechanically decoupled. A linear band of seismic activity, possibly indicating magmatism, crosscuts the 13°30′N domed detachment surface, confirming previous evidence for fault abandonment. Farther south, where the 2016 OBS network spatially overlapped with a similar survey done in 2014, significant changes in the patterns of seismicity between these surveys are observed. These changes suggest that oceanic detachments undergo previously unobserved cycles of stress accumulation and release as plate spreading is accommodated.

Bibliographic note

Funding Information: This work was funded by UK Natural Environmental Research Council (NERC) grants NE/J02029X/1, NE/J022551/1, and NE/J021741/1 and by U.S. National Science Foundation grants OCE-1458084 and OCE-1839727. OBSs were provided by NERC UK Ocean-Bottom Instrumentation Facility (Minshull et al., 2005). We thank all those involved with the data acquisition, and I. Grevemeyer and two anonymous reviewers for their helpful input. Publisher Copyright: © 2020 The Authors.

Details

Original languageEnglish
Pages (from-to)320-324
Number of pages5
JournalGeology
Volume49
Issue number3
Early online date4 Nov 2020
Publication statusPublished - Mar 2021

ASJC Scopus subject areas