Exceptionally low mercury concentrations and fluxes from the 2021 and 2022 eruptions of Fagradalsfjall volcano, Iceland.

Mercury (Hg) is naturally released by volcanoes and geothermal systems, but the global flux from these natural sources is highly uncertain due to a lack of direct measurements and uncertainties with upscaling Hg/SO mass ratios to estimate Hg fluxes. The 2021 and 2022 eruptions of Fagradalsfjall volcano, southwest Iceland, provided an opportunity to measure Hg concentrations and fluxes from a hotspot/rift system using modern analytical techniques. We measured gaseous Hg and SO concentrations in the volcanic plume by near-source drone-based sampling and simultaneous downwind ground-based sampling.

Rapid shifting of a deep magmatic source at Fagradalsfjall volcano, Iceland.

Recent Icelandic rifting events have illuminated the roles of centralized crustal magma reservoirs and lateral magma transport, important characteristics of mid-ocean ridge magmatism. A consequence of such shallow crustal processing of magmas is the overprinting of signatures that trace the origin, evolution and transport of melts in the uppermost mantle and lowermost crust. Here we present unique insights into processes occurring in this zone from integrated petrologic and geochemical studies of the 2021 Fagradalsfjall eruption on the Reykjanes Peninsula in Iceland.

Increased respiratory morbidity associated with exposure to a mature volcanic plume from a large Icelandic fissure eruption.

The 2014-15 Holuhraun eruption in Iceland was the largest fissure eruption in over 200 years, emitting prodigious amounts of gas and particulate matter into the troposphere. Reykjavík, the capital area of Iceland (250 km from eruption site) was exposed to air pollution events from advection of (i) a relatively young and chemically primitive volcanic plume with a high sulphur dioxide gas (SO) to sulphate PM (SO) ratio, and (ii) an older and chemically mature volcanic plume with a low SO/SO ratio. Whereas the advection and air pollution caused by the primitive plume were successfully forecast and forewarned in public advisories, the mature plume was not.

Gradual caldera collapse at Bárdarbunga volcano, Iceland, regulated by lateral magma outflow.

Large volcanic eruptions on Earth commonly occur with a collapse of the roof of a crustal magma reservoir, forming a caldera. Only a few such collapses occur per century, and the lack of detailed observations has obscured insight into the mechanical interplay between collapse and eruption. We use multiparameter geophysical and geochemical data to show that the 110-square-kilometer and 65-meter-deep collapse of Bárdarbunga caldera in 2014-2015 was initiated through withdrawal of magma, and lateral migration through a 48-kilometers-long dike, from a 12-kilometers deep reservoir.

Numerical simulations examining the possible role of anthropogenic and volcanic emissions during the 1997 Indonesian fires.

The regional atmospheric chemistry and climate model REMOTE has been used to conduct numerical simulations of the atmosphere during the catastrophic Indonesian fires of 1997. These simulations represent one possible scenario of the event, utilizing the RETRO wildland fire emission database. Emissions from the fires dominate the atmospheric concentrations of O(3), CO, NO(2), and SO(2) creating many possible exceedances of the Indonesian air quality standards.