Onset Of Eruption Research Articles

A Seismic Precursor 15 min Before the Giant Eruption of Hunga Tonga‐Hunga Ha'apai Volcano on 15 January 2022

AbstractThe 15 January 2022, eruption at Hunga Tonga‐Hunga Ha'apai (HTHH) volcano started shortly after 4:00UTC. There had been noted unconfirmed precursory events. We analyzed seismometer data recorded in Fiji and Futuna, the closest stations operated during the eruption and located over 750 km away. We extracted Rayleigh waves and estimated their powers and source directions, assuming retrograde particle motions. We found a Rayleigh wave from the HTHH's direction about 15 min before the eruption onset. The arrival time difference of the Rayleigh wave between the two stations was consistent with that of the M5.8 earthquake during the eruption located beneath the HTHH. Referring to other seismic signals and satellite images, we concluded that the Rayleigh wave was the most significant eruption precursor with no apparent surface activity. Including our findings and results of previous studies, we propose a scenario of the beginning of the caldera‐forming eruption.

Conduit armouring preceding explosive activity at an andesitic stratovolcano, an example from Taranaki Mounga, New Zealand

The strength and permeability of volcanic conduits can directly influence eruption dynamics via moderating the outgassing of ascending magma and the density of eruption plumes. Lithic clasts in pyroclastic ejecta can be used to understand the dynamic evolution of conduit walls because they are incorporated into the ascending melt-gas-particle mixture during volcanic eruptions. We examine the 1655 CE Burrell eruption of Taranaki Mounga, which transitioned from effusive activity to an explosive sub-Plinian phase and ended in unsteady columns. This episode was followed by a series of effusive eruptions of lower explosivity. Using textural analysis and physical properties, we distinguish five dominant lithic clast types within Burrell deposits that represent different regions of the shallow conduit and vent. Lithic types 1–3 represent juvenile (‘intrusive cognate’) and older (‘intrusive accessory’) conduit-filling plug materials. Lithic type 4 represents juvenile (‘extrusive cognate’) vent-filling lava dome extruded at the eruption onset, while Type 5 lithics (‘extrusive cognate’) represent sintered/compacted cognate material from the shallow vent accumulated during transitions in eruptive style. Crystalline andesite lithics (type 1) show a microlite-dominated groundmass. Hydrothermally altered andesite lithics (type 2) show breakdown of phenocrysts and increased seismic velocity relative to type 1 lithics. Brecciated andesite lithics (type 3) comprise fractured and sintered clasts of crystalline andesite. Glassy andesite lithics (type 4) show sub-rounded vesicles and glass-hosted microlites. Banded vitrophyre lithics (type 5) show bands of varying vesicularity, crystallinity and clast load. Physical property data reveals porosity, fracturing, sintering and alteration extent dictate dynamic changes in conduit permeability and potentially strength. Our results show how, during the explosive phase of the Burrell eruption, the conduit was lined with juvenile and remnant shallow plug material that was variably fractured, sintered and altered before being eroded and ejected. Comparison with previous work on Taranaki and dome-plug material from around the world shows how fracturing and sintering of conduit walls, combined with lining with dense juvenile material, cause overall permeability reduction and strengthening of the conduit. This inhibits outgassing and preserves conduit structure, facilitating the transition to explosive activity and the establishment of a stable eruption column.

Volcanomagnetic signals related to the 2021 Tajogaite volcanic eruption in the Cumbre Vieja rift (La Palma, Canary Islands)

