Paroxysmal Phase Research Articles

Radiative impacts of the Australian bushfires 2019–2020 – Part 2: Large-scale and in-vortex radiative heating

Abstract. Record-breaking wildfires ravaged south-eastern Australia during the fire season 2019–2020. The intensity of the fires reached its paroxysmal phase at the turn of the year 2019–2020, when large pyro-cumulonimbi developed. Pyro-convective activity injected biomass burning aerosols and gases in the upper-troposphere–lower-stratosphere (UTLS), producing a long-lasting perturbation to the atmospheric composition and the stratospheric aerosol layer. The large absorptivity of the biomass burning plume produced self-lofting of the plume and thus modified its vertical dynamics and horizontal dispersion. Another effect of the in-plume absorption was the generation of compact smoke-charged anticyclonic vortices which ascended up to 35 km altitude due to diabatic heating. We use observational and modelling description of this event to isolate the main vortex from the dominant Southern Hemispheric biomass burning aerosol plume. Entering this information into an offline radiative transfer model, and with hypotheses on the absorptivity and the angular scattering properties of the aerosol layer, we estimate the radiative heating rates (HRs) in the plume and the vortex. We found that the hemispheric-scale plume produced a HR of 0.08±0.05 K d−1 (from 0.01 to 0.15 K d−1, depending on the assumption on the aerosol optical properties), as a monthly average value for February 2020, which is strongly dependent on the assumptions on the aerosol optical properties and therefore on the plume ageing. We also found in-vortex HRs as large as 15–20 K d−1 in the denser sections of the main vortex (8.4±6.1 K d−1 on average in the vortex). Our results suggest that radiatively heated ascending isolated vortices are likely dominated by small-sized strongly absorbing black carbon particles. The hemispheric-scale and in-vortex HR estimates are consistent with the observed ensemble self-lofting (a few kilometres in 4 months) and the main isolated vortex rise (∼ 20 km in 2 months). Our results also show evidence of the importance of longwave emission in the net HR of biomass burning plumes.

Ictogenesis proceeds through discrete phases in hippocampal CA1 seizures in mice

Epilepsy is characterized by spontaneous non-provoked seizures, yet the mechanisms that trigger a seizure and allow its evolution remain underexplored. To dissect out phases of ictogenesis, we evoked hypersynchronous activity with optogenetic stimulation. Focal optogenetic activation of putative excitatory neurons in the mouse hippocampal CA1 reliably evoked convulsive seizures in awake mice. A time-vs-time pulsogram plot characterized the evolution of the EEG pulse response from a light evoked response to induced seizure activity. Our results depict ictogenesis as a stepwise process comprised of three distinctive phases demarcated by two transition points. The induction phase undergoes the first transition to reverberant phase activity, followed by the second transition into the paroxysmal phase or a seizure. Non-seizure responses are confined to either induction or reverberant phases. The pulsogram was then constructed in seizures recorded from a murine model of temporal lobe epilepsy and it depicted a similar reverberance preceding spontaneous seizures. The discovery of these distinct phases of ictogenesis may offer means to abort a seizure before it develops.

Western Mediterranean Precipitation Extremes, the Result of Quasi-Resonant Sea–Atmosphere Feedbacks

