Inset at upper left shows locations of NOAA towed camera tracks made between 1987 and 1991. Figure 2 . Location shown in Figure 1. Dashed line shows gradient of portion of north rift zone of the Krafla central volcano, Iceland. Figure 3a .
White ribbons are center beam of sidescan.
White is high reflectivity, and black is low reflectivity or shadows. Each swath is 1 km on each side with 1048 pixels across total swath. See Figure 3b for full names of abbreviations. Approximate latitudinal limits of sidescan swaths shown in Figure 4 are indicated by arrows. Figure 3b .