Eruptive Processes Research Articles

Temporal evolution of the magmatic system at Nevado del Ruiz Volcano (Colombia) inferred from long-period seismic events in 2003–2020

Long-period (LP) seismic events have been broadly assumed to be generated by oscillations of crack fluid-filled resonators. We investigated the waveforms and spectral characteristics of LP seismic events recorded by five stations at Nevado del Ruiz Volcano, Colombia. The observed event types of LP events exhibited decaying harmonic oscillations with either monochromatic or polychromatic spectral features (NLP events) or events characterized by non-decaying harmonic oscillations (BLP events). The NLP events occurred over four periods: September 2003 (period I), January 2004–October 2004 (period II), October 2010–March 2012 (period III), and October 2019–April 2020 (period IV). Their source locations were determined to be within the first kilometer of the conduit placed below the Arenas crater. Their locations involved a distinct resonator for each of the four periods but a single resonator for all the events during a single period. Assuming a crack geometry at their sources and based on their locations, we considered a dusty gas (mixture of ash and water vapor) filling a crack resonator. We estimated the crack model parameters to investigate the temporal processes generating variations in frequency and quality factor Q. Then, the estimated parameters indicate that NLP events were triggered by magma fragmentation. We found that events from period III preceded phreatomagmatic eruptions, increased ash and gas emissions and SO2 flux, and increased overall seismic activity. Three years after this period III, a dome was emplaced at the base of the Arenas crater. Besides, events from period IV also preceded by ~3 years a significant increase in the overall seismic activity, which led to a change in alert activity at the volcano. We argue that BLP events were driven by resonances provoked by the unstable degassing through the uppermost magma plug's open cracks (tuffisite veins).In contrast, NLP events occurred by overpressure released through fractures along the conduit's walls (shear fractures). The shear fractures at the conduit wall were in a region of high strain rate where a decrease in confining pressure triggered fragmentation, resulting in dusty gas and, subsequently, a resonance of the crack. NLP and BLP events were in a narrow relationship with the ascent of vesiculated magma to the surface. Our results show that the LP events help diagnose the state of magmatic fluids and understand the eruption processes of Nevado del Ruiz Volcano. LP events are not always followed by explosive eruptions, but they do indicate significant overpressure developing in the shallow conduit.

The January 2022 Hunga Volcano explosive eruption from the multitechnological perspective of CTBT monitoring

SUMMARYThe massive eruption of the Hunga Volcano on 15 January 2022 provides an ideal test case for reviewing established methods to discriminate and analyse source processes. Discriminating source mechanisms and identifying their origins is a key task when analysing suspicious events in the frame of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Earthquakes and explosions can be distinguished in some cases using well established methods such as inversion for the seismic moment tensor. In more complex cases the combination of analyses of the seismic, infrasonic and hydroacoustic waveform content can be of help. More challenging is the discrimination of the specific kind of explosive source such as a nuclear test and a volcano eruption based on the data from the three waveform technologies alone. Here, we apply standard techniques destined to analyse relevant events in the frame of the CTBT, that is all three waveform technologies (seismology, infrasound and hydroacoustic) and atmospheric transport modelling of radionuclides. We investigate the potential of standard analysis methods to discriminate a source and identify their possible weaknesses. We show that the methods applied here work very well to identify, investigate and discriminate an explosive event. During discrimination we could not only exclude a shear-source (i.e. earthquake) but also distinguish the volcanic explosion in contrast to a man-made explosion. However, some tasks remain difficult with the available methods. These tasks include the reliable estimation of the strength of a non-shear event and thereupon a yield estimation of a possibly CTBT relevant event. In addition to evaluating our methods, we could relate our results with specific phases of the eruption process providing a more detailed insight of what happened. Our investigations of the eruption details only provide a starting point for further in-depth analysis. However, they underline the importance of the Hunga eruption event for science. The huge amount of observations provide a unique opportunity for knowledge gain in several subdisciplines of the geosciences. In addition, although not being a nuclear test, it also provides a useful and important data set for further developing multitechnology analyses in the frame of the CTBT.

