FEDERICO_final:Layout 6 ANNALS OF GEOPHYSICS, 56, 4, 2013, S0447; doi:10.4401/ag-6453 S0447 Groundwater geochemistry of the Mt. Vesuvius area: implications for volcano surveillance and relationship with hydrological and seismic signals Cinzia Federico1,*, Paolo Madonia1, Paola Cusano2, Simona Petrosino2 1 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, Palermo, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Napoli, Osservatorio Vesuviano, Naples, Italy ABSTRACT Geochemical data obtained between 1998 and 2011 at the Mt. Vesuvius aquifer are discussed, focusing on the effects of both the hydrological regime and the temporal pattern of local seismicity. Water samples were collected in a permanent network of wells and springs located in the areas that are mostly affected by the ascent of magmatic volatiles, and their chemical composition and dissolved gas content were analyzed. As well as the geochemical parameters that describe the behavior of groundwater at Mt. Vesuvius, we discuss the temporal distribution of volcano-tectonic earthquakes. The seismological data set was collected by the stations forming the permanent and mobile network of the Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Vesuviano (INGV-OV). Our analysis of seismic data collected during 1998-2011 identified statistically significant variations in the seismicity rate, marked by phases of de- creasing activity from October 1999 to May 2001 and increasing activity from August 2004 to mid-2006. The water chemistry shows peculiar pat- terns, characterized by a changeable input of CO2-rich and saline water, which must be related to either a changing stress field or an increased input of CO2-rich vapor. The water chemistry data from 1999 to 2003 ac- count for both higher fluid pressure (which induced the seismic crisis of 1999 that peaked with a 3.6-magnitude earthquake in October 1999) and the increased input of CO2-rich fluids. The highest emission of CO2 from the crater fumaroles and the corresponding increase in dissolved carbon in groundwater characterize the phase of low seismicity. The termination of the phase of intense deep degassing is associated with a change in water chemistry and a peculiar seismic event that was recorded in July 2003. All these seismic and geochemical patterns are interpreted accord- ing to temporal variations in the regional and local stress field. Introduction Fluids circulating in volcanic edifices are attracting increasing interest from scientists, mostly because their role in triggering flank instability, phreatic explosions, and eruptions has been documented in dozens of cases worldwide [Day 1996, Reid 2004, Thomas et al. 2004]. In- ternal pressurization of magmatic volatiles and hy- drothermal systems can lead to dramatic steam blasts and, eventually, to eruptions [Hill et al. 2002]. The fluid pore pressure can also be changed by external mecha- nisms, such as variation of the stress field or, more gen- erally, variation of the porosity/permeability of volcanic rocks. Static or dynamic stress changes, which have a clear expression in seismicity, exert a significant control on fluid patterns and eventually on the ascent of melts [Newhall et al. 2001, Hill et al. 2002, Mortimer et al. 2011]. The re- ciprocal roles of tectonics and magmatic/hydrothermal activity, and their influence in determining the so-called crises, is still under investigation [Roeloffs et al. 2003, Gottsman et al. 2007]. Monitoring of groundwater in vol- canic systems is useful for predicting changes in the tec- tonic and volcanic stress field [Newhall et al. 2001, Hurwitz and Johnston 2003, Biagi et al. 2004, Koizumi et al. 2004]. Changes in water level in some wells were ob- served prior to the 2000 eruption of Mt. Usu, Japan [Shi- bata and Akita 2001], and is a frequent characteristic in eruptions of Mt. Vesuvius [Bertagnini et al. 2006]. Mt. Vesuvius hosts a shallow aquifer which receives magmatic/hydrothermal gases mostly in correspon- dence of the main tectonic lineaments [Federico et al. 2002]. Some changes in water and dissolved gas com- position have been recorded in concomitance with the seismic crisis that occurred in 1999 [Federico et al. 2004, Madonia et al. 2008]. The present study aimed at elucidating the roles of both the stress field and the magmatic/hydrother- mal degassing in changes in water chemistry in the vesuvian shallow aquifer. We report on the composi- tion of major ions, temperature, and dissolved gas con- Article history Received August 7, 2012; accepted December 17, 2012. Subject classification: Water chemistry, Seismicity, Hydrology, Volcanic surveillance. Special Issue: Vesuvius monitoring and knowledge tents (which were partly reported by Madonia et al. [2008]) measured between 1998 and 2011 at selected springs and wells located on the lower flanks of Mt. Vesuvius. Temporal variations of water chemistry can be attributed to either