After almost 50 years of quiescence, the Cumbre Vieja rift in La Palma underwent a reactivation process that culminated in the eruption of the Tajogaite volcano from September 19 to December 13, 2021. In July 2021, a magnetic station (CFU) was deployed in the western flank of the Cumbre Vieja rift, 2 km away from the site where the eruptive vents would open two months later. In September 2021, a second magnetic station (SAN) was installed near the southern end of the rift. In this paper we study two months of geomagnetic data at CFU before the eruption and three months of geomagnetic data at SAN during the eruption. The analysis of these time series revealed a magnetic signal at the CFU station with an amplitude of 10 nT and a duration of 10 days by mid-August, one month before the eruption onset. We studied possible correlations with other physical parameters (ground deformation, long-period and very-long-period seismic activity) and concluded that this signal could be related to changes in the magnetization of rocks beneath the volcanic edifice caused by magma intrusion and volcanic/hydrothermal fluids circulation preceding the eruption. At the SAN magnetic station, the time series suggests that a slight decrease in the geomagnetic field could reflect the end of the eruptive process.

Fast Downflows Observed during a Polar Crown Filament Eruption

Solar filaments can undergo eruptions that result in the formation of coronal mass ejections, which can significantly impact planetary space environments. Observations of eruptions involving polar crown filaments, situated in the polar regions of the Sun, are limited. In this study, we report a polar crown filament eruption (SOL2023-06-12), characterized by fast downflows below the filament. The downflows appear instantly after the onset of the filament eruption and persist for approximately 2 hr, exhibiting plane-of-sky velocities ranging between 92 and 144 km s−1. They originate from the leading edge of the filament, and no clear acceleration is observed. Intriguingly, these downflows appear at two distinct sites, symmetrically positioned at the opposite ends of the conjugate flare ribbons. Based on the observations, we propose that the filament might be supported by a magnetic flux rope (MFR), and these downflows possibly occur along the legs of the MFR. The downflows likely result from continuous reconnections between the MFR and the overlying magnetic field structures and could either be reconnection outflows or redirected filament materials. We also observed horizontal drifting of the locations of downflows, which might correspond to the MFR’s footpoint drifting. This type of downflow can potentially be utilized to track the footpoints of MFRs during eruptions.

Seismo‐Acoustic Characterization of the 2018 Sierra Negra Caldera Resurgence and Fissure Eruption in the Galápagos Islands

AbstractThe 2018 eruption of Sierra Negra volcano, Galápagos, Ecuador has provided new insights into the mechanisms of caldera resurgence, subsidence, and fissuring at basaltic shield volcanoes. Here, we integrate local (∼0.4 km) seismo‐acoustic records and regional (∼85 km) infrasound array data to present new observations of the 2018 Sierra Negra eruption with improved time and spatial resolutions. These observations include: air‐to‐ground coupling ∼2 hr before the time of the eruption onset, migration of the infrasound tremor from 22:54 June 26 to 12:31 June 27 UT (all times in UT), and persistent infrasound detections during the weeks between 5 July and 18 August from an area that does not coincide with the previously documented eruptive fissures. We interpret air‐to‐ground coupling as infrasound tremor generated in the nearby fissures before the main eruptive phase started, although ambiguity remains in interpreting a single seismic‐infrasonic sensor pair. The progressive location change of the infrasound tremor agrees with the migration of the eruption down the north flank of Sierra Negra at a rate of ∼0.15 ± 0.04 m/s. The weeks‐long persistent detections coincide with a region that has thermal anomalies, co‐eruptive deformation, lava fields, and geological features that could be interpreted as multiple lava tube skylights. Our observations and interpretations provide constraints on the mechanisms underlying fissure formation and magma emplacement at Sierra Negra.

Psoriasiform drug eruption: A case series with a review of the literature.

The present case series examined five instances of psoriasiform drug eruption diagnosed between 2014 and 2022 at the study site and 23 cases of drug eruption manifesting psoriasiform lesions which had been reported between 1986 and 2022. The causative drug, distribution of the skin eruptions, clinical latency to eruption, treatment course, and histopathological findings were investigated. The most common causative agents were calcium channel blockers (CCB) (64.5%). Of the 28 cases of psoriasiform drug eruption for which details of the eruption sites were reported, 46.4% occurred on the face, which was slightly higher than the usual distribution of psoriasis. CCB were responsible for 80.0% of the cases of facial skin rash. The mean time from the administration of the suspected drug to eruption onset was 25.0 months (range: 0.5-120 months; median: 13.0 months). In all the cases, the skin rash improved after the causative drug was discontinued. CCB were the most common causative agent, and the eruptions more commonly occurred on the face than in normal psoriasis, suggesting that it is especially important to confirm whether there is a history of CCB administration in psoriasis patients with extensive, facial skin eruptions.

