Helicopter vs. volcanic tremor: Characteristic features of seismic harmonic tremor on volcanoes

Eibl, Eva P. S.; Lokmer, Ivan; Bean, Christopher J.; Akerlie, Eggert; Vogfjörd, K. S.

doi:10.1016/j.jvolgeores.2015.08.002

Cited by 34 publications

(39 citation statements)

References 38 publications

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“…The acoustic signal generated by a helicopter appears as repeating closely spaced pressure pulses caused by the rotation of the rotor blades (Eibl et al, 2015;Malovrh & Gandhi, 2005;Hardin & Lamkin, 1986). This type of signal (from moving objects) was reported in various studies on acoustic sensors (Kam & Ferguson, 2000;Damarla, 2010;Kalkan & Baykal, 2009;Nishie & Akagi, 2013;Oh & Lee, 2014).…”

Section: Introductionmentioning

confidence: 79%

“…A detailed description of the helicopter generated tremor is given in Eibl et al (2015) and Damarla & Ufford (2008). We therefore only provide a short summary here.…”

Section: Helicopter Generated Tremormentioning

confidence: 99%

“…3). time domain, as visible in Figs. 2a and b, is equal to the inverse of the spacing between spectral lines in the frequency domain (see Eibl et al (2015)). The central fundamental frequency of this tremor corresponds to the RPM times the number of rotor blades and is 27.53 Hz in our case.…”

Section: Helicopter Generated Tremormentioning

confidence: 99%

“…Due to the movement of the helicopter with respect to the stationary receivers the seismometers record a frequency up or down gliding caused by the Doppler effect (Fig. 2d or figs 2 and 5 in Eibl et al (2015)). For the four-bladed helicopter we observed frequency gliding from 34 Hz down to 23 Hz within less than 40 s (Fig.…”

Section: Helicopter Generated Tremormentioning

confidence: 99%

“…Due to the analogy of natural tremor, the helicopter-generated tremor can be recorded and analysed using seismological tools and techniques. Similarities and differences of volcano and helicopter related seismic tremor are highlighted in Eibl et al (2015). Here, we expand this study and use a seismic array composed of seven seismometers in order to deduce rotor revolutions per minute (RPM), number of blades, speed, flight direction, altitude and approximate location of a helicopter.…”

Section: Introductionmentioning

confidence: 97%

See 4 more Smart Citations

Helicopter location and tracking using seismometer recordings

Eibl¹,

Lokmer²,

Bean³

et al. 2017

Geophysical Journal International

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Section: Introductionmentioning

confidence: 79%

“…A detailed description of the helicopter generated tremor is given in Eibl et al (2015) and Damarla & Ufford (2008). We therefore only provide a short summary here.…”

Section: Helicopter Generated Tremormentioning

confidence: 99%

Section: Helicopter Generated Tremormentioning

confidence: 99%

Section: Helicopter Generated Tremormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

See 3 more Smart Citations

Helicopter location and tracking using seismometer recordings

Eibl¹,

Lokmer²,

Bean³

et al. 2017

Geophysical Journal International

Self Cite

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Automated detection and characterization of harmonic tremor in continuous seismic data

Roman

2017

Geophysical Research Letters

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Harmonic tremor is a common feature of volcanic, hydrothermal, and ice sheet seismicity and is thus an important proxy for monitoring changes in these systems. However, no automated methods for detecting harmonic tremor currently exist. Because harmonic tremor shares characteristics with speech and music, digital signal processing techniques for analyzing these signals can be adapted. I develop a novel pitch‐detection‐based algorithm to automatically identify occurrences of harmonic tremor and characterize their frequency content. The algorithm is applied to seismic data from Popocatepetl Volcano, Mexico, and benchmarked against a monthlong manually detected catalog of harmonic tremor events. During a period of heightened eruptive activity from December 2014 to May 2015, the algorithm detects 1465 min of harmonic tremor, which generally precede periods of heightened explosive activity. These results demonstrate the algorithm's ability to accurately characterize harmonic tremor while highlighting the need for additional work to understand its causes and implications at restless volcanoes.

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Seismic characterization of hyperconcentrated flows in a volcanic environment

Coviello

Capra

Vázquez

et al. 2018

Earth Surf Processes Landf

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We present direct observations and monitoring data of a hyperconcentrated flow that occurred along La Lumbre ravine, one of the most active channels of Volcán de Colima in Mexico. Flow properties were inferred from video images and seismic data recorded by a geophone installed outside the channel. We collected flow samples 400 m upstream from the monitoring station and analyzed the variation of sediment concentration and grain-size distribution over time. A joint analysis of hydrological (i.e. flow velocity, wetted perimeter) and rheological (i.e. yield stress τ y and dynamic viscosity μ m ) parameters was performed to characterize the flow. Different flow regimes and sediment transport processes were identified and analyzed in comparison with both the amplitude and spectral features of the seismic signal. We observed differing sediment concentrations at the same discharge, suggesting a decoupling between sediment transport processes and discharge for low-magnitude flows. A straightforward correlation was found between the amplitude of the seismic signal and the sediment concentration, and a value of 1.8 × 10 À3 mm/s was identified that can be used as a threshold to recognize the hyperconcentrated phase of the flow. This information was tested on the complete seismic dataset gathered at La Lumbre ravine during the 2015 rainy season. We identified the transition from streamflow to hyperconcentrated flow (and/or vice versa) in 16 low-magnitude events and we validated this result using the video recordings. The correlation between seismic amplitude and sediment concentration is valid at La Lumbre ravine but would need to be tested in other locations for the development of automatic flow classification methods. This work contributes to standardized seismic methods for characterizing flow processes in volcanic environments, also for the development of lahar early warning systems. Copyright

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Helicopter vs. volcanic tremor: Characteristic features of seismic harmonic tremor on volcanoes

Cited by 34 publications

References 38 publications

Helicopter location and tracking using seismometer recordings

Helicopter location and tracking using seismometer recordings

Automated detection and characterization of harmonic tremor in continuous seismic data

Seismic characterization of hyperconcentrated flows in a volcanic environment

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