changes in porosity/permeabil- ity and fluid circulation or the input of CO2-rich vapor, and provide insights into the present rest period. Finally, we compare the variations of the geochemical param- eters with those of the seismic activity. Study area Geological summary With a radius of ca 10 km, the Somma-Vesuvius complex (1281 m a.s.l.) in southern Italy is a polygenetic volcanic complex composed of an old stratovolcano (Somma), which is mainly preserved on the northern sector of the edifice, and the younger cone of Mt. Vesu- vius (Figure 1). The Somma-Vesuvius complex devel- oped within a wide gravimetric anomaly located in the central part of the Campanian Plain (a depression bor- dered by Tertiary and Mesozoic carbonate massifs) named the Acerra graben [Scandone et al. 1991, Mar- zocchi et al. 1993]. This anomaly is related to the sub- sidence of the carbonate basement lying about 2 km beneath Mt. Vesuvius. The stratovolcano developed at the intersection of two regional tectonic fault systems (running NW–SE/NNW–SSE and NNE–SSW/NE– SW). In addition to these two regional structures there are also local eruptive fractures aligned in the E–W and N–S directions inside the Somma caldera and on the southern flank of the volcano [Bianco et al. 1998]. The volcanic activity of the volcanic complex has been characterized by the alternation between pyro- clastic eruptions (separated by quiescent periods) and open conduit phases, characterized by Strombolian and effusive activity [Santacroce et al. 1994, Cioni et al. 1998]. The Somma volcano mainly consists of lava flows (K-rich basalts and latites) and minor pyroclastics (strombolian scoria fall deposits) and was active be- tween 25 and 18 ka BP [Santacroce 1987, Ayuso et al. 1998]. Four Plinian eruptions between 18 ka BP and A.D. 79 caused the summit to collapse and gave rise to the formation of a multistage summit caldera (i.e., the Somma caldera) [Santacroce 1987, Andronico et al. 1995, Principe et al. 1999, De Vivo and Rolandi 2001]. After the sub-Plinian eruption in 1631, an open conduit phase lasted until the 1944 eruption, since when the vol- cano has been in a state of weak volcanic-hydrothermal activity characterized by diffuse CO2 degassing and low-temperature fumarolic activity in the crater area, thermal submarine features, and low seismic activity [Aiuppa et al. 2004, Del Pezzo et al. 2004, Frondini et al. 2004, Caliro et al. 2011]. Seismicity The natural vesuvian seismicity mainly consists of volcano tectonic (VT) earthquakes [Chouet 1996], which are characterized by clear P- and S-wave packets and a high-frequency content, mostly peaking in the band 5-15 Hz. They are usually located within a volume centered along the crater axis, at depths shallower than FEDERICO ET AL. 2 Figure 1. Map of the Mt. Vesuvius area showing the locations of earthquakes and measuring points of the seismic and geochemical sur- veillance networks. 3 about 4 km below sea level (b.s.l.). The transition zone between the volcanic edifice and the carbonate base- ment, at 2-3 km b.s.l., coincides with the maximum of the spatial distribution of the hypocenters [Saccorotti et al. 2002, Scarpa et al. 2002, Del Pezzo et al. 2004]. Assumptions about the source dynamics for the vesuvian VT earthquakes involve failures in the brittle rocks, with strike-slip and normal/reverse dip-slip focal mechanisms. A wide variety of nodal plane orienta- tions is indicated, but overall the directions are NW–SE and NE–SW [Bianco et al. 1998, Ventura and Vilardo 1999]. The P and T axes are mainly assumed to be pres- ent along the NNE–SSW and ESE–WNW directions and along the ESE–WNW and NNE/N–SSW/S direc- tions, respectively [Bianco et al. 1998, Ventura and Vi- lardo 1999, Zollo et al. 2002]. According to Del Pezzo et al. [2004], the deepest events are associated with average stress drop between 1 and 10 MPa and are mainly caused by the release of regional tectonic stress in the prefractured carbonate basement. On the other end, the shallowest earth- quakes are characterized by stress drop of up to 1 MPa and are probably triggered by increasing pore fluid pres- sure caused by changes in the hydrothermal aquifer, which is located beneath the crater at about 1 km b.s.l. Madonia et al. [2008] revealed two statistically sig- nificant variations in the seismicity behavior between 1998 and 2005: in May 2001 and July 2004. Two phases corresponding to these variations can be identified. The first is relative to the 1999 crisis. The highest-magnitude (3.6) earthquake since the last eruption (in 1944) occurred during this crisis, at 07:41 UT on October 9, 1999. This earthquake was located about 4 km beneath the crater area, inside the carbonate basement. Several studies have demonstrated that this event was generated by tectonic stress release along a pre-existing fracture system [Ven- tura and Vilardo 1999, Zollo et al. 2002, Del Pezzo et al. 