The Campi Flegrei caldera: historical revision and new data on seismic crises, bradyseisms, the Monte Nuovo eruption and ensuing earthquakes (twelfth century 1582 ad)

Abstract

This paper presents the results of a systematic historical study of the seismic, bradyseismic and eruptive activity of the Campi Flegrei caldera. The aim is to make a revised historical data available for accurate volcanological interpretation, supplying additional data and highlighting spurious previous data. The analysis begins with the supposed 1198 eruption, which did not actually take place. No information is available for the thirteenth and fourteenth centuries. As far as the fifteenth and sixteenth centuries are concerned, only direct sources were examined for this paper, and they include many different types of evidence. The chronological breadth of the analysis has also provided information about the seismic crises and bradyseisms prior to the eruption of 1538. The exceptional nature of this 1538 eruption attracted the attention of intellectuals, diplomats and natural philosophers, who left valuable accounts, which we have analysed, and which include many that are still available in their original manuscript form. The previous studies concerning the 1538 eruption were based on 23 (variously used) sources. We have examined 35 additional sources bringing the overall corpus of sources analysed to 58. The results provide a more precise scenario of events preceding the 1538 eruption, including bradyseismic activity starting from the end of the fifteenth century. The chronology of the phenomena described comprises the core result of this study, and has been constructed so as to clarify the time, location and impact of each event. For the 1538 eruption, a countdown is included which may also have a predictive value. For the last 36 hours before eruption began, the countdown is hour-by-hour. The effects of the eruption and earthquakes on people, structures and society are also described for Pozzuoli, Agnano and Naples. The areas where heavy materials and ash fell are likewise indicated, as well are the earth tremors felt by the population from the eruptive crisis up to 1582.

Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions

“…Volatileundersaturated recharge would require greater crustal deformation than volatile-saturated mixing to accommodate new melt without exceeding the fracture criterion 43 . Such deformation may be responsible for observed large-scale inter-eruptive bradyseismicity at Campi Flegrei 44,45 , with recharge events inducing significant magma chamber dilation during repose periods.…”

“…Although magma chamber assembly can occur on decadal timescales 48 , there is a growing number of examples where deformation pulses are not immediately followed by eruption; and others, including the only historic eruption of Campi Flegrei 44 , where explosive eruptions begin with little or no early geodetic 'warning' 49,50 . This suggests that the final pre-eruptive 'priming' of the system may occur on timescales far shorter than timescales of assembly; perhaps as short as days to months.…”

Constraining pre-eruptive magma conditions and unrest timescales during the Monte Nuovo eruption (1538 ad; Campi Flegrei, Southern Italy): integrating textural and CSD results from experimental and natural trachy-phonolites

“…1 The Monte Nuovo tuff cone location (a) with image of the lowermost ash to sand levels and the uppermost scoria deposits (b) and (c), respectively. The diagrams show the timing of the phenomena preceding the eruption since 1470 AD (d) and 1538 (e), on the basis of Guidoboni and Ciuccarelli (2011). The panels (d) and (e) indicate the time of occurrence for seismicity (vertical bars), flow output (cloud), and ground deformation (arrows and dotted lines; right concavity inflation, left concavity deflation).…”

“…The eruption started in the night between September 29th and 30th (Guidoboni and Ciuccarelli 2011), after an intensification of decadal fumarolic and bradyseism activity (Parascandola 1947;Lirer et al 1987;Guidoboni and Ciuccarelli 2011) occurred about 3 months before the eruption (Guidoboni and Ciuccarelli 2011;Fig. 1d, e).…”

“…The Monte Nuovo eruption is particularly interesting because it occurred after 3000 years of volcanic quiescence and following a period of ground level movements and seismicity (as described in historical chronicles; Guidoboni and Ciuccarelli 2011) that have characteristics comparable to the recent bradyseisms in the Campi Flegrei area (Parascandola 1947;Del Gaudio et al 2010). Constraining the timing of magma movements in the subsurface shortly before the eruption is a key factor to unraveling the significance of phenomena affecting the Campi Flegrei during volcanic quiescence.…”