The recent awakening of the Fagradalsfjall (Iceland), Cumbre Vieja (La Palma, Canary Islands) and Hunga Tonga-Hunga Ha’apai (Tonga) volcanoes reminded us that eruptions are often preceded by variable styles and magnitudes of precursory signals, can have a range of sizes and impacts, and represent serious threats to the environment and society. These events show that despite considerable progress in the understanding of volcanic processes in recent decades, there are still scientific barriers to better predict the occurrence, style, and magnitude of eruptions and to anticipate their consequences. These manifestations are controlled by physico-chemical processes that occur at various time and length scales and largely out of view in the subsurface, and that depend on the chemical composition of the magmas as well as the pressure and temperature conditions.
Fundamental questions remain concerning many aspects of volcanic processes (National Academies of Sciences, Engineering, and Medicine, 2017). For example, how do batches of eruptible magmas assemble, evolve over time, and ascend to the surface? Under what circumstances do volcanic edifices become unstable and collapse? What processes control the effusive or explosive style of eruptions and possible transitions over time? What processes control the dispersion of volcanic products at the Earth’s surface and in the atmosphere?
Addressing these questions and forecasting volcanic eruptions requires the use of complementary methods employed from different fields (Sparks, 2003; Poland and Anderson, 2020). Analysis of samples and data acquisition using ground and remote sensors produces time-series data that provide key information about fundamental processes and are essential for forecasting eruptions. These data also serve to define input parameters and test models, with applications that are constantly improving due to ever-evolving computational capabilities. Models are also fed by the results of laboratory experiments that aid in the interpretation of field observations.
New types of models have emerged in recent years to simulate volcanic eruptions and mitigate hazards. Estimation of uncertainties due to ranges of values of the input parameters and the nature of the models themselves enables the production of probabilistic hazard maps (Bevilacqua et al., 2015; Neri et al., 2015), while machine learning algorithms can filter through enormous databases to identify patterns useful for eruption forecasting (Curtis et al., 2020; Ren et al., 2020).
Many volcanic phenomena are characterized by multiphase flows. Although very different in appearance, flows of crystal and gas bubble-laden magmatic liquids (in magma reservoirs and dikes or as lava flows at the Earth’s surface), of mixtures of gas and magma fragments (eruptive plumes, pyroclastic density currents), or of water and solid particles (lahars) generally obey the same physical principles (Iverson et al., 2010; Dufek, 2016; Bachman and Huber, 2019). The dynamics of these flows depend fundamentally on the relative proportions of the different phases and their interactions. Better understanding the mechanisms of these multiphase mixtures and defining rheological laws are crucial steps for the development of robust models.
Increasing focus on climate change is opening new fields of study for the volcano research community. Melting of glaciers due to climate warming causes crustal stress relaxation and may be a factor in increased eruptive activity (Rawson et al., 2016). A growing number of studies also suggest that volcanic eruptions that inject large amounts of aerosols into the stratosphere may affect atmospheric currents and consequently the evolution of climate (Khodri et al., 2017; DallaSanta et al., 2021). In this context, investigating the impact of the largest volcanic eruptions, which are relatively rare but may have significant forcing effects, appears to be a major issue (Guillet et al., 2017).
The new special collection on “Advances in understanding volcanic processes” is intended to address the many open challenges in volcanology. The collection will bring together articles that present new scientific results and highlight developments or applications of modern techniques employed to investigate volcanic processes. Contributions are expected to clearly identify new knowledge and understanding of volcanic phenomena.
This is a joint special collection between JGR: Solid Earth, JGR: Atmospheres, Geochemistry, Geophysics, Geosystems, and Earth and Space Science. Manuscripts can be submitted to any of these journals, depending on their fit with the journal’s scope and requirements. At JGR: Solid Earth, submissions will be handled by a team of Guest Editors: Yosuke Aoki, Nickolai Bagdassarov, Michael Heap, Sigrun Hreinsdottir, Qinghua Huang, Daniel Pastor-Galan, Michael Poland, Olivier Roche, Maria Sachpazi, Fang-Zhen Teng, and Gregory Waite, along with regular Editors. At G-Cubed, submissions will be handled by the Editors Marie Edmonds and Paul Asimow. At Earth and Space Science, submissions will be handled by the Editor in Chief, Graziella Caprarelli. At JGR: Atmospheres, submissions will be handled by the Editor in Chief and editors.
—Olivier Roche (email@example.com,