The Mediterranean region has been identified as a climate change hotspot, and 13 case studies of extreme rainfall events (EREs) make it possible to categorize convective systems according to whether they are tropical-like or extratropical cyclones. This study, which focuses on the western Mediterranean basin from 2000 to 2021, is based on the cross-wavelet analysis in the period range of 11.4 to 45.7 days of (1) the height of precipitation at a particular place representative of the deep convective system used as the temporal reference and (2) the amount of precipitation in the western Mediterranean basin, as well as the sea surface temperature (SST) in the Mediterranean, the Adriatic, the Aegean Sea, the Black Sea, the Baltic, the North Sea and the Atlantic Ocean. Extratropical cyclones result from quasi-resonant atmospheric water and SST feedbacks, reflecting the co-evolution of the clustering of lows and the harmonization of thermocline depths and a relative stability of the atmospheric blocking circulation. When the SST anomaly in the western Mediterranean is greater than 0.5 °C, in its paroxysmal phase, the deep convective system is centered both over the southeast of France and the Mediterranean off the French coast. However, when the SST anomaly is weaker, deep convective systems can develop in different patterns, depending on SST anomalies in the peripheral seas. They can produce a low-pressure system extending from the Pyrenees to southern Italy or Sicily when the SST anomaly in the western Mediterranean is in phase opposition with EREs. In some cases, partial clustering of Atlantic and Mediterranean low-pressure systems occurs, producing a large cyclonic system. Tropical-like cyclones develop in the absence of any significant SST anomalies. Like extratropical cyclones, they occur in autumn or even winter, when the thermal gradient between the sea surface and the upper atmosphere is greatest but, this way, non-resonantly. Their return period is around 2 to 3 years. However, due to the gradual increase in the SST of the western Mediterranean in summer resulting from global warming, they can now lead to an ERE as happened on 21 January 2020.

Global shockwaves of the Hunga Tonga-Hunga Ha’apai volcano eruption measured at ground stations

The eruption of the Tonga volcano created globally propagating spherical shockwaves in the atmosphere. Analyses are done to data from two southern U.S. stations of the author sampling at 3-21s intervals and 189 weather stations at 1-5min intervals. The shockwaves arrived from two routes in the atmosphere: the shortest spherical arc and the longer spherical arc through the antipole. In most stations, signals up to the 6th path of shockwaves were recorded as the waves traveled around the globe multiple times. The speed of shockwaves is estimated to be 309.5± 2.9m/s, consistent with the speed of sound at the top of the troposphere where a waveguide exists. Discussion is made on the post-shockwave ringing of 4-8min as higher amplitude oscillations above the level of pre-shockwaves background noise. A theoretical wave dispersion is derived which verifies that the spherical shockwave's phase speed is the same as the speed of sound.

Transitional shale quality and exploration potential: A case study from the Lower Carboniferous Jiusi Formation in northwest Weining, China

The organic-rich shale of the early Carboniferous Jiusi Formation in the Weining area, Southwestern China, has large geological gas reserves, making the Jiusi Formation another target after the Ordovician-Silurian marine shale in South China. The complex superposition of multi-stage tectonic phases since the Himalayan paroxysmal phase has induced a series of controversies in the sedimentology of the Jiui Formation, as only a few drillings were executed. In order to better understand the development potential of the shale associated with the Jiui Formation, five outcrops and a well (YS302) were studied, clarifying the sedimentary evolution of the formation, while two 2D seismic sections were used to analyze the regional structural styles. The result shows that the Jiusi Formation was significantly influenced by the synsedimentary extension of the northwestern margin of the Yadu-Ziyun-Luodian Fault, with the depositional center of the Jiusi Formation extending to well YS302 along a NW direction and asymmetrically thinning in a NE–SW direction. Fifteen lithofacies and three facies associations were identified, from tidal or delta settings to lagoon environments, finally turning into platform facies at the base of the Shangsi Formation. According to the geochemical analysis of 27 core samples and 37 outcrop samples, as well as the well YS302 logging interpretation result. The transitional Jiusi shale in the Weining area has a strong heterogeneity, with high total organic content (TOC) values being mostly provided by the surrounding coal seams. XRD analyses show that the minerals of the transitional shale are dominated by a high clay content (42 wt%). The content of water-sensitive minerals in Jiusi shale is also relatively high, with clay minerals dominated by an illite/smectite mixture (52.8%). When compared with the commercially developed Ordovician-Silurian marine shale, the Jiusi transitional shale shows relatively poor quality, related to dense bioturbation and terrestrial input affecting the preservation of organic matter. Therefore, the evaluation standard for marine shale is difficult to apply to the transitional Jiusi shale. The cumulative thickness of shale in YS302 worthy of shale gas development is nearly 100 m. Meanwhile, considering that the transitional shales are often interlayered with coal, the shale gas and coalbed methane can be developed together.

