Eruption Height Research Articles

Research on the thermal runaway mechanism and eruption flame dynamics of NCM811 lithium-ion battery stimulated by the coupling abuse of heat and penetration

Thermal abuse and mechanical abuse are the main triggers of thermal runaway (TR) in lithium-ion batteries (LIBs). With the emergence of stimulus superposition application scenarios makes the TR mechanism of LIBs under a single stimulus no longer applicable, and the TR characteristics of LIBs induced by heat-penetration coupled stimulation has become one of the key bottlenecks constraining the intrinsic safety design and control of LIBs. In this paper, an experimental platform for heat-penetration coupled stimulation on LIBs was built, and an experimental research on the TR mechanism and eruption dynamics of LIBs under penetration with different initial thermal load was carried out. The results show that the maximum temperature of cell induced by penetration increases from 537.4 °C to 746 °C, an increase of 38.8 %, as the initial thermal load of the cell increases from 10 °C to 130 °C. When the initial thermal load is further increased to 160 °C, the penetration stimulation no longer induces TR, which is closely related to the “separator melt protection channel”. Based on this, a “kebab” micro-short circuit model is proposed. At 10 °C, 40 °C, 70 °C, and 100 °C, the cell safety valve is destroyed and a “column fire” is formed above the positive electrode. And at 100 °C, the flame eruption height is the largest, up to 185.10 cm, and the jet flame area is the largest, up to 5687.62 cm2.And with the initial thermal load increases, the eruption particles are smaller in size. Increasing content of O in eruption particles, which characterizes the strength of the reaction within the cell, and F elements characterizing toxicity are detected in the eruption particles. The results enrich the theory of TR induced by thermal–mechanical abuse, which is of great guiding significance for the intrinsic safety design of LIBs and the prevention and control of TR risk.

Video camera and seismic monitoring of water bulge explosion at Strokkur Geyser, Iceland

Eruptions of volcanoes and geysers share many fundamental similarities: for example, they are manifestations of Earth’s geothermal energy, involving the pressure-driven expulsion of fluids from the Earth’s interior. However, while volcanoes can produce spectacular lava bubbles that burst, water bubbles are rarely observed on the surface of geysers. It is still unclear why some of these low-viscosity geyser systems produce none, while others produce them regularly. There is no quantification of the size, speed, and height of these bubbles at geysers, which is the gap we fill here. Strokkur creates a water bulge in its surface pool (bulge stage). When the bulge bursts, water is ejected into the air (jet stage). The steam then continues to rise buoyantly and drift away (drift stage). Here we study the evolution of the three stages using records from video camera campaigns and a local seismic network. We find that larger bulges are associated with larger ascent velocities and cause larger jet heights. As energy is channeled into a high jet, small seismic ground motions are recorded. The bulge formation itself is barely visible seismically. Our work suggests that the 0.74±0.27 s-long bulge stage can be used as a first-order proxy for predicting eruption height. This study might also be relevant for understanding fluid dynamics in volcanic systems.

A cross-sectional study on three-dimensional compensatory characteristics of maxillary teeth in patients with different types of skeletal Class III malocclusion with mandibular asymmetry.

