A method and apparatus for providing an alerting tool to measure the amount of logging in a network component, for example a network element, and to provide an alarm to a network operator or an automated system when the amount of logging reaches a predefined threshold are disclosed. The measuring apparatus of the present invention limits the place of the body under measurement to one body region, i. In another embodiment, an array of two or more marine vibrators is used as the source of seismic energy, with the vibrators in the array being disposed at different depths.