A Temporal Change in Coda Wave Attenuation Observed During an Eruption of Mount St. Helens

Fehler, Michael; Roberts, Peter M.; Fairbanks, Tom

doi:10.1002/9781118782064.ch18

Cited by 3 publications

(4 citation statements)

References 20 publications

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“…Fehler et al 1988;Gusev 1995a;Hiramatsu et al 2000;Jin and Aki 1986;Jin et al 2004;Sato 1988b). Fehler et al 1988;Gusev 1995a;Hiramatsu et al 2000;Jin and Aki 1986;Jin et al 2004;Sato 1988b).…”

Section: Chapter 3 Phenomenological Study Of Coda Wavesmentioning

confidence: 99%

“…If we make the band-width too small, the filtered coda envelope changes rapidly and a stable estimation of Q 1 c becomes difficult. In some studies, the estimate is stabilized by using data from many seismograms and simultaneously finding the decay gradient that best fits all the data (Fehler et al 1988). We can then estimate Q 1 c directly from the decay gradient against lapse time using the least square method.…”

Section: Measurements Of Coda Attenuationmentioning

confidence: 99%

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Seismic Wave Propagation and Scattering in the Heterogeneous Earth : Second Edition

Sato¹,

Fehler²,

Maeda³

2012

450

385

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Scattering due to randomly distributed small-scale heterogeneities in the earth significantly changes seismic waveforms of local earthquakes especially for short periods. Scattering excites long lasting coda waves after the direct arrival and broadens the apparent duration of oscillation with increasing travel distance much longer than the source duration time. Models of propagation through deterministic structures such as those with horizontally uniform velocity layers cannot explain those observed phenomena. Our goal in writing this book is to put a focus on the phenomena of seismic wave scattering by distributed heterogeneities in the earth, especially in the lithosphere, where stochastic treatment is essential to describe both heterogeneous media and wave propagation through them. Stochastic approaches and deterministic approaches are complementary for the construction of a unified image of the earth's structure.Keiiti Aki was a distinguished pioneer who extensively developed various stochastic methods for short-period seismology. His strong encouragement and continuous support for us were essential in motivating us to write the first edition of this book. Before Kei passed away in 2005, he kindly cited our book when he argued for the importance of the study on seismic wave scattering caused by small-scale heterogeneity in his letter to V. I. Keilis-Borok, ". . . To a geodynamicist, the earth's property is smoothly varying within bodies bounded by large-scale interfaces. Most seismologists also belong to this "smooth earth club," because once you start with an initial model of smooth earth your data usually do not require the addition of smallscale heterogeneity to your initial model. As summarized well in a recent book by Sato and Fehler (1998), the acceptance of coda waves in the data set is needed for the acceptance of small-scale seismic heterogeneity of the lithosphere. There are an increasing number of seismologists who accept it, forming the "rough earth club." I believe that you are also a member of the rough earth club, judging from the emphasis on the hierarchical heterogeneity of the lithosphere. . . . "(Aki 2009).The first edition of this book was fortunately accepted in the geophysical community as a textbook, especially for graduate students. Furthermore it has been often cited in the physics community since this book introduced various aspects of wave scattering in real heterogeneous media. During the decade following the vii viii Preface to the Second Edition publication of the first edition, there were developments in stochastic methods and analyses focusing on seismogram envelopes. Radiative transfer theory has been used not only for the study of coda envelopes but also for the analysis of whole seismogram envelopes. These studies made it possible to resolve the spatial variation of scattering strength. There have been developments in the statistical description of wave propagation in random media that reliably predict the delay of peak amplitude from the onset and the broadening of seismogr...