The purpose of this study was to analyze three-dimensional dental compensation in patients with different types of skeletal Class III malocclusion with mandibular asymmetry, using cone-beam computed tomography (CBCT) and three-dimensional reconstruction measurement technology, thereby providing clinical guidance and reference for combined orthodontic and orthognathic treatment. 81 patients with skeletal Class III malocclusion with mandibular asymmetry were selected in accordance with the inclusion criteria. According to a new classification method based on the direction and amount of menton deviation relative to ramus deviation, patients were divided into three groups called Type 1, Type 2, and Type 3. In Type 1, the direction of menton deviation was consistent with that of ramus deviation and the amount of menton deviation was greater than that of ramus deviation. In Type 2, the direction of menton deviation was consistent with that of ramus deviation and the amount of menton deviation was smaller than that of ramus deviation. In Type 3, the direction of menton deviation was inconsistent with that of ramus deviation. The maxillary occlusal plane (OP), anterior occlusal plane (AOP), and posterior occlusal plane (POP) were measured on reconstructed CBCT images. The vertical, transverse, and anteroposterior distances from maxillary teeth to reference planes and the 3D angles between the long axis of these teeth and reference planes were measured. These dental variables measured from the deviated and non-deviated sides were compared within each group, as well as among each other. Of the 81 patients with asymmetrical Class III malocclusion, 52 patients were categorized in Type 1, 12 patients in Type 2, and 17 patients in Type 3. There were significant differences between deviated and non-deviated sides in Type 1 and Type 3 (p < 0.05). In Type 1, the vertical distances of maxillary teeth on the deviated side were lower than those on the non-deviated side, and AOP, OP, and POP on the deviated side were larger than those on the non-deviated side (p < 0.05). In Type 3, the vertical distances of the maxillary teeth on the deviated side were lower (p < 0.05), and the AOP and OP on the deviated side were larger than those on the non-deviated side. In all three groups, the transverse distances of the maxillary teeth from the mid-sagittal plane on the deviated side were larger than those on the non-deviated side (p < 0.05), and the angles between the long axis of maxillary teeth and the mid-sagittal plane on the deviated side were larger, respectively (p < 0.05). The maxillary teeth on the deviated side were observed to have smaller eruption heights in Type 1 and Type 3. In Type 1, AOP, POP, and OP were greater on the deviated side, while in Type 3, only AOP and OP were greater on the deviated side. The maxillary teeth of patients in all three groups on the deviated side were buccal and buccally inclined. Larger sample observations are still needed to further verify these findings.

Investigation of two-phase jet flow from a degassing pipe used for a lake with potential gas-driven eruption

Gas-driven limnic eruption can happen in a lake with an aqueous gas solution that becomes supersaturated due to some reason. In this case, the exsolution of massive gases dissolved in the water could occur in a very short time, resulting in a disaster as happened in the Lake Nyos (Cameroon, Africa) in 1986. Using degassing pipe to artificially release the dissolved gases is a good way to minimize the risk of an eruption. In this study, a transient multi-component gas-liquid two-phase flow model of the degassing pipe used in Lake Nyos has been established and verified with the observed eruption data. The drift flux model has been used for modelling of a transient multi-component gas-liquid flow formed due to the spontaneous exsolution of gases dissolved in the water inside the degassing pipe. The governing equations for the mechanistic drift model include continuity equation for each phase, a single momentum equation for a homogeneous mixture of the fluid, constitutive equations for mass transfer rates between the phases, and the drift velocity formulas. The model considered not only CO2 but also CH4 as dissolved gases. The “chain reaction” conjecture predicted to have the degassing-point migrating downward with time during the transient degassing process is verified by using this model. The relationship between the eruption height and the CO2 concentration at the bottom of the degassing pipe has been simulated in detail. This relationship supplies people with a quick and convenient way to estimate the CO2 concentration in the lake, based on which one can evaluate the risk of lake eruption and hence to formulate or adjust the degassing plan. In addition, the effects of diameter and equivalent roughness of the degassing pipe on the eruption height has been investigated. Meanwhile, the eruption height upper-limit in different lake-depth scenarios has also been determined. Finally, the role of CH4 component in the degassing process has been analyzed. Although the influence of CH4 on eruption height can be neglected in Lake Nyos' case, CH4 as a dissolved gas plays an important role at Lake Kivu. The multi-component gas-liquid flow model developed in this study is useful to study the role of CH4 in the degassing process.

