ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aUW3. Seismo-acoustic remote sensing and inversion of sea ice fracture events.

H. Schmidt

Y. Dudko

MIT, Cambridge, MA 02139

K. von der Heydt

E. K. Scheer

Woods Hole Oceanogr. Inst., Woods Hole, MA 02543

A new, layered seismo-acoustic remote sensing concept was developed and applied during the SIMI field experiments in the Beaufort Sea in the Fall of 1993 and the Spring of 1994. A large-aperture, 32-element, horizontal hydrophone array was used to record the acoustic emission from ice events. Using real-time array processing, maps of the seismic activity of the ice cover out to a range of 2 to 3 km were continuously generated. Once an active zone was detected, clusters of five 3-axis geophones and a single hydrophone were deployed in the active zone for near-field recording of the seismo-acoustic emission. The data were transmitted back to the main camp via a wireless local area network, and recorded on tape. During the Spring experiment data were recorded continuously on the hydrophone array for 4 weeks, and several deployments of the geophone clusters were performed in the vicinity of active ice mechanical processes such as ridge building, finger rafting, and floe fracturing. In addition, the clusters were deployed on specimens used for artificial fracturing experiments. The layered remote sensing concept is described, and examples are given of the seismo-acoustic emission produced by the different types of ice events. Finally, the matched-field fracture plane analysis of the seismic data is described.