Pressure fluctuations on the open-ocean floor: Mid-Tasman Sea at 38°30′S., 162°38′E., near the Lord Howe rise

Abstract

A record, of 114 days duration, of pressure fluctuations on the floor of the Tasman Sea has been obtained from December 1983 to March 1984 at a site (38º 30′ S.,162º 38′ E.) near the Lord Howe Rise. The pressure fluctuations are due primarily to the ocean tides, and a first analysis of the record reveals clearly resolved open-ocean amplitude and phase values for four of the diurnal and semi-diurnal tidal components, namely Q₁, O₁, N₂ and M₂. Such observational results are important for comparison with global tidal models, and may allow their refinement, especially because tides in the seas around New Zealand are known to be complex. For the present site there is general agreement between the tidal results and the predictions of Schwiderski.

The pressure record also shows seismic signals from a strong earthquake that occurred on 7 February 1984 in the Solomon Islands, at a distance of approximately 3000 km from the pressure-record site. The detection of the seismic signals demonstrates the response and versatility of the pressure instrument used, and raises the possibility of its use in a different recording mode to study such seismic-generated pressure events more fully.