Vent Locations Research Articles

Evaluation of thermal comfort, IAQ and energy consumption in an impinging jet ventilation (IJV) system with/without ceiling exhaust

One of the alternative ventilation systems for an occupied space is the impinging jet ventilation (IJV) system. Several design factors influence on the thermal comfort, the local thermal discomfort and the energy consumption of the system. Draught discomfort and vertical temperature gradient are the main reasons of local discomfort in IJV systems. In this study, the effect of return air vent location, existence and non-existence of ceiling exhaust, on the IJV system performance is investigated under three different supply air temperatures. Computational fluid dynamics (CFD) method is employed to evaluate each case. The results are validated against experimental measurements of previous research works. The results indicate that the location of return air vent has major impact on the thermal comfort and the energy consumption of the system and minor effect on the draught discomfort criteria. In addition, using ceiling exhaust reduces the system energy requirement. Based on the results, the energy consumption in cases with ceiling exhaust air vent may be reduced up to 30% depending on inlet air temperature. The vertical temperature gradient changes with the inlet air temperature and decreases using ceiling exhaust.

Overview of hydrogen combustion experiments performed in a large scale vented vessel at Canadian Nuclear Laboratories

Hydrogen combustion inside a post-accident containment environment may pose a threat to the integrity of the containment structure and equipment. In CANDU reactors, combustion-generated overpressures in an accident will be relieved by venting to adjacent from one compartment volumes through relief panels or existing openings. To have a better understanding of the fundamental mechanisms that control the overpressures resulting from a vented hydrogen deflagration, a 120 m3 large scale vented combustion test facility was constructed at Canadian Nuclear Laboratories. A number of experiments have been completed in this facility to investigate hydrogen combustion behavior simulated in a post-accident reactor containment environment. A selected number of experimental results are presented in this paper to demonstrate several parameter effects on vented combustion dynamics by varying the number of chambers (single, two or three interconnected), volume and vent size, initial turbulence (quiescent vs. turbulent), initial temperature and steam concentration, mixture uniformity (well mixed vs. highly stratified), vent locations, and number of igniters. These results have provided useful insights for hydrogen management for the Canadian nuclear industry and CANDU utilities participating in the CANDU Owners Group research program. Most experimental data have been used for validation of combustion models and development of user guidelines.

A parametric study of the combined effects of window property and air vent placement

The creation of energy-efficient buildings that maintain thermal comfort is a major goal of architectural design. The study on the interrelation of vent location and window properties on indoor the...

Mechanism and capability of ventilation openings for alleviating micro-pressure waves emitted from high-speed railway tunnels

Micro-pressure waves are a major environmental problem related to modern high-speed railway systems. The strength of this harmful noise is proportional to the amplitude of the compression wave gradient generated by a high-speed train entering a tunnel. Employing an accurate numerical method, the mechanism and effects of ventilation openings on these compression waves are parametrically investigated. The numerical results indicate that after installing an opening, the compression wave is principally developed as multiple series of wave families, and thus, the pressure gradient curve is formed by numerous peaks and troughs. The gradient peaks UP0 and UV0 are generated successively by the train nose entering the tunnel and passing over the opening, respectively, and dominate the maximum pressure gradient. The vent ratio of the opening can be optimized by balancing these two peaks. However, the vent location and train Mach number can significantly affect the optimizing and the aerodynamic behaviour of the optimized opening, which is attributed to wave superposition. Three original engineering equations are proposed for understanding the effects of the vent ratio, vent location and train Mach number on the gradient peaks, respectively, and the denoising capability of the opening is evaluated.

