Kilauea Infrasound

The Pu`u O`o crater complex is the active section of Kilauea Volcano, Hawaii . Since 1992, continuous effusion and sustained degassing has occurred from the vent system. The lava flows from the crater complex ~13 km through a complicated conduit system until it meets the ocean. The effusive activity at Pu`u O`o produces a continuous vibration, known as tremor, which can be recorded through both the ground (seismic) and atmosphere (infrasound). Tremor is considered to be one of the best precursors to volcanic eruption and is indicative of the type of eruptive activity.

ISLA deployed a portable infrasound array near Pu`u O`o in late 2002. Near continuous infrasound was detected from the active vent between ~0.3-10 Hz. Using the Progressive Multi-Channel Cross-Correlation technique, infrasonic tremor was recorded from the active Pu`u O`o vent and was also distributed along the lava tube system. For more details see: http://www.agu.org/pubs/crossref/2003.../2003GL018038.shtml

Citation: Garcés, M., A. Harris, C. Hetzer, J. Johnson, S. Rowland, E. Marchetti, and P. Okubo (2003), Infrasonic tremor observed at Kilauea Volcano, Hawai'i , Geophys. Res. Lett. , 30 (20), 2023, doi:10.1029/2003GL018038.

To further study and characterize the infrasonic tremor, another portable array was deployed in the vicinity of Pu`u O`o in August 2005. This array recorded significant infrasonic tremor between 0.5-3 Hz, with nearly all of the signals originating from the active vent. However, clear diurnal variations in tremor recordings were detected and are attributed to the region's changing wind conditions (Fig. 1).

Figure 1. Coherency of bandpassed waveforms. Data has been filtered between 0.5-3 Hz and the travel time to the active vent has been removed. a) High correlation of infrasonic tremor during times of low wind/noise. b) Low correlation of infrasonic tremor during high wind/noise.

Because of its persistence, infrasonic signals from Kilauea volcano may be used to assess the range-dependent capabilities of infrasound monitoring. Further, the region's diurnal wind pattern provides a good study area for testing the effects of wind on acoustic wave propagation. This study demonstrates that adequate site and instrument selection and recognition of the regional wind patterns is necessary to permit robust infrasonic remote sensing of volcanic processes. More detailed results from this study will be presented soon.