Video camera and seismic monitoring of water bulge explosion at Strokkur Geyser, Iceland (original) (raw)
Related papers
Eruptions at Lone Star geyser, Yellowstone National Park, USA: 2. Constraints on subsurface dynamics
Journal Of Geophysical Research: Solid Earth, 2014
We use seismic, tilt, lidar, thermal, and gravity data from 32 consecutive eruption cycles of Lone Star geyser in Yellowstone National Park to identify key subsurface processes throughout the geyser's eruption cycle. Previously, we described measurements and analyses associated with the geyser's erupting jet dynamics. Here we show that seismicity is dominated by hydrothermal tremor (~5-40 Hz) attributed to the nucleation and/or collapse of vapor bubbles. Water discharge during eruption preplay triggers high-amplitude tremor pulses from a back azimuth aligned with the geyser cone, but during the rest of the eruption cycle it is shifted to the east-northeast. Moreover,~4 min period ground surface displacements recur every 26 ± 8 min and are uncorrelated with the eruption cycle. Based on these observations, we conclude that (1) the dynamical behavior of the geyser is controlled by the thermo-mechanical coupling between the geyser conduit and a laterally offset reservoir periodically filled with a highly compressible two-phase mixture, (2) liquid and steam slugs periodically ascend into the shallow crust near the geyser system inducing detectable deformation, (3) eruptions occur when the pressure decrease associated with overflow from geyser conduit during preplay triggers an unstable feedback between vapor generation (cavitation) and mass discharge, and (4) flow choking at a constriction in the conduit arrests the runaway process and increases the saturated vapor pressure in the reservoir by a factor of~10 during eruptions.
Nature Communications, 2015
Effusive eruptions are explained as the mechanism by which volcanoes restore the equilibrium perturbed by magma rising in a chamber deep in the crust. Seismic, ground deformation and topographic measurements are compared with effusion rate during the 2007 Stromboli eruption, drawing an eruptive scenario that shifts our attention from the interior of the crust to the surface. The eruption is modelled as a gravity-driven drainage of magma stored in the volcanic edifice with a minor contribution of magma supplied at a steady rate from a deep reservoir. Here we show that the discharge rate can be predicted by the contraction of the volcano edifice and that the very-long-period seismicity migrates downwards, tracking the residual volume of magma in the shallow reservoir. Gravity-driven magma discharge dynamics explain the initially high discharge rates observed during eruptive crises and greatly influence our ability to predict the evolution of effusive eruptions.
The fluid mechanics inside a volcano
2007
The style and evolution of volcanic eruptions are dictated by the fluid mechanics governing magma ascent. Decompression during ascent causes dissolved volatile species, such as water and carbon dioxide, to exsolve from the melt to form bubbles, thus providing a driving force for the eruption. Ascent is influenced not only by the nucleation and growth of gas bubbles, but also magma rheology and brittle deformation (fragmentation). In fact, all processes and magma properties within the conduit interact and are coupled. Ultimately, it is the ability of gas trapped within growing bubbles to expand or to be lost by permeable gas flow, which determines whether ascending magmas can erupt nonexplosively. We review and integrate models of the primary conduit processes to show when each process or property dominates and how these interact within a conduit. In particular, we illustrate how and why ascent rate may control eruptive behavior: slowly ascending magmas erupt effusively and rapidly ascending magmas erupt explosively.
Bulletin of Volcanology
Cyclic behaviour is observed in volcanic phenomena ranging from caldera collapses to explosions, spattering or lava fountaining. The repeating processes can define irregular, regular or systematically changing patterns. These patterns yield information about the subsurface structure, which often is not considered in detail. We analyse the pattern of 7058 lava fountaining episodes that occur between 2 May and 14 June 2021 during the Geldingadalir eruption, Iceland. Our seismometer records the lava fountaining episodes as tremor episodes. We analyse the seismic tremor amplitude, the episode duration, the repose time and the sum of episode duration and repose time (cycle duration). We define six periods characterised by different patterns: Three periods feature long episodes that exponentially shorten with time. One period features coexisting long and short episodes in a haphazard sequence. One period shows a stable pulsing duration but increasing repose time, and one period has stable...
Seismic triggering of eruptions in the far field: volcanoes and geysers
2006
Approximately 0.4% of explosive volcanic eruptions occur within a few days of large, distant earthquakes. This many "triggered" eruptions is much greater than expected by chance. Several mechanisms have been proposed to explain triggering through changes in magma overpressure, including the growth of bubbles, the advection of large pressures by rising bubbles, and overturn of magma chambers. Alternatively, triggered eruptions may occur through failure of rocks surrounding stored magma. All these mechanisms require a process that enhances small static stress changes caused by earthquakes or that can convert (the larger) transient, dynamic strains into permanent changes in pressure. All proposed processes, in addition to viscoelastic relaxation of stresses, can result in delayed triggering of eruptions, although quantifying the connection between earthquakes and delayed, triggered eruptions is much more challenging. Mud volcanoes and geysers also respond to distant earthquakes. Mud volcanoes that discharge mud from depths greater than many hundreds of meters may be triggered by liquefaction caused by shaking, and may thus be similar to small mud volcanoes that originate within a few meters of the surface. Changes in permeability of the matrix surrounding main geyser conduits, by opening or creating new fractures, may explain the observed changes in their eruption frequency. 263 Annu. Rev. Earth Planet. Sci. 2006.34:263-291. Downloaded from arjournals.annualreviews.org by University of California -Santa Cruz on 08/01/06. For personal use only. www.annualreviews.org • Triggered Eruptions 265 Annu. Rev. Earth Planet. Sci. 2006.34:263-291. Downloaded from arjournals.annualreviews.org by University of California -Santa Cruz on 08/01/06. For personal use only. 266 Manga · Brodsky Annu. Rev. Earth Planet. Sci. 2006.34:263-291. Downloaded from arjournals.annualreviews.org by University of California -Santa Cruz on 08/01/06. For personal use only. www.annualreviews.org • Triggered Eruptions 267 Annu. Rev. Earth Planet. Sci. 2006.34:263-291. Downloaded from arjournals.annualreviews.org by University of California -Santa Cruz on 08/01/06. For personal use only. www.annualreviews.org • Triggered Eruptions 277 Annu. Rev. Earth Planet. Sci. 2006.34:263-291. Downloaded from arjournals.annualreviews.org by University of California -Santa Cruz on 08/01/06. For personal use only.