2004]. This was followed by a sequence of low-energy earthquakes, and the seismic activity decreased up to May 2001. Low levels of seismicity were observed until July 2004, when a slight increase in the seismicity rate marked the beginning of the second phase. Hydrogeology Two main aquifers exist in the vesuvian area [Corniello et al. 1990, Celico et al. 1998]: (1) a deep car- bonate aquifer hosted in the buried Mesozoic series be- neath the Campanian Plain and recharged by precipi- tation falling on the Apennines, and (2) a shallower vol- canic aquifer (the vesuvian aquifer) hosted in fractured lavas and coarse-grained pyroclastic deposits of the Somma-Vesuvius complex. As generally observed in stratovolcanoes, water at Mt. Vesuvius circulates in sev- eral overlapping water bodies separated by imperme- able fine-grained pyroclastic layers. The transmissivity values of these aquifers range from 10–4 to 10–1 m2·s–1 [Celico et al. 1998], with the highest values (10–2 to 10–1 m2·s–1) being found on the southern flank of the vol- cano. The exchanges between the deep and shallow water bodies are easier in this area due to both the vol- canic cover being thinner and the presence of fractures in the carbonate basement, which facilitate upward water circulation. The numerous studies concerning the chemistry of Somma-Vesuvius groundwaters have clarified the mechanisms of gas–water–rock interactions, highlight- ing the role of volcanic CO2 in controlling rock leach- ing and water chemistry [Caliro et al. 1998, Celico et al. 1998, Federico et al. 2002, Aiuppa et al. 2005, Caliro et al. 2005]. Analysis of stable isotopes in dissolved gases (CO2 and He) have demonstrated that magmatic volatiles are actively transported by groundwaters flow- ing along the main faults and fractures, trending NW– SE and NE–SW, which affect both the volcanic edifice and the sedimentary basement [Federico et al. 2002]. Moreover, a systematic contrast in the chemical com- positions of the groundwaters flowing on the southern and northern sectors of the volcanic edifice has been demonstrated, with the former being typically charac- terized by higher outlet temperatures, total dissolved solids, and dissolved CO2 contents. These findings clearly indicate that the gas supply is lower on the northern sector of the volcano than on the southern one, which could be ascribed to a structural-geological control of water circulation. According to Federico et al. [2002], carbonate groundwaters flowing from the Apennines to the Tyrrhenian Sea would interact with the central conduit system, thus becoming heated and gas-charged by the ascending hot fluids sustained by deep magma degassing. Further south these CO2-charged carbonate groundwaters may represent a CO2 source for the shallow volcanic aquifer, for example in the Torre Annunziata area, where the carbonate aquifer lies at a depth of only 500 m [Celico et al. 1998]. In an alternative proposed model the northern walls of the Somma caldera represent an impermeable barrier to water in- filtration, thus forcing groundwaters to flow southward [Federico et al. 2002, Caliro et al. 2005], in which case the groundwaters would dissolve CO2 mainly in the crater area [Caliro et al. 2005]. Methods The seismological monitoring of Mt. Vesuvius is performed by INGV-OV personnel using a permanent seismic network that has been active since 1972. Cur- rently the monitoring network consists of 10 stations HYDROLOGY AND SEISMICITY ON MT. VESUVIUS equipped with short-period geophones, of which 3 are three-component stations and 2 are short-period three- component digital stations. Moreover, six broadband three-component digital stations are present in the crater area. The installed sensors are 1-Hz velocime- ters (Geotech S13 and Mark LE-3D) and broadband sensors (Guralp CMG 40T and Trillium 120P). Seismic data are continuously acquired at 100 sample·s–1, trans- mitted to an acquisition center in Naples, and stored on hard disks. More information is available in Giudi- cepietro et al. [2010]. The Mobile Seismic Network of INGV-OV has in- stalled four digital stations at Mt. Vesuvius. MARSlite and Lennartz M24 devices equipped with three-com- ponent broadband sensors (Guralp CMG-40T or Lennartz LE-3D/20s) operate on the volcano. The sig- nals are acquired in situ at a sampling rate of 125 or 100 Hz. Further technical details are available elsewhere [Castellano et al. 2012]. A seismic catalogue of Mt. Vesuvius, which con- tains the occurrence time and the duration magnitude (MD) values of the VT earthquakes, has been compiled since 1972. The relation between the magnitude and the seismic trace duration was calibrated by Del Pezzo et al. [1983] for vesuvian VT earthquakes recorded on the vertical component of the OVO station, located in the western sector of the volcano (Figure 1). Figure 2 shows the monthly distribution of the number of VT earthquakes based on this