Effects of idiopathic hypoparathyroidism on tooth eruption of rats

Objective: To explore the effects of reduced parathyroid function in early growth and development on tooth eruption and enamel development by establishing an animal model of idiopathic hypoparathyroidism (IHP) and to explore the mechanism of IHP affecting tooth eruption with a view to provide experimental basis for early diagnosis and clinical treatment of IHP. Methods: Forty-eight SD rats at postnatal day 7 were randomly and equally divided into sham operation group and IHP group. The bilateral parathyroidectomy (PTX) was performed by using carbon nanoparticles technique to establish an IHP rat model, while no parathyroids were removed in the sham operation group using the same technique. Serum was extracted after surgery, serum calcium, serum phosphorus, and serum parathyroid hormone (PTH) concentrations were detected in order to verify the success of the modeling. At postnatal day 14, day 25 and day 38 (P14, P25 and P38) the rats were sacrificed to collect the mandible samples (six from each group) and to analyze the volume of enamel, the height of the tooth eruption and the bone microarchitecture parameters of the root-oriented alveolar bone of mandibular third molar quantitatively by micro-CT scanning. Histological sections were prepared. The distribution and expression levels of osteoblast differentiation markers runt-related transcription factor 2 (RUNX2) and osterix (OSX) in the alveolar bone around the third molar were detected by immunohistochemical staining and the osteoclast activity was detected by tartrate-resistant acid phosphatase (TRAP) staining. After each of the third molars was isolated, the microhardness of the enamel was measure by using a microhardness tester and the enamel microstructure was photographed by using scanning electron microscope. Primary dental follicle stem cells were isolated from other six mandibulars from each group at P14 and cultured in vitro. The cell proliferation activity was tested by cell colony forming units detection. After induction of dental follicle stem cells into osteogenic differentiation, the degree of mineralization was detected by using alkaline phosphatase staining and alizarin red staining. The mRNA of mandibular tissues and dental follicle cells were extracted, the expression of genes related to osteoblasts and osteoclast differentiations and parathyroid hormone receptor 1 (PTH1R) were detected by real-time quantitative PCR. Results: Bilateral parathyroidectomy was successfully performed on rats with the help of carbon nanoparticles under stereomicroscope. After surgery, the serum calcium concentration reduced, the serum phosphorus concentration increased and the serum PTH concentration distinctly reduced (P<0.01). The volume of enamel [(4.58±0.24) mm3] and the microhardness [(167.76±21.86) MPa] in IHP group were significantly lower than that in sham operation group [(5.22±0.46) mm3, P<0.05; (223.92±10.94) MPa, P<0.01, respectively]. The eruption height of the mandibular third molar in the IHP group was respectively lower than that in the sham operation group (P<0.05). The bone volume over total volume and trabecular number of the root-oriented alveolar bone of the mandibular third molars in the IHP group were respectively lower than that in sham operation group (P<0.05). The expression levels of RUNX2 and OSX proteins in the root-oriented alveolar bone of the mandibular third molars in the IHP group respectively reduced, compared to that in sham operation group (P<0.05). Furthermore, the number of osteoclasts (3.86±1.07) in crown-oriented alveolar bone in the IHP group was respectively lower than that in sham operation group (6.43±1.27) (P<0.01). The proliferative activity of dental follicle stem cells in the IHP group respectively decreased (P<0.01). After the induction of osteogenic differentiation, the mineralization ability of dental follicle stem cells in the IHP group was weakened. In the mandibular tissues of IHP group, the expression levels of osteogenesis related genes such as RUNX2 and OSX and the the expression of PTH1R significantly reduced (P<0.05). The receptor activator of nuclear factor-κB ligand/osteoprotegerin (RANKL/OPG) ratio reduced significantly (P<0.01) compared to those of sham operation group. Also in the dental follicle cells of IHP group, the expression levels of osteogenesis related genes such as RUNX2 and OSX, the RANKL/OPG ratio and the expression of PTH1R significantly decreased simultaneously compared to that in sham operation group (P<0.01). Conclusions: Under the condition of idiopathic hypoparathyroidism, the weakening of PTH/PTH1R signaling may reduce the proliferative activity of dental follicle stem cells, inhibit their regulation for osteoblast and osteoclast differentiations and functions, thereby interfere the bone remodeling of alveolar bone around the tooth germ during tooth eruption, which eventually leads to delayed tooth eruption.

