Atex‐HOF methodology: Innovation driven by human and organizational factors (HOF) in explosive atmosphere risk assessment

ATEX (explosive atmosphere) risk assessment is required when any equipment or system could generate a potentially explosive atmosphere. Despite the fact that many operations on plants and equipment containing dangerous substances are performed by operators, influences of human and organizational factors (HOF) are mostly neglected in the ATEX risk assessment. The integrated methodology described here is proposed to address two challenges: (1) identification of the HOF influence on the ATEX risk assessment, and (2) quantification of the HOF influence. The proposed methodology enriches the traditional ATEX risk assessment procedure, which consists of four steps: (1) area classification, (2) ignition source identification, (3) damage analysis, and (4) ATEX risk evaluation. The advantages of the ATEX‐HOF methodology are demonstrated through the application to a paint mixing station in an automotive manufacturing plant. The ATEX risk assessment methodologies are mainly semi‐quantitative. The ATEX‐HOF methodology provides a quantitative analysis for the area classification and ignition source identification, and a semi-quantitative approach for the damage analysis. As a result, the ATEX‐HOF risk evaluation becomes more accurate. An event tree‐based probabilistic assessment has been introduced, considering both the technical barrier failure (Prtbf) and the human intervention in terms of human error probability (HEP). The case study allowed for demonstrating how taking HOFs into account is particularly important in companies where the safety culture is lower and consequently, the usual hypothesis of the correctness of operator intervention (in maintenance, normal operations, and emergency) could bring to non‐conservative results

The role of syn-eruptive vesiculation on explosive basaltic activity at Mt. Etna, Italy

We investigated the dynamics of explosive activity at Mt. Etna between 31 August and 15 December 2006 by combining vesicle studies in the erupted products with measurements of the gas composition at the active, summit crater. The analysed scoria clasts present large, connected vesicles with complex shapes and smaller, isolated, spherical vesicles, the content of which increases in scoriae from the most explosive events. Gas geochemistry reports CO2/SO2 and SO2/HCl ratios supporting a deep-derived gas phase for fire-fountain activity. By integrating results from scoria vesiculation and gas analysis we find that the highest energy episodes of Mt. Etna activity in 2006 were driven by a previously accumulated CO2-rich gas phase but we highlight the lesser role of syn-eruptive vesicle nucleation driven by water exsolution during ascent. We conclude that syn-eruptive vesiculation is a common process in Etnean magmas that may promote a deeper conduit magma fragmentation and increase ash formation

The role of syn-eruptive vesiculation on explosive basaltic activity at Mt. Etna, Italy

We investigated the dynamics of explosive activity at Mt. Etna between 31 August and 14 December 2006 by combining vesicle studies in the erupted products with measurements of the gas composition at the active, summit crater. The analysed scoria clasts present large, connected vesicles with complex shapes and smaller, isolated, spherical vesicles, the content of which increases in scoriae from the most explosive events. Gas geochemistry reports CO2/SO2 and SO2/HCl ratios supporting a deep-derived gas phase for fire-fountain activity. By integrating results from scoria vesiculation and gas analysis we find that the highest energy episodes of Mt. Etna activity in 2006 were driven by a previously accumulated CO2-rich gas phase but we highlight the lesser role of syn-eruptive vesicle nucleation driven by water exsolution during ascent. We conclude that syn-eruptive vesiculation is a common process in Etnean magmas that may promote a deeper conduit magma fragmentation and increase ash formatio

