Vp/Vs ratios in the Yellowstone National Park region, Wyoming

Chatterjee, Snehamoy; Pitt, A. M.; Iyer, H. M.

doi:10.1016/0377-0273(85)90057-5

Cited by 61 publications

(36 citation statements)

References 25 publications

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“…Similar characteristics have been observed in other active volcanoes1417. P -wave velocity is sensitive to composition, whereas S -wave velocities are mostly affected by the presence of liquid or gas phases (volatiles or melts)1819. Therefore, the coexistence of higher P and lower S velocities is often interpreted as due to magma with a more primitive composition (higher P ) that is saturated with volatiles and carries a gas phase with a small crystal load (lower S ).…”

Section: Time Changes Of Seismic Structure Beneath Nrvsupporting

confidence: 65%

Breathing of the Nevado del Ruiz volcano reservoir, Colombia, inferred from repeated seismic tomography

Vargas

Koulakov

Jaupart

et al. 2017

Sci Rep

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Nevado del Ruiz volcano (NRV), Columbia, is one of the most dangerous volcanoes in the world and caused the death of 25,000 people in 1985. Using a new algorithm for repeated tomography, we have found a prominent seismic anomaly with high values of the Vp/Vs ratio at depths of 2–5 km below the surface, which is associated with a shallow magma reservoir. The amplitude and shape of this anomaly changed during the current phase of unrest which began in 2010. We interpret these changes as due to the ascent of gas bubbles through magma and to degassing of the reservoir. In 2011–2014, most of this gas escaped through permeable roof rocks, feeding surface fumarole activity and leading to a gradual decrease of the Vp/Vs ratio in the reservoir. This trend was reversed in 2015–2016 due to replenishment of the reservoir by a new batch of volatile-rich magma likely to sustain further volcanic activity. It is argued that the recurring “breathing” of the shallow reservoir is the main cause of current eruptions at NRV.

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Section: Time Changes Of Seismic Structure Beneath Nrvsupporting

confidence: 65%

Breathing of the Nevado del Ruiz volcano reservoir, Colombia, inferred from repeated seismic tomography

Vargas

Koulakov

Jaupart

et al. 2017

Sci Rep

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“…The limit between high and low Vp/Vs areas at~2-3 km depth is marked by strong seismicity. As follows from experimental studies [e.g., Takei, 2002] and field experiments [e.g., Chatterjee et al, 1985], the variations of Vp/Vs ratio is strongly sensitive to the porosity and the state of the pore content. A liquid phase is thought to increase the Vp/Vs, whereas gases and steam decrease it.…”

Section: Discussionmentioning

confidence: 99%

Fluid ascent during the 2004–2005 unrest at Mt. Spurr inferred from seismic tomography

Koulakov

West²,

Izbekov³

2013

Geophysical Research Letters

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We present a seismic model of the crust beneath Mt. Spurr Volcano in Alaska based on tomographic inversion of local earthquake data recorded by temporary seismic network during the unrest of Mt. Spurr in 2004–2005. Beneath the northern vent of Mt. Spurr, where the most intensive fumarolic activity was observed during the last unrest, we observe a finger‐shaped anomaly with a higher P and lower S velocity, which corresponds to high Vp/Vs ratio. Another anomaly is located to the south of Crater Peak approximately beneath the same location where an explosive eruption occurred in 1992. We propose that these two finger anomalies represent separated conduits of magma and volatiles. The NE conduit extends to the surface and enables free volatile flux. The SE conduit seems to be blocked at a ca. 20 km depth and in case of continuous pressure build up may become a source of an explosive eruption.

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“…Deep, high Vp/Vs values are rather related to bodies of partial melt (as in Etna [Patané et al, 2006], Yellowstone [Husen et al, 2004] and Long Valley [Sanders et al, 1995]). Low ratios can be also found in geothermal systems near the water-steam transition as in Yellowstone [Chatterjee et al, 1985] and Onikobe volcanic area [Nakajima and Hasegawa, 2003]. …”

Section: Discussionmentioning

confidence: 99%