Emplacement controls for the basaltic-andesitic radial dikes of Summer Coon volcano and implications for flank vents at stratovolcanoes

Mafic flank eruptions are common events that pose a serious hazard to the communities and infrastructure often encroaching on the slopes of stratovolcanoes. Flank vent locations are dictated by the propagation path of their feeder dikes. The dikes are commonly thought to propagate either laterally from the central conduit or vertically from a deeper source. However, these interpretations are often based on indirect measurements, such as surface deformation and seismicity at active systems, and several studies at eroded volcanoes indicate the propagation paths may be more complex. We investigated the Oligocene age Summer Coon volcano (Colorado, USA), where erosion has exposed over 700 basaltic-andesitic radial dikes, to constrain the propagation directions, geometries, and spatial distributions of mafic dikes within a stratovolcano. The mean fabric angle of aligned plagioclase crystals was measured in oriented samples from the margins of 77 dikes. Of the 41 dikes with statistically significant flow fabrics, 85% had fabric angles that were inclined—plunging both inward and outward relative to the center of the volcano. After comparing fabric angles to those reported in other studies, we infer that, while most of the dikes with outward-plunging fabrics descended toward the flanks from a source within the edifice and near its axis, dikes with inward-plunging fabrics ascended through the edifice and toward the flanks from a deeper source. A possible control for the inclination of ascending dikes was the ratio between magma overpressure and the normal stress in the host rock. While higher ratios led to high-angle propagation, lower ratios resulted in inclined emplacement. Dikes crop out in higher frequencies within a zone surrounding the volcano axis at ~ 2500 m radial distance from the center and may be the result of ascending dikes, emplaced at similar propagation angles, intersecting the current level of exposure at common distances from the volcano axis. The process of inclined dike emplacement may be common at other stratovolcanoes and should be considered from a monitoring and hazard perspective as slight variations in the propagation angle would translate to major shifts in the anticipated vent location.

Lava flows and cinder cones at Barren Island volcano, India (2005–2017): a spatio-temporal analysis using satellite images

Barren Island volcano erupted during January–February 2017. Located near the Andaman trench and over a subduction zone, it is the only active volcano in India. It comprises a prominent caldera within which there is a polygenetic intra-caldera cinder cone system, with a record of eruptive events which date back to eighteenth century (1787–1832). Major eruptions occurred in 1991, 1994–1995, 2005 and, since 2008, the volcano has been showing near continuous activity with periodic eruptions. We used coarse spatial resolution “fire” products (Band I4) from Suomi National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite to detect days of eruption during the January–February 2017 period. Moderate spatial resolution (23.5 m) short-wavelength infrared (SWIR) data of Resourcesat-2 Linear Imaging Self Scanning Sensor–III available for specific days during this period were used to verify signatures of volcanic eruption. Thermal infrared band data from the Landsat series over the 2005–2017 periods were used to estimate the brightness temperature and location of the active vent within the polygenetic cinder cone field. High-spatial resolution images (1–5.8 m) in the visible bands (Resourcesat-2 LISS-IV, Cartosat-1 and 2) were used to delineate the changes in overall morphology of the volcano and to identify an inner crater ring fault, new paths of lava flow and the formation of a new cinder cone on the old crater. These multi-temporal data sets show significant changes in the paths of lava flows from 2005 to 2017. The observations also document periodic shifts in the location of effusive vents. Morphogenetic changes in recent eruptive phases of the Barren Island volcano were successfully delineated using a combination of multi-temporal and multi-resolution satellite images in visible, SWIR and thermal infrared regions of the electromagnetic spectrum.

Study on the Flow-dynamic Characterization of the Lateral Mechanical Extraction System in Tunnel Fire

Abstract A reasonable mechanical extraction rate is the key to ensure a better exhausting efficiency in case of a tunnel fire. According to the application of the lateral smoke exhaust system in the tunnel, the FDS numerical simulation is used to study the flow-dynamic characterization. An orthogonal test is conducted to analyze the influence of the smoke vent area, location of smoke vent and the exhaust rate on smoke exhausting efficiency. The interface temperature calculated by the N-percent method, the temperature distribution and the smoke flow near the smoke vent are analyzed. According to this research, the exhaust rate and location of smoke vent have a great influence on the smoke exhaust efficiency than the smoke vent area. The lateral smoke vent should be mounted in the top of the side wall and the exhaust velocity of a single smoke vent should not greater than 6m/s.

