Structure of Volatile Conduits beneath Gorely Volcano (Kamchatka) Revealed by Local Earthquake Tomography

Kuznetsov, Pavel; Koulakov, Ivan; Jakovlev, Andrey; Abkadyrov, Ilyas; Деев, Е. В.; Гордеев, Е. И.; Senyukov, S.; Khrepy, Sami El; Al-Arifi, Nassir

doi:10.3390/geosciences7040111

Cited by 28 publications

(29 citation statements)

References 26 publications

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“…At a zero level (3 km below the surface), we can observe the transition from a high- to a low-Vp/Vs ratio. The same transitions at similar depths have been observed in other strongly degassing volcanoes, such as Nevado del Ruiz 23 and Gorely in Kamchatka 26 . This limit might represent the level of phase separation in which the liquid phase is converted to gas.…”

Section: Resultssupporting

confidence: 80%

Causes of volcanic unrest at Mt. Spurr in 2004–2005 inferred from repeated tomography

Koulakov

Smirnov

Gladkov

et al. 2018

Sci Rep

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Mt. Spurr is the largest active volcano in Alaska of high explosive potential. The most recent activity, including two recent magmatic eruptions in 1953 and 1992, has occurred via the flanking Crater Peak. From 2004 to 2006, strong seismicity, gas flux, and heating were observed in the summit area, which had remained inactive for more than 5 Ka. To understand the cause of this reactivation, we performed repeated tomography inversions that clearly imaged the magma reservoir beneath Mt. Spurr and showed temporal changes in its shape and intensity. During the two years preceding the unrest, we observed ascension of the upper limit of the reservoir-related anomaly from a depth of 5 to 3 km below the surface, accompanied by strong seismicity. During the following years, the shape of the anomaly remained unchanged, but its intensity weakened. These observations may indicate the release of fluids from the ductile reservoir and fast upward ascent through the brittle cover that caused intensive seismicity and gas flux during the unrest from 2004 to 2006. The origin of this zone will possibly cause a resumption of explosive eruptions in the summit area of Mt. Spurr.

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Section: Resultssupporting

confidence: 80%

Causes of volcanic unrest at Mt. Spurr in 2004–2005 inferred from repeated tomography

Koulakov

Smirnov

Gladkov

et al. 2018

Sci Rep

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“…At shallower depths, beneath Koryaksky, we observe dominantly low values of the Vp/Vs ratio in a range of 1.7–1.8. Similar transition from high to low values of the Vp/Vs ratio can be observed in some other active volcanoes, such as Mount Spurr (Koulakov et al, ) and Gorely (Kuznetsov et al, ). In many cases, such low Vp/Vs anomalies are explained by degassing of fluid saturated magmas during ascent and decompression.…”

Section: Discussionsupporting

confidence: 76%

Tomographic Images of Magma Chambers Beneath the Avacha and Koryaksky Volcanoes in Kamchatka

et al. 2019

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A new tomographic model (Vp, Vs, and Vp/Vs ratio) was built for two neighboring active volcanoes, Avacha and Koryaksky, which represent a serious hazard to the population and infrastructure of Petropavlovsk‐Kamchatsky, the main city of Kamchatka, Russia. Arrival times of seismic P and S waves from almost 5,000 local events, recorded by a permanent network of seismic stations during 2009–2018, were used for tomography. The resolution of the derived models was carefully tested by a series of synthetic simulations. Prominent anomalies with extremely high Vp/Vs ratios (up to 2.4) were retrieved directly beneath both volcanoes and interpreted as magma reservoirs containing high degrees of partial melt and/or fluids. Beneath Avacha, the upper limit of the anomaly is located at the depth of ~2 km below the surface. The reservoir appears to be connected to the surface by a neck‐shaped anomaly of high Vp/Vs ratio associated with active seismicity, which is interpreted as a magma and fluid conduit. Beneath Koryaksky, the magma related anomaly is deeper: Its upper limit is located at a depth of ~7 km below the surface. This anomaly is connected with the volcanic cone and is associated with a vertical seismicity cluster, which possibly marks the pathway of fluid ascent and degassing. Between the volcanoes, a 2‐ to 3‐km thick layer of very low Vp and Vs is interpreted as deposits of volcanoclastic sediments. Generally low Vp/Vs ratios in the area between the volcanoes show that the magma reservoirs in the upper crust are not interconnected.

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“…In both models, anomaly (2) seems to be separated from the shallower anomaly (1), and its top is located at approximately 2 km below the surface. Note that very similar anomalies were observed beneath other volcanoes, such as Nevado del Ruiz (Vargas et al, 2017), Gorely (Kuznetsov et al, 2017), and Mount Spurr (Koulakov, West, & Izbekov, 2013). This anomaly is interpreted as a volatile-rich magma conduit.…”

Section: Discussionsupporting

confidence: 67%

Evolution of the Magma Conduit Beneath the Galeras Volcano Inferred From Repeated Seismic Tomography

Koulakov

Vargas

2018

Geophysical Research Letters

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The Colombian volcano Galeras is one of the most active volcanoes in the world, and it has an andesitic composition and high explosive potential. We consider the period of 1989–2015, in which the volcano manifested frequent eruptions and high seismic activity. To study the temporal variations in the seismic structure beneath Galeras, we implemented an algorithm of repeated tomography using selected data sets with similar geometries. We obtained the variations in the seismic velocity structures beneath Galeras during the three time episodes of 1989–2000, 2001–2007, and 2008–2015. In the second episode, we observe a columnar anomaly with a high Vp/Vs ratio that possibly represents a conduit transporting a new portion of magma material from below. This result may indicate that in this period, which culminated with dome emplacement and collapse, the volcano was directly fed from deeper magma sources. In other episodes, the conduit is less visible in the tomography models, and we propose that the volcanic activity was merely controlled by shallow magma reservoirs at 2–4 km below the surface.

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Structure of Volatile Conduits beneath Gorely Volcano (Kamchatka) Revealed by Local Earthquake Tomography

Cited by 28 publications

References 26 publications

Causes of volcanic unrest at Mt. Spurr in 2004–2005 inferred from repeated tomography

Causes of volcanic unrest at Mt. Spurr in 2004–2005 inferred from repeated tomography

Tomographic Images of Magma Chambers Beneath the Avacha and Koryaksky Volcanoes in Kamchatka

Evolution of the Magma Conduit Beneath the Galeras Volcano Inferred From Repeated Seismic Tomography

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