Micro-earthquake seismicity of the Mid-Atlantic ridge at 5° S: a different style of tectonic extension
Abstract
Based on an ocean-bottom micro-earthquake survey of the Mid-Atlantic ridge just south of the 5° S transform fault/fracture zone, we find seismic activity to be concentrated within the western half of the median valley. The median valley seismic zone is bounded in along-axis direction by the transform faults to the north, and the tip of the axial volcanic ridge to the south. A few scattered events occurred within the inside corner high, on the transform fault, and in the western side wall close to the segment center. Earthquakes reach a maximum depth of 8 km below the median valley floor and appear to be predominantly in the mantle although a few crustal earthquakes also occurred. The presence of earthquakes in the mantle indicates it is not extensively serpentinized. We infer the median valley seismic activity to arise from slip on two parallel low-angle normal faults which dip from the inside corner toward the spreading axis.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2003
- Bibcode:
- 2003AGUFM.T12D0501T
- Keywords:
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- 3035 Midocean ridge processes;
- 7230 Seismicity and seismotectonics;
- 9325 Atlantic Ocean