Sexual dimorphism and morphometric study of Caspian pond turtle, Mauremyscaspica, (Testudines: Geoemydidae) in Golestan Province, southeast of the Caspian Sea

The Caspian pond turtle, Mauremyscaspica, is a terrapin belonging to family Geoemydidae. Totally 130 specimens (67 males and 63 females) were collected manually and by net from different aquatic habitats in Golestan Province from 2016 through 2017. Morphometric characteristics such as length were measured using digital caliper and weight by electronic weighting scale. Skin of this turtle was dark olive green in color and had rows of longitudinal yellow stripes around the head and neck. Their carapace was relatively flat, the bridges between the dorsal and ventral shells were bony, and the ends of anal scutes were found to be pointed. Fingers and toes had swimming membranes. Sexes were identified using the location of vent on the tail. Sex ratios of males to females were nearly 1:1. The maximum straight carapace length (SCL2) was 80.66- 230.16 (156.72 ± 42.93) and 56.96 - 236.84 (147.02 ± 50.76) in males and females respectively. Ratios of SCL2 to maximum plastron length (PL2) were found to be 1.013 - 1.32 (1.15 ± 0.04) in males and 1.01 - 1.15 (1.08 ± 0.03) in females; ratios of SCL2 to straight carapace width (SCW) were 1.24 - 2.60 (1.40 ± 0.16) in males and 1.20 -1.47 (1.35 ± 0.07) in females; ratios of SCL2 to carapace height (CH) were 2.28 - 3.55 (2.79 ± 0.22) in males and 2.05 - 8.78 (2.87 ± 1.11) in females; ratios of SCL2 to tail length2 (TL2) were 2.33 - 7.59 (3.76 ± 0.91) in males and 2.34 - 4.78 (3.06 ± 0.62) in females. Ratios of straight width of femuro-anal suture (FASW) to anal seam length (AnSL) were 2.95 – 5.89 (3.78 ± 0.54) in males and 2.65 - 4.13 (3.23 ± 0.40) in females. The ratio of TL2 to TL1 and TL1 to RBrL are found to be the fast and simple grouping index to determine sex of the specimens.

3D simulation of polyurethane foam injection and reacting mold flow in a complex geometry

The aim of the present work is to develop a flow model which can be used to determine the paths of the polyurethane foam in the mold filling process of a refrigerator cabinet so that improvements in the distribution and the size of the venting holes can be achieved without the expensive prototyping and experiments. For this purpose, the multi-component, two-phase chemically reacting flow is described by Navier Stokes and 12 scalar transport equations. The air and the multi-component foam zones are separated by an interface, which moves only with advection since the mass diffusion of species are set zero in the air zone. The inverse density, viscosity and other diffusion coefficients are calculated by a mass fraction weighted average of the corresponding temperature-dependent values of all species. Simulations are performed in a real refrigerator geometry, are able to reveal the problematical zones where air bubbles and voids trapped in the solidified foam are expected to occur. Furthermore, the approach proves itself as a reliable design tool to use in deciding the locations of air vents and sizing the channel dimensions.

Explosive volcanism on Mercury: Analysis of vent and deposit morphology and modes of eruption

