The catastrophic explosion of Mount Lamington volcano, Papua New Guinea on January 21, 1951 produced a devastating pyroclastic density current (PDC) that knocked down dense tropical rainforest over ...an area of 230 km2 and killed approximately 3000 people. We present results of a field reinvestigation of the 1951 PDC deposit combined with an analysis of the available photographs and eyewitness accounts of the eruption first published in the fundamental work of G. A. M. Taylor (1958).
We have concluded that the six-days-long pre-climactic activity before the 1951 eruption (which included felt local seismicity, frequent ash-laden explosions of vulcanian type, bulging of the volcano slope accompanied with landslides) was associated with shallow-level intrusion of a highly viscous magma body (cryptodome/dome) of andesitic composition with a volume of approximately 0.01 km3. This intrusion destabilized Mount Lamington's prehistoric intra-crater lava dome.
On January 21 the destabilized dome gravitationally collapsed and produced a relatively small-volume debris avalanche, the deposit of which was not recognized during Taylor's original investigation. The debris avalanche had a volume of approximately 0.02–0.04 km3, travelled a distance (L) of 8.5 km and had the ratio of vertical drop (H) to runout (L) of 0.14. The edifice collapse decompressed the intruding cryptodome and triggered its explosive fragmentation.
Photographs of the climactic explosion show that the eruptive cloud initially rose vertically but subsequently collapsed upon the terrain around the vent, and formed a PDC which flowed radially outward. The enhanced northward propagation of the PDC to a maximum distance of 13 km reveals that the northern breach in the ancient crater's high walls influenced the distribution of the deposit. In the studied NE-N-NW sector of the devastated area, in the zone proximal to the volcano, the PDC emplaced a normally graded layer of coarse ash and lapilli mixed in the base with picked-up soil and plant fragments. The layer gradually becomes thinner and finer-grained with distance from the volcano. The PDC deposit has a volume of approximately 0.025 km3 and consists of approximately 80% juvenile rock fragments derived from the explosively fragmented cryptodome. The remaining 20% consists of accidental clasts derived from the old volcanic edifice. The juvenile material is crystal-rich andesite with a unimodal vesicularity distribution (4 to 36%). The reconstructed eruption sequence, the PDC tree blowdown pattern and characteristics of the PDC deposit are similar to those of catastrophic laterally-directed blasts of volcanoes Bezymianny in 1956, Mount St.Helens in 1980, and Soufriere Hills, Montserrat in 1997. In contrast to the cases of these “classic” lateral blasts, the blast cloud of Lamington was initially vertically-directed before collapsing to produce a PDC. We speculate that the climactic explosion of Mount Lamington was initially vertical because the rupture surface of the triggering sector collapse intersected the apex of the intruding cryptodome (it exposed a subhorizontal surface of the cryptodome apex), while at Bezymianny, Mount St.Helens, and Soufriere Hills the rupture intersected the main body of the cryptodome/dome, and exposed their steeply inclined surfaces.
•We present results of field reinvestigation of pyroclastic deposits of the 1951 catastrophic eruption of Mount Lamington volcano, Papua New Guinea.•Six-days-long pre-climactic activity was associated with intrusion of small cryptodome /dome.•As a result of edifice destabilization a small-volume debris avalanche with volume ~ 0.03 km3 was produced. The edifice collapse triggered explosive fragmentation of the dome and climactic explosion.•The eruptive cloud initially rose vertically but subsequently collapsed and formed PDC which flowed radially.•The 1951 blast of Mt.Lamington is similar to blasts of volcanoes Bezymianny (1956), St.Helens (1980), and Montserrat (1997).
The concentration and distribution of heavy minerals in tsunami deposits is not random and mostly source-dependent. Heavy minerals may thus be good indicators of sediment provenance and tsunami flow ...dynamics. The tsunamis generated by the 1996 phreato-magmatic eruption in Karymskoye Lake represent a relevant case-study because the provenance of the abundant heavy minerals found in the tsunami deposits is well constrained (the on-going basaltic eruption itself). X-ray computed tomography (X-CT) of cores of tsunami sediments is used to identify heavy minerals and characterise their source and spatial distribution in the tsunami deposit, and to propose a scenario of the coupled eruption and tsunamis. An original combination of methods including X-CT, SEM and XRF core scanner allows distinguishing subunits corresponding to pulses of sediments deposition and associated inputs of heavy minerals, together with erosive contacts, laminations, and rip-up clasts of the substratum. The structure of the tsunami deposits suggests that a major tsunami consisting of two main waves inundated the coastal terrace up to 100m inland on the eastern shore of the lake; a scenario that is consistent with waves generated by experimental explosions. This largest tsunami might have occurred when underwater explosions were at a critical water depth of 40m (corresponding to a two-third submerged explosion in the 60m deep lake). However, more investigations are needed to better understand the critical conditions leading to a tsunami during underwater eruptions.