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Section: Chapter 3 Phenomenological Study Of Coda Wavesmentioning

confidence: 99%

Section: Measurements Of Coda Attenuationmentioning

confidence: 99%

Seismic Wave Propagation and Scattering in the Heterogeneous Earth : Second Edition

Sato¹,

Fehler²,

Maeda³

2012

450

385

View full text Add to dashboard Cite

show abstract

“…P and coda wave attenuation studies that used seismicity recorded during the 1980–1986 and 1996–1998 seismic swarms showed that temporal changes and an increased complexity with depth affect seismic observations sampling the cone and the volumes underneath [ Fehler et al , ; Tusa et al , ]. The temporal changes may reflect changes in the upper feeding system of the volcano, as suggested by the petrological studies of Pallister et al [].…”

Section: Introductionmentioning

confidence: 99%

Attenuation and scattering tomography of the deep plumbing system of Mount St. Helens

et al. 2014

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We present a combined 3-D P wave attenuation, 2-D S coda attenuation, and 3-D S coda scattering tomography model of fluid pathways, feeding systems, and sediments below Mount St. Helens (MSH) volcano between depths of 0 and 18 km. High-scattering and high-attenuation shallow anomalies are indicative of magma and fluid-rich zones within and below the volcanic edifice down to 6 km depth, where a high-scattering body outlines the top of deeper aseismic velocity anomalies. Both the volcanic edifice and these structures induce a combination of strong scattering and attenuation on any seismic wavefield, particularly those recorded on the northern and eastern flanks of the volcanic cone. North of the cone between depths of 0 and 10 km, a low-velocity, high-scattering, and high-attenuation north-south trending trough is attributed to thick piles of Tertiary marine sediments within the St. Helens Seismic Zone. A laterally extended 3-D scattering contrast at depths of 10 to 14 km is related to the boundary between upper and lower crust and caused in our interpretation by the large-scale interaction of the Siletz terrane with the Cascade arc crust. This contrast presents a low-scattering, 4-6 km 2 "hole" under the northeastern flank of the volcano. We infer that this section represents the main path of magma ascent from depths greater than 6 km at MSH, with a small north-east shift in the lower plumbing system of the volcano. We conclude that combinations of different nonstandard tomographic methods, leading toward full-waveform tomography, represent the future of seismic volcano imaging.

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“…With these techniques, researchers can better illuminate and interpret Earth features and characterize structural heterogeneities (Schurr et al 2003;De Gori et al 2005;Eberhart-Phillips et al 2008). Attenuation is, in fact, more sensitive than velocity to strong spatial changes in the Earth composition, temperature, and pressure (Romanowicz, 2003) and an excellent marker of time-dependent changes in the physical and chemical properties of the medium (O'Connell and Budiansky, 1977;Fehler, 1982;Gusev and Lemzikov, 1985;Fehler et al, 1988).…”

Section: Introductionmentioning

confidence: 99%

Scattering images from autocorrelation functions of P-wave seismic velocity images: the case of Tenerife Island (Canary Islands, Spain)

et al. 2018

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We present a P-wave scattering image of the volcanic structures under Tenerife Island using the autocorrelation functions of P-wave vertical velocity fluctuations. We have applied a cluster analysis to total quality factor attenuation (−1) and scattering quality factor attenuation (−1) images to interpret the structures in terms of intrinsic and scattering attenuation variations on a 2D plane, corresponding to a depth of 2000 m, and check the robustness of the scattering imaging. The results show that scattering patterns are similar to total attenuation patterns in the South of the island. There are two main areas where patterns differ: at Cañadas-Teide-Pico Viejo Complex high total attenuation and average-to-low scattering values are observed. We interpret the difference as induced by intrinsic attenuation. In the Santiago Ridge Zone (SRZ) region, high scattering values correspond to average total attenuation. In our interpretation, the anomaly is induced by an extended scatterer, geometrically related to the surficial traces of Garachico and El Chinyero historical eruptions and the area of highest seismic activity during the 2004-2008 seismic crises.

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A Temporal Change in Coda Wave Attenuation Observed During an Eruption of Mount St. Helens

Cited by 3 publications

References 20 publications

Seismic Wave Propagation and Scattering in the Heterogeneous Earth : Second Edition

Seismic Wave Propagation and Scattering in the Heterogeneous Earth : Second Edition

Attenuation and scattering tomography of the deep plumbing system of Mount St. Helens

Scattering images from autocorrelation functions of P-wave seismic velocity images: the case of Tenerife Island (Canary Islands, Spain)

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