Remote Characterization of the 12 January 2020 Eruption of Taal Volcano, Philippines, Using Seismo-Acoustic, Volcanic Lightning, and Satellite Observations

ABSTRACT On 12 January 2020, an eruption began on the shores of the Main Crater Lake (MCL) of Taal Volcano—a caldera system on the southern end of Luzon Island in the Philippines. Taal, one of the most active volcanoes in the Philippines, is located 30 km south of Manila—a major metropolitan area with a population of 13.5 million people. Eruptive activity intensified throughout the day on 12 January, producing prolific volcanic lightning, ashfall, and a sustained plume that reached 16–17 km altitude. The chronology of events was well documented by the Philippine Institute of Volcanology and Seismology and the Tokyo Volcanic Ash Advisory Center. The wealth of data collected during the eruption provides a unique opportunity to investigate how the combination of different remote sensing methods may complement local observations and monitoring. Remote systems tend to provide lower resolution data but are also less likely to be compromised by the eruptive activity, thus providing continuous records of eruptive processes. Here, we present a postevent analysis of the 12 January activity, including data from long-range lightning, infrasound, and seismic arrays located at distances up to several thousands of kilometers from the volcano. By combining these datasets, we distinguish five phases of activity and infer a major shift in eruption behavior around 12:00 on 12 January (UTC). The remote observations suggest that the most of the water within the MCL (∼42 million m3) was vaporized and incorporated into the volcanic plume within the first 12 hr of the eruption.

Prevalence of Dental Anomalies in Non-syndromic Cleft Lip And Palate Patients in Erbil City (an Orthopantomogramic Study)

Background and objectives: Cleft lip and palate deformity is one of the highly frequent and most difficult problems arising in the orthodontic clinics, one of the problems associated with these deformities is the dental anomalies presented as defect in the number and eruption process, this study aimed to find the prevalence of these dental anomalies in the cleft lip and palate patients in Erbil city. Method: One hundred orthopantomograms out of 167 cleft lip and palate patients examined by a well-trained orthodontist for the presence of hypodontia, supernumerary teeth and any impactions and arranged according to the age, gender and the grouping of the deformity whether involving the alveolus or its unilateral or bilateral clefts then analyzed using statistical packages. Results: Prevalence of dental anomalies involved a total of 271 dental anomalies distributed between the most frequent anomaly, starting with hypodontia (139) teeth missed, Impactions (103) teeth impacted and Supernumerary of a total (29) teeth, (96%) of the cases examined has at least one dental anomaly. Conclusion: Dental anomalies commonly present with cleft lip and palate cases in Erbil city, orthodontists should consider these anomalies for managing such cases

Ladoga-Lake-Area Lambeosaurus Capture by A Falling Black Hole, and Its Re-Emergence Through Hydrated Lateral Extrusion, Explanation of The Scandinavian Peninsula and of the Finnish Lakes as Well as of the Low-Ob’s Delta and of the Novaya Zemlya

Two Lambeosauridae in a homosexual act were gobbled into the Earth by a small black hole descending along the axis of the Moon to the Earth. These animals killed into the mantle explain the shape of Scandinavia and of lakes in Central and Eastern Finland as well as topographical structures in Russia’s North. They were shattered into the small black hole and their bodies triggered rerise of corresponding structures explaining the peculiarities of the area in a topographical way and geological way as well, from the olivines of the Scandinavian Alps to the pattern of the Urals and of Novaya Zemlya. The construction from eruptive processes within the mantle explains also the still-ongoing counter-subsidence of the Turun Saaristo and of the Kvarken archipelagoes, altogether with oil reserves on the Norwegian side.