We compare eruptive dynamics, effects and deposits of the Bezymianny 1956 (BZ), Mount St Helens 1980 (MSH), and Soufrière Hills volcano, Montserrat 1997 (SHV) eruptions, the key events of which ...included powerful directed blasts. Each blast subsequently generated a high-energy stratified pyroclastic density current (PDC) with a high speed at onset. The blasts were triggered by rapid unloading of an extruding or intruding shallow magma body (lava dome and/or cryptodome) of andesitic or dacitic composition. The unloading was caused by sector failures of the volcanic edifices, with respective volumes for BZ, MSH, and SHV c. 0.5, 2.5, and 0.05 km3. The blasts devastated approximately elliptical areas, axial directions of which coincided with the directions of sector failures. We separate the transient directed blast phenomenon into three main parts, the burst phase, the collapse phase, and the PDC phase. In the burst phase the pressurized mixture is driven by initial kinetic energy and expands rapidly into the atmosphere, with much of the expansion having an initially lateral component. The erupted material fails to mix with sufficient air to form a buoyant column, but in the collapse phase, falls beyond the source as an inclined fountain, and thereafter generates a PDC moving parallel to the ground surface. It is possible for the burst phase to comprise an overpressured jet, which requires injection of momentum from an orifice; however some exploding sources may have different geometry and a jet is not necessarily formed. A major unresolved question is whether the preponderance of strong damage observed in the volcanic blasts should be attributed to shock waves within an overpressured jet, or alternatively to dynamic pressures and shocks within the energetic collapse and PDC phases. Internal shock structures related to unsteady flow and compressibility effects can occur in each phase. We withhold judgment about published shock models as a primary explanation for the damage sustained at MSH until modern 3D numerical modeling is accomplished, but argue that much of the damage observed in directed blasts can be reasonably interpreted to have been caused by high dynamic pressures and clast impact loading by an inclined collapsing fountain and stratified PDC. This view is reinforced by recent modeling cited for SHV. In distal and peripheral regions, solids concentration, maximum particle size, current speed, and dynamic pressure are diminished, resulting in lesser damage and enhanced influence by local topography on the PDC. Despite the different scales of the blasts (devastated areas were respectively 500, 600, and >10 km2 for BZ, MSH, and SHV), and some complexity involving retrogressive slide blocks and clusters of explosions, their pyroclastic deposits demonstrate strong similarity. Juvenile material composes >50% of the deposits, implying for the blasts a dominantly magmatic mechanism although hydrothermal explosions also occurred. The character of the magma fragmented by explosions (highly viscous, phenocryst-rich, variable microlite content) determined the bimodal distributions of juvenile clast density and vesicularity. Thickness of the deposits fluctuates in proximal areas but in general decreases with distance from the crater, and laterally from the axial region. The proximal stratigraphy of the blast deposits comprises four layers named A, B, C, D from bottom to top. Layer A is represented by very poorly sorted debris with admixtures of vegetation and soil, with a strongly erosive ground contact; its appearance varies at different sites due to different ground conditions at the time of the blasts. The layer reflects intense turbulent boundary shear between the basal part of the energetic head of the PDC and the substrate. Layer B exhibits relatively well-sorted fines-depleted debris with some charred plant fragments; its deposition occurred by rapid suspension sedimentation in rapidly waning, high-concentration conditions. Layer C is mainly a poorly sorted massive layer enriched by fines with its uppermost part laminated, created by rapid sedimentation under moderate-concentration, weakly tractive conditions, with the uppermost laminated part reflecting a dilute depositional regime with grain-by-grain traction deposition. By analogy to laboratory experiments, mixing at the flow head of the PDC created a turbulent dilute wake above the body of a gravity current, with layer B deposited by the flow body and layer C by the wake. The uppermost layer D of fines and accretionary lapilli is an ash fallout deposit of the finest particles from the high-rising buoyant thermal plume derived from the sediment-depleted pyroclastic density current. The strong similarity among these eruptions and their deposits suggests that these cases represent similar source, transport and depositional phenomena.
Southeast Asia has had both volcanic tsunamis and possesses some of the most densely populated, economically important and rapidly developing coastlines in the world. This contribution provides a ...review of volcanic tsunami hazard in Southeast Asia. Source mechanisms of tsunami related to eruptive and gravitational processes are presented, together with a history of past events in the region. A review of available data shows that many volcanoes are potentially tsunamigenic and present often neglected hazard to the rapidly developing coasts of the region. We highlight crucial volcanic provinces in Indonesia, the Philippines and Papua New Guinea and propose strategies for facing future events.