The color systematics of volcanic ashfall samples in estimating eruption sequences: a case study of the 2017–2018 eruption at Shinmoe-dake, Kirishima volcano, Southwest Japan

The color of pyroclasts is fundamental, because it reflects various magma properties and eruption processes, including particle morphology, chemistry, and petrological characteristics. However, deriving the componentry ratio (CR) of pyroclasts for ongoing eruption monitoring remains challenging due to the lack of a robust quantitative standard. The derivation of the CR, as well as other petrological analyses, is too laborious and time-consuming to introduce as a sustainable monitoring method. To address this, we employed spectroscopic colorimetry to rapidly and quantitatively describe eruptive product colors, enabling CR derivation based on clear, objective standards for ash particle classification. Through color spectroscopy of bulk and sieved ash samples, we analyzed the major size fraction for time-series samples during the waxing stage of the 2017–2018 Shinmoe-dake eruption in Kirishima volcano, Southwest Japan. Our findings reveal that the color changes in bulk ash systematically changed with the evolution of componentry. This temporal color change was due to an increase in the amount of vesicular particles with clear glass against dark angular lava particles, as well as a grain size change, which we interpret as an indication of a transition from phreatic/phreatomagmatic to magmatic eruption. Subsequently, the color of the ash changed when the amount of different lava particles increased gradually, coinciding with a shift toward a more dominant effusion of lava. As the lava effusion continued, a slight reddening of the ash, indiscernible to the naked eye, was clearly detected by the spectrometer before the onset of intermittent Vulcanian eruptions. We interpreted this reddening as oxidation resulting from decreased ascent speed and caprock formation, which accumulates overpressure for Vulcanian explosions. These results highlight the potential of rapid, objective color value and componentry derivation for sustainable quasi-real-time monitoring of ongoing eruption materials.Graphical

Explosive eruption style modulates volcanic electrification signals

Volcanic lightning detection has proven useful to volcano monitoring by providing information on eruption onset, source parameters, and ash cloud directions. However, little is known about the influence of changing eruptive styles on the generation of charge and electrical discharges inside the eruption column. The 2021 Tajogaite eruption (La Palma, Canary Islands) provided the rare opportunity to monitor variations in electrical activity continuously over several weeks using an electrostatic lightning detector. Here we show that throughout the eruption, silicate particle charging is the main electrification mechanism. Moreover, we find that the type of electrical activity is closely linked to the explosive eruption style. Fluctuations in the electrical discharge rates are likely controlled by variations in the mass eruption rate and/or changes in the eruption style. These findings hold promise for obtaining near real-time information on the dynamic evolution of explosive volcanic activity through electrostatic monitoring in the future.

Source Region and Launch Characteristics of Magnetic-arch-blowout Solar Coronal Mass Ejections Driven by Homologous Compact-flare Blowout Jets

We study the formation of four coronal mass ejections (CMEs) originating from homologous blowout jets. All of the blowout jets originated from NOAA Active Region (AR) 11515 on 2012 July 2, within a time interval of ≈14 hr. All of the CMEs were wide (angular widths ≈ 95°–150°), and propagated with speeds ranging between ≈300 and 500 km s−1 in LASCO coronagraph images. Observations at various EUV wavelengths in Solar Dynamics Observatory/Atmospheric Imaging Assembly images reveal that in all the cases, the source region of the jets lies at the boundary of the leading part of AR 11515 that hosts a small filament before each event. Coronal magnetic field modeling based on nonlinear force-free extrapolations indicates that in each case, the filament is contained inside of a magnetic flux rope that remains constrained by overlying compact loops. The southern footpoint of each filament is rooted in the negative polarity region where the eruption onsets occur. This negative polarity region undergoes continuous flux changes, including emergence and cancellation with opposite polarity in the vicinity of the flux rope, and the EUV images reveal brightening episodes near the filament’s southeastern footpoint before each eruption. Therefore, these flux changes are likely the cause of the subsequent eruptions. These four homologous eruptions originate near adjacent feet of two large-scale loop systems connecting from that positive polarity part of the AR to two remote negative polarity regions, and result in large-scale consequences in the solar corona.