Corrigendum: Using eruption source parameters and high-resolution grain-size distributions of the 7.7 ka cleetwood eruption of mount mazama (Oregon, United States) to reveal primary and secondary eruptive processes

CORRECTION article Front. Earth Sci., 06 April 2023Sec. Volcanology Volume 11 - 2023 | https://doi.org/10.3389/feart.2023.1182638

Insights into the Magmatic Feeding System of the 2021 Eruption at Cumbre Vieja (La Palma, Canary Islands) Inferred from Gravity Data Modeling

This study used spatiotemporal land gravity data to investigate the 2021 eruption that occurred in the Cumbre Vieja volcano (La Palma, Canary Islands). First, we produced a density model by inverting the local gravity field using data collected in July 2005 and July 2021. This model revealed a low-density body beneath the western flank of the volcano that explains a highly fractured and altered structure related to the active hydrothermal system. Then, we retrieved changes in gravity and GNSS vertical displacements from repeated measurements made in a local network before (July 2021) and after (January 2022) the eruption. After correcting the vertical surface displacements, the gravity changes produced by mass variation during the eruptive process were used to build a forward model of the magmatic feeding system consisting of dikes and sills based on an initial model defined by the paths of the earthquake hypocenters preceding the eruption. Our study provides a final model of the magma plumbing system, which establishes a spatiotemporal framework tracing the path of magma ascent from the crust–mantle boundary to the surface from 11–19 September 2021, where the shallowest magma path was strongly influenced by the low-density body identified in the inversion process.

Salivary Protein and Electrolyte Profiles during Primary Teeth Eruption: A Cross-Sectional Study.

This study aimed to assess the qualitative changes in the saliva during the process of primary teeth eruption. This cross-sectional study was conducted on 147 children from 2 to 48 months, of which 49 were in group A (no erupted primary teeth), 53 were in group B (at least one active erupting primary tooth), and 45 were in group C (eruption of all 20 primary teeth was completed). Salivary proteins were evaluated by sodium dodecyl sulfate electrophoresis with polyacrylamide gel, while the concentrations of salivary sodium, potassium, chloride, and calcium ions were evaluated by ion selective electrodes. The data were analyzed using ANOVA and Bonferroni tests (alpha = 0.05). The concentration of proteins with molecular weights of 20-30 KDa was significantly higher in group A, and it gradually decreased with age. The concentration of proteins with molecular weights of 50-60 KDa in group B was significantly lower than those of groups A and C. The calcium ion concentration in group A was significantly higher than that of the other groups. The concentration of potassium ions was minimal in group C. The proteins and electrolyte profiles of the subjects' saliva changed in the process of primary tooth eruption. The highest concentrations of proteins such as statherin, histatin, P-B peptide, and cystatin and the lowest concentrations of proteins such as amylase were present in group B.

Distal tephra reveal new MIS 5e Kos eruptions: Implications for the chronology and volcanic evolution histories in the Eastern Mediterranean region

The Kos Plateau Tuff (KPT), was an enormous caldera forming eruption originating from a vent within the Kos/Nisyros/Yali volcanic complex, occurring at 161 ka. It is the largest recognised Late Quaternary eruption in the Eastern Mediterranean. With its distinctive, highly silicic chemical composition, the resulting ash deposits have been used both as a synchronous marker for palaeoenvironmental records in the region, and to provide information on eruption processes and magnitude. Here, we describe ash layers detected at multiple sites (deep-sea sequences and a terrestrial archaeological site) with ages generated by radiometric dating and sapropel correlation, to demonstrate the existence of a later, but geochemically similar eruption from the Kos volcano which has not previously been identified in proximal volcanic units. This eruption is dated to MIS 5e (∼124–129 ka), i.e. ∼40 kyr younger than the KPT. This tephra marks the start of MIS5e, and presents a rare opportunity to independently and precisely align paleoenvironmental records and archaeological sites during a time of rapid warming and sea level rise analogous to the present day. The presence of multiple tephras also implies the possibility of multiple eruptions during this period. This adds to our knowledge of the active and hazardous nature of Kos/Nisyros/Yali volcanic complex.