Explosive Paroxysmal Events at Etna Volcano of Different Magnitude and Intensity Explored through a Multidisciplinary Monitoring System

Between 13 December 2020 and 21 February 2022, Etna volcano produced a sequence of 66 paroxysmal explosive eruptions, with Strombolian activity at the summit craters climaxing in lava fountains and eruption columns extending several kilometers above the craters, accompanied by minor and short-lasting lava flows from the crater rim. We selected three of these episodes that occurred within a short space of time, between 13 December 2020 and 12 March 2021, of different magnitude (i.e., erupted volume) and intensity (i.e., mass eruption rate or instantaneous eruption rate), and analyzed them from a multidisciplinary perspective. The aim was to gain insights into those parameters that mostly reveal the eruptive process for hazard assessment purposes. The multidisciplinary data consist of calibrated visible images, thermal images, seismic and infrasound data, ground deformation detected from the strainmeters, as well as satellite SEVIRI images. From these data, we obtained the timing of each paroxysmal event, the erupted volume in terms of tephra and lava flows, and the corresponding deflation of the source region, together with the development of the lava fountains and eruption columns with time. The results enabled determining that the smallest episode was that of 13 December 2020, which comprised three distinctive pulses but did not produce an eruptive column detectable from either monitoring cameras or satellites. The 28 February 2021 episode was remarkable for the short amount of time required to reach the climax, and was the most intense, whereas the 12 March 2021 event showed the longest duration but with an intensity between that of the previous two. Our results show that these three paroxysmal events display a typical trend, with the first event also being the smallest in terms of both erupted volume and intensity, the second being the most intense, and the third the one of greatest magnitude but less intense than the second. This is coherent with the end of the first paroxysmal phase on 1 April 2021, which was followed by 48 days of eruptive pause before starting again. In this context, the end of the paroxysmal phase was anticipated by a more effusive episode, thus heralding a temporary decline in the gas content within the feeding magma batch.

Changes in the Eruptive Style of Stromboli Volcano before the 2019 Paroxysmal Phase Discovered through SOM Clustering of Seismo-Acoustic Features Compared with Camera Images and GBInSAR Data

Two paroxysmal explosions occurred at Stromboli on 3 July and 28 August 2019, the first of which caused the death of a young tourist. After the first paroxysm an effusive activity began from the summit vents and affected the NW flank of the island for the entire period between the two paroxysms. We carried out an unsupervised analysis of seismic and infrasonic data of Strombolian explosions over 10 months (15 November 2018–15 September 2019) using a Self-Organizing Map (SOM) neural network to recognize changes in the eruptive patterns of Stromboli that preceded the paroxysms. We used a dataset of 14,289 events. The SOM analysis identified three main clusters that showed different occurrences with time indicating a clear change in Stromboli’s eruptive style before the paroxysm of 3 July 2019. We compared the main clusters with the recordings of the fixed monitoring cameras and with the Ground-Based Interferometric Synthetic Aperture Radar measurements, and found that the clusters are associated with different types of Strombolian explosions and different deformation patterns of the summit area. Our findings provide new insights into Strombolian eruptive mechanisms and new perspectives to improve the monitoring of Stromboli and other open conduit volcanoes.

The first hour of the paroxysmal phase of the 2022 Hunga Tonga–Hunga Ha'apai volcanic eruption as seen by a geostationary meteorological satellite

Abstract online onlyDuring the late afternoon (local time) of 15 January 2022, the Hunga‐Tonnga Hunga‐Ha'apai islands were destroyed by a cataclysmic volcanic eruption. A sequence of images from a geostationary meteorological satellite, Himawari‐8 is presented showing the early evolution of the resulting eruption column and ash cloud. The ash‐rich umbrella cloud reached to over 30km in height and up to 400km in diameter. A smaller area of over‐shooting cloud tops appears to have reached a much higher altitude, greater than 50km, well into the upper stratosphere. The explosion also produced at least one major shock wave, evidence for which can be seen by subtracting visible channel images at 10‐minute intervals.