Volcanic soil gas 4He/CO2 ratio: a useful geochemical tool for real-time eruption forecasting

At many dormant volcanoes, magmatic gases are not channeled through preferential degassing routes as fumaroles and only percolate through the flanks of the volcano in a diffuse way. This type of volcanic gas emission provides valuable information, even though the soil matrix contains an important atmospheric component. This study aimed to demonstrate that chemical ratios such as He/CO2 in soil gases provide excellent information on the evolution of volcanic unrest episodes and help forecast the volcanic eruption onset. Before and during the occurrence of the October 2011–March 2012 submarine of El Hierro, Canary Islands, more than 8500 soil He analyses and diffuse CO2 emission measurements were performed. The results show that the soil He/CO2 emission ratio began increasing drastically one month before eruption onset, reaching the maximum value 10 days before. During the eruptive period, this ratio also showed a maximum value several days before the period with the highest magma emission rate. The He/CO2 ratio was also helpful in forecasting the eruption onset. We demonstrate that this tool can be applied in real-time during volcanic emergencies. Our results also encourage a reevaluation of the global He emission from the subaerial volcanism.

Negative-energy Waves in the Vertical Threads of a Solar Prominence

Solar prominences, intricate structures on the Sun’s limb, have been a subject of fascination owing to their threadlike features and dynamic behaviors. Utilizing data from the New Vacuum Solar Telescope, Chinese Hα Solar Explorer, and Solar Dynamics Observatory, this study investigates the transverse swaying motions observed in the vertical threads of a solar prominence during its eruption onset on 2023 May 11. The transverse swaying motions were observed to propagate upward, accompanied by upflowing materials at an inclination of 31° relative to the plane of the sky. These motions displayed small-amplitude oscillations with corrected velocities of around 3–4 km s−1 and periods of 13–17 minutes. Over time, the oscillations of swaying motion exhibited an increasing pattern in displacement amplitudes, oscillatory periods, and projected velocity amplitudes. Their phase velocities are estimated to be about 26–34 km s−1. An important finding is that these oscillations’ phase velocities are comparable to the upward flow velocities, measured to be around 30–34 km s−1. We propose that this phenomenon is associated with negative-energy wave instabilities, which require comparable velocities of the waves and flows, as indicated by our findings. This phenomenon may contribute to the instability and observed disruption of the prominence. By using prominence seismology, the Alfvén speed and magnetic field strength of the vertical threads have been estimated to be approximately 21.5 km s−1 and 1–3G, respectively. This study reveals the dynamics and magnetic properties of solar prominences, contributing to our understanding of their behavior in the solar atmosphere.

HLA-B*57:01-dependent intracellular stress in keratinocytes triggers dermal hypersensitivity reactions to abacavir.