Carbon stored in live ponderosa pines in the Sierra Nevada will not return to pre-drought (2012) levels during the 21st century due to bark beetle outbreaks

Outbreaks of several bark beetle species can develop rapidly in response to drought and may result in large transfers of carbon (C) stored in live trees to C stored in dead trees (10s of Tg C yr-1 in the western U.S. alone), which over time will be released back to the atmosphere. The western pine beetle (WPB) outbreak incited by the 2012–2015 mega-drought in the Sierra Nevada, California, U.S., could portend more frequent and/or severe bark beetle outbreaks as the temperature warms and drought frequency and intensity increase in the future. However, changes in the frequency and/or severity (resultant levels of host tree mortality) of beetle outbreaks are difficult to predict as outbreaks are complex with non-linear and eruptive processes primarily driven by interactions among beetle populations, the demography of hosts and other tree species, and climate and weather. Using an insect phenology and tree defense model, we projected the future likelihood of WPB outbreaks in the Sierra Nevada with climate drivers from different Earth System Models. Our goal was to understand how host (ponderosa pine, PIPO) recovery and future warming and drought affect the frequency and severity of WPB outbreaks and their C consequences. Our projections suggested that by 2100 the C stored in live PIPO (mean: 1.98 kg C m-2, 95% CI: 1.74–2.21 kg C m-2) will not return to levels that occurred before the 2012–2015 drought (2012: ∼2.30 kg C m-2) due to future WPB outbreaks. However, differences in climate models indicate a wide range of possible WPB outbreak frequencies and severities. Our results suggest that total plot basal area is the most significant factor in the mortality rate of PIPO by WPB in any given year, followed by drought severity and temperature. High levels of host basal area, higher temperature, and extreme drought all contribute to the frequency and severity of future WPB outbreaks. While PIPO basal area may decline under increased drought and warming, limiting high-stand basal area (>60 m2 ha-1) may reduce the severity of future WPB outbreaks in the Sierra Nevada.

The complex construction of a glaciovolcanic ridge with insights from the 2021 Fagradalsfjall Eruption (Iceland)

Glaciovolcanic landforms provide global-scale records of paleoenvironmental conditions and yield insights into subglacial eruption processes. Models for the formation of glaciovolcanic ridges, or tindars, are relatively simple, proposing a monogenetic eruption and a fairly uniform stratigraphy with or without a single transition from effusive pillow lavas to explosive fragmental deposits. Others have suggested that tindars are more complicated. To build a more robust model for tindar formation, we conducted a field and geochemical study of Undirhlíðar ridge on the Reykjanes Peninsula in southwestern Iceland. We show that the ridge was built through a complex sequence of eruptive and intrusive events under dynamically changing ice conditions. Quarry walls expose a continuous cross-section of the ridge, revealing multiple pillow and fragmental units. Pillow lava orientations record the emplacement of discrete pillow-dominated lobes and the migration of volcanic activity between eruptive vents. Volatile contents in glassy pillow rinds show repeated pulses of pillow lava emplacement under glaciostatic conditions, with periods of fragmentation caused by depressurization. Variations in major elements, incompatible trace element ratios, and Pb-isotopes demonstrate that the eruption was fed from separate crustal melt reservoirs containing melts from a compositionally heterogeneous mantle source. A shift in mantle source signature of pillow lavas suggests that the primary ridge-building phase was triggered by the injection of magma into the crust. Within the growing edifice, magma was transported through dykes and irregularly shaped intrusions, which are up to 20% by area of exposed stratigraphy sequences. The model for tindar construction should consider the significant role of intrusions in the growth of the ridge, a detail that would be difficult to identify in natural erosional exposures. The 2021–22 eruptions from the adjacent Fagradalsfjall vents allow us to draw parallels between fissure-fed eruptions in subaerial and ice-confined environments and test hypotheses about the composition of the mantle underlying the Reykjanes Peninsula. Both Fagradalsfjall and Undirhlíðar ridge eruptions may have occurred over similar spatial and temporal scales, been triggered by mixing events, erupted lavas with varying mantle source signatures, and focused volcanic activity along migrating vents. Differences in composition between the two locations are not related to systematic lateral variations in the underlying mantle. Rather, the Undirhlíðar ridge and Fagradalsfjall eruptions capture complex interactions among the crustal magma plumbing system, mantle source heterogeneity, and melting conditions for a moment in time.