Vulcanian explosions are hazardous and are often spontaneous and direct observations are therefore challenging. Ebeko is an active volcano on Paramushir Island, northern Kuril Islands, showing ...characteristic Vulcanian-type activity. In 2019, we started a comprehensive survey using a combination of field station records and repeated unoccupied aircraft system (UAS) surveys to describe the geomorphological features of the edifice and its evolution during ongoing activity. Seismic data revealed the activity of the volcano and were complemented by monitoring cameras, showing a mean explosion interval of 34 min. Digital terrain data generated from UAS quadcopter photographs allowed for the identification of the dimensions of the craters, a structural architecture and the tephra deposition at cm-scale resolution. The UAS was equipped with a thermal camera, which in combination with the terrain data, allowed it to identify fumaroles, volcano-tectonic structures and vents and generate a catalog of 282 thermal spots. The data provide details on a nested crater complex, aligned NNE-SSW, erupting on the northern rim of the former North Crater. Our catalog of thermal spots also follows a similar alignment on the edifice-scale and is also affected by topography on a local scale. This paper provides rare observations at Ebeko volcano and shows details on its Vulcanian eruption style, highlighting the relevance of structural and morphologic control for the geometry of craters and tephra fallout as well as for structurally controlled geothermal activity.
Lava domes grow by extrusions and intrusions of viscous magma often initiating from a central volcanic vent, and they are frequently defining the source region of hazardous explosive eruptions and ...pyroclastic density currents. Thus, close monitoring of dome building processes is crucial, but often limited to low data resolution, hazardous access, and poor visibility. Here, we investigated the 2016–2017 eruptive sequence of the dome building Bezymianny volcano, Kamchatka, with spot-mode TerraSAR-X acquisitions, and complement the analysis with webcam imagery and seismic data. Our results reveal clear morphometric changes preceding eruptions that are associated with intrusions and extrusions. Pixel offset measurements show >7 months of precursory plug extrusion, being locally defined and exceeding 30 m of deformation, chiefly without detected seismicity. After a short explosion, three months of lava dome evolution were characterised by extrusions and intrusion. Our data suggest that the growth mechanisms were significantly governed by magma supply rate and shallow upper conduit solidification that deflected magmatic intrusions into the uppermost parts of the dome. The integrated approach contributes significantly to a better understanding of precursory activity and complex growth interactions at dome building volcanoes, and shows that intrusive and extrusive growth is acting in chorus at Bezymianny volcano.
Today, the entire education of the Russian Federation is being reformed, high requirements for the quality of education have been set. The restructuring and integration of the world educational ...process expects high efficiency of all educational activities, therefore, the problem of the study of mathematical abilities and the ability to convey meaning of students is particularly relevant today. Equally important is the problem of educating socially approved personality traits in the younger generation, including empathy. The study allowed us to establish that students with an average level of development of mathematical abilities have significantly less formed empathy, and vice versa, with the development of communicative properties, there is an increase in empathy abilities. It has been established that empathy is best formed in students of the direction "Ecology and nature management" with an active, emotionally dominant and cognitively dominant strategy for conveying meaning.
Digitalization of education during the pandemic of COVID-19 fosters the problem of learning motivation of high school students, the polarity in the development of emotional intelligence may appear. ...The purpose of the study was to identify the relationship between indicators of learning motivation and emotional intelligence in terms of digitalization among high school students. The sample consisted of 63 high school students aged 16 to 17 years. Research methods were questionnaires: “Learning motivation of high school students” (Lukyanova & Kalinina, 2004); "Motivation for success and fear of failure" (Rean, 1999); "Test of emotional intelligence" (Lyusin, 1999); "Emotional intelligence test" (Hall, adapted by Knyazev, Mitrofanova & Bocharov, 2013). The results of the study showed the domination of the affiliation and social motivation of high school students. It means the desire to take a certain position in relations with others and the necessity to have authority in the referent group. The relationship between the general level of emotional intelligence of high school students and the general level of learning motivation was determined. It was recognized that emotion as a special type of knowledge is related to the category of “intelligence” and enables a person to successfully adapt to changing conditions. Emotions and intellect allow motivation to solve cognitive tasks and to build constructive communication.
The results of research on emotional intelligence and personal characteristics of teenagers under suspended sentence are considered in the article. The purpose of research: studying of emotional ...intelligence level and comparison of aggression and anxiety between teenagers under suspended sentence and law-abiding teenagers. Methods of research: Bass – Darki test (BDI) - for evaluation of aggression and animosity; questionnaire of Spielberger-Khanin (STАI) for evaluation of situational and personal anxiety; EIS test (Hall) - for studying emotional intelligence level. It is shown, that the comparative analysis has revealed authentic distinctions of all parameters using EIS technique, parameters of situational and personal anxiety using STAI technique, indirect aggression and feeling of fault using BDI questionnaire among teenagers under suspended sentence and law-abiding teenagers. The correlation analysis revealed that the more aggressive a teenager under suspended sentence is, the lower his/her emotional intelligence, self-motivation and emotional awareness are, and as a result, the worse he/she distinguishes emotions of other people. The revealed significant interrelations between personal characteristics, emotional intelligence and aggression have shown that it is possible to control animosity and aggression of teenagers under suspended sentence if their self-motivation and emotional awareness are raised. The psychological status of teenagers under suspended sentence shows directions for psych corrective work with them which should include, besides individual consultations, group work to decrease aggression, situational and personal anxiety and, what is the most important, to form emotional competence.
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