<i>Q</i> and upward extension of VSP data through the energy-flux theorem

Many theoretical studies have been made of layered systems and their internal wavetrains. A number of interesting theorems have resulted from this work, but very few papers have been published which demonstrate the value of these theorems on field data. In an attempt to redress the balance, this paper looks at one such theorem which is known as the energy-flux theorem or net-downgoing-energy theorem.