Comparison of the Composition of ICMEs from Active Regions and Quiet-Sun Regions

The composition of interplanetary coronal mass ejections (ICMEs), including the ionic charge states and elemental abundances of heavy elements, is tightly correlated with their source regions and eruption processes. This can help in analyzing the eruption mechanisms and plasma origins of CMEs, and deepen our understanding of energetic solar activities. The active regions and quiet-Sun regions have different physical properties; thus, from a statistical point of view, ICMEs originating from the two types of regions should exhibit different compositional characteristics. To demonstrate the differences comprehensively, we conduct survey studies on the ionic charge states of five elements (Mg, Fe, Si, C, and O) and the relative abundances of six elements (Mg/O, Fe/O, Si/O, C/O, Ne/O, and He/O) within ICMEs from 1998 February to 2011 August using data from the Advanced Composition Explorer. The results show that ICMEs from active regions have higher ionic charge states and relative abundances than those from quiet-Sun regions. For the active-region ICMEs, we further analyze the relations between their composition and flare class, and find a positive relationship between them, i.e., the higher the classes of the associated flares, the larger the means of the ionic charge states and relative abundances (except the C/O) within ICMEs. As more (less) fractions of ICMEs originate from active regions around the solar maximum (minimum), and active-region ICMEs usually are associated with higher-class flares, our studies might answer why the composition of ICMEs measured near 1 au exhibits a solar cycle dependence.

CBCT Assessment of the Anatomical Characteristics of Gubernacular Canal in Impacted Teeth.

Gubernacular canal (GC) is a canal that extends from the follicle of unerupted permanent teeth to the alveolar bone crest filled with remnants of the dental lamina. This canal is thought to guide tooth eruption and be related to some pathologic conditions. This study aimed to determine the presence of GC and its anatomical characteristics in teeth, which failed to erupt normally on cone beam computed tomography (CBCT) images. This cross-sectional study evaluated CBCT images of 77 impacted permanent and supernumerary teeth obtained from 29 females and 21 males. The frequency of GC detection, its location in relation to the crown and root, the anatomical surface of the tooth from which the canal has originated, and the adjacent cortical table to which the canal opens, along with the length of the GC were studied. GC was observed in 53.2% of teeth. The anatomical tooth aspect of origin was occlusal/ incisal in 41.5% and crown in 82.9% of teeth. Moreover, 51.2% of GCs opened in palatal/lingual cortex and 63.4% of canals were not located along the tooth long axis. Finally, GC was detected in 85.7% of teeth undergoing the crown formation stage. Although GC was introduced as an eruption pathway, this canal is also present in impacted teeth. This means that presence of this canal does not promise the normal eruption of tooth and the anatomical characteristics of GC may influence the eruption process.

Early fumarolic minerals from the Tajogaite volcanic eruption (La Palma, 2021)

This work constitutes the first geochemical, mineralogical and textural analysis of the early fumarolic deposits that appeared in the Tajogaite Volcano (La Palma island, Spain) one month after the official end of the eruptive process. Fourteen fumaroles grouped into 5 study areas have been characterized following a novel methodology that includes on-site microscopic observations and weak samples preservation for their laboratory characterization. Three main mineralogical zones were identified in the fumaroles: 1) sulphur-sulphate; 2) halides; and 3) salammoniac zone. Zones 1 and 2 are included in the S-gas domain and the predominance of sulphur-sulphate minerals or halides in the mineral deposits is dependent on the gas temperature (halides appear in the high temperature fumaroles). Zone 3 overlaps the (HCl-CO) and (HCl) -gas domains. The thermal analysis of the fumaroles provides the sequence of mineral suites according to the vent temperature. Sylvite-halite-tenorite are revealed as typical minerals of high-temperature fumaroles (>530 °C), whilst Ca, Mg and Na sulphates appear in low-temperature fumaroles (<200 °C). Salammoniac-Mascagnite forms in intermediate ranges (170–350 °C). Finally, three different fumarole types are recognized (punctual, diffuse and associated to fissures), establishing different environmental conditions for mineral precipitation. Differences are based on the gas flux mechanism, the gas-rock interaction intensity, temperature and gas concentrations. All these data will serve as a referenced starting point for later studies focused on fumarole evolution and the degassing process of volcanic systems in oceanic volcanic islands framework.