Magnetofrictional Modeling of an Erupting Pseudostreamer

Abstract In this study, we present the magnetic configuration of an erupting pseudostreamer observed on 2015 April 19, on the southwest limb of the Sun, with a prominence cavity embedded inside. The eruption resulted in a partial halo coronal mass ejection. The prominence eruption begins with a slow rise and then evolves to a fast-rise phase. We analyze this erupting pseudostreamer using the flux-rope insertion method and magnetofrictional relaxation to establish a sequence of plausible out-of-equilibrium magnetic configurations. This approach allows the direct incorporation of observations of structures seen in the corona (filament and cavity) to appropriately model the pseudostreamer based on SDO/HMI line-of-sight photospheric magnetograms. We also perform a topological analysis in order to determine the location of quasiseparatrix layers (QSLs) in the models, producing Q-maps to examine how the QSL locations progress in the higher iterations. We found that the axial flux in our best-fit unstable model was a factor of 20 times higher than we found in our marginally stable case. We computed the average magnetic field strength of the prominence and found that the unstable model exhibits twice the average field strength of the stable model. The eruption height from our modeling matches very well with the prominence eruption height measured from the AIA observation. The Q-maps derived from the model reproduce structures observed in LASCO/C2. Thus, the modeling and topological analysis results are fully consistent with the observed morphological features, implying that we have captured the large magnetic structure of the erupting filament in our magnetofrictional simulation.

The 2018 reawakening and eruption dynamics of Steamboat Geyser, the world’s tallest active geyser

Steamboat Geyser in Yellowstone National Park's Norris Geyser Basin began a prolific sequence of eruptions in March 2018 after 34 y of sporadic activity. We analyze a wide range of datasets to explore triggering mechanisms for Steamboat's reactivation and controls on eruption intervals and height. Prior to Steamboat's renewed activity, Norris Geyser Basin experienced uplift, a slight increase in radiant temperature, and increased regional seismicity, which may indicate that magmatic processes promoted reactivation. However, because the geothermal reservoir temperature did not change, no other dormant geysers became active, and previous periods with greater seismic moment release did not reawaken Steamboat, the reason for reactivation remains ambiguous. Eruption intervals since 2018 (3.16 to 35.45 d) modulate seasonally, with shorter intervals in the summer. Abnormally long intervals coincide with weakening of a shallow seismic source in the geyser basin's hydrothermal system. We find no relation between interval and erupted volume, implying unsteady heat and mass discharge. Finally, using data from geysers worldwide, we find a correlation between eruption height and inferred depth to the shallow reservoir supplying water to eruptions. Steamboat is taller because water is stored deeper there than at other geysers, and, hence, more energy is available to power the eruptions.

Spatiotemporal variations in eruption style and magnitude at Yasur volcano, Vanuatu: part 2—extending Strombolian eruption classifications

In this companion study to Simons et al. (Bull Volcanol 82, 2020a), we examine Strombolian style explosive activity at Yasur (Vanuatu) over 11 weeks via seismic, thermal-infrared and visual observations. In part 1 of this study (Simons et al., Bull Volcanol 82, 2020a), we investigated the link between variations in the surface expression and style of volcanism at Yasur in relation to vent, shallow conduit and shallow magma reservoir processes. Now, in part 2, based on the database of 4998 explosions, we describe, define and classify Yasur’s Strombolian eruption styles and magnitudes, and compare and contrast to Stromboli and other similar centres. The styles of most of Yasur’s explosions fit with other known Strombolian eruptions, but they are 2–3 times more frequent and with higher average eruption heights than at Stromboli. Observed activity at Yasur also produced more ash than at Stromboli. The most powerful eruptive periods are dominated by type 2a explosions (ballistics and ash) and type 2b (ash-dominated) explosions. A new type of Strombolian style explosion was observed at Yasur and is here termed a type 3 explosion. They occur when vents are buried by a thick cap of loose, poorly sorted pyroclastic breccia. Type 3 explosions begin as a series of emergent ash-rich jets that rupture and fountain from the breccia cover, generating prolonged jetting of ash to form vigorous low plumes. The loose breccia cover apparently dissipates the violent early phase of the explosion. The greatest hazard of type comes from their occurrence with little warning from a smooth crater floor without an apparent vent and after longer than typical intervals between eruptions. The findings extend the observed range of Strombolian explosion styles and imply that surficial vent cover and burial may influence gas slug stability and contribute to variations in ash and ballistic output.

