IMI30: How a 30kHz system fills a resolution gap in the NSF supported mapping systems pool.
Seafloor mapping (bathymetry and sidescan sonar) is a recognized necessity for marine geophysical research. NSF supports a variety of multibeam and sidescan sonars for ocean mapping, which are available on a shared-use basis. However, a gap exists between currently-available higher-resolution/slow-survey-rate towed sonars (DSL-120) and lower-resolution/fast-survey-rate surface-towed (HAWAII MR-1) or hull-mounted multibeam sonars (Figure 1). An intermediate frequency deep towed sonar, which currently does not exist within the NSF quiver of shared-use sonar instruments, is the most appropriate tool for mapping missions that require the identification of features having length scales of tens of meters (small faults, lava flow boundaries, seafloor channels) over survey areas of several thousand square kilometers. IMI-30 will fulfill this role, and will be operated as a shared-use NSF facility. The IMI-30 system will include a 30 kHz bathymetric sidescan sonar, a multibeam chirp subbottom profiler, a three-axis magnetometer, CTD, sound velicometer, and will include support for other sensors that can be mounted on or towed behind the sonar towfish.