Acknowledgments

Special thanks to Joe Calantoni at the Naval Research Laboratory at Stennis Space Center, Mississippi, for his help in setting up and running experiments in the S-OFT. Thanks also to Molly McLaughlin for developing and implementing a method of constructing artificial sand and oil agglomerates. Finally, thanks to Timothy Nelson for carrying out the comparison of amplitude excursion calculated from observed velocity spectrum to an assumed value based on stroke length.