Specific human leukocyte antigen (HLA) polymorphisms combined with certain drug administration strongly correlate with skin eruption. Abacavir hypersensitivity (AHS), which is strongly associated with HLA-B*57:01, is one of the most representative examples. Conventionally, HLA transmits immunological signals via interactions with T cell receptors on the cell surface. This study focused on HLA-mediated intracellular reactions in keratinocytes that might determine the onset of skin immunotoxicity by drug treatments. Abacavir exposure resulted in keratinocytes expressing HLA-B*57:01 exhibiting endoplasmic reticulum (ER) stress responses, such as immediate calcium release into the cytosol and enhanced HSP70 expression. In contrast, keratinocytes expressing HLA-B*57:03 (closely related to HLA-B*57:01) did not show these changes. This indicated that HLA-B*57:01 has a specific intracellular response to abacavir in keratinocytes in the absence of lymphocytes. Furthermore, abacavir exposure in HLA-B*57:01-expressing keratinocytes elevated the expression of cytokines/chemokines such as interferon-γ, interleukin-1β, and CCL27, and induced T lymphoblast migration. These effects were suppressed by ER stress relief using 4-phenylbutyrate (4-PB). HLA-B*57:01-transgenic mice also exhibited ER stress in epidermal areas following abacavir administration, and abacavir-induced skin toxicity was attenuated by the administration of 4-PB. Moreover, abacavir bound to HLA-B*57:01 within cells and its exposure led to HLA-B*57:01 protein aggregation and interaction with molecular chaperones in the ER of keratinocytes. Our results underscore the importance of HLA-mediated intracellular stress responses in understanding the onset of HLA-B*57:01-mediated AHS. We provide the possibility that the intracellular behavior of HLA is crucial for determining the onset of drug eruptions.

Forecasting the onset of volcanic eruptions using the increase in seismicity during magma ascent

The Failure Forecast Method (FFM) has been used to forecast the onset of volcanic eruptions with varying degrees of success. The method involves fitting its empirical equation to precursory observables, e.g., seismic data. Current models explaining the empirical equation assume that the seismic observables used (e.g., seismic event-rate, seismic moment-rate or seismic energy-rate) are related to accelerated fracture growth. In these models, such fracture growth results in an apparent increase in seismic activity. In this study, however, we propose an alternative explanation for the increase in seismicity culminating in volcanic eruptions. We suggest that the increase in seismicity, particularly in the seismic amplitudes, can result from ascending seismic sources towards the surface and that the increase can be used for eruption forecasts using the FFM. Our argument is based on the need for magma to migrate towards the surface to produce an eruption.To test our argument, we used synthetic and field/real data and fitted them with the FFM model. The synthetic data is generated using the body wave attenuation equation, and the real data is from the Piton de la Fournaise eruption on January 2nd, 2010. We used seismic amplitudes and seismic amplitude ratios as the precursory observables and used a combination of Simulated Annealing and Bayesian Inversion algorithms to obtain the best-fit parameters of the FFM model and their posterior distributions. For the synthetic cases, we found that the method gave reasonable estimates of failure or eruption time, suggesting that the seismic amplitudes and the seismic amplitude ratios can be used for forecasting using the FFM. For the field/real cases, the results gave information about the timing of magma chamber failure, magma propagation, and the eruption onset. Our results highlight an example of modelling volcano monitoring data with the FFM that gives reasonable estimates of eruption time even if the data may not fully represent failure processes. We suggest that the result may still be reasonable owing to the empirical and asymptotic nature of the FFM combined with the underlying physics of magma and seismic migrations.

Tephra dispersal and composition reveal the explosive onset of a large basaltic fissure eruption: Timanfaya, Lanzarote, 1730–1736 CE

Tephra dispersal and composition reveal the explosive onset of a large basaltic fissure eruption: Timanfaya, Lanzarote, 1730–1736 CE

Estimating volcanic ash emissions using retrieved satellite ash columns and inverse ash transport modeling using VolcanicAshInversion v1.2.1, within the operational eEMEP (emergency European Monitoring and Evaluation Programme) volcanic plume forecasting system (version rv4_17)

