Volcanic edifice stability during cryptodome intrusion

Temperature plays a critical role in defining the seismogenic zone, the area of the crust where earthquakes most commonly occur; however, thermal controls on fault ruptures are rarely observed directly. We used a rapidly deployed seismic array to monitor an unusual earthquake cascade in 2018 at Lombok, Indonesia, during which two magnitude 6.9 earthquakes with surprisingly different rupture characteristics nucleated beneath an active arc volcano. The thermal imprint of the volcano on the fault elevated the base of the seismogenic zone beneath the volcanic edifice by 8 km, while also reducing its width. This thermal “squeezing” directly controlled the location, directivity, dynamics, and magnitude of the earthquake cascade. Earthquake segmentation due to thermal structure can occur where strong temperature gradients exist on a fault.

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Lithofacies and eruptive conditions of the southernmost volcanoes in the world (87° S)

Bulletin of Volcanology ◽

10.1007/s00445-021-01475-y ◽

2021 ◽

Vol 83 (8) ◽

Author(s):

J. L. Smellie ◽

K. S. Panter

Keyword(s):

Volcanic Edifice ◽

Rift System ◽

The West ◽

Basal Diameter ◽

Monogenetic Volcano ◽

West Antarctic ◽

Ice Stream ◽

Free Environment ◽

West Antarctic Rift System ◽

West Antarctic Rift

AbstractNeogene volcanic centres are uncommon in the Transantarctic Mountains but at least three basaltic examples occur within 300 km of South Pole, above 2200 m asl and inland of the margin of the West Antarctic Rift System. They are the southernmost volcanoes on Earth and have yielded Early—mid Miocene isotopic ages. Two of the centres, at Mt Early and Sheridan Bluff, have been examined. The centre at Mt Early is unequivocally glaciovolcanic. It formed a tall monogenetic volcanic edifice at least 1 km high and > 1.5 km in diameter. It erupted under significantly thicker-than-modern ice, which was probably a fast-moving ice stream at the eruptive site and resulted in a distinctive constructive architecture and lithofacies. It is the first described example of a glaciovolcano erupted beneath an ice stream. The characteristics of the second centre at Sheridan Bluff indicate that it was also a monogenetic volcano but with a shield-like profile, originally c. 6 km in basal diameter but just c. 400 m high. It probably erupted in a substantial pluvial lake in an ice-poor or ice-free environment. The strongly contrasting eruptive settings now identified by the volcanic sequences at both centres examined testify to a highly dynamic Antarctic Ice Sheet during the Early—mid Miocene.

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Isochronal maps at Mt. Etna volcano (Italy): a simple and reliable tool for investigating large-scale heterogeneities

Annals of Geophysics ◽

10.4401/ag-3874 ◽

1997 ◽

Vol 40 (5) ◽

Author(s):

G. Patanè ◽

C. Centamore ◽

S. La Delfa

Keyword(s):

Large Scale ◽

Volcanic Edifice ◽

P Wave ◽

Etna Volcano ◽

Low Velocity ◽

Seismic Stations ◽

Arrival Times ◽

Mt Etna ◽

Wave Arrival ◽

Feeding Systems

This paper analyses twelve etnean earthquakes which occurred at various depths and recorded at least by eleven stations. The seismic stations span a wide part of the volcanic edifice; therefore each set of direct P-wave arrival times at these stations can be considered appropriate for tracing isochronal curves. Using this simple methodology and the results obtained by previous studies the authors make a reconstruction of the geometry of the bodies inside the crust beneath Mt. Etna. These bodies are interpreted as a set of cooled magmatic masses, delimited by low-velocity discontinuities which can be considered, at present, the major feeding systems of the volcano.

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Seismo-volcanic sources on Stromboli volcano

Annals of Geophysics ◽

10.4401/ag-3969 ◽

1996 ◽

Vol 39 (2) ◽

Author(s):

J. Neuberg ◽

R. Luckett

Keyword(s):

Detailed Analysis ◽

Particle Motion ◽

Volcanic Edifice ◽

Stromboli Volcano ◽

Eruptive Activity ◽

Strombolian Activity ◽

Video Recordings ◽

Surface Correction ◽

Steep Slopes ◽

Precise Time

A detailed analysis of broadband seismic recordings leads to models of eruption mechanisms for Strombolian activity. The data used comprise signals from arrays of nine three-component seismometers and video recordings of visual eruptive activity with precise time reference. As a major tool particle motion analysis is used to locate the seismo-volcanic sources. Here, a surface correction is employed to account for the effects of the steep slopes of the volcanic edifice. After careful filtering of the data single seismic phases can be separated and linked to corresponding eruptive features.

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Earthquake-induced debris flows at Popocatépetl Volcano, Mexico

10.5194/esurf-2020-36 ◽

2020 ◽

Author(s):

Velio Coviello ◽

Lucia Capra ◽

Gianluca Norini ◽

Norma Dávila ◽

Dolores Ferrés ◽

...

Keyword(s):

Debris Flows ◽

Horizontal Stress ◽

Structural Features ◽

Volcanic Edifice ◽

Western Slope ◽

Slope Failures ◽

Ground Shaking ◽

Seismic Records ◽

Maximum Horizontal Stress ◽

First Time

Abstract. The M7.1 Puebla-Morelos earthquake that occurred on 19 September 2017, with epicenter located ∼ 70 km SW from Popocatépetl volcano, severely hit central Mexico. Seismic shaking of the volcanic edifice induced by the earthquake triggered hundreds of shallow landslides on the volcanic flanks, remobilizing loose pyroclastic deposits and saturated soils. The largest landslides occurred on the slopes of aligned ENE-WSW-trending ravines on opposite sides of the volcanic cone, roughly parallel to the regional maximum horizontal stress and local volcanotectonic structural features. This configuration may suggest transient reactivation of local faults and extensional fractures as one of the mechanisms that has weakened the volcanic edifice and promoted the largest slope failures. The seismic records from a broadband station located at few kilometers from the main landslides are used to infer the intensity of ground shaking that triggered the slope failures. The material involved in the larger landslides, mainly ash and pumice fall deposits from late Holocene eruptions with a total volume of about 106 cubic meters, transformed into two large debris flows on the western slope of the volcano and one on its eastern side. The debris flows were highly viscous and contained abundant large woods (about 105 cubic meter). Their peculiar rheology is reconstructed by field evidences and analyzing the grain size distribution of samples from both landslide scars and deposits. This is the first time that such flows were observed at this volcano. Our work provides new insights to constrain a multi-hazard risk assessment for Popocatépetl and other continental active volcanoes.

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