The evolution of volcanic plume morphology in short-lived eruptions
Geology, 2015
The details of volcanic plume source conditions or internal structure cannot readily be revealed by simple visual images or other existing remote imaging techniques. For example, one predominant observable quantity, the spreading rate, in steady or quasisteady volcanic plumes is independent of source buoyancy flux. However, observable morphological features of short-duration unsteady plumes appear to be strongly controlled by volcanic source conditions, as inferred from recent work in Chojnicki et al. [2014b]. Here we present a new technique for using simple morphological evolution to extract the temporal evolution of source conditions of short-lived unsteady eruptions. In particular, using examples from Stromboli and Santiaguito volcanoes, we illustrate simple morphologic indicators of a) increasing source injection during the early phase of an eruption; b) onset of source injection decline; and c) the timing of source injection cessation. Combined, these indicators allow estimation of changes in eruption discharge rate, injection duration, and may assist in estimating total mass erupted for a given event. In addition, we show how morphology may provide clues about the vertical mass distribution in these plumes, which could be important for predicting ash dispersal patterns.
Seismogenic magma intrusion before the 2010 eruption of Eyjafjallajökull volcano, Iceland
Geophysical Journal International, 2014
We present relatively relocated earthquake hypocentres for >1000 microearthquakes (M L < 3) that occurred during the 2 weeks immediately prior to the 2010 March 20 fissure eruption at Fimmvör uháls on the flank of Eyjafjallajökull volcano in Iceland. Our hypocentre locations lie predominantly in horizontally separated clusters spread over an area of 10 km 2 and approximately 4 km below sea level (5 km below the surface). Seismic activity in the final 4 d preceding the eruption extended to shallower levels <2 km below sea level and propagated to the surface at the Fimmvör uháls eruption site on the day the eruption started. We demonstrate using synthetic data that the observed apparent ∼1 km vertical elongation of seismic clusters is predominantly an artefact caused by only small errors (0.01-0.02 s) in arrival time data. Where the signal-to-noise ratio was sufficiently good to make subsample arrival time picks by cross-correlation of both P-and S-wave arrivals, the mean depth of 103 events in an individual cluster were constrained to 3.84 ± 0.06 km. Epicentral locations are significantly less vulnerable to arrival time errors than are depths for the seismic monitoring network we used. Within clusters of typically 100 recorded earthquakes, most of the arrivals exhibit similar waveforms and identical patterns of P-wave first-motion polarities across the entire monitoring network. The clusters of similar events comprise repetitive sources in the same location with the same orientations of failure, probably on the same rupture plane. The epicentral clustering and similarity of source mechanisms suggest that much of the seismicity was generated at approximately static constrictions to magma flow in an inflating sill complex. These constrictions may act as a form of valve in the country rock, which ruptures when the melt pressure exceeds a critical level, then reseals after a pulse of melt has passed through. This would generate recurring similar source mechanisms on the same weak fault plane as the connection between segments of the sill system is repeatedly refractured in the same location. We infer that the magmatic intrusion causing most of the seismicity was likely to be a laterally inflating complex of sills at about 4 km depth, with seismogenic pinch-points occurring between aseismic compartments of the sills, or between adjacent magma lobes as they inflated. During the final 4 d preceding the eruption onset between 22:30 and 23:30 UTC on 2010 March 20, the seismicity suggests that melt progressed upwards to a depth of ∼2 km. This seismicity was probably caused by fracturing of the country rock at the margins of the propagating dyke. Subsequently, on the morning of the eruption a dyke propagated eastward from the region of precursory seismic activity to the Fimmvör uháls eruption site.
Volcanotectonics: the tectonics and physics of volcanoes and their eruption mechanics
Bulletin of Volcanology, 2022
The physical processes that operate within, and beneath, a volcano control the frequency, duration, location, and size of volcanic eruptions. Volcanotectonics focuses on such processes, combining techniques, data, and ideas from structural geology, tectonics, volcano deformation, physical volcanology, seismology, petrology, rock and fracture mechanics, and classical physics. A central aim of volcanotectonics is to provide sufficient understanding of the internal processes in volcanoes so that, when combined with monitoring data, reliable forecasting of eruptions, vertical (caldera) and lateral (landslide) collapses and related events becomes possible. To gain such an understanding requires knowledge of the material properties of the magma and the crustal rocks, as well as the associated stress fields, and their evolution. The local stress field depends on the properties of the layers that constitute the volcano and, in particular, the geometric development of its shallow magma chamber. During this decade an increasing use of data from InSAR, pixel offset, and structure-from-motion, as well as dense, portable seismic networks will provide further details on the mechanisms of volcanic unrest, magma-chamber rupture, the propagation of magmafilled fractures (dikes, inclined sheets, and sills), and lateral and vertical collapse. Additionally, more use will be made of accurate quantitative data from fossil and active volcanoes, combined with realistic numerical, analytical, and machine-learning studies, so as to provide reliable models on volcano behaviour and eruption forecasting.