Source amplitudes of volcano-seismic signals determined by the amplitude source location method as a quantitative measure of event size

Kumagai, Hiroyuki; Lacson, Rudy; Maeda, Yuta; Figueroa, Melquiades S.; Yamashina, Tadashi; Ruiz, Mario; Palacios, P.; Ortiz, H. D.; Yépes, Hugo

doi:10.1016/j.jvolgeores.2013.03.002

Cited by 35 publications

(45 citation statements)

References 29 publications

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“…12). The best locations were obtained with Q = 40.6 (0.4-4.0 Hz), which is comparable to Q values used in other volcanic regions, for instance Q = 50 (3 and 7.5 Hz) for Piton de la Fournaise volcano (Battaglia & Aki 2003), Q = 60 (5-12 Hz) for Cotopaxi and Tungurahua volcanoes (Kumagai et al 2010), and Q = 60 (7-12 Hz) for Taal volcano (Kumagai et al 2013). The cluster appears beneath the north-western flank, but the locations might be influenced by the lack of azimuthal coverage of the July-August 2006 seismic network.…”

Section: Seismic Source Locationsupporting

confidence: 74%

Site effect determination using seismic noise from Tungurahua volcano (Ecuador): implications for seismo-acoustic analysis

Palacios

Kendall²,

Mader³

2015

Geophysical Journal International

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University of Bristol -Explore Bristol Research General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. S U M M A R YScattering and refractions that occur in the heterogenous near-surface beneath seismic stations can strongly affect the relative amplitudes recorded by three-component seismometers. Using data from Tungurahua volcano we have developed a procedure to correct these 'site effects'. We show that seismic noise signals store site information, and then use their normalized spectral amplitudes as site frequency response functions. The process does not require a reference station (as per the S-wave and coda methods) or assume that the vertical amplitude is constant (the H/V component ratio method). Correcting the site effects has three consequences on data analysis: (1) improvement of the seismic source location and its energy estimation; (2) identification of a strong influence on the volcanic acoustic seismic ratio (VASR) and (3) decoupling the air wave impact on the ground caused by explosions or eruption jets. We show how site effect corrections improve the analysis of an eruption jet on 2006 July 14-15, appearing two periods of strong acoustic energy release and a progressive increase of the seismic energy, reaching the maximum before finishing the eruption.

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Section: Seismic Source Locationsupporting

confidence: 74%

Site effect determination using seismic noise from Tungurahua volcano (Ecuador): implications for seismo-acoustic analysis

Palacios

Kendall²,

Mader³

2015

Geophysical Journal International

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“…We follow the ASL method of Kumagai et al (2010Kumagai et al ( , 2013, in which grid nodes are distributed in a search domain and the far-field S-wave approximation is used. Since we focus on tremor signals associated with eruptions and lahars, grid nodes are positioned over the volcano surface.…”

Section: Methodsmentioning

confidence: 99%

“…Following Kumagai et al (2010Kumagai et al ( , 2013, we used filtered (5-10-Hz band-pass) vertical velocity seismograms. We did not correct for site amplification factors because Kumagai et al (2010) reported that the normalized residuals for an explosion event at Tungurahua were smaller without the corrections.…”

Section: Tremor Signalsmentioning

confidence: 99%

“…Battaglia et al (2005a, b) showed that a source location method using seismic amplitudes is useful for locating the source of tremor signals associated with eruptions at the Piton de la Fournaise volcano, and they used the tremor source amplitude to estimate the amount of erupted lava. Kumagai et al (2013) demonstrated that the source amplitude determined by the amplitude source location (ASL) method in a frequency band of 5-10 Hz can be used as a quantitative measure of the size of various volcano-seismic events. In this study, we extended the methodology of the above studies to estimate the source amplitudes and cumulative source amplitudes for individual tremor signals associated with eruptions and lahars and explosion events at Tungurahua volcano, Ecuador.…”