Magmatic and phreatomagmatic contributions on the ash-dominated basaltic eruptions: Insights from the April and November–December 2005 paroxysmal events at Karthala volcano, Comoros

Basaltic eruptions are commonly associated with lava emissions and relatively weak explosive activities, but they can sometimes produce strong explosive eruptive phases. In April and November 2005, two paroxysmal eruptive events occurred within the summit crater of Karthala basaltic shield volcano (Grande Comore Island, Comoros), which hosted a water lake before each of these events. Both 2005 ash plumes spread across the Comoros Archipelago and heavily impacted the whole Grande Comore Island. Associated deposits on the volcano summit are extremely fine-grained (up to 50 wt% of fine ash <63 μm for some analyzed layers) and rich in millimeter-sized rounded accretionary lapilli aggregates. Field observations, as well as textural and chemical analyses performed on both coarse- and fine-grained pyroclasts permit to identify juvenile and non-juvenile components and quantify their peculiar characteristics. Coarse ash (710–1000 μm) mainly consists of juvenile pumice particles (vesicle number density NV = 4.5 104 mm−3 and gas to melt ratio VG/VL = 1.5, on average), characterized by glassy groundmasses and representative of magma portions ascending quickly within the eruptive conduits (up to 10 m s−1). A relatively low amount of juvenile scoria particles are also observed in the coarse ash fractions, which are characterized by magma degassing (NV = 4.7 104 mm−3 and VG/VL = 0.5 on average) and associated crystallization (occurrence of dendritic microlites). Non-juvenile fragments (from blocks to coarse ash) are dense lava or intrusive fragments. Their amount decreases exponentially towards the fine ash fractions, which are mainly composed of juvenile, blocky, dense and glassy particles that are characterized by unambiguous textural signs of brittle fragmentation (hackle lines, stepped features and cracks). We support that Molten Fuel-Coolant Interactions between highly porous fast ascending basaltic magmas and external waters occurred during the paroxysmal phases of the studied eruptions, leading to a brittle-dominant and efficient regime of magma fragmentation. Variable but large amount of fine ash grains through the stratigraphic depth of the deposits can be ascribed to the brittle failure of the vesicle walls of the initial porous magma. Concurrently, thermohydraulic explosions caused the host rock fragmentation at shallow level, generating the relatively coarse non-juvenile particles. A short-lived episode of intense lava fountaining associated with steam explosions eventually occurred at the end of the November 2005 paroxysm, forming the last and relatively coarse tephra layer at the top of the studied eruptive sequence. Each paroxysmal phase lasted about a day as each associated water lake and shallow water table progressively vaporized and dried away. Both eruptions ended with lava pond and weak lava fountaining activities confined within the summit crater. We conclude that the contributions of both magmatic processes and phreatomagmatic interaction mechanisms ultimately generated the grain size, grain component and grain texture variabilities observed within the paroxysmal deposits. This work contributes to a better understanding of the generation of unusual fine ash from basaltic explosions as well as their eruptive dynamics and associated mechanisms, from magma ascent in the conduit to the fragmentation level and the interaction with intra-crateric lake waters.