Using Satellite Data to Determine Empirical Relationships between Volcanic Ash Source Parameters

Poor knowledge of dispersion model source parameters related to quantities such as the total fine ash mass emission rate, its effective spatial distribution, and particle size distribution makes the provision of quantitative forecasts of volcanic ash a difficult problem. To ameliorate this problem, we make use of satellite-retrieved mass load data from 14 eruption case studies to estimate fine ash mass emission rates and other source parameters by an inverse modelling procedure, which requires multidimensional sampling of several thousand trial simulations with different values of source parameters. We then estimate the dependence of these optimal source parameters on eruption height. We show that using these empirical relationships in a data assimilation procedure leads to substantial improvements to the forecasts of ash mass loads, with the use of empirical relationships between parameters and eruption height having the added advantage of computational efficiency because of dimensional reduction. In addition, the use of empirical relationships, which encode information in satellite retrievals from past case studies, implies that quantitative forecasts can still be issued even when satellite retrievals of mass load are not available in real time due to cloud cover or other reasons, making it especially useful for operations in the tropics where ice and water clouds are ubiquitous.

Operational Modelling of Umbrella Cloud Growth in a Lagrangian Volcanic Ash Transport and Dispersion Model

Large explosive eruptions can result in the formation of an umbrella cloud which rapidly expands, spreading ash out radially from the volcano. The lateral spread by the intrusive gravity current dominates the transport of the ash cloud. Hence, to accurately forecast the transport of ash from large eruptions, lateral spread of umbrella clouds needs to be represented within volcanic ash transport and dispersion models. Here, we describe an umbrella cloud parameterisation which has been implemented into an operational Lagrangian model and consider how it may be used during an eruption when information concerning the eruption is limited and model runtime is key. We examine different relations for the volume flow rate into the umbrella, and the rate of spreading within the cloud. The scheme is validated against historic eruptions of differing scales (Pinatubo 1991, Kelud 2014, Calbuco 2015 and Eyjafjallajökull 2010) by comparing model predictions with satellite observations. Reasonable predictions of umbrella cloud spread are achieved using an estimated volume flow rate from the empirical equation by Bursik et al. and the observed eruption height. We show how model predictions can be refined during an ongoing eruption as further information and observations become available.

A three-dimensional analysis of primary failure of eruption in humans and mice.

Primary failure of eruption (PFE) is a genetic disorder exhibiting the cessation of tooth eruption. Loss-of-function mutations in parathyroid hormone (PTH)/parathyroid hormone-related peptide (PTHrP) receptor (PTH/PTHrP receptor, PPR) were reported as the underlying cause of this disorder in humans. We showed in a PFE mouse model that PTHrP-PPR signaling is responsible for normal dental follicle cell differentiation and tooth eruption. However, the mechanism underlying the eruption defect in PFE remains undefined. In this descriptive study, we aim to chronologically observe tooth eruption and root formation of mouse PFE molars through 3D microCT analyses. Two individuals with PFE were recruited at Showa University. A mouse PFE model was generated by deleting PPR specifically in PTHrP-expressing dental follicle and divided into three groups, PPRfl/fl ;R26RtdTomato/+ (Control), PTHrP-creER;PPRfl/+ ;R26RtdTomato/+ (cHet), and PTHrP-creER;PRRfl/fl ;R26RtdTomato/+ (cKO). Images from human PFE subjects were acquired by CBCT. All groups of mouse samples were studied at postnatal days 14, 25, 91, and 182 after a tamoxifen pulse at P3, and superimposition of 3D microCT images among three groups was rendered. Mouse and human PFE molars exhibited a similar presentation in the 3D CT analyses. The quantitative analysis in mice demonstrated a statistically significant decrease in the eruption height of cKO first and second molars compared to other groups after postnatal day 25. Additionally, cKO molars demonstrated significantly shortened roots with dilacerations associated with the reduced interradicular bone height. Mouse PFE molars erupt at a much slower rate compared to normal molars, associated with shortened and dilacerated roots and defective interradicular bones.