Time‐Lapse Geophysical Investigation of Geyser Dynamics at Spouter Geyser, Yellowstone National Park: Geyser Dynamics II

AbstractGeysers are unique hydrothermal features, requiring specific geometry, fluid, and vapor input, and heat to produce eruptions. In a geyser eruption, the decompression of superheated hydrothermal fluids results in a conversion of thermal to kinetic energy. Recent studies conclude that a laterally offset cavity structure (bubble trap) plays an integral role in the geyser eruption process. In this second study of Spouter Geyser, Yellowstone National Park (YNP), we build on the geyser structure developed in the first publication and explore how structural components, such as the bubble trap, control eruption dynamics. We utilize time‐lapse electrical resistivity tomography (ERT) and transient electromagnetics (TEM) geophysical methods to track changes in the saturation of conductive hydrothermal fluid and resistive vapor through the eruption cycle. Additionally, we use pressure‐temperature transducer data to measure eruption and recharge durations over the past 23 years at Spouter Geyser, identifying long‐period trends in geyser behavior. The geophysics results support the bubble trap model, capturing an increase in resistivity in the bubble trap structure during the recharge phase interpreted as a vapor saturation increase. The TEM also captures a resistivity increase in the 20–30 m depth interval during the eruption phase, interpreted as a vapor‐dominated “flash eruption zone” where the superheated hydrothermal fluids flash into steam and drive fluid out of this zone during the eruption. From the temperature time‐series detailing 23 years of eruption and recharge durations, we find that eruption durations have remained constant at ∼2 hr while recharge durations have decreased linearly at 6.6 min/year.

Stochastic Modeling of the Eruption History of Nyiragongo Volcano in the Virunga Volcanic Province, Western Branch of the East African Rift System

The modeling of statistical distribution of the eruptive frequency provides basic information to quantitatively assess the volcanic hazard and constrain the physics of the eruptive process. Here, we discuss the statistics of the time series of lateral eruptions of the Nyiragongo volcano in the Virunga Volcanic Province, western branch of the East African Rift System. We examine eruption data with a volcanic explosivity index of at least 1 listed in the Global Volcanism Network Bulletins. After investigating the completeness, stationarity, and independence of the eruption time series, we employ five distribution models (Brownian passage time, gamma, log-logistic, lognormal, and Weibull) to fit the repose time. First, we identify a clear tendency for events to cluster in time. We hypothesize two clusters, the ‘pre-1927’ cluster related to the intracraterial and volcanic activity of the lava lake, and the ‘post-1977’ cluster mainly related to lateral eruptions (i.e. those potentially generating lava flows). Using the maximum likelihood estimations, we evaluate the model parameters with a 95% confidence interval. Next, we use the Akaike Information Criterion to determine the most suitable distribution and we perform the Bayesian Model Averaging approach to assess uncertainty issues in model selection process. The results suggest that the BPT distribution provides the best fit for data of lateral eruptions (post-1977). Then we estimate the time-dependent probability of the occurrence of a lateral eruption for the 50-year period between 2022 and 2072. The estimates reach 50.79%, 88.61%, 97.59%, 99.50%, and 99.89% for 2032, 2042, 2052, 2062, and 2072 years, respectively.

Application of the global neutron monitor network for assessment of spectra and anisotropy and the related terrestrial effects of strong SEPs