catalogue. The vesuvian VT earthquakes included in the catalogue were localized using a 3D probabilistic algorithm (NonLinLoc) [Lomax et al. 2000] over the 3D velocity model inferred by Scarpa et al. [2002]. The hypocenter depth as a func- tion of the time is reported in Figure 2. The hydrogeochemical parameters of the vesu- vian aquifer have been monitored since 1998. The first hydrogeochemical monitoring network consisted of 10 private wells that were mainly used for irrigation and 2 springs (Figure 1). Currently the network consists of six wells and two springs, while temperature is recorded hourly at selected sites (data not shown). Temperature, pH, Eh, and alkalinity were determined by sampling with conventional field instrumentation; laboratory de- terminations were carried out at INGV, Palermo, fol- lowing the procedures described by Federico et al. [2002]. The concentrations of major ions were meas- ured by applying ion chromatography to filtered (Cl–, NO3 – , and SO4 2–) and filtered and acidified (Na+, K+, Ca2+, and Mg2+) samples, with an analytical uncer- tainty of <5%. The dissolved gases in water samples were measured after equilibration in a host gas (Ar) and extraction, following the procedure described by Ca- passo and Inguaggiato [1998]. Analyses were performed using a gas chromatograph (Perkin-Elmer 8500), equipped with 4-m Carbosieve II columns and two de- tectors (hot wire and flame ionization), with Ar as the carrier gas. The analytical uncertainty was <5%. Results The number of VT earthquakes peaked at the time of the October 1999 seismic crisis. The earth- quakes belonging to this crisis occurred in the prefrac- tured carbonate basement in response to a release of the regional tectonic stress and are characterized by deep locations and large reductions in stress drop values [Del Pezzo et al. 2004]. The effects of this crisis lasted until the beginning of 2002, after which the seismic ac- tivity decreased to very low levels. The hypocenters clustered within the volcanic edifice at depths in the range 0-2.5 km diminished dramatically, and those deeper than 2.5 km practically disappeared. Moreover the stress drop assumed low values. As asserted by many authors [Saccorotti et al. 2002, Del Pezzo et al. 2004], it is likely that most of these VT earthquakes were caused by variations of the pore fluid pressure. These variations could be induced by the local stress perturbations themselves or by charging and discharg- ing mechanisms of the shallow aquifer. On July 20, 2003, an anomalous low-frequency earthquake with a quasimonochromatic spectrum in the frequency band of 3.5-4 Hz was recorded by all of the stations of the INGV-OV seismic network. It was located at about 4 km b.s.l., and Bianco et al. [2005] re- ported that it was probably of hydrothermal-volcanic origin. A slight seismic anomaly began in August 2004, after which the number of VT earthquakes began to in- crease, reaching a relative maximum in 2006 before re- turning to very low values. This period included an earthquake (on August 30, 2005) at the very shallow depth of 300 m a.s.l. Using a combination of seismo- logical and geochemical methods, Madonia et al. [2008] FEDERICO ET AL. 4 Figure 2. Hypocentral depths of vesuvian VT earthquakes as func- tions of time (upper panel) and the monthly number of VT earth- quakes (lower panel). 5 modeled the source mechanism of this VT earthquake as the superposition of tensile cracking and shear fail- ures. The crack opened along the direction orthogonal to the maximum stress axis of the faulting, due to an increase of the pore fluid pressure. This increase could in turn be caused by the variation of the local stress field that enhanced the upward migration of thermal fluids. The 2005 year was also characterized by the ab- solute minimum of deep seismicity. As shown by Federico et al. [2002, 2004], the wa- ters circulating through the vesuvian aquifers are char- acterized by large spatial and temporal variations in chemical composition (Figure 3). In general, these wa- ters are rich in HCO3 – and their alkali content (here rep- resented by the K+ content) is strictly controlled by the CO2-driven mechanism of rock dissolution. Neverthe- less, a variable enrichment in either Cl– or SO4 2– with respect to the volcanic rock is observed. Sample 14 shows the lowest relative content of SO4 2–, while its rel- ative content of Cl– is higher than that in the host rock. As suggested by Federico et al. [2002], the southern sector of the vesuvian aquifer is characterized by the local ascent of brine-type warm fluids along faults. Among collected samples, well 14 is the most saline (Cl = 2000 mg·l–1 on average) and, together with spring 13, it is the warmest, which suggests that it is contami- nated by hot Cl-rich brines. The enrichment in SO4 2–, which is mostly observed in samples (namely sites 13, 19, and 29) collected in the Torre