Numerical investigation of field-scale geysers in a vertical shaft

Geysers in dropshafts of stormsewer systems are consecutive eruptions of a mixture of gas and liquid that can attain heights of more than 30 m. The present study investigates the mechanisms and characteristics of these extreme events numerically using OpenFOAM toolbox. The numerical model is based on a compressible two-phase flow solver and was validated using laboratory tests that achieved large eruption heights. The results show that the aforementioned experimental geysers can be reasonably well simulated using two- and three-dimensional numerical models. Further studies are needed to verify the applicability of two-dimensional models for simulating geysers in actual stormsewer systems. Moreover, the results suggest that compressibility of air plays a critical role in the formation of geysers. Overall, the conducted numerical study provides insights into the characteristics of geyser eruptions and presents some criteria for performing efficient numerical simulations of these events.

The Relationship Between Lava Fountaining and Vent Morphology for the 2014–2015 Holuhraun Eruption, Iceland, Analyzed by Video Monitoring and Topographic Mapping

Fissure eruptions are associated with lava fountains which often show complex distinct venting activity, in pulsating form, and the development of characteristic morphologic expressions such as scoria or spatter cones. Most morphological studies are based on observations of old structures and are not related to direct observations and systematic records of vents activity, which are rare. The 2014 - 2015 Holuhraun eruption site, Iceland, offered an exceptional opportunity to study with unprecedented details the location and evolution of those cones and their relationship to the venting dynamic. Here we analyse records from lava fountains activity at distinguished vents, captured during the 2014-2015 Holuhraun eruption, and compare them with the developing morphology of spatter cones. We conducted a fieldwork mapping project combining Terrestrial Laser Scanning (TLS) and Unmanned Aerial Vehicle (UAV) aerophoto techniques to characterize the cone morphologies. We recorded videos of the eruption and used edge detection and particle image velocimetry to estimate venting heights and particle velocities. We find that at those locations where spatter cone morphology developed the strongest, the highest lava fountains and larger ejection velocities were recorded, already at the very first days of the eruption. Instead, those sites that finally developed moderate or weak morphologies are also identified as less active lave fountain locations during the early stage of the eruption. The comparison of our topographic datasets shows that spatter cones remain similar in shape but increase in size as the eruption progress. In addition, we suggest that the observed changes in morphology may affect lava ponding in the crater, which in turn is strongly affecting eruption heights. Our results improve the general understanding of landscape evolution at rift zones, and demonstrate the close relationship between the cone morphology and the lava fountain activity at the onset of an eruption.

Video monitoring reveals pulsating vents and propagation path of fissure eruption during the March 2011 Pu'u 'Ō'ō eruption, Kilauea volcano

Lava fountains are a common eruptive feature of basaltic volcanoes. Many lava fountains result from fissure eruptions and are associated with the alignment of active vents and rising gas bubbles in the conduit. Visual reports suggest that lava fountain pulses may occur in chorus at adjacent vents. The mechanisms behind such a chorus of lava fountains and the underlying processes are, however, not fully understood.The March 2011 eruption at Pu'u 'Ō'ō (Kilauea volcano) was an exceptional fissure eruption that was well monitored and could be closely approached by field geologists. The fissure eruption occurred along groups of individual vents aligned above the feeding dyke. We investigate video data acquired during the early stages of the eruption to measure the height, width and velocity of the ejecta leaving eight vents. Using a Sobel edge-detection algorithm, the activity level of the lava fountains at the vents was determined, revealing a similarity in the eruption height and frequency. Based on this lava fountain time series, we estimate the direction and degree of correlation between the different vents. We find that the height and velocity of the eruptions display a small but systematic shift in time along the vents, indicating a lateral migration of lava fountaining at a rate of ~11m/s from W to E. This finding is in agreement with a propagation model of a pressure wave originating at the Kilauea volcano and propagating through the dyke at ~10m/s from W to E. Based on this approach from videos only 30s long, we are able to obtain indirect constraints on the physical dyke parameters, with important implications for lateral magma flow processes at depth. This work shows that the recording and analysis of video data provide important constraints on the mechanisms of lava fountain pulses. Even though the video sequence is short, it allows for the confirmation of the magma propagation direction and a first-order estimation of the dyke dimensions.