The MESSENGER mission revealed, for the first time, conclusive evidence of explosive volcanism on Mercury. Several previous works have cataloged the appearance and location of explosive volcanism on the planet using a variety of identifying characteristics, including vent presence and deposit color as seen in multispectral image mosaics. We present here a comprehensive catalog of vents of likely volcanic origin; our classification scheme emphasizes vent morphology. We have analyzed the morphologies of all vents in our catalog, and recognize three main morphologies: “simple vent”, “pit vent”, and “vent-with-mound”. The majority of vents we identify are located within impact craters. The spatial distribution of vents does not correlate with the locations of volcanic smooth plains deposits, in contrast to the Moon, nor do vents correlate with the locations of large impact basins (except for the Caloris and Tolstoj basins). Using the degradation state of the vent host crater as a proxy for maximum age, we suggest that vent formation has been active through the Mansurian and into the Kuiperian periods, although the majority of vents were likely formed much earlier in mercurian history. The morphologies and locations of vents are used to investigate a set of plausible formation geometries. We find that the most likely and most prevalent formation geometry is that of a dike, stalled at depth, which then explosively vents to the surface. We compare the vent and deposit size of mercurian pyroclastic deposits with localized and regional lunar pyroclastic deposits, and find a range of possible eruption energies and corresponding variations in eruption style. Localized lunar pyroclastic deposits and the majority of mercurian pyroclastic deposits show evidence for eruption that is consistent with the magmatic foam at the top of a dike reaching a critical gas volume fraction. A subset of mercurian vents, including the prominent Copland-Rachmaninoff vent to the northeast of the Rachmaninoff basin, indicates eruption at enhanced gas volume fractions. This subset of vents shows a similar eruptive behavior to the lunar Orientale dark mantle ring deposit, suggesting that the dikes that formed these vents and deposits on Mercury underwent some form of additional volatile build-up either through crustal volatile incorporation or magma convection within the dike. There also exists a population of mercurian vents that no longer retain a visible associated pyroclastic deposit; we hypothesize that the visible signature of the pyroclastic deposit has been lost through space weathering and regolith mixing processes. Together, these results provide a comprehensive analysis of explosive volcanism on Mercury, and inform continued research on the thermal history of Mercury and magma composition and evolution.

Using infrasound waves to monitor tropospheric weather and crater morphology changes at Volcán Tungurahua, Ecuador

We use infrasound waves generated during eruptions of Volcán Tungurahua (Ecuador) to study both, changing atmospheric conditions and volcanic source characteristics. Analyzed infrasound data were recorded for a 32-month period by a five-station network located within 6.5km from the vent. We use cross-network correlation to quantify the recurrent eruptive behavior of Tungurahua and results are corroborated by reports from the Ecuadorian monitoring agency. Cross-network lag times vary over short time periods (minutes to days) when vent location is stable and attribute these variations to changes in atmospheric structure. Assuming a fixed source location, we invert for average air temperatures and winds in Tungurahua's vicinity (<6.5km) and find evidence for diurnal and semidiurnal tropospheric tides. We also use cross-network correlation lag times to compute infrasound source positions with resolutions of ~11.6m, taking into account coarse NOAA atmospheric models for local winds and temperatures. Variable infrasound-derived source locations suggest source migration during the 32months of analyzed data. Such source position variability is expected following energetic eruptions that destructively altered the crater/vent morphology as confirmed by imagery obtained during regular overflights.

Flame deflagration in side-on vented detonation tubes: A large scale study

Venting is often used in process industries to reduce the possibility of dangerous rises in pressure levels and the severity of explosions. To date, the effectiveness of side-on venting on methane flame deflagration in large scale operations has not been clearly addressed. This work explicitly investigates the influences of side-on venting on varied methane flame deflagration concentrations in a 30m long Detonation Tube (DT). Resultscorresponding to this study prove the existence of a significant correlation between the fire and explosion driving parameters such as pressure rise and flame propagation velocity with the vent location. It observed venting the explosion at distance between 6.5m and 20.5m from the ignition source resulted in reducing the explosion total pressure by about 33% to 56%. For methane concentration of 7.5% the dynamic and static pressures reduced by about 66% and 33%, respectively. The reduced pressure observed to decelerate the flame velocity by about 70%. Significant pressure rise and flame deflagration velocity reductions were observed in both upstream and downstream of the DT corresponding to the location of the vent. For high methane concentrations vacuum effect observed to drawback the flame into the vent and trigger the secondary pressure rise.