Pertussis

The bacterium Bordetella pertussis causes disease by producing various virulence and adhesion factors, among them pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN) and agglutinogens (Agg), also called fimbriae (FIM) "Typical" pertussis or whooping cough starts with unspecific respiratory symptoms (catarrhal phase) followed by severe coughing spasms with whoops and vomiting (paroxysmal phase) and only after weeks or months disease severity slowly wanes (convalescent phase). "Atypical pertussis" with unspecific, long-lasting coughing episodes is seen in adolescents and adults; very young infants may die from apnoea. B. pertussis is transmitted by droplets, and neither infection nor vaccination produce long lasting protection. Macrolide antibiotics are given to patients and their contacts to reduce spread of the organism; however, antibiotics do NOT change the duration or course of the disease once symptoms are present. Whole cell pertussis vaccines (wP) consist of whole inactivated B. pertussis-cells, whereas acellular vaccines (aP) consist of one to five single components like PT, FHA, PRN or FIM. Pertussis vaccines are currently only available as combination vaccines with tetanus und diphtheria (DTP). Among these are DTwP; DTaP; TdaP; and various DTP-combinations with Hib, IPV, HBV vaccines. Whole cell pertussis (DTwP) combination vaccines are more reactogenic, whereas DTaP vaccines are generally well tolerated. Some DTwP had good efficacy/effectiveness (90%), it was low (40%) with others. Vaccine efficacy of DTaP vaccines ranges between 70% and 90%. As with most vaccines, efficiency is higher for severe disease. While pertussis vaccines did control clinical disease, protection is limited. Vaccination is recommended for all infants (three doses) worldwide with a booster in the second year of life. Many countries give additional doses at school entry and in adolescents, and some to adults. Vaccination of pregnant women effectively protects newborn infants and is increasingly recommended.

Pertussis

The bacterium Bordetella pertussis causes disease by producing various virulence and adhesion factors, among them pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (PRN) and agglutinogens (Agg), also called fimbriae (FIM) "Typical" pertussis or whooping cough starts with unspecific respiratory symptoms (catarrhal phase) followed by severe coughing spasms with whoops and vomiting (paroxysmal phase) and only after weeks or months disease severity slowly wanes (convalescent phase). "Atypical pertussis" with unspecific, long-lasting coughing episodes is seen in adolescents and adults; very young infants may die from apnoea. B. pertussis is transmitted by droplets, and neither infection nor vaccination produce long lasting protection. Macrolide antibiotics are given to patients and their contacts to reduce spread of the organism; however, antibiotics do NOT change the duration or course of the disease once symptoms are present. Whole cell pertussis vaccines (wP) consist of whole inactivated B. pertussis-cells, whereas acellular vaccines (aP) consist of one to five single components like PT, FHA, PRN or FIM. Pertussis vaccines are currently only available as combination vaccines with tetanus und diphtheria (DTP). Among these are DTwP; DTaP; TdaP; and various DTP-combinations with Hib, IPV, HBV vaccines. Whole cell pertussis (DTwP) combination vaccines are more reactogenic, whereas DTaP vaccines are generally well tolerated. Some DTwP had good efficacy/effectiveness (90%), it was low (40%) with others. Vaccine efficacy of DTaP vaccines ranges between 70% and 90%. As with most vaccines, efficiency is higher for severe disease. While pertussis vaccines did control clinical disease, protection is limited. Vaccination is recommended for all infants (three doses) worldwide with a booster in the second year of life. Many countries give additional doses at school entry and in adolescents, and some to adults. Vaccination of pregnant women effectively protects newborn infants and is increasingly recommended.

Characterization of Acoustic Infrasound Signals at Volcán de Fuego, Guatemala: A Baseline for Volcano Monitoring

