2017-2018 USAP Field Season
Flow and fracture dynamics in an ice shelf lateral margin: Observations and modeling of the McMurdo Shear Zone
Dr. Laura E Ray
Supporting Stations: McMurdo Station
The McMurdo Shear Zone (SZ) is a five-kilometer wide swath of intensely and extensively crevassed ice about 40 kilometers from McMurdo Station. At present, there is little understanding of its dynamics with regard to how often, how wide, and where crevasses form, other than a general knowledge of the mechanics of fracture. It is unknown if the SZ is a stable or a transient and chaotic boundary layer evolving into even more chaotic flow that will eventually degrade and separate the Ross and McMurdo ice shelves. During this multi-year project, researchers hope to answer this question of present and future stability by gathering observations required for the development of a three-dimensional finite element time-dependent model of the McMurdo SZ stress fields. To accomplish this objective, the science team will establish a GPS network and perform ground-penetrating radar (GPR) surveys both within and outside the SZ. Two 150-pound battery-powered robots, the Yeti and Scotty, will be used to obtain GPR profiles, particularly in crevassed terrain.
Field Season Overview
A team of six, including three scientists, two robot operators, and a mountaineer, will camp near the McMurdo Shear Zone (SZ) for three weeks. The team will conduct repeat GPS surveys to obtain surface strain rates and will perform robotic GPR surveys within the SZ. Two days of helicopter support will be needed to resurvey the GPS network. Two 150 lb. battery-powered robots will be deployed in the field. The robots navigate autonomously along pre-set routes comprised of GPS waypoints to conduct transect and grid surveys in the SZ. The range of these robots is approximately 18 km. The GPS network was established in the first field season and has been resurveyed in subsequent seasons.
Deploying Team Members