Annunziata–Torre del Greco area (where S-rich gas manifestations have been identified along the coast), can be attributed to either the oxidation of hy- drothermal S-bearing minerals (i.e., pyrite) or the dis- solution of a H2S-bearing gas phase by groundwater during circulation at depth [Federico et al. 2002]. The enrichment of SO4 2– in a few of the wells can be ascribed to the contribution of fluids related to human activi- ties, in particular to the use of SO and N-rich fertilizers or rural sewage, as suggested by Federico et al. [2004]. This effect is evident in samples 47 and 19, which also have higher NO3 − contents (see Appendix). During the monitored period the vesuvian groundwater exhibited compositional variability, which can be quantified as SO4 2–/HCO3 − and Cl−/SO4 2– ratios (Figure 3a). Moreover, significant changes in water salinity are observed at some sites. Figures 4-7 plot the time trends of some significant parameters at selected sites during the entire monitored period. Figure 4 displays the time trends of the water tem- perature measured at sites 13, 14 and 29. A common fea- ture is the small (<1°C) and slow increase in temperature after the 1999 earthquake, with a marked decrease of as high as 4°C occurring after 2003 or 2006 (spring 13). Temperature variations are paralleled by changes in chemical parameters, as shown in Figures 5-7. Figure 5 shows the time trends of HCO3 − contents, Cl−/SO4 2– ra- tios (for sites 13 and 29), dissolved CO2 content (for site 29), and water temperature. The time trends of esti- mated pCO2 for the hydrothermal system, computed HYDROLOGY AND SEISMICITY ON MT. VESUVIUS Figure 3. a) Cl−-SO4 2−-HCO3 − triangular diagram. b) Cl−-SO4 2−-K+ tri- angular diagram. The average composition of lava and scorias from Belkin et al. [1998] and the point representative of seawater are plot- ted for comparison. Concentrations are expressed in units of mg·l−1. Figure 4. Time trends of water temperature at wells 29 and 14 and spring 13. Arrows indicate phases of increases (red) and decreases (blue) in temperature. The time trend of pCO2 values, computed for the hydrothermal aquifer by Caliro et al. [2011], is plotted as a shaded area. The histogram shows the monthly number of seismic events. from chemical data of fumarole FC2 by Caliro et al. [2011], are shown in Figure 5 as a shaded area. At well 29, the above-described time trends of temperature fol- low the changes in dissolved CO2 content fairly well, with both dramatically decreasing after 2004. The HCO3 − concentration exhibits a relative minimum co- inciding with the November 1999 earthquake, and then increases along with CO2 until 2002-2003, when a long- lasting decreasing trend begins, with an overall decrease of about 30%, which is approximately paralleled by changes in the Cl−/SO4 2– ratio. From 2006 onward, while Cl−/SO4 2– ratio remains steady, the HCO3 − con- tent continues decreasing. Similarly, the HCO3 − con- tent, temperature, and Cl−/SO4 2– ratio at site 13 follow very similar trends in the months before and after the 1999 earthquake. Thereafter, while Cl−/SO4 2– starts de- creasing in 2003 before remaining steady from 2006 on- ward, HCO3 − and temperature start long-lasting decreasing trends in 2004-2005 that stop in 2009-2010, with an overall decrease in the HCO3 − content of al- most 50%. The time trends of HCO3 − contents at two other CO2-rich sites from the Torre Annunziata area, namely wells 6 and 14 (Figure 6), confirm the above-de- scribed general pattern, characterized by relative de- creases in 1999, followed by marked increases soon thereafter and new long-lasting declines from 2003 or 2004. The chemical variations observed at well 19 (Fig- ure 7) in the Torre Annunziata area are worth noting. During 1998-2003 its HCO3 − content shows time trends very similar to those for the other described sites. A sharp negative peak in HCO3 − was detected in mid- 2003, paralleled by comparable positive peaks in the NO3 − content and SO4 2–/HCO3 − ratio, which last only a few months. The HCO3 − finally declines after 2007, which is still ongoing. Figure 8 illustrates the time trends of some geo- chemical parameters measured at a spring (yield <0.1 l·min–1) located on the northern flank of the volcano (Olivella spring; Figure 1). This site shows significant modifications in the water and dissolved gas chemistries and pH at the beginning of the investigated period, cor- responding to the seismic sequence of October 1999, which have been attributed to the stress-induced input of acidic volcanic gases – essentially CO2 and H2S [Fed- erico et al. 2004]. An overall increase in HCO3 − is evident after the November 1999 earthquake, paralleled by a si- multaneous slight decrease in pH (about 0.2 pH units FEDERICO ET AL. 6 Figure 5. a) From top to bottom: time trends of the Cl−/SO4 2− ratio (triangles), dissolved CO2 content (open circles), HCO3 − content (squares), and water temperature (filled circles) at well 29 (Torre del Greco). b) From top to bottom: time trends of the Cl−/SO4 2− ratio (triangles), HCO3 − content (squares), and water temperature (filled circles) at spring 13 (Torre Annunziata). Arrows indicate phases of increases (red) and decreases (blue) in the plotted parameters. The time trend of pCO2 values, computed for the hydrothermal aquifer by Caliro et al. [2011], is plotted as a shaded area. The histogram shows the monthly number of seismic events. Figure 6. Time trends of HCO3 − contents at wells 6 and 14. Arrows indicate phases of increases (red) and decreases (blue) in HCO3 − con- tents. The time trend of pCO2 values, computed for the hy- drothermal aquifer by Caliro et al. [2011], is plotted as a shaded area. The histogram shows the monthly number of seismic events. Figure 7. From top to bottom: time trends of the SO4 2−/HCO3 − ratio, NO3 − content, and HCO3 − content at well 19. The time trend of pCO2 values, computed for the hydrothermal aquifer by Caliro et al. [2011], is plotted as a shaded area. The histogram shows the monthly number of seismic events. 7 on average) and a marked decline in the NO3 − contents (from 60 to 20 mg·l–1), which represents a marker for the shallower polluted endmember. The compositional change appears particularly evident after 2003. Finally, time trends of dissolved CH4/CO2 molar ratios at selected sites (where CH4 is detectable) – namely sites 1, 31, and 48 – are shown in Figure 9, in which the CO2/CH4 ratios measured at fumarole FC2 are plotted as a shaded area [Caliro et al. 2011]. We can observe relatively high CH4/CO2 ratios at wells 1 and 31 in 1999 (and low CO2/CH4 ratios at fumarole FC2), followed by very low values during 2000-2001, when CO2 progressively increased to CH4 at the crater fumarole [Caliro et al. 2011]. Since 2002, pro- gressively higher CH4/CO2 ratios have been measured in dissolved gases, remaining almost steady during the entire analyzed period. This coincides with the de- crease in CO2 concentrations at the fumaroles in the crater area. General discussion According to previous studies, water circulation on Mt. Vesuvius occurs in different overlapped water bod- ies that are characterized by different temperatures and salt contents. Higher salinity and Cl content character- ize the deep-circulating and gas-charged fluids (partly contaminated by brines in the southern and western sectors), whereas the shallower endmember has a typ- ical bicarbonate-richer composition [Federico et al. 2002, 2004]. Where the brine contribution is small (i.e., at well 6), the water salinity is almost exclusively con- trolled by the extent of the CO2-driven rock-leaching and, ultimately, by the amount of interacting CO2. Therefore, time changes in the water chemistry at the sampled sites can be reliably ascribed to changes in the mixing proportions of the deeper and shallower end- members and to the input of CO2. The mixing proportions of the deeper and shal- lower endmembers are reliably related to the water flow rate within the aquifers, which in turn results from the variation of pressure gradients and/or permeability, according to the Darcy’s law, which describes water flow in porous media. In a volcano-hydrothermal set- ting we can expect variations of fluid pressure to be controlled by magma degassing and/or the heat and vapor supply to hydrothermal systems [Day 1996, Reid 2004, Thomas et al. 2004]. Additionally, changes in pore pressure can be attributed to changes in the pore space volume, due to stress or self-sealing processes [Kim et al. 1997, Lazear 2009, Mortimer et al. 2011]. As sug- gested by Madonia et al. [2008], the crustal deforma- tion that caused intense seismic activity in 1999 could also have changed the fluid circulation, as suggested by water chemistry data (Figures 5-7). Analysis of the en- tire data record reveals a clear-cut compositional differ- ence between the first 5 years of observations and the later period. In general, the salinity, temperature, and CO2 and HCO3 − contents of the wells were highest be- fore 2003, since when (and especially after 2005) there has been a systematic decrease in these parameters characterizing the vesuvian aquifer. We suggest that the higher Cl−/SO4 2– ratios measured during 1998-2003 at wells 13 and 29, paralleled by higher temperatures and HCO3 − and CO2 contents, are indicative of a higher fluid pressure resulting from both the preseismic crustal deformation and the magmatic gas release correspon- ding to the 1999 seismic crisis. It is worth noting that the fluids emitted from fumaroles in the crater area in- deed display the highest magmatic He and CO2 con- tributions for typical hydrothermal gases (CH4 and H2O) from 2000 to 2003 [Caliro et al. 2011]. The short- lived and moderate decreases in salinity and HCO3 − contents observed in the few months of 1999 when the largest number