Monitoring volcanic unrest and understanding seismic and acoustic signals associated with eruptive activity is key to mitigate its impacts on population and infrastructure. On June 3, 2018, Volcan de Fuego, Guatemala, produced a violent eruption with very little warning. The paroxysmal phase of this event generated pyroclastic density currents (PDC) that impacted nearby settlements resulting in 169 fatalities, 256 missing, and nearly 13,000 permanently displaced from their homes. Since then, Volcan de Fuego has been instrumented with an extensive network of seismic and infrasound sensors. Infrasound is a new monitoring tool in Guatemala. A key step toward its effective use in volcano monitoring at Volcan de Fuego is establishing a baseline for the interpretation of the recorded signals. Here, we present the first comprehensive characterization of acoustic signals at Volcan de Fuego for the whole range of surface activity observed at the volcano. We use data collected during temporary deployments in 2018 and from the permanent infrasound network. Infrasound at Fuego is dominated by the occurrence of short-duration acoustic transients linked to both ash-rich and gas-rich explosions, at times associated with the generation of shock waves. The rich acoustic record at Fuego includes broadband and harmonic tremor, and episodes of chugging. We explore the occurrence of these signals in relation to visual observations of surface activity, and we investigate their source mechanisms within the shallow conduit system. This study provides a reference for the interpretation of acoustic signals at Volcan de Fuego and a baseline for real-time monitoring of its eruptive activity using infrasound data. Our results suggest that changes in the style of activity and morphology of the summit crater are reflected in the acoustic signature of eruption; as such our study provides a reference for the interpretation of acoustic signals at Volcan de Fuego and a baseline for real-time monitoring of its eruptive activity using infrasound.

Imaging the Salinelle Mud Volcanoes (Sicily, Italy) using integrated geophysical and geochemical surveys

Geochemical and geophysical prospecting methods (including measurements of soil heat flux and soil CO2 flux, gravimetry, self-potential and geomagnetism) are used to produce an integrated data set aimed at imaging the migration of fluids in the sub-surface at the Salinelle mud volcanoes, located on the lower southwestern flank of Mt Etna (Sicily, Italy). This area was affected by magmatic eruptions from local volcanic centers between about 48 and 27 ka. Today, only pseudo-volcanic phenomena due to over-pressured multiphase pore fluids there occur. Carbon dioxide of magmatic origin, mixed with biogenic hydrocarbons, warm hypersaline waters and mud, are constantly released at the surface through the main conduits of mud volcanoes, whose activity is characterized by alternation of mild gas bubbling periods and strong paroxysmal phases. The latter produce violent gas eruptions that eject warm water (T ≈ 50° C) to a height up to about 1 m. Surface distribution of the geophysical and geochemical parameters have been investigated to detect the main pathways through which fluids move toward the shallow crust. Integration of geochemical, geophysical and geological maps allowed for the tracing of the fluid flow in the shallowest (a few tens of meters below the surface) part of the local hydrothermal system. Our results showed that the rising of fluids from a deep reservoir is controlled by the main structural and geological features of the area and their temporal and spatial evolution depends on pressure conditions inside the hydrothermal system.

Neurologic alterations in an HIV adult patient with pertussis: a case report

BackgroundPertussis is a highly contagious disease of public health interest caused by the bacterium Bordetella pertussis. Although its incidence has decreased substantially after the introduction of a vaccination, the burden of the disease remains high. Although the paroxysmal phase is highly disabling, complications are uncommon and more prevalent in children than in adults. The most frequent neurological complication is encephalopathy, but seizures, paresis, paraplegia, ataxias, aphasias, and decerebration postures have also been described. The complication of decerebration postures has not been previously reported in adults.Case presentationWe present a video case of an adult HIV patient with severe coughing paroxysms, post-tussive emesis and syncope, whose workup confirmed the diagnosis of a B. pertussis respiratory infection. During hospitalization, he had fluctuant encephalopathy and post-tussive decerebration postures following paroxysms. He was treated with antibiotic therapy and finally sent home without residual neurological deficits.ConclusionThis case illustrates the biological plausibility of neurologic complications of pertussis in adults, which, albeit rare, can cause important morbidities. Future research should explore whether there are differences in the clinical presentation, risk factors and pathophysiology of the disease among adults or interventions aimed at preventing or treating pertussis encephalopathy.

