Simultaneous eruptions from multiple vents at Campi Flegrei (Italy) highlight new eruption processes at calderas

Abstract

Volcanic eruptions are typically characterized by the rise and discharge of magma at the surface through a single conduit/vent system. However, in some cases, the rise of magma can be triggered by the activation of eruptive fissures and/or vents located several kilometers apart. Simultaneous eruptions from multiple vents at calderas, note related to caldera collapse (e.g., ring faults) are traditionally regarded as an unusual phenomenon, the only historically reported examples occurring at Rabaul caldera, Papua New Guinea. Multiple venting within a caldera system is inherently difficult to demonstrate, owing partly to the infrequency of such eruptions and to the difficulty of documenting them in time and space. \ud We present the first geological evidence that 4.3 ka ago the Solfatara and Averno vents, 5.4 km apart, erupted simultaneously in what is now the densely populated Campi Flegrei caldera (Southern Italy). Using tephrostratigraphy and geochemical fingerprinting of tephras, we demonstrate that the eruptions began almost at the same time and alternated with phases of variable intensity and magnitude. The results of this study demonstrate that multi-vent activity at calderas could be more frequent than previously thought and volcanic hazards could be greater than previously evaluated. More generally we infer that the simultaneous rise of magma and gas along different pathways (multiple decrepitation of chamber/s) could result in a sudden pressure rise within sub-caldera magmatic system

Theory for Deducing Volcanic Activity From Size Distributions in Plinian Pyroclastic Fall Deposits

“…A single vent along the caldera rim is rejected because this leads to unlikely narrow width of 0.2 to 1.7 m compared to the present caldera radius of 5 km. The picture of multiple vents is in accordance with the suggestion of the recent geological and petrological study that simultaneous eruptions from multiple vents are commonly associated with precursory events of caldera‐forming eruptions (e.g., Pistolesi et al, ).…”

Seismically Induced Soft‐Sediment Deformation Phenomena During the Volcano‐Tectonic Activity of Campi Flegrei Caldera (Southern Italy) in the Last 15 kyr

“…The seismically induced SSDs, such as sand dikes and volcanoes, were confined between the two major eruptions of AMS and AVS, clearly testifying to an unrest period predating the AVS eruptive activity (Pistolesi et al, ). We cannot verify if the sand dikes and sand volcanoes formed in separate unrest events in the past owing to the lack of geological constraints.…”

Volcano‐Tectonic Setting of the Pisciarelli Fumarole Field, Campi Flegrei Caldera, Southern Italy: Insights Into Fluid Circulation Patterns and Hazard Scenarios

“…In general, the caldera central sector hosts several high‐angle faults associated with the last volcano‐tectonic activity that frequently reactivated preexisting deep‐seated faults (e.g., Vitale et al., 2019). Epoch 3B includes a cluster of small volcanic edifices within and around the present Solfatara maar‐diatreme volcano (Isaia, Marianelli, & Sbrana, et al., 2009; Isaia, Vitale, Di Giuseppe, et al., 2015), which erupted contemporaneously with the Averno volcano located in the western caldera sector (Pistolesi et al., 2016). Two large volcanoes (Astroni and Fossa Lupara; Figure 1), located along a NW‐SE trending fissure a few km northward of the Solfatara crater, formed immediately after the Solfatara eruption (Di Vito, Isaia, et al., 1999; Isaia, D'Antonio, et al., 2004; Isaia, Marianelli, & Sbrana, 2009).…”