Diverse dynamics of Holocene mafic-intermediate Plinian eruptions at Mt. Taranaki (Egmont), New Zealand

Over the last 5000 years, at least 53 eruptive episodes have occurred at Mt. Taranaki (western North Island, New Zealand), from either its summit crater (~ 2500 m) or a satellite vent on Fanthams Peak (~ 1900 m). The magmas erupted have a wide range of compositions from basaltic to trachy-andesitic (~ 48–60 wt% SiO2). Five large-magnitude episodes from this sequence were studied so as to characterize a typical range of explosive eruption styles at andesitic stratovolcanoes, including three eruptions from the summit crater and two from Fanthams Peak. Sustained eruption columns characterized the climactic phase of all five eruptions, but these were interspersed with pulsating, collapsing, or oscillating conditions. Eruption columns reached between 14 to 29 km in height and ejected minimum volumes of 0.1–1.1 km3 at mass discharge rates of 1 × 107–2 × 108 kg/s, indicating magnitudes of 4.1 to 5.1. The simplest eruptions occurred from Fanthams Peak with basaltic magmas producing high-climactic eruption columns rapidly after vent opening, followed by gentle waning phases or a passage into a lava-fountaining phase. Eruptions of higher-silica magmas at the summit vent, by contrast, showed longer pre-climactic eruptive phases with either dome growth or complex phases of vent clearance and blockage producing unsteady eruption columns. The latter eruption types produced block-and-ash flows, lateral-blast surges, and column-collapse pumice-and-ash flows, with run-out distances of 3–19 km, covering 5–70 km2 with volumes of up to 0.022 km3. Our results demonstrate that very different eruption scenarios may occur at different vent locations, or with subtly different compositions erupted, on the same stratovolcano so that emergency management planning must take such a range of possibilities into account.

Probabilistic-numerical assessment of pyroclastic current hazard at Campi Flegrei and Naples city: Multi-VEI scenarios as a tool for "full-scale" risk management.

The Campi Flegrei volcanic field (Italy) poses very high risk to the highly urbanized Neapolitan area. Eruptive history was dominated by explosive activity producing pyroclastic currents (hereon PCs; acronym for Pyroclastic Currents) ranging in scale from localized base surges to regional flows. Here we apply probabilistic numerical simulation approaches to produce PC hazard maps, based on a comprehensive spectrum of flow properties and vent locations. These maps are incorporated in a Geographic Information System (GIS) and provide all probable Volcanic Explosivity Index (VEI) scenarios from different source vents in the caldera, relevant for risk management planning. For each VEI scenario, we report the conditional probability for PCs (i.e., the probability for a given area to be affected by the passage of PCs in case of a PC-forming explosive event) and related dynamic pressure. Model results indicate that PCs from VEI<4 events would be confined within the Campi Flegrei caldera, PC propagation being impeded by the northern and eastern caldera walls. Conversely, PCs from VEI 4–5 events could invade a wide area beyond the northern caldera rim, as well as part of the Naples metropolitan area to the east. A major controlling factor of PC dispersal is represented by the location of the vent area. PCs from the potentially largest eruption scenarios (analogous to the ~15 ka, VEI 6 Neapolitan Yellow Tuff or even the ~39 ka, VEI 7 Campanian Ignimbrite extreme event) would affect a large part of the Campanian Plain to the north and the city of Naples to the east. Thus, in case of renewal of eruptive activity at Campi Flegrei, up to 3 million people will be potentially exposed to volcanic hazard, pointing out the urgency of an emergency plan. Considering the present level of uncertainty in forecasting the future eruption type, size and location (essentially based on statistical analysis of previous activity), we suggest that appropriate planning measures should face at least the VEI 5 reference scenario (at least 2 occurrences documented in the last 10 ka).

