Dirty thunderstorms caused by volcano explosive eruptions in Kamchatka by the data of electromagnetic radiation

During volcano eruptions, so called dirty thunderstorms are the sources of electromagnetic radiation. They are caused by ash-gas clouds formed during explosive eruptions. Thunderstorm activity in an ash-gas cloud during volcano eruption is monitored by radio equipment. The VLF direction finder, located at Paratunka, monitors thunderstorm activity in the region of Kamchatka Peninsula including dirty thunderstorms accompanying explosive eruptions of Shiveluch and Bezymyanniy volcanoes. In the paper, we analyze records of electromagnetic radiation associated with dirty thunderstorms occurring during volcano eruptions from 2017 to 2020. During that period 24 eruptions of Shiveluch volcano and 5 eruptions of Bezymyanniy volcano occurred. Seventeen and three of them, respectively, caused dirty thunderstorms. Two-stage scenario of development is typical for all the dirty thunderstorms. The first stage lasts for 5–7 minutes and accompanies eruptive column development. However, if the eruption begins according to a smooth scenario, the first stage may be weak. The second stage lasts for 20–80 minutes and is associated with eruptive cloud formation and propagation. The intensity of this dirty thunderstorm stage depends on eruption power as well as on the interaction of an eruptive cloud during its propagation with the clouds of meteorological origin. Based on the obtained data, that is indicated by the increase of cloud-to-cloud stroke number.

The mud volcanoes at Santa Barbara and Aragona (Sicily, Italy): a contribution to risk assessment

The Santa Barbara and Aragona areas are affected by mud volcanism (MV) phenomena, consisting of continuous or intermittent emission of mud, water, and gases. This activity could be interrupted by paroxysmal events, with an eruptive column composed mainly of clay material, water, and gases. They are the most hazardous phenomena, and today it is impossible to define the potential parameters for modelling the phenomenon. In 2017, two digital surface models (DSMs) were performed by drone in both areas, thus allowing the mapping of the emission zones and the covered areas by the previous events. Detailed information about past paroxysms was obtained from historical sources, and, with the analysis of the 2017 DSMs, a preliminary hazard assessment was carried out for the first time at two sites. Two potentially hazardous paroxysm surfaces of 0.12 and 0.20 km2 for Santa Barbara and Aragona respectively were defined. In May 2020, at Aragona, a new paroxysm covered a surface of 8721 m2. After this, a new detailed DSM was collected with the aim to make a comparison with the 2017 one. Since 2017, a seismic station was installed in Santa Barbara. From preliminary results, both seismic events and ambient noise showed a frequency of 5–10 Hz.

Climate change modulates the stratospheric volcanic sulfate aerosol lifecycle and radiative forcing from tropical eruptions

Explosive volcanic eruptions affect climate, but how climate change affects the stratospheric volcanic sulfate aerosol lifecycle and radiative forcing remains unexplored. We combine an eruptive column model with an aerosol-climate model to show that the stratospheric aerosol optical depth perturbation from frequent moderate-magnitude tropical eruptions (e.g. Nabro 2011) will be reduced by 75% in a high-end warming scenario compared to today, a consequence of future tropopause height rise and unchanged eruptive column height. In contrast, global-mean radiative forcing, stratospheric warming and surface cooling from infrequent large-magnitude tropical eruptions (e.g. Mt. Pinatubo 1991) will be exacerbated by 30%, 52 and 15% in the future, respectively. These changes are driven by an aerosol size decrease, mainly caused by the acceleration of the Brewer-Dobson circulation, and an increase in eruptive column height. Quantifying changes in both eruptive column dynamics and aerosol lifecycle is therefore key to assessing the climate response to future eruptions.

Using dense seismo-acoustic network to provide timely warning of the 2019 paroxysmal Stromboli eruptions

Stromboli Volcano is well known for its persistent explosive activity. On July 3rd and August 28th 2019, two paroxysmal explosions occurred, generating an eruptive column that quickly rose up to 5 km above sea level. Both events were detected by advanced local monitoring networks operated by Istituto Nazionale di Geofisica e Vulcanologia (INGV) and Laboratorio di Geofisica Sperimentale of the University of Firenze (LGS-UNIFI). Signals were also recorded by the Italian national seismic network at a range of hundreds of kilometres and by infrasonic arrays up to distances of 3700 km. Using state-of-the-art propagation modeling, we identify the various seismic and infrasound phases that are used for precise timing of the eruptions. We highlight the advantage of dense regional seismo-acoustic networks to enhance volcanic signal detection in poorly monitored regions, to provide timely warning of eruptions and reliable source amplitude estimate to Volcanic Ash Advisory Centres (VAAC).

Seismo-acoustic characterization of the 2019 Stromboli volcano paroxysm events

<p>Stromboli volcano is well known for its persistent explosive activity, with hundreds of explosions every day ejecting ash and scoria up to heights of several tens/few hundreds of meters. Such a mild activity is however punctuated by lava flows and major/paroxysmal explosions, that represent a much larger hazard. On July 3rd and August 28th 2019, two paroxysmal explosions occurred at Stromboli, generating an eruptive column that quickly raised up to 5 km above the sea level. The Toulouse Volcanic Ash Advisory Center (VAAC) emitted an advisory to the civil aviation with a two-hour delay. The various processes of this event were monitored near and far field by infrasonic arrays up to distance of 3,500 km and by the Italian national seismic network at range of hundreds of kilometres. Using state-of-the-art propagation modeling, we aim at identifying the various seismic and infrasound phases of the event to better characterize the volcanic source. We highlight the need for the integration of the global infrasound International Monitoring System (IMS) network with local and regional infrasound arrays capable of providing a timely early warning to VAACs. This study opens new perspectives in volcano monitoring for hazard assessment and could represent, in the future, an efficient tool in supporting VAACs activity.</p>

