Seismic properties of the Eltanin Transform System, South Pacific
Abstract
We present a compilation of the seismic properties of the Eltanin Transform Fault (TF) system, compelled by the recent discovery of the Hollister Ridge and the possibility of a change of plate kinematics pattern in the region. The Hollister Ridge is a major volcanic system located on the Western flank of the Pacific-Antarctic Ridge (PAR), immediately south of the Eltanin Fracture Zones (FZs). We find or confirm two anomalous characteristics: the occurrence of seven normal faulting events on the transform segments, expressing extension across the plate boundary in the azimuth N26°W, and more than 90% deficiency in the seismic moment released during strike-slip events on the transforms, as compared to the rate expected from kinematic models. Other seismic properties are typical of the seismicity of a fast-spreading mid-ocean ridge (MOR) system. In particular, we could not document a single teleseismically recorded event on the Hollister Ridge; earthquakes are confined to narrow TFs with no activity present on the ridge segments. The transform events have regular frequency-moment statistics, and we could not document any significantly slow sources. These seismic properties generally support conventional plate tectonics models such as NUVEL-1, and cannot be reconciled with a proposed reorientation of the Pacific plate 4 Ma ago.
- Publication:
-
Physics of the Earth and Planetary Interiors
- Pub Date:
- May 2000
- DOI:
- 10.1016/S0031-9201(99)00169-7
- Bibcode:
- 2000PEPI..119..185O