Abstract. Accurate modeling of ash clouds from volcanic eruptions requires knowledge about the eruption source parameters including eruption onset, duration, mass eruption rates, particle size distribution, and vertical-emission profiles. However, most of these parameters are unknown and must be estimated somehow. Some are estimated based on observed correlations and known volcano parameters. However, a more accurate estimate is often needed to bring the model into closer agreement with observations. This paper describes the inversion procedure implemented at the Norwegian Meteorological Institute for estimating ash emission rates from retrieved satellite ash column amounts and a priori knowledge. The overall procedure consists of five stages: (1) generate a priori emission estimates, (2) run forward simulations with a set of unit emission profiles, (3) collocate/match observations with emission simulations, (4) build system of linear equations, and (5) solve overdetermined systems. We go through the mathematical foundations for the inversion procedure, performance for synthetic cases, and performance for real-world cases. The novelties of this paper include a memory efficient formulation of the inversion problem, a detailed description and illustrations of the mathematical formulations, evaluation of the inversion method using synthetic known-truth data as well as real data, and inclusion of observations of ash cloud-top height. The source code used in this work is freely available under an open-source license and is able to be used for other similar applications.

Temporal evolution of roof collapse from tephra fallout during the 2021-Tajogaite eruption (La Palma, Spain)

Although dominantly effusive, the 2021 Tajogaite eruption from Cumbre Vieja volcano (La Palma, Spain) produced a wide tephra blanket over 85 days of activity. About one month after the eruption onset, clean-up operations were implemented to mitigate the impact of tephra load on primary buildings. Here, we present a post-event impact assessment of 764 primary buildings, which expands our empirical knowledge of building vulnerability to tephra fallout to include impacts from long-lasting eruptions. Field observations are analyzed in the perspective of existing fragility curves, high-resolution satellite imagery and a reconstruction of the spatio-temporal evolution of the tephra blanket to characterize the evolution of roof collapse due to static loads over time. Thanks to a chronological correlation between the temporal evolution of tephra sedimentation and the timing of clean-up operations, we quantified their effectiveness in mitigating roof collapse. If no clean-up measures had been taken 11% of the surveyed buildings would have exceeded a 75% probability of roof collapse, while only 10 roof collapses have been observed (1.3% of the analysed buildings). This work provides key insights for further development of emergency plans for the management of long-lasting eruptions characterised by the sustained emission of tephra over weeks to months.

Atmospheric resonant oscillations by the 2022 January 15 eruption of the Hunga Tonga–Hunga Ha'apai volcano from GNSS-TEC observations

SUMMARY Continuous Plinian eruptions often excite atmospheric modes of ∼3.7 and ∼4.4 mHz, which are observed as harmonic oscillations of ionospheric total electron content (TEC) by global navigation satellite system (GNSS) receivers. Such TEC oscillations started shortly after the great eruption of the Hunga Tonga–Hunga Ha'apai (HTHH) submarine volcano at ∼4:14 UT, on 2022 January 15. Here I analyse GNSS data at stations within ∼4000 km from the volcano to study temporal and spatial distribution of such atmospheric modes. Strong ∼3.7 mHz TEC oscillations in near fields started shortly after the eruption onset and propagated outward with the sound speed from HTHH. Later such TEC oscillations became strong again with the amplitude peak at the distance ∼1400 km from HTHH. Such far field oscillations occurred also above New Zealand and the Solomon Islands, ∼3000 km from HTHH. Their amplitudes seem correlated with those of the 0S29 solid earth mode, suggesting that vertical surface vibrations underneath may play a role in maintaining the atmospheric mode. Onset of the far field TEC oscillations are synchronized with the local sunrise, possibly controlled by diurnal changes in the ionospheric electron density.