Typical displacement behaviours of slope movements

Understanding and quantifying the evolution of landslides are research topics that have always engaged researchers. Indeed, scientific literature provides a large number of contributions introducing and/or applying procedures, which are based on mechanical or phenomenological methods. The first ones are usually implemented to analyse the mechanical behaviour of a single complex phenomenon for which a consistent dataset is available. Phenomenological models are aimed at identifying common characteristics of landslides to be used for different purposes, such as forecasting the time of failure. This paper presents the implementation of a phenomenological model that allows the identification and quantification of well-defined dimensionless displacement trends for a large number of phenomena that are well documented in the literature. The analysed landslides involve different materials and are characterized by different stages of activity induced by seasonal and/or occasional triggering factors. The case studies include the well-known Vajont landslide, for which the obtained results show that the displacement trend was different from those usually characterizing occasionally reactivated landslides, since the beginning of the paroxysmal phase.

Tephra Mass Eruption Rate From Ground-Based X-Band and L-Band Microwave Radars During the November 23, 2013, Etna Paroxysm

The morning of November 23, 2013, a lava fountain formed from the New South-East Crater (NSEC) of Mt. Etna (Italy), one of the most active volcanoes in Europe. The explosive activity was observed from two ground-based radars, the X-band polarimetric scanning and the L-band Doppler fixed-pointing, as well as from a thermal-infrared camera. Taking advantage of the capability of the microwave radars to probe the volcanic plume and extending the volcanic ash radar retrieval (VARR) methodology, we estimate the mass eruption rate (MER) using three main techniques, namely surface-flux approach (SFA), mass continuity-based approach (MCA), and top-plume approach (TPA), as well as provide a quantitative evaluation of their uncertainty. Estimated exit velocities are between 160 and 230 m/s in the paroxysmal phase. The intercomparison between the SFA, MCA, and TPA methods, in terms of retrieved MER, shows a fairly good consistency with values up to $2.4\times 10^{6}$ kg/s. The estimated total erupted mass (TEM) is $3.8\times 10^{9}$ , $3.9\times 10^{9}$ , and $4.7\times 10^{9}$ kg for SFA with L-band, X-band, and thermal-infrared camera, respectively. Estimated TEM is between $1.7\times 10^{9}$ kg and $4.3\times 10^{9}$ for TPA methods and $3.9\times 10^{9}$ kg for the MCA technique. The SFA, MCA, and TPA results for TEM are in fairly good agreement with independent evaluations derived from ground collection of tephra deposit and estimated to be between $1.3\,\,\pm \,\,1.1\times 10^{9}$ and $5.7\times 10^{9}$ kg. This article shows that complementary strategies of ground-based remote sensing systems can provide an accurate real-time monitoring of a volcanic explosive activity.

DinSAR monitoring of the landslide activity affecting a stretch of motorway in the Campania region of Southern Italy

The paper deals with the landslide activity affecting a wide and steep slope crossed by a stretch of about 2.5 km of the provincial road Tirrena inferiore in the Campania region of Southern Italy. Some years ago, the road has been affected by the partial reactivation of dormant landslides, which caused both severe damages to the piers of a viaduct and considerable road surface deformations. By means of geognostic surveys, laboratory tests, geophysical prospecting as well as rainfall data, the modeling of landslides was performed in detail, and residual slope movements were monitored by means of inclinometers and satellite-based measurements (Cosmo-SkyMed interferometric data). A good correlation there is between the results provided by the two used techniques. With reference to the viaduct failure, DinSAR data allowed to ascertain the date on which the sudden acceleration of the landslide body pointed out the beginning of the landslide reactivation, in its paroxysmal phase. Ground deformations happened starting from January 2014 following an intense rainfall period that has been spreading between December 25 2013 and January 26 2014.