Degassing behavior of Mt. Etna volcano (Italy) during 2007-2008, inferred

Studies on volcanic degassing have recently shown the important role of volatile release from active volcanoes in understanding magmatic processes prior to eruptions. Here we present and discuss the evolution of magmatic degassing that preceded and accompanied the 2008 Mt. Etna eruption. We tracked the ascent of magma bodies by high-temporal resolution measurements of SO2 emission rates and discrete sampling of SO2/HCl and SO2/HF molar ratios in the crater plume, as well as by periodic measurement of soil CO2 emission rates. Our data suggest that the first signs of upward migration of gas-rich magma before the 2008 eruption were observed in June 2007, indicated by a strong increase in soil CO2 efflux followed by a slow declining trend in SO2 flux and halogens. This degassing behavior preceded the mid-August 2007 summit activity culminated with the September 4th paroxysmal event. Five months later, a new increase in both soil CO2 and SO2 emission rates occurred before the November 23rd paroxysm, to drop down in late December. In the following months, geochemical parameters showed high variability, characterized by isolated sudden increases occurred in early December 2007 and late March 2008. In early May soil CO2, SO2 emission rates and S/Cl molar ratio gradually increased. Crater degassing peaked on May 13th marking the onset of the eruption. Eruptive activity was accompanied by a general steady-state of SO2 flux characterized by two main degassing cycles. These cycles preceded explosive activity at the eruptive vents, indicating terminal new-arrival of deep gas-rich magma bodies in the shallow plumbing system of Mt Etna. Conversely, halogens described a slight increasing trend till the end of 2008. These observations suggest an impulsive syn-eruptive dynamics of magma transfer from depth to the surface. Differently from the SO2 emission rates, the S/Cl ratio and the soil CO2 efflux values showed an increasing trend from mid-April to mid-July 2008, indicating steady-increasing input of deeper, gas-rich magma. Since August, geochemical parameters decreased, suggesting that new magma has not arrived from depth. According to our interpretation, both the CO2 efflux and the S/Cl ratio increases observed in early November may indicate a new input of fresh magma form depth. Finally, the estimated volume of degassing magma showed substantial equilibrium between degassed and erupted magma suggesting an “eruptive” steady-state of the volcano

Installation and first results from a remote-controlled automatic FTIR spectrometer on

The first successful FTIR measurements on Stromboli were conducted in 2000, producing remarkable insights into the rapidly changing dynamics of degassing and explosive processes. The ability of the FTIR to simultaneously measure all the major species contained in volcanic gas emissions (H2O, CO2, SO2, HCl, HF, CO, OCS, SiF4) at high temporal resolution, when combined with the automatic SO2 flux monitoring system already installed on Stromboli could allow fluxes of all these gases to be determined accurately and automatically. In order to achieve this objective, we have designed a remotely controlled FTIR-scanner system that allows directional control over the field of view of the spectrometer. The system is planned for installation in June/July 2008, and we will present the first results from the system in this paper

The first period of the 2002 Etna eruption (27 October-5 November): preliminary results

We report on the first period of the 2002 Etna eruption started on 27th October and ended on 5th November, occurring 15 months after the end of the 2001 eruption. Volcanological and geochemical data are presented in order to characterize the complex intrusion mechanism that contemporaneously involved the NE and S flanks of the volcano. Preliminary data outline that two distinct magma intrusions fed the eruptive fissures. Strong fire fountain activity mainly from the S fissure, produced copious ash fall in eastern Sicily, causing prolonged closure of Catania and Reggio Calabria airports. Lava emitted from the NE fissure formed a 6.2 km long lava flow field that destroyed the tourist facilities of Piano Provenzana area and part of Linguaglossa pine forest.Published1-10reserve

Domain wall motion governed by the spin Hall effect

Perpendicularly magnetized materials have attracted tremendous interest due to their high anisotropy, which results in extremely narrow, nano-sized domain walls. As a result, the recently studied current-induced domain wall motion (CIDWM) in these materials promises to enable a novel class of data, memory, and logic devices. In this letter, we propose the spin Hall effect as a radically new mechanism for CIDWM. We are able to carefully tune the net spin Hall current in depinning experiments on Pt/Co/Pt nanowires, offering unique control over CIDWM. Furthermore, we determine that the depinning efficiency is intimately related to the internal structure of the domain wall, which we control by small fields along the nanowire. This new manifestation of CIDWM offers a very attractive new degree of freedom for manipulating domain wall motion by charge currents, and sheds light on the existence of contradicting reports on CIDWM in perpendicularly magnetized materials