Supplementary material to “Seismic Imaging in Three Dimensions on the East Pacific Rise”
Published 20 October 2009
John C. Mutter and Suzanne Carbotte, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
Mladen Nedimovic, Dalhousie University, Halifax, Nova Scotia, Canada
Juan Pablo Canales, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
Hélène Carton, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York
Citation:
Mutter, J. C., S. Carbotte, M. Nedimovic, J. P. Canales, and H. Carton (2009), Seismic imaging in three dimensions on the East Pacific Rise, Eos Trans. AGU, 90(42), 374–375. [Full Article (pdf)]
FIGURE S1. Major components of the towed source and receiving arrays. Note that the four streamers are six kilometers long and so cannot be shown correctly at the scale of this illustration. All other components are shown approximately to scale. Photos included here show some of the components mentioned in the text and diagramed in this figure.
FIGURE S2. View of the R/V Marcus G. Langseth. Features of interest include the three enclosed decks at the stern. The lowest is the deck from which airgun arrays and floats are deployed (see S4). The next above is the streamer deck, and above that the deck from which the paravanes are deployed. The starboard paravane can be seen secured to the side of the vessel near the stern of the vessel. The high structure in the middle of the vessel is the marine mammal observation station.
FIGURE S3. The starboard paravane about to enter the water. The paravanes permit the streamers and other towed equipment to be widely separated as shown in FIGURE S1.
FIGURE S4. The upper image shows the gun strings on board looking aft on the gun deployment deck. Below at left At right is one of the airgun arrays being depoyed, and below at right an array in its towed configuration. The GPS antenna can be seen in the mid section of the float.
FIGURE S5. Schematic of a typical racetrack 3D shooting pattern showing fold taper and migration aperture scaled to be approximately correct for MGL0812. The length of the shooting lines (the straight line segments) exceeds the width of the area to be imaged (shown in deep gray) to account for two factors — the migration aperture (light gray shading) that recognizes that dipping events will have their reflection response outside the volume to be imaged, the run-in and run-out tapers needed to ensure that the streamer is straight following a turn and to obtain full fold in the imaged volume plus migration aperture (Yilmaz, 2001; Ashton et al, 1994). In practice run in and run out taper lengths may differ and lines shot in different sail directions will have different taper geometries. We acquired lines 24 km long giving full-fold coverage over approximately16km (full fold here means offsets to 4km available and 4km of the streamer tracking straight). We accomplished two complete and one incomplete racetrack (Figure 1b). Both the migration aperture and fold tapers will differ depending on streamer length and survey objectives. For deep targets a wider aperture would be recommended.
Ashton, C.P., B. Bacon, C. Deplante, D. T. Siclair and G. Redekop. 1994, 3D seismic Survey Design. Oilfield Review, April 1994, p 19–32.
Yilmaz, O. Seismic Data Analysis (2 Volumes), SEG, Investigations in Geophysics, No. 10, 2001.