Association Between Weight and Height of Children and Eruption of Permanent Teeth in Mosul City Center-Iraq

Association Between Weight and Height of Children and Eruption of Permanent Teeth in Mosul City Center-Iraq

Detecting geyser activity with infrasound

We monitored geyser activity in the Lower Geyser Basin (LGB) of Yellowstone National Park with dual four-element microphone arrays separated by ~600m. The arrays were independently used to identify incident coherent plane wave energy, then conjoint cross beam back-azimuths from the two arrays were used to precisely locate signal sources. During a week in August 2011 we located repeating infrasound events, peaked in energy between 1 and 10Hz, originating from at least five independent geothermal features, including the episodically erupting Great Fountain, Fountain and Kaleidoscope Geysers, as well as periodic infrasound from nearby Botryoidal and persistent sound from Firehole Spring. Although activity from nearby cone-type geysers was not detected in the infrasound band up through 50Hz, the major fountain-type geysers (i.e., with columns greater than 10m) could be detected at several kilometers, and two minor geysers (i.e., a few meters in eruption height) could be tracked at distances up to a few hundred meters. Detection of geyser activity was especially comprehensive at night when ambient noise was low. We conclude that infrasound monitoring of fountain-type geysers permits convenient tracking of geyser activity, episodicity, signal duration, energy content, and spectral content. These parameters enable objective statistical quantification of geyser behavior and changes over time that may be due to external forcing. Infrasonic study of geyser activity in an individual basin has great monitoring utility and can be reasonably accomplished with two or more distributed sensor arrays.

Image analysis of the eruptive positions of third molars and adjacent second molars as indicators of age evaluation in Thai patients

PurposeThis study was performed to determine the relationship between the stage of tooth eruption (both vertical and mesio-angular) and chronological age.Materials and MethodsIndirect digital panoramic radiographs were used to measure the distances from the dentinoenamel junction (DEJ) of the second molars to the occlusal plane of the second molar teeth and of the adjacent third molars in 264 Thai males and 437 Thai females using ImageJ software. The ratio of those distances was calculated by patient age, and the correlation coefficient of the ratio of the third molar length to the second molar length was calculated.ResultsThe correlation between the height of the vertically erupted upper third molar teeth and age was at the intermediate level. The age range of ≥15 to <16 years was noted to be the range in which the correlation between the chronological age determined from the eruptional height and actual chronological age was statistically significant. The mean age of the female subjects, in which the position of the right upper third molar teeth was at or above the DEJ of the adjacent second molar but below one half of its coronal height was 19.9±2.6 years. That for the left side was 20.2±2.7 years. The mean ages of the male subjects were 20.1±3.3 years and 19.8±2.7 years for the right and left sides, respectively.ConclusionIt might be possible to predict chronological age from the eruption height of the wisdom teeth.

