Submitted to: Geophysical Research Letters
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2003
Publication Date: 12/20/2003
Citation: DICARLO, D.A., CIDONCHA, J.I., HICKEY, C. 2003. ACOUSTIC MEASUREMENTS OF PORE SCALE DISPLACEMENTS. GEOPHYSICAL RESEARCH LETTERS 30(17)1901.
Interpretive Summary: When water moves in a soil, sound is emitted from the movement of the water/air interfaces. We record these signals and find that they are different when water is draining or wetting the soil. We relate the observed signals to the processes that are expected to go on within the soil on the microscopic pore scale. The statistics and patterns of the acoustic signals yield invaluable knowledge on how the fluids move at the micro-scale, which is necessary for building larger scale models of flow through soils.
Technical Abstract: We describe how experimentally measurable acoustic and hydroacoustic events occur when one fluid displaces another within a porous medium. We show that the events are directly related to discrete fluid bursts ('Haines jumps') that occur at the pore scale. The events show power law statistics with respect to magnitude for drainage (air invading) but not for imbibition (water invading). These observations agree with simple conceptual arguments on how the displacements take place. The results show that acoustic and hydroacoustic measurements can be an excellent technique for observing Haines jumps in-situ.