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Infrasound From Volcanic Rockfalls, Jeffrey B. Johnson, Timothy J. Ronan
Infrasound From Volcanic Rockfalls, Jeffrey B. Johnson, Timothy J. Ronan
CGISS Publications and Presentations
Proximal infrasound arrays can robustly track rapidly moving gravity-driven mass wasting, which occurs commonly at erupting volcanoes. This study reports on detection, localization, and quantification of frequent small rockfalls and infrequent pyroclastic density currents descending the southeast flanks of Santiaguito’s active Caliente Dome in January of 2014. Such activities are identified as moving sources, which descend several hundred meters at bulk flow speeds of up to ~10 m/s, which is considerably slower than the descent velocity of individual blocks. Infrasound rockfall signal character is readily distinguishable from explosion infrasound, which is manifested by a relatively fixed location source with lower …
A Small Acoustic Goniometer For General Purpose Research, Michael Pook
A Small Acoustic Goniometer For General Purpose Research, Michael Pook
Boise State University Theses and Dissertations
Understanding acoustic events and monitoring their occurrence is a useful aspect of many research projects. In particular, acoustic goniometry allows researchers to determine the source of an event based solely on the sound it produces. The vast majority of the acoustic goniometry research projects used custom hardware targeted to the specific application under test. Unfortunately, due to the wide range of sensing applications, a flexible general purpose hardware/firmware system does not exist for this research. This dissertation focuses on the development of such a system which encourages the continued exploration of general purpose hardware/firmware and lowers barriers to research in …
Lahar Infrasound Associated With Volcán Villarrica's 3 March 2015 Eruption, Jeffrey B. Johnson, Jose L. Palma
Lahar Infrasound Associated With Volcán Villarrica's 3 March 2015 Eruption, Jeffrey B. Johnson, Jose L. Palma
Geosciences Faculty Publications and Presentations
The paroxysmal 2015 eruption of Volcán Villarrica (Chile) produced a 2.5 h long lahar, which descended more than 20 km within the Rio Correntoso/Turbio drainage and destroyed two small bridges. A three-element infrasound array 10 km from the summit, and 4 km from the lahar’s closest approach, was used to study the flow’s progression. Array processing using cross-correlation lag times and semblance places constraints on the lahar’s dynamics, including detection of an initial flow pulse that traveled from 2 to 12 km at an average speed of 38m/s. Subsequently, the lahar signal evolved to a relatively stationary infrasonic tremor located …
Tracking And Characterization Of Moving Acoustic Sources Using An Infrasound Array At Volcán Santiaguito, Guatemala, Brian R. Terbush
Tracking And Characterization Of Moving Acoustic Sources Using An Infrasound Array At Volcán Santiaguito, Guatemala, Brian R. Terbush
Boise State University Theses and Dissertations
Active volcanic processes produce large amounts of acoustic energy within the infrasound band (0-20 Hz). Infrasound-sensitive microphones are often installed in addition to other forms of volcano monitoring equipment to increase the ability to remotely detect volcanic activity. In this study, an array of microphones was deployed without any additional sensor types for 36 hours at Santiaguito, Guatemala, to test the detection capabilities of a standalone microphone array. Array processing was applied to the recorded data, through frequency-domain beamforming and calculating a Fisher statistic (F). A changing F-threshold value was applied to differentiate between desired detections, or …