P. Berest et al., ANHARMONIC OSCILLATIONS IN UNDERGROUND CA VITIES, Comptes rendus de l'Academie des sciences. Serie II. Mecanique, physique, chimie, astronomie, 325(12), 1997, pp. 701-707
Strongly anharmonic pressure oscillations generated by fluid injection
stops have been observed at the well head of an underground cavern. T
hey are due to a small gas pocket, trapped in the well head, whose exi
stence was unknown.