Mud Density Prospection Using a Tuning Fork

Several instruments using different technologies are available for the survey and characterization of underwater mud deposits. This paper is concerned with an instrument that uses tuning fork technology to estimate mud density in the field. A model explaining how the tuning fork operates and how it can be used to measure mud properties is presented. In this model, the tuning fork is represented as a damped harmonic oscillator, and the mud is considered a viscoelastic medium showing an elastic response for small deformations and a viscous response for large deformations. The model clearly shows that the tuning fork must be calibrated for the local mud at each survey location. This was confirmed during surveys at the Amazon estuary and the Río de la Plata during 2011 and 2012. The measurements obtained during these surveys are compared with measurements performed with optical and acoustic instruments with very good results.