Temporal models for the episodic volcanism of Campi Flegrei caldera (Italy) with uncertainty quantification

Abstract

After the large‐scale event of Neapolitan Yellow Tuff (~15 ka B.P.), intense and mostly explosive volcanism has occurred within and along the boundaries of the Campi Flegrei caldera (Italy). Eruptions occurred closely spaced in time, over periods from a few centuries to a few millennia, and were alternated with periods of quiescence lasting up to several millennia. Often events also occurred closely in space, thus generating a cluster of events. This study had two main objectives: (1) to describe the uncertainty in the geologic record by using a quantitative model and (2) to develop, based on the uncertainty assessment, a long‐term subdomain specific temporal probability model that describes the temporal and spatial eruptive behavior of the caldera. In particular, the study adopts a space‐time doubly stochastic nonhomogeneous Poisson‐type model with a local self‐excitation feature able to generate clustering of events which are consistent with the reconstructed record of Campi Flegrei. Results allow the evaluation of similarities and differences between the three epochs of activity as well as to derive eruptive base rate of the caldera and its capacity to generate clusters of events. The temporal probability model is also used to investigate the effect of the most recent eruption of Monte Nuovo (A.D. 1538) in a possible reactivation of the caldera and to estimate the time to the next eruption under different volcanological and modeling assumptions.

The Effects of Vent Location, Event Scale, and Time Forecasts on Pyroclastic Density Current Hazard Maps at Campi Flegrei Caldera (Italy)

“…In this section we will briefly review the methods adopted in Bevilacqua et al (2015) and Neri et al (2015), and we will present the new procedures for convolving the spatial hazard mapping with the temporal modeling of Bevilacqua et al (2016). In particular, in the Section PDC Hazard Maps Conditional on the Occurrence of an Explosive Eruption, we will describe the methods aimed at combining the vent opening location and the invaded area estimates thus producing hazard maps conditional on the occurrence of a PDC.…”

“…In case of a longer time window (i.e., T ≥ 50 years), the potential occurrence of clustered sequences of eruptive events (e.g., Isaia et al, 2004;Bevilacqua et al, 2016) is also considered. All the explosive eruptions possibly taking place in the selected time frame are included in the hazard mapping, and the area invaded by PDC is assumed equal to the union of the single extents in the sequence.…”

“…The model has been developed by Bevilacqua (2016) and Bevilacqua et al (2016), where the reader can find more details. In the following the temporal model is briefly summarized.…”

“…Moreover (Section Conditional Maps for Specific PDC Scales and Vent Locations), new PDC invasion hazard maps conditional on specific eruption scales and vent locations inside particular zones of the caldera are presented. Finally (Section Effects of Temporal Assessments on the Maps), and most importantly, temporal assessments are included in the maps based on the statistical models of Bevilacqua et al (2016). These achievements permit to calculate the PDC invasion hazard in the next 10 and 50 years under the assumptions that the volcano entered, or not, after the last Monte Nuovo eruption, a new epoch of activity similar to the previous ones.…”

“…During this period, which is typically considered representative for hazard assessment studies, past eruptive vents opened in the central part of the caldera as well as at its boundaries, with individual events spanning a large range of eruptive scales including large explosive eruptions characterized by tephra volumes over 1 km 3 . Sequences of events often occurred closely in time and space thus generating a cluster of events (e.g., Isaia et al, 2004Isaia et al, , 2009Bevilacqua et al, 2016). Subsidence and uplift (bradyseism) of the central part of the caldera are documented from the Roman times and the most recent Monte Nuovo eruption was in A.D. 1538, after ∼3,000-3,500 years of quiescence (e.g., Guidoboni and Ciuccarelli, 2011; FIGURE 1 | Mosaic of aerial/satellite photos of Campi Flegrei caldera and surrounding areas (including part of the city of Napoli on the east) showing the large urbanization inside and around this active volcano, modified from the ESRI dataset World_Imagery-www.arcgis.com.…”