of seismic events occurred [Madonia et al. 2008] could be ascribed to fracture reopening and an increase in permeability caused by the intense seis- HYDROLOGY AND SEISMICITY ON MT. VESUVIUS Figure 8. From top to bottom: time trends of the pH, HCO3 − con- tent, and dissolved CO2 content at Olivella spring. The histogram shows the monthly number of seismic events. Figure 9. Time trends of CH4/CO2 molar ratios in the dissolved gas phase at selected sites (namely wells 1, 31, and 48). The time trend of CO2/CH4 molar ratios, measured at the crater fumarole by Caliro et al. [2011], is plotted as a shaded area. The histogram shows the monthly number of seismic events. micity. As demonstrated by both field data and numer- ical modeling, the increase in permeability should favor the circulation of shallow fluids at greater depth [Lazear 2009], thus supporting that the shallow water endmember predominated over the deeper one. After 2003 there was a clear-cut change in water cir- culation at several sites – namely 6, 13, 19, and 29, that marks an increasing contribution of the shallower Cl- poorer endmember relative to the deeper saline one. In- terestingly, a dramatic change was recorded at well 19 in 2003, where a peak in the NO3 − content (which prob- ably reflects the contribution of shallower polluted water) is paralleled by a decrease in the HCO3 − content. Mid-2003 was also characterized by the occurrence of an anomalous low-frequency seismic event. Cusano et al. [2013] classified this event as a Long Period (LP) earthquake. The spectral and coda envelope analyses provided evidence of the dominance of sustained low- frequency oscillations, typical of the long-period seis- micity (fluid-filled crack resonance). The presence of fluids at the depth of the vesuvian LP event (about 4 km b.s.l.) support the conceptual geochemical model of the volcanic system of Mt. Vesuvius depicted by Caliro et al. [2011], in which the brine sources were positioned just shallower than the LP hypocenter. On these grounds and taking into account the vari- ations in the groundwater chemistry described in the present work, we suggest that the LP seismic event that occurred in summer 2003 could have caused a pressure decrease that was sustained until that moment by the degassing of magmatic volatiles (mostly CO2), as ob- served by Caliro et al. [2011]. The pressure drop could have increased the circulation of shallower fluids into a deeper aquifer, thus explaining the change in chemical composition and the decrease in the saline contents of fluids at the monitored sites. While the water composition indicates the domi- nant contribution of shallow water since 2003, the tem- perature and/or CO2 and HCO3 − concentrations at some wells (namely wells 26, 13, 14, and 29) remained high until 2005-2006. This would support inputs of water vapor and CO2 into the shallow aquifer, and we cannot exclude that this is also an effect of a reduced confining pressure in the hydrothermal aquifer caused by the 2003 event. Otherwise, as observed in Figure 8, an increase in HCO3 − content from 2003 at Olivella spring is paralleled by a slight reduction in pH (of about 0.2 units), which supports a subsequent higher input of CO2. The time trends of CH4/CO2 ratios measured at selected wells (where dissolved CH4 is detectable, at >10–5 cc·l–1 STP) are compatible with the CO2/CH4 ra- tios measured at the crater fumarole [Caliro et al. 2011], and support that the contribution from the hydrother- mal vapor has been greater than that from the mag- matic CO2-richer gases since 2003. Additionally, the CH4/CO2 ratios in groundwater can vary due to a re- duced flux of deep gases, since these gas species have different solubilities in water. Indeed, partial dissolution of gases in water can modify the original gas composi- tion as an effect of the specific solubility coefficients and the relative amount of residual gas, according to a Rayleigh-type fractionation [Federico et al. 2002, Cara- causi et al. 2003, Capasso et al. 2005]: (1) where subscripts liq, gas, and in indicate the liquid phase, gas phase, and initial condition, respectively, KH,CH4 and KH,CO2 are Henry’s constants for the gas species CH4 and CO2, and mCO 2 is the number of moles of CO2. Given the large difference in Henry’s constant between CH4 and CO2 (39,900 and 1667 atm·mol·mol –1, respectively, at 25°C [Wilhelm et al. 1977]), the exponent in Equation (1) is <0. Therefore, a dramatic reduction in the fraction of the residual gas (i.e., ) due to the progres- sive dissolution in water can be expected to increase the CH4/CO2 ratios. The lower salinities, temperatures, and CO2 con- tents from 2006 onward clearly indicate a reduced input of volcanic volatiles and lower fluid pressure in the vol- canic aquifer. Conclusions The chemical analyses of water and dissolved gas samples obtained during 1998-2011 indicate that the geochemical behavior