Geodetic imaging of magma ascent through a bent and twisted dike during the Tajogaite eruption of 2021 (La Palma, Canary Islands)

On Sept. 19th, 2021, the largest historical eruption on the island of La Palma began, which had a significant scientific, social, and economic impact. The 2021 Tajogaite eruption was characterised by short precursors, lasting only 8 days. The seismicity started on Sept. 11th with a westward and upward migration of hypocenters. Permanent GNSS stations started recording deformation on Sept. 12th on the island's western side, which reached more than 15 cm just before the eruption. After the eruption onset, the ground deformation increased, reaching a maximum on Sept. 22nd and showing a nearly steady deflation trend in the following months. To better understand the dynamics of the eruption, we exploited a joint dataset of GNSS and Sentinel-1 SBAS time series along both ascending and descending orbits. To obtain the geometry of the causative source of the ground deformation, we combined the result of a preliminary non-linear inversion and the precise location of the seismicity. The resulting geometry of the source is that of a twisted dike bending eastward. We performed inverse modelling to obtain the spatiotemporal kinematics of the opening function of the dike. The forward modelling has been realised using a 3D finite-element approach considering the island's topography. Our findings reveal a close correspondence between the magmatic intrusion and pre-eruptive seismicity. The ascent of the magma occurred along two branches, and the rheology of a previously identified ductile layer strongly affected the magma propagation process. Finally, we found evidence of an early shallow deformation, which we interpret as the effect of ascending hydrothermal fluids. Our findings highlight the need for advanced modelling to understand pre-eruptive processes in basaltic volcanoes.

A Double-decker Flux Rope Model for the Solar Eruption on 2012 March 10

We present a magnetic configuration of a compound solar eruption observed on 2012 March 10, from NOAA AR 11429 near the disk center, which displayed a soft X-ray sigmoid before the eruption. We constructed a series of magnetic field models, including double-decker flux rope configurations, using the flux rope insertion method. This produces three-dimensional coronal magnetic field models constrained by the photospheric magnetogram and observed EUV coronal structures. We used different combinations of flux rope paths. We found that two flux ropes sharing the same path at different heights quickly experience a partial merging in the initial iteration of the magnetofrictional relaxation process. Different paths with less than 30% overlap allowed us to construct stable double-decker structures. The high spatial and temporal resolution of the Solar Dynamics Observatory/Atmospheric Imaging Assembly facilitated the selection of a best-fit model that matches the observations best. Moreover, by varying fluxes in this validated nonlinear force-free field double-decker configuration, we successfully reproduce all three scenarios of eruptions of double-decker configurations: (i) eruption due to the instability of higher flux rope; (ii) eruption due to rising lower flux rope and merging with higher flux rope; and (iii) eruption due to the instability of both flux ropes. This demonstrates that magnetofrictional simulation can capture the large-scale magnetic structure of eruptions for a realistic field configuration at eruption onset.

Plutonic Nature of a Transcrustal Magmatic System: Evidence from Ultrahigh Resolution Sr-Disequilibria in Plagioclase Microantecrysts from the Southern Taupo Volcanic Zone, New Zealand

Abstract The residence timescales of antecrystic minerals contribute a key piece of information regarding the petrologic evolution of transcrustal magmatic systems and may be inferred using a combination of observations derived from microanalytical chemistry and diffusion modelling. Here, we present state-of-the-art stacked CMOS-type active pixel sensor (SCAPS) isotopographic images of tephra-hosted plagioclase microantecrysts from Tongariro Volcanic Centre in the southern Taupo Volcanic Zone, New Zealand. These crystals exhibit high-frequency Sr and anorthite zonation at sub-micron spatial resolution. We also find that all crystals display high-frequency intracrystalline Sr chemical potential variations, indicating that they have not resided at magmatic temperature for diffusive relaxation to advance significantly. To quantify crystal residence times at the well-constrained magmatic temperatures of these tephras, we first forward-modeled intracrystalline Sr diffusion over time using numerical methods. Results were then analyzed using novel spatial Fourier-transform techniques developed to understand the systematics the diffusive decay of Sr disequilibria in the spatial frequency domain. This ultimately permitted the estimation of Sr concentration profiles at crystal formation, prior to uptake into the carrier melt at the onset of eruption. Our data imply residence times of hours to days for the studied microantecrysts. This is inconsistent with long antecryst residence times in magmatic mushes at elevated temperatures, pointing instead to a cool plutonic nature of the magmatic plumbing system beneath the southern Taupo Volcanic Zone.