Thermal Conditions Controlled by Thermostats: An Occupational Comfort and Well-being Perspective

From the perspective of occupational comfort and well-being, indoor thermal condition characterized by its temperature levels, spatial variations, and airflow patterns plays an important role. Studies have demonstrated strong correlations among indoor comfort levels and users' well-being, productivity, and overall health. Computational fluid dynamics (CFD) has been used to investigate indoor thermal comfort. In this research, a private office on the University of Cincinnati campus was selected and studied in order to spatially map the thermal comfort index. Autodesk® CFD, a ventilation simulation software, was utilized to model the office space and air conditioning systems, as well as simulate the airflow in the indoor space. Based on the simulation results, the air speed, ambient temperature, and relative humidity were all obtained for different vent locations. These simulated parameters can be used in dynamic anthropometry to acquire the predicted mean vote (PMV) and temperature in specific office areas. Through this method, a visualized indoor comfort map was developed as a means of indicating potential user comfort effects; spatial variations in the indoor comfort index have also been analyzed and discussed.

The Effects of Vent Location, Event Scale, and Time Forecasts on Pyroclastic Density Current Hazard Maps at Campi Flegrei Caldera (Italy)

This study presents a new method for producing long-term hazard maps for pyroclastic density currents (PDC) originating at Campi Flegrei caldera. Such method is based on a doubly stochastic approach and is able to combine the uncertainty assessments on the spatial location of the volcanic vent, the size of the flow and the expected time of such an event. The results are obtained by using a Monte Carlo approach and adopting a simplified invasion model based on the box model integral approximation. Temporal assessments are modelled through a Cox-type process including self-excitement effects, based on the eruptive record of the last 15 kyr. Mean and percentile maps of PDC invasion probability are produced, exploring their sensitivity to some sources of uncertainty and to the effects of the dependence between PDC scales and the caldera sector where they originated. Conditional maps representative of PDC originating inside limited zones of the caldera, or of PDC with a limited range of scales are also produced. Finally, the effect of assuming different time windows for the hazard estimates is explored, also including the potential occurrence of a sequence of multiple events. Assuming that the last eruption of Monte Nuovo (A.D. 1538) marked the beginning of a new epoch of activity similar to the previous ones, results of the statistical analysis indicate a mean probability of PDC invasion above 5% in the next 50 years on almost the entire caldera (with a probability peak of ~25% in the central part of the caldera). In contrast, probability values reduce by a factor of about 3 if the entire eruptive record is considered over the last 15 kyr, i.e. including both eruptive epochs and quiescent periods.

A Physical Model of Sill Expansion to Explain the Dynamics of Unrest at Calderas with Application to Campi Flegrei

Many calderas show remarkable unrests, which often do not culminate in eruptions (non-eruptive unrest). In this context the interpretation of the geophysical data collected by the monitoring networks is difficult. When the unrest is eruptive, a vent opening process occurs, which leads to an eruption. In volcanic calderas, vent locations typically are scattered over a large area and monogenic cones form. The resulting pattern is characterized by a wide dispersion of eruptive vents, therefore, the location of the future vent in calderas is not easily predictable. We propose an interpretation of the deformation associated to unrest and vent pattern commonly observed at volcanic calderas, based on a physical model that simulates the intrusion and the expansion of a sill. The model can explain both the uplift and the subsequent subsidence, through a single geological process. In particular, we simulate the vertical displacement that occurred at the central area of Campi Flegrei caldera during the last decades, and we obtain good agreement with the data of a leveling benchmark near the center of the caldera. Considering that the stress mainly controls the vent opening process, we try to gain insight on the vent opening in calderas through the study of the stress field produced by the intrusion of an expanding sill. We find that the tensile stress in the rock above the sill is concentrated in a ring-shaped area with radius depending on the physical properties of magma and rock, the feeding rate and the magma cooling rate. This stress field is consistent with widely dispersed eruptive vents and monogenic cone formation, which are often observed in the calderas. However, considering the mechanical properties of the elastic plate and the rheology of magma, we show that remarkable deformations may be associated with low values of stress in the rock at the top of the intrusion, thereby resulting in non-eruptive unrests. Moreover, we have found that, under the assumption of isothermal conditions, the stress values decrease over time during the intrusion process. This result may explain why the long-term unrests, in general, do not culminate in an eruption.