Decoding sea surface and paleoclimate conditions in the eastern Mediterranean over the Tortonian-Messinian Transition

New sedimentological, micropaleontological and geochemical data from the Upper Miocene pre-evaporitic sedimentary sequence of the Faneromeni section (Crete Island, eastern Mediterranean) revealed a stepwise restriction of the Mediterranean Sea preceding the Messinian Salinity Crisis (MSC), which was modulated by a sedimentary cyclicity responding to orbital parameters. This cyclicity is manifested by lithological alternations from laminated to indurated homogeneous marls and clayey limestones, and covers the Tortonian-Messinian Transition (TMT; 7.6–6.7 Ma). This time window covers the successive closure of the marine Mediterranean-Atlantic gateways, which culminated in the onset of the MSC. In the present study, we present the first evidence for changes in the upper water column reflected by sea surface temperature (SST) and salinity (SSS) variations that correlate with pronounced paleoclimatic fluctuations. Planktonic foraminiferal isotopes, in combination with paired mixed layer Sr/Ca-derived SST data, reveal that the very warm late Tortonian interval has been followed by a strong long-term cooling (~10 °C) and desalination (~10‰) trend during the earliest Messinian, attributed to the paroxysmal phase of the so-called “siphon” event. In particular, the climate shift that occurred at the end of a global carbon isotope (δ13C) decrease suggests that changes in the carbon cycle were instrumental in driving late Miocene climate dynamics (cooling and aridity) in the progressively isolated eastern Mediterranean Sea. The observed salinity variability during this time interval also provides further insights about seasonal freshwater inputs and gives new support to the much-debated hydrologic regime (linear salinity increase vs step-function evolution with strong salinity fluctuations) preceding the deposition of evaporites. The novel methodology of foraminiferal Sr/Ca paleothermometry and results of this study could have numerous potential applications to other regions and relevant extreme geological events. Therefore, in the near future we expect this approach to add important new information to our understanding of Neogene climates.

Changes in SO2 Flux Regime at Mt. Etna Captured by Automatically Processed Ultraviolet Camera Data

We used a one-year long SO2 flux record, which was obtained using a novel algorithm for real-time automatic processing of ultraviolet (UV) camera data, to characterize changes in degassing dynamics at the Mt. Etna volcano in 2016. These SO2 flux records, when combined with independent thermal and seismic evidence, allowed for capturing switches in activity from paroxysmal explosive eruptions to quiescent degassing. We found SO2 fluxes 1.5–2 times higher than the 2016 average (1588 tons/day) during the Etna’s May 16–25 eruptive paroxysmal activity, and mild but detectable SO2 flux increases more than one month before its onset. The SO2 flux typically peaked during a lava fountain. Here, the average SO2 degassing rate was ~158 kg/s, the peak emission was ~260 kg/s, and the total released SO2 mass was ~1700 tons (in 3 h on 18 May, 2016). Comparison between our data and prior (2014–2015) results revealed systematic SO2 emission patterns prior to, during, and after an Etna’s paroxysmal phases, which allows us to tentatively identify thresholds between pre-eruptive, syn-eruptive, and post-eruptive degassing regimes.

Initial constraints on triggering mechanisms of the eruption of Fuego volcano (Guatemala) from 3 June 2018 using IASI satellite data

On 3 June 2018 Volcán de Fuego (Guatemala) erupted explosively with unusual intensity, producing wide-spread ash dispersal and pyroclastic flows of >11 km length, which destroyed a community on Fuego's flanks, causing hundreds of fatalities. Here, we analyze satellite measurements of the SO2 plume emitted during the most intense eruptive phase. Key eruption parameters including the injection height and SO2 flux time-series indicate a degassing intensity at least three orders of magnitude above baseline levels. Our results suggest a steady ~2.5 hour climactic paroxysmal phase of the eruption with a mass eruption rate of ~1.4kg s−1 based on the combination of plume height estimates and an eruption column model, producing 0.03 ± 0.004 km3 of tephra. We detect at least 130 kt of emitted SO2 from satellite images, producing a minimum dissolved magmatic sulfur concentration of 500 ppm. Possible source mechanisms are discussed, which may be useful in assessing the risks posed by future large-magnitude eruptions to the large populations that live on Fuego's flanks. This study shows that even under challenging conditions of a tropical atmosphere during the rainy season, vital eruption parameters to constrain source mechanisms of eruptions can be retrieved from satellite remote sensing data.