Studies of the characteristic of strong solar energetic particles (SEPs), that is events that can be registered by ground-based instruments such as neutron monitors, allow one to understand their acceleration and propagation in interplanetary space and gives the necessary basis to quantify the related cosmic-ray-induced terrestrial effects. After solar eruptive processes, such as solar flares and/or coronal mass ejections, solar ions are accelerated to the high-energy range. In most cases, the energy of the accelerated solar ions reaches several tens of MeV/n, yet occasionally it exceeds 100 MeV/n or even reaches the GeV/n range. In the latter case, the energy of SEPs is enough, so that they induce an atmospheric particle shower, whose secondary particles reach the ground, eventually registered by ground-based detectors, specifically neutron monitors. This particular class of events is known as ground-level enhancements (GLEs). Here we present a full-chain scheme for assessment of spectra and anisotropy and the related terrestrial effects of GLE causing SEPs. We discuss the application of a method for analysis of GLEs using neutron monitor data and the employment of the derived spectra as a basis to quantify cosmic-ray-induced terrestrial effects during GLEs, specifically atmospheric ionization and exposure to secondary radiation (radiation dose) at cruising aviation altitudes. We present an example study of two GLEs, namely their SEP energy/rigidity spectra derived using records from the global NM network and models for quantification of the atmospheric ionization and exposure to radiation at flight altitudes (ambient dose) during the considered events.

CLASSIFICATION OF WINTER IMPACTION OF MANDIBLE THIRD MOLAR ON THE DISTANCE OF THE MANDIBULAR CANALS ON PANORAMIC RADIOGRAPHS AT RSGMP UNJANI

Impacted teeth are teeth obstructed during the eruption process; the high prevalence of impacted teeth, especially third molars, accompanied by complaints that arise, requires omentectomy. Winter's classification shows various positions of impacted third molars based on angulation. This classification is judged to be describe the relationship of the apical position of the mandibular third molar tooth to the mandibular canal more clearly. The odontectomy procedure requires an excellent preoperative approach to consider the structures around the mandibular third molar, one of which is the mandibular canal, because the canal's proximity to the third molar root can increase the risk of nerve injury during the odontectomy procedure. This study aims to determine the relationship between the third mandibular impaction Winter classification and the mandibular canal distance on panoramic radiographs. The samples of this study were 53 and were grouped according to the position of the impaction vertically, mesioangularly, horizontally, and distoangularly. The study was conducted cross-sectionally by measuring the apical distance of the mandibular third molar to the upper border of the canal on a panoramic radiograph using a manual caliper. The space obtained was statistically analyzed using the eta correlation test. The results showed that 38 and 48 impactions were found to have the most mesioangular impaction, followed by horizontal, vertical, and distoangular paping the least. The mesioangular position measured the distance from the apical third molar of the impacted mandible to the closest distance to the mandibular canal, followed by the horizontal and the longest distance in the vertical position. Statistical tests were conducted to determine the relationship between the mandibular third molars and the mandibular canal. In the test results, the calculated F value on tooth 38 (2.64) and tooth 48 (0.507) was smaller than the F table value (2.794); this indicates there is no significant relationship between the two variables. The absence of a close relationship between the mandibular third molar distance and the mandibular canal indicates the possible low risk of complications in paresthesia after the odontectomy procedure.

Direct diastema closure: a case report

The maxillary diastema is a common asthetic problem in patients. Assess and diagnose may be challenging due to the many factors that influences the alteration of tooth eruption process and tooth shape. Appropriate technique and material for effective treatment are based on time, physical, psychological, and economical limitations. Direct composite resins in diastema cases allow dentist and patient complete control of these limitations and formation of natural smile. In this case report multiple maxillary diastemas were closed with direct composite resin restorations in without any preparation.

Solid Earth-atmosphere interaction forces during the 15 January 2022 Tonga eruption.

Rapid venting of volcanic material during the 15 January 2022 Tonga eruption generated impulsive downward reaction forces on the Earth of ~2.0 × 1013 N that radiated seismic waves observed throughout the planet, with ~25 s source bursts persisting for ~4.5hours. The force time history is determined by analysis of teleseismic P waves and Rayleigh waves with periods approximately <50 s, providing insight into the overall volcanic eruption process. The atmospheric acoustic-gravity Lamb wave expanding from the eruption produced broadband ground motions when transiting land, along with driven and conventional tsunami waves. Atmospheric standing acoustic waves near the source produced oscillatory peak forces as large as 4 × 1012 N, exciting resonant solid Earth Rayleigh wave motions at frequencies of 3.7 and 4.6 mHz.