An experimental study to assess the effect of soffit louvered vents on wind loads and wind driven rain intrusion on low rise buildings

Wind-driven rain (WDR) intrusion in buildings during hurricanes often leads to significant damage to building interior and contents, causing major losses. Many buildings in hurricane-prone U.S. coastal states are fitted with soffit vents with louvers that are designed to close during high winds and reduce rain intrusion. This paper focuses on the topic of WDR intrusion through soffit vents and, in particular, studies the effects of louvered soffit vents on (i) reduction of water intrusion, and (ii) overall aerodynamic loading of buildings’ roofs. A gable and a hip roof building retrofitted with open and closed vents were tested at the Wall of Wind (WOW) experimental facility. WDR intrusion studies were carried out only on the hip roof building, while wind pressure distributions were estimated for the gable and hip roof buildings. Results from the WDR intrusion study indicate a marked reduction in water intrusion for the closed vent roofs. Moreover, the net mean and peak pressure coefficients for the closed vent roofs are reduced in magnitude (less suction) compared to the open vent roofs. Future research is recommended to study the effect of different vent sizes and locations, besides considering other roof types (e.g. mono-slope).

CFD analysis of internal ventilation in high-speed human powered vehicles

When dealing with fully faired human powered vehicles (HPVs) for speed or endurance record attempts, the need for internal ventilation of the rider arises. Different solutions have been proposed in the literature and in practice by designers and builders of these bicycles. The present paper proposes an analytical approach to design the frontal air inlet according to the VO $$_{2}$$ max of the rider in speed competitions. A 3D computational fluid dynamics (CFD) model is presented to analyse the external and internal flow interaction with respect to three design parameters: the presence of wheel covers, the location of the rear vent and its geometry. The CFD results predict that the wheel covers save 23 W of aerodynamic power at 125 km/h. A secondary but significant design parameter is the rear vent position that can provide a further reduction of 11 W at 125 km/h if properly located. Finally, the effect of the rear vent geometry was below the model confidence level, resulting in a likely negligible design parameter.

Assessing future vent opening locations at the Somma‐Vesuvio volcanic complex: 2. Probability maps of the caldera for a future Plinian/sub‐Plinian event with uncertainty quantification

AbstractIn this study, we combine reconstructions of volcanological data sets and inputs from a structured expert judgment to produce a first long‐term probability map for vent opening location for the next Plinian or sub‐Plinian eruption of Somma‐Vesuvio. In the past, the volcano has exhibited significant spatial variability in vent location; this can exert a significant control on where hazards materialize (particularly of pyroclastic density currents). The new vent opening probability mapping has been performed through (i) development of spatial probability density maps with Gaussian kernel functions for different data sets and (ii) weighted linear combination of these spatial density maps. The epistemic uncertainties affecting these data sets were quantified explicitly with expert judgments and implemented following a doubly stochastic approach. Various elicitation pooling metrics and subgroupings of experts and target questions were tested to evaluate the robustness of outcomes. Our findings indicate that (a) Somma‐Vesuvio vent opening probabilities are distributed inside the whole caldera, with a peak corresponding to the area of the present crater, but with more than 50% probability that the next vent could open elsewhere within the caldera; (b) there is a mean probability of about 30% that the next vent will open west of the present edifice; (c) there is a mean probability of about 9.5% that the next medium‐large eruption will enlarge the present Somma‐Vesuvio caldera, and (d) there is a nonnegligible probability (mean value of 6–10%) that the next Plinian or sub‐Plinian eruption will have its initial vent opening outside the present Somma‐Vesuvio caldera.