Cruise report, Hawaiian GLORIA legs 3 and 4 F3-88-HW and F4-88-HW

Abstract

This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 1. 071/1930 Depart Hilo, Hawaii. 2. 071/2020 Slow to deploy the 3.5-and 10-kHz tow vehicles. Equipment problems delay deployment of remaining gear until 072/0413. 3. 072/0948 Begin pass 1 on logging GLORIA with normal underway watchkeeping; all gear deployed and operational, if not ideally so (see Equipment Review). As each system came on line, logging started to allow the temporary watchstanders to become familiar with underway procedures. 4. 072/1030 End line "0" to begin official survey. Start line 1, a northerly traverse across several lines from F5-86-HW toward the endpoint of that survey to finish the outer part of the EEZ area and to provide further navigational constraints for the earlier lines, which were poorly located because of inadequate navigational data. 5. 076/1520 End of line 9 and end of watchstanding for F3; gear pulled for short transit to Honolulu.

Cruise report, Hawaiian GLORIA Leg 5 F5-88-HW

“…Air hose leaks, MASSCOMP hang-ups, excessive streamer noise, and LSR jams required extra attention. Problems and solutions regarding the LSR were similar to those described in Holmes et al, 1987, and Normark et al, 1987and 1989 The LSR recorder was vulnerable to a loss of sweep/sync that was manifested by a decrease in the paper feed rate (about 50%). Record quality was not affected by this problem, that proved to be a dirty optical coupler on the Al sensor board.…”

“…However, the structures visible on the GLORIA mosaic suggest that there were also significant tectonic changes near the point of disappearance. The termination on the side-scan occurs at 20°00' N 159°00' W. Extending the fracture zone from this termination point along the 076° strike would place the central fracture zone ridge directly beneath the insular slope of eastern Maui as it crosses the Hawaiian Ridge, and aligns with strand C of the four strands described from Leg F4-88-HW on the windward side (Normark et al, 1989). There is also an oblique ridge intersecting the fracture zone near its termination that we interpret as the extension of the fracture zone to the east This probable change in orientation, discussed below, suggests that a simple direct extension of the main fracture zone beneath the island chain is probably incorrect, and that the intersection probably lies further to the southeast It also makes correlation of individual strands on the windward and leeward sides difficult…”

“…Similar to Clague et al, 1988, andNormark et al, 1989, the shipboard positioning systems generally performed well. We were able to avoid most of the problems encountered during the first two GLORIA cruises (Holmes et al, 1987, andNormark et al, 1987) owing to the improved GPS network coupled with the addition of the real-time, rho-rho Loran positioning system.…”

“…We were able to avoid most of the problems encountered during the first two GLORIA cruises (Holmes et al, 1987, andNormark et al, 1987) owing to the improved GPS network coupled with the addition of the real-time, rho-rho Loran positioning system. The new system (described in Normark et al, 1989) incorporates a real-time trackline display for the ships' bridge personnel, that displays ships position relative to the desired survey line.…”

“…The techniques employed in shipboard processing are described in detail in Normark et al, 1987 and1989, and accordingly will not be elaborated upon here. Unlike Normark et al, 1989, no special shading techniques were applied.…”