The July 2019 explosive activity of Ubinas Volcano, Peru

<p>Ubinas is a stratovolcano located in the Central Volcanic Zone of the Andes. It is one of the most active volcanoes in Peru, with more than 26 eruptive episodes recorded in the last 500 years (VEI 1-3). Its latest eruption began in early 2019, whit the occurrence of some distal VT seismicity accompanied by low levels of LP seismicity and in sometimes high frequency seismic signals associated with rockfalls. Concurrently, SO<sub>2</sub> emissions increased from a few hundred to over 1,000 t/d between January and June while no significant ground deformation could be detected. Throughout the month of June, SO<sub>2</sub> emissions climbed further to over 4,000 t/d, proximal VT swarms began to occur beneath the volcanic edifice, and deformation measurements indicated a pressurization of the system. This ramp-up in activity culminated with an explosive eruption on 19 July 2019 (07:28:49 UTC). The eruption released a cumulative energy of 336 MJ and vented an estimated 4.6x10<sup>6</sup> m<sup>3</sup> of volcanic ash, making this one of the most energetic eruptive events of the last decade. Filled with hot gas and ash, the eruptive column reached 6,500 meters above the volcanic vent, with blocks and ballistic projectiles that reached 3.5 km from the crater and fragments up to 2.5 cm in diameter reported in the Ubinas town, 6.5 km to the southeast. By the time the eruption ended, up to 4 kg/m<sup>2</sup> of tephra had fallen at this distance. Most of the plume was dispersed in east to southeast directions, crossing the regions of Moquegua, Puno. Ashfall was observed as far as Oruro, Bolivia, some 180 km from the volcano. Subsequent analyses of monitoring data and eruptive products allow classification of this event as a VEI 2 eruption caused by a rapid magmatic intrusion to shallow depths below the volcanic edifice.</p>

Design of parametric risk transfer solutions for volcanic eruptions: an application to Japanese volcanoes

Volcanic eruptions are rare but potentially catastrophic phenomena, affecting societies and economies through different pathways. The 2010 Eyjafjallajökull eruption in Iceland, a medium-sized ash-fall-producing eruption, caused losses in the range of billions of dollars, mainly to the aviation and tourism industries. Financial risk transfer mechanisms such as insurance are used by individuals, companies, governments, etc., to protect themselves from losses associated with natural catastrophes. In this work, we conceptualize and design a parametric risk transfer mechanism to offset losses to building structures arising from large, ash-fall-producing volcanic eruptions. Such a transfer mechanism relies on the objective measurement of physical characteristics of volcanic eruptions that are correlated with the size of resulting losses (in this case, height of the eruptive column and predominant direction of ash dispersal) in order to pre-determine payments to the risk cedent concerned. We apply this risk transfer mechanism to the case of Mount Fuji in Japan by considering a potential risk cedent such as a regional government interested in offsetting losses to dwellings in the heavily populated prefectures of Tokyo and Kanagawa. The simplicity in determining eruptive column height and ash fall dispersal direction makes this design suitable for extrapolation to other volcanic settings worldwide where significant ash-fall-producing eruptions may occur, provided these parameters are reported by an official, reputable agency and a suitable loss model is available for the volcanoes of interest.

On The Use of Dense Seismo-Acoustic Network to Provide Timely Early Warning of Volcanic Eruptions

The Stromboli volcano is well known for its persistent explosive activity. On July 3rd and August 28th 2019, two paroxysmal explosions occurred, generating an eruptive column that quickly rose up to 5 km above sea level. For the first eruption, the Toulouse Volcanic Ash Advisory Center (VAAC) issued a volcanic ash advisory to the civil aviation users with a two-hour delay. The various processes of these events were monitored in the near and far fields by infrasonic arrays up to distance of 3700 km and by the Italian national seismic network at a range of hundreds of kilometres. Using state-of-the-art propagation modelling, we identify the various seismic and infrasound phases for precise timing of the eruptions. We highlight the advantage of a dense seismo-acoustic network to enhance the monitoring capability of a global network at a regional scale for providing both a reliable source characterisation and a timely early warning to VAACs.

The mud volcanoes at Santa Barbara and Aragona (Sicily, Italy): Their potential hazards for a correct risk assessment

The Santa Barbara and Aragona areas are affected by mud volcanism (MV) phenomena, consisting of continuous or intermittent emission of mud, water and gases. This activity could be interrupted by paroxysmal events, with an eruptive column composed mainly of clay material, water and gases. They are the most hazardous phenomena and, nowadays, it is impossible to define the potential parameters for modeling the phenomenon. In 2017, two DSM were performed by drone in both areas, thus allowing the mapping of the emission zones and the covered areas by the previous events. Detailed information about past paroxysms was obtained from historical sources and, with the analysis of the 2017 DSMs, a preliminary hazard assessment was carried out, for the first time at two sites. Two potentially hazardous paroxysm surfaces of 0.12 km2 and 0.20 km2 for Santa Barbara and Aragona respectively, were defined. In May 2020, at Aragona, a new paroxysm covered a surface of 8,721 m2. After this, a new detailed DSM was collected with the aim to make a comparison with 2017 one. Since 2017, a seismic station was installed at Santa Barbara. From preliminary results, both seismic events and ambient noise showed a frequency of 5–10 Hz.