Section: Introductionmentioning

confidence: 99%

“…The ASL method has been used in various volcano-seismic studies (e.g., Battaglia et al , 2005aBattaglia et al , 2005bKumagai et al 2011bKumagai et al , 2014Yomogida 2012, 2015). Kumagai et al (2013) estimated the source amplitudes of volcano-tectonic earthquakes, long-period events, and explosion events using the ASL method and found the following scaling relation between seismic magnitude (M) and source amplitude (A s ):…”

Section: Introductionmentioning

confidence: 99%

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An approach to source characterization of tremor signals associated with eruptions and lahars

et al. 2015

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Tremor signals are observed in association with eruption activity and lahar descents. Reduced displacement (D R ) derived from tremor signals has been used to quantify tremor sources. However, tremor duration is not considered in D R , which makes it difficult to compare D R values estimated for different tremor episodes. We propose application of the amplitude source location (ASL) method to characterize the sources of tremor signals. We used this method to estimate the tremor source location and source amplitude from high-frequency (5-10 Hz) seismic amplitudes under the assumption of isotropic S-wave radiation. We considered the source amplitude to be the maximum value during tremor. We estimated the cumulative source amplitude (I s ) as the offset value of the timeintegrated envelope of the vertical seismogram of tremor corrected for geometrical spreading and medium attenuation in the 5-10-Hz band. For eruption tremor signals, we also estimated the cumulative source pressure (I p ) from an infrasonic envelope waveform corrected for geometrical spreading. We studied these parameters of tremor signals associated with eruptions and lahars and explosion events at Tungurahua volcano, Ecuador. We identified two types of eruption tremor at Tungurahua: noise-like inharmonic waveforms and harmonic oscillatory signals. We found that I s increased linearly with increasing source amplitude for lahar tremor signals and explosion events, but I s increased exponentially with increasing source amplitude for inharmonic eruption tremor signals. The source characteristics of harmonic eruption tremor signals differed from those of inharmonic tremor signals. We found a linear relation between I s and I p for both explosion events and eruption tremor. Because I p may be proportional to the total mass involved during an eruption episode, this linear relation suggests that I s may be useful to quantify eruption size. The I s values we estimated for inharmonic eruption tremor were consistent with previous estimates of volumes of tephra fallout. The scaling relations among source parameters that we identified will contribute to our understanding of the dynamic processes associated with eruptions and lahars. This new approach is applicable in analyzing tremor sources in real time and may contribute to early assessment of the size of eruptions and lahars.

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High‐precision relocation of long‐period events beneath the summit region of Kı̄lauea Volcano, Hawai‘i, from 1986 to 2009

Matoza

Shearer

Okubo

2014

Geophysical Research Letters

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Long‐period (0.5–5 Hz, LP) seismicity has been recorded for decades in the summit region of Kı̄lauea Volcano, Hawai‘i, and is postulated as linked with the magma transport and shallow hydrothermal systems. To better characterize its spatiotemporal occurrence, we perform a systematic analysis of 49,030 seismic events occurring in the Kı̄lauea summit region from January 1986 to March 2009 recorded by the ∼50‐station Hawaiian Volcano Observatory permanent network. We estimate 215,437 P wave spectra, considering all events on all stations, and use a station‐averaged spectral metric to consistently classify LP and non‐LP seismicity. We compute high‐precision relative relocations for 5327 LP events (43% of all classified LP events) using waveform cross correlation and cluster analysis with 6.4 million event pairs, combined with the source‐specific station term method. The majority of intermediate‐depth (5–15 km) LPs collapse to a compact volume, with remarkable source location stability over 23 years indicating a source process controlled by geological or conduit structure.

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Source amplitudes of volcano-seismic signals determined by the amplitude source location method as a quantitative measure of event size

Cited by 35 publications

References 29 publications

Site effect determination using seismic noise from Tungurahua volcano (Ecuador): implications for seismo-acoustic analysis

Site effect determination using seismic noise from Tungurahua volcano (Ecuador): implications for seismo-acoustic analysis

An approach to source characterization of tremor signals associated with eruptions and lahars

High‐precision relocation of long‐period events beneath the summit region of Kı̄lauea Volcano, Hawai‘i, from 1986 to 2009

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