Magma-fluid interactions beneath the Akutan Volcano in Aleutian Arc based on the results of local earthquake tomography

Koulakov, Ivan; Smirnov, S. Z.; Бортникова, С Б

doi:10.1002/essoar.10503824.1

Cited by 3 publications

(6 citation statements)

References 47 publications

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“…However, we see that the Vp/Vs ratio presented in our study successfully solves this problem and clearly differentiates between the low‐ Vp/Vs in volcanoclastic sediments and the very high Vp/Vs ratio in the magma reservoir. Similar differentiation was observed in the area between Avacha and Koryaksky volcanoes (Bushenkova et al., 2019), Akutan (Koulakov et al., 2021) and in many other places. For Okmok, the Vp/Vs ratio demonstrates a very shallow location of the magma source beneath the cone A.…”

Section: Discussionsupporting

confidence: 72%

“…The P ‐wave velocity is primarily sensitive to the composition, whereas the variation of the S ‐wave velocity is mostly controlled by the presence of a liquid phase. The coexistence of higher P ‐ and lower S ‐wave velocity, and the corresponding very high values of Vp/Vs ratio is a rather typical feature observed beneath many active volcanoes and interpreted as magma reservoirs or conduits (Bushenkova et al., 2019; Koulakov et al., 2013, 2020, 2021). Indeed, the intruded magma has a different composition compared to the host crustal rocks, which determines the higher Vp .…”

Section: Discussionmentioning

confidence: 97%

“…As a starting model, we used the 1D velocity distribution, which was defined at several depth levels and linearly interpolated. For the first run of the tomography procedure, we took a model from Akutan island (Koulakov et al., 2021), which presumably has similar structure. After completing the calculations, we calculated average P ‐wave velocities in horizontal levels and used them as a new starting velocity model.…”

Section: Data and Algorithmsmentioning

confidence: 99%

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Multiple Magma Sources Beneath the Okmok Caldera as Inferred From Local Earthquake Tomography

et al. 2022

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Okmok volcano located on the northeastern part of the Umnak Island is one of the most active volcanoes in the Aleutian Arc. It was initially built as a large shield volcano, but 12,000 and 2,050 years ago, it experienced two caldera‐forming eruptions that destroyed the central part of the volcano. The post‐caldera eruptions have occurred mostly along the inner perimeter of the caldera from cinder and tuff cones. Here, we use the local earthquake data of the Alaska Volcano Observatory (AVO) in the time period from 2003 to 2017 to build a model with the 3D distributions of the P and S wave velocities and Vp/Vs ratio. At depths of more than 10 km, we observe a vertically aligned anomaly of high Vp/Vs ratio interpreted as a long‐lived conduit likely responsible for the volcano evolution since its origin. Above this conduit, we reveal a large anomaly of high Vp/Vs ratio representing the main magma reservoir that is connected with several shallow anomalies located below the centers of recent eruptions in the caldera. One of such anomalies represents a large shallow reservoir below the Cone A, which was the source of most of Okmok's historical eruptions. The most recent eruption occurred in 2008 and was fed by a magma diapir that was initially formed in the central magma reservoir and then slowly ascended through a ductile silica rich layer at depths from 6 to 2 km. This interpretation is consistent with the petrology studies and modeling of ground deformations.

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Section: Discussionsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 97%

Section: Data and Algorithmsmentioning

confidence: 99%

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Multiple Magma Sources Beneath the Okmok Caldera as Inferred From Local Earthquake Tomography

et al. 2022

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“…Tomographic inversion was based on the local earthquake tomography code LOTOS 18 , which has been used to investigate dozens of different volcanoes 9,[19][20][21][22] . First, event locations in the reference 1D velocity model are determined using a grid-search method and linear approximation of ray paths 9 .…”

Section: Tomographic Inversionmentioning

confidence: 99%

Voluminous Storage and Rapid Magma Ascent Beneath La Palma Revealed by Seismic Tomography

D’Auria

Koulakov

Prudencio

et al. 2022

Preprint

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Seismic tomography provides a window into magmatic plumbing systems; however, obtaining sufficient data for ‘real-time’ imaging is challenging. Until now, syn-eruptive tomography has not been successfully demonstrated. For the first time, we obtained high-resolution images of Earth's interior during an ongoing volcanic eruption. We used data from 11,349 earthquakes, most of which during La Palma eruption (19 September-13 December, 2021), to perform travel-time seismic tomography. We present high-precision earthquake relocations and 3D distributions of P and S-wave velocities highlighting the geometry of magma sources. We identified three distinct structures: (1) a shallow localised region (< 3 km) of hydrothermal alteration; (2) spatially extensive, consolidated, oceanic crust extending to ~10 km depth and; (3) a large (> 400 km3) sub-crustal magma-filled rock volume intrusion extending from ~7 to 25 km depth. Our results suggest that this large magma reservoir feeds the La Palma eruption continuously for almost three months. Prior to eruption onset, magma ascended from ~10 km depth to the surface in < 7 days. In the upper 3 km, melt migration is along the western contact between consolidated oceanic crust and altered hydrothermal material. Similar structural weaknesses along the eastern contact could potentially cause new eruptive centres in the future.

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“…We therefore speculate that different positions of the negative P‐ and S‐velocity anomaly may be real and result from the different sensitivity of the wave types to rock parameters. S‐velocities are usually interpreted in the context of fluid content, while P‐velocities also carry other information besides the presence of melt mainly the composition of rocks (Koulakov et al., 2021; Takei, 2002). We suggest, that reduced P‐velocities are mainly the consequence of higher temperatures, whereas the presence of melt drastically reduces the S‐wave velocities and thus results in high Vp/Vs‐ratios.…”

Section: Discussion and Interpretationmentioning

confidence: 99%

Magmatic Activity and Dynamics of Melt Supply of Volcanic Centers of Ultraslow Spreading Ridges: Hints From Local Earthquake Tomography at the Knipovich Ridge

Meier

Schlindwein

Schmid

2022

Geochem Geophys Geosyst

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Ultraslow spreading ridges with spreading rates below 20 mm/yr exhibit different characteristics and behavior than any faster spreading ridges (Dick et al., 2003). At ultraslow pace, melt supply is not high enough to sustain a spatially continuous shallow melt reservoir underneath the rift valley and therefore volcanic activity and magmatism do not occur along the entire rift axis. Instead, they are bound to distinct regions along the ridge that receive more melt than the ridge on average does (Cannat et al., 2003;Standish et al., 2008). Those magmatic segments build volcanic centers that are widely spaced, often by several tens of kilometers (Cannat et al., 2003;Curewitz et al., 2010;Standish et al., 2008). Volcanic centers receive enough melt to build volcanic edifices in the rift valley. If the melt supply persists over time, seamount chains or a line of elevations form in spreading direction (Jokat et al., 2003;Mendel et al., 2003) (e.g., Figure 1b). The regions in between volcanic centers are dominated

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Magma-fluid interactions beneath the Akutan Volcano in Aleutian Arc based on the results of local earthquake tomography

Cited by 3 publications

References 47 publications

Multiple Magma Sources Beneath the Okmok Caldera as Inferred From Local Earthquake Tomography

Multiple Magma Sources Beneath the Okmok Caldera as Inferred From Local Earthquake Tomography

Voluminous Storage and Rapid Magma Ascent Beneath La Palma Revealed by Seismic Tomography

Magmatic Activity and Dynamics of Melt Supply of Volcanic Centers of Ultraslow Spreading Ridges: Hints From Local Earthquake Tomography at the Knipovich Ridge

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