## 1 Introduction  
Mt. Vesuvius is one of the most dangerous volcanoes on Earth since it is located inside the densely urbanized area which includes the city of Naples (Italy), and its past eruptions have destroyed towns and impacted thousands of victims. Although presentely Mt. Vesuvius is in a quiescent state, it is one of the most monitored volcanoes in the world. The main goal of this monitoring is the recognition of possible precursors of imminent or future eruptions. One of the strategies to reach this goal is to determine the background dynamical state which would allow for the detection of deviations from this basic condition. Multidisciplinary advanced studies using ground tilt, meteorological, ground water and seismicity monitoring have been carried out to determine significant volcano behavior [1; 2; 3; 4]. An understanding of the links among the different monitored observables is then crucial. In recent times the joint analyses of ground tilt and seismicity have allowed the tracking of significant changes in the activity state of volcanoes. [PERSON] et al. discovered inflation cycles due to magma pressurization below the base of Soufriere Hills' dome (Montserrat) in 1996-1997 using tilt data recorded at the crater rim, and the combination with seismic and volcanological data permitted the forecasting of times of increased volcanic hazard [5]. Ground tilt and seismicity recorded at Stromboli volcano (Italy) in 2008 showed that its explosive activity is accompanied by small ground inflation-deflation cycles associated with gas recharge and discharge in the magma inside the conduit [6]. [PERSON] et al. modeled the pressure source beneath the eruption center during the unrest of Hakone volcano (Japan) in 2015, by using the earthquake swarm activity and the simultaneous rapid tilt changes and established that the intrusion of hydrothermal water may have triggered the phreatic eruption [7]. Mt. Vesuvius, Campi Flegrei and Ischia, the volcanoes of the Campanian district (southern Italy), are study areas for several investigations in which seismicity and ground tilt, sometimes together with other parameters (meteorological, geochemical, etc. ), are jointly used to shed light on the dynamics of the volcanic/hydrothermal system [1,4,8]. In particular, [PERSON] et al. [1] outlined the dynamics of Mt. Vesuvius in the years 2012-2019 using combined investigations of ground tilt, seismicity, and geofluid circulation. These authors identified a change in the activity state occurring after the minimum level of volcanic activity of 2014. They noted the migration towards the SE of the centroid of the surface manifestations, such as seismicity, differential ground tilt, and thermal and compositional anomalies in groundwater and fumaroles. [PERSON] et al. stressed that the occasional variations of co-seismic and aseismic deformation could be correctly interpreted only in conjunction with the other observables, otherwise, those changes would likely have been interpreted as pseudo-random oscillations of the background signals. Mt. Vesuvius is a stratovolcano (1281 m high and 10 km wide) which is part of the Somma-Vesuvius volcanic complex in the Campanian Plan. It is located at the intersection of two regional tectonic fault systems (NW-SE and NE-SW), whereas the main eruptive fractures and local faults are mostly aligned in the E-W and N-S directions [9,10]. Volcanic activity controlled by the dynamics of the Adriatic slab has been characterized by explosive and effusive phases, and periods of quiescence. Four Plinian and sub-Plinian eruptions occurred in the last 20 kyr: Pomici di Base (18-20 kyr), Mercato (8.0 kyr), Avellino (3.9 kyr), and Pompei (79 AD). The last period of activity started in 1631 A.D. and ended in 1944, with a strombolian eruption from the Gran Cano crater. Since then, Mt. Vesuvius has been in a state of weak activity, characterized by general subsidence, diffuse CO\({}_{2}\) degassing and low-temperature fumarolic emissions in the crater area, and low seismicity rates [1]. The seismicity of Mt.