Meteorological responses to Mt. Baekdu volcanic eruption over east asia in an offline global climate-chemistry model: A pilot study

We examine the meteorological responses due to the probable eruption of Mt. Baekdu using an off-line Climate-Chemistry model that is composed of the National Center for Atmospheric Research (NCAR) Climate Atmosphere Model version 3 (CAM3) and a global chemistry transport model (GEOS-Chem). Using the aerosol dataset from the GEOS-Chem driven by GEOS-5 meteorology, experiment and control simulations of the climate model are performed and their meteorological differences between the two simulations are analyzed. The magnitudes of volcanic eruption and column injection height were presumably set to 1/200 of the Mt. Pinatubo eruption and 9 km, respectively. Significant temperature drop in the lower troposphere (850 hPa), which is mainly due to a direct effect of prescribed volcanic aerosols from Mt. Baekdu, has been simulated up to about −4 K. The upper atmosphere (150 hPa) right above the volcano, however, shows significant warming due to the absorption of the infrared radiation by volcanic aerosols. As a result of the volcanic eruption in the climate model, wave-like patterns are shown in both the geopotential height and horizontal wind. The changes in the lower atmospheric temperature are well associated with the modification of the atmospheric circulation through the hydrostatic balance. In spite of limitations in our current simulations due to several underlying assumptions, our results could give a clue to understanding the meteorological impacts from Mt. Baekdu eruptions that are currently attracting considerable public attention.

Modelling concentrations of volcanic ash encountered by aircraft in past eruptions

Abstract Prolonged disruption to aviation during the April–May 2010 eruption of Eyjafjallajokull, Iceland resulted in pressure to predict volcanic ash plume concentrations for the purpose of allowing aircraft to fly in regions with low ash contamination. Over the past few decades there have been a number of incidents where aircraft have encountered volcanic ash resulting in damage to the aircraft and loss of power to engines. Understanding the volcanic ash concentrations that these aircraft have encountered provides important input to determining a safe concentration limit. Aircraft encounters with six volcanic eruption plumes have been studied and ash concentrations predicted using the atmospheric dispersion model NAME. The eruptions considered are Galunggung 1982, Soputan 1985, Redoubt 1989, Pinatubo 1991, Hekla 2000 and Manam 2006. Uncertainties in the eruption source details (start time, stop time and eruption height) and in the aircraft encounter location and flight path are found to be major limitations in some cases. Errors in the driving meteorological data (which is often coarse in resolution for historic studies) and the lack of eruption plume dynamics (e.g. umbrella cloud representation) results in further uncertainties in the predicted ash concentrations. In most of the case studies, the dispersion modelling shows the presence of ash at the aircraft encounter location. Maximum ash concentrations in the vicinity of the aircraft are predicted to be at least 4000 μg m −3 although confidence in the estimated concentrations is low and uncertainties of orders of magnitude are shown to be possible.

Tall clouds from small eruptions: the sensitivity of eruption height and fine ash content to tropospheric instability

A critical factor in successfully monitoring and forecasting volcanic ash dispersion for aviation safety is the height reached by eruption clouds, which is affected by environmental factors, such as wind shear and atmospheric instability. Following earlier work using the Active Tracer High Resolution Atmospheric Model for strong Plinian eruptions, this study considered a range of eruption strengths in different atmospheres. The results suggest that relatively weak volcanic eruptions in the moist tropics can trigger deep convection that transports volcanic material to 15–20 km. For the same volcanic strength there can be ~9 km difference between eruption heights in moist tropical and dry subpolar environments (a larger height difference than previously suggested), which appears consistent with observations. These results suggest that eruption intensity should not be estimated from eruption height alone for tropospheric eruptions and also that the average height of volcanic eruptions may increase if the tropical atmospheric belt widens in a changing climate. Ash aggregation is promoted by hydrometeors (particularly liquid water), so the smaller modelled eruptions in moist atmospheres, which have a relatively small ash content for their height and water content, result in a relatively small proportion of fine ash in the dispersing cloud when compared to a dry atmosphere. This in turn makes the ash clouds much more difficult to detect using remote sensing than those in dry atmospheres. Overall, a weak eruption in the tropics is more likely to produce a plume above cruising levels for civil aviation, harder to detect and track, but with a lower concentration of fine ash than a mid-latitude or polar equivalent. There is currently no defined ‘acceptable’ concentration of ash for aircraft, but as these results suggest low-grade encounters in the tropics from undetected clouds are likely, it would be desirable to explore that issue.