GIS applications in volcano monitoring: the study of seismic swarms at the Campi Flegrei volcanic complex, Italy

Abstract

Abstract. Campi Flegrei caldera (Southern Italy) is one of the most hazardous volcanic complexes in the world since it is located inside the densely inhabited urban district of Naples-Pozzuoli. In the past, the caldera has produced devastating to moderate eruptions and periodically undergoes from strong to minor uplift episodes, named “bradyseism”, almost always accompanied by seismic swarms. Starting from 2005 Campi Flegrei has undergone an unrest crisis, characterized by ground uplift, localized gas emissions and seismicity, often occurring in seismic swarms. As a consequence, the monitoring activities have been progressively increasing, producing a huge amount of data, difficult to manage and match. GIS (Geographical Information System) represents a potent tool to manage great quantity of data, coming from different disciplines. In this study, we show two GIS technology applications to the seismic catalogue of Campi Flegrei. In the first one, a high-quality dataset is extracted from the GeoDatabase addressed to seismological studies that require high precision earthquake locations. In the second application, GIS are used to extract, visualize and analyse the typical seismic swarms of Campi Flegrei. Moreover, density and seismic moment distribution maps were generated for these swarms. In the last application, the GIS allow to highlight a clear variation in the temporal trend of the seismic swarms at Campi Flegrei.

Preface to “Understanding volcanic processes through geophysical and volcanological data investigations: some case studies from Italian sites (EGU2019 GMPV5.11 session, COV10 S01.11 session)”

“…The work of Berrino and Ricciardi (2020) presented the results of several absolute gravity measurements carried out at the Campi Flegrei active caldera (Italy) over a dense absolute gravity network. The latter was established in 2015, permitting an advanced approach for volcano monitoring.…”

“…The work of Bellucci Sessa et al (2021) showed the ability of GIS (Geographical Information System) to manage a great quantity of data. Two GIS technology applications, based on the seismic catalogue of Campi Flegrei (Italy) from 2005 to 2019 were shown, in addition to the creation of a new Geo-Database.…”

Fluid migrations and volcanic earthquakes from depolarized ambient noise

“…2b). Here, shear-wave-splitting anisotropy 39 , InSAR 11 , and gravity gradiometry 33 identify a SN anomaly that accumulates the highest lateral stress during unrest 10 , producing small-magnitude earthquakes 31 (Fig 2b,diamonds).…”

“…The azimuth of the horizontal polarization vector derived from ambient noise and the resultant length of its distribution (R) 1,2,29,30 are used here for the rst time as both imaging and diagnostic tools (Methods, 0.2-1 Hz). During periods of low seismic release 31,32 , they detect the hypothesized link between deep extensional and caldera-bounding faults (extensional structures) that bear regional stress [33][34][35][36][37] north and east of the caldera (Fig. 1a, white dotted line), and a dynamic transfer…”

“…1a), the direction of the volcanic ridge under the caldera 34 . When hydrothermal pressure, gas emission and seismicity increase (2018) 31,32 , the transfer structure depolarizes, allowing to monitor uid migrations leading to high-duration-magnitude (Md>3) earthquakes (Figs. 1b-d).…”