of the vesuvian aquifer is strictly controlled by variations in the input of deep-seated vol- canic gases and in the stress field. The changes in the stress field, which were responsible for the seismic cri- sis of 1999, and the almost simultaneous increased input of CO2-rich vapor, significantly affected the recorded composition and temperature of the ground- water. Indeed, an increase in fluid pressure character- ized the period from 1998 to 2003, inducing a change in water circulation and the predominance of a deeper water endmember over the shallower one in the vesu- vian aquifer. Moreover, the groundwater temperature and dissolved carbon contents (in terms of both HCO3 − and CO2) are clearly indicative of inputs of CO2 and steam until 2005-2006. The termination of the phase of intense deep degassing, as observed in the crater area and in groundwater, is associated with a pressure de- crease evident in the water chemistry and paralleled by a peculiar seismic event that was recorded in July 2003. The recent observations of low salinity, temperature, FEDERICO ET AL. 8 CO CH CO CH m m K K ,,, , CO in CO gas inliq H CH H CO K K 2 4 2 4 1 , , H CH H CO 2 2 4 2 4 2 $$= - 6 6 6 6 @ @ @ @c c c c em m m m o m m 1 ,CO in CO 2 2 % 9 and dissolved carbon contents in groundwater provide strong evidence for reduced pressure in the volcano-hy- drothermal system at Mt. Vesuvius. The variations of specific geochemical parameters can therefore be as- cribed to either stress-induced changes in water circu- lation or changes in the inputs of deep gases. 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Am., 92 (2), 625-640; doi:10.1785/ 0120000287. *Corresponding author: Cinzia Federico, Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, Palermo, Italy; email: c.federico@pa.ingv.it. © 2013 by the Istituto Nazionale di Geofisica e Vulcanologia. All rights reserved. HYDROLOGY AND SEISMICITY ON MT. VESUVIUS Appendix FEDERICO ET AL. 12 Si te 6 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C H 4 cc /l S T P C O 2 cc /l S T P 11 /9 8 16 .9 5. 9 -2 70 14 2 25 2 83 58 20 9 < 0. 1 36 99 0 17 70 5. E -0 1 10 60 1/ 99 16 .8 5. 9 -1 30 13 6 24 2 83 57 20 2 < 0. 1 39 10 10 17 70 1. E + 00 10 90 3/ 99 16 .4 6. 1 -9 0 14 1 25 8 81 57 21 0 0. 5 39 85 0 17 10 < 0. 00 01 52 0 10 /9 9 16 .7 5. 8 -1 20 14 4 25 2 90 59 16 8 0. 5 41 99 0 16 60 5. E -0 1 12 00 11 /9 9 16 .9 5. 9 -2 80 14 9 24 3 89 64 17 0 0. 3 34 99 0 17 10 7. E -0 1 94 3 3/ 00 16 .8 6. 1 -2 75 14 6 25 0 84 59 16 8 4. 3 36 99 0 17 30 n. m . n. m . 5/ 00 16 .8 5. 9 -2 00 15 1 25 9 89 56 16 5 1. 9 31 10 40 17 90 2. E -0 1 99 0 7/ 00 17 .1 5. 8 -1 80 13 9 24 0 92 67 18 1 1. 5 44 10 30 17 70 2. E -0 1 12 30 10 /0 0 16 .7 5. 7 -2 10 13 6 24 1 92 52 14 9 < 0. 1 34 10 00 16 80 n. d. 15 20 11 /0 0 16 .6 5. 8 -1 60 13 4 23 5 85 54 17 1 < 0. 1 38 10 20 17 40 4. E -0 1 12 40 1/ 01 16 .5 6. 0 n. m . 13 7 25 1 75 57 16 8 0. 2 36 96 0 16 90 5. E -0 2 74 0 3/ 01 16 .6 5. 9 n. m . 14 4 24 2 78 71 17 0 < 0. 1 35 10 10 17 40 6. E -0 4 97 0 4/ 01 16 .7 5. 9 -5 0 13 7 23 7 84 55 15 5 3. 0 40 97 0 17 00 5. E -0 1 95 0 5/ 01 17 .1 5. 7 24 13 4 23 0 88 59 14 8 0. 2 34 10 30 17 70 7. E -0 2 11 90 6/ 01 17 .1 5. 9 57 13 5 23 4 88 57 17 4 0. 2 45 97 0 17 00 < 0. 00 01 83 0 8/ 01 16 .7 5. 9 -8 5 13 8 24 1 89 62 17 9 5 45 99 0 17 50 n. m . n. m . 9/ 01 16 .6 5. 9 60 14 4 24 3 89 66 17 1 4. 3 46 10 00 17 60 n. m . n. m . 10 /0 1 16 .7 5. 9 -3 4 14 4 23 9 93 66 16 5 3. 7 47 10 20 17 70 4. E -0 2 85 0 11 /0 1 16 .6 5. 8 25 14 3 23 7 90 64 16 9 < 0. 1 35 10 10 17 50 < 0. 00 01 45 0 12 /0 1 16 .7 6. 0 15 13 4 24 1 84 64 16 0 < 0. 1 33 10 00 17 10 n. m . n. m . 1/ 02 16 .7 5. 9 -1 30 13 6 23 4 81 60 17 7 < 0. 1 59 97 0 17 20 1. E -0 1 10 30 2/ 02 16 .7 6. 1 30 14 1 23 6 81 58 14 4 < 0. 1 39 10 10 17 10 6. E -0 2 10 30 3/ 02 16 .4 5. 9 -2 00 14 2 24 8 83 61 17 3 < 0. 1 43 98 0 17 30 2. E -0 1 68 0 4/ 02 16 .8 5. 8 -3 6 14 4 23 8 89 59 18 7 < 0. 1 35 97 0 17 20 3. E -0 1 83 0 5/ 02 16 .9 5. 9 -3 8 14 3 23 6 86 58 16 8 < 0. 1 59 10 10 17 60 5. E -0 1 87 0 6/ 02 16 .9 6. 0 -2 0 14 9 24 9 87 62 17 4 < 0. 1 47 99 0 17 60 1. E -0 1 82 0 7/ 02 17 .5 5. 9 -2 00 14 9 24 8 87 62 17 1 < 0. 1 48 99 0 17 50 5. E -0 1 85 0 9/ 02 17 .4 5. 9 -1 80 13 9 23 6 80 56 16 8 < 0. 1 36 10 10 17 30 6. E -0 1 82 0 9/ 02 16 .7 5. 9 -1 80 13 8 23 5 78 55 16 8 < 0. 1 37 90 0 16 10 8. E -0 1 85 0 12 /0 2 16 .3 5. 8 -9 0 13 8 23 9 79 55 14 6 < 0. 1 39 10 10 17 10 4. E -0 4 71 0 1/ 03 16 .5 0 5. 6 -1 10 14 1 23 6 81 52 16 3 3 33 10 00 17 00 1. E -0 1 77 0 3/ 03 16 .9 5. 8 -1 20 15 8 24 8 86 57 17 0 < 0. 1 44 10 20 17 80 2. E -0 4 76 0 4/ 03 16 .9 5. 9 -1 50 15 3 24 3 85 55 21 0 < 0. 1 37 98 0 17 60 1. E -0 4 83 0 5/ 03 17 .3 5. 9 -2 10 13 9 24 8 84 53 17 2 < 0. 1 36 99 0 17 20 1. E -0 4 71 0 T ab le A 1 (c on ti nu es o n ne xt p ag e) . 13 HYDROLOGY AND SEISMICITY ON MT. VESUVIUS 6/ 03 17 .6 n. m . -1 80 14 4 25 2 87 55 17 4 < 0. 1 38 99 0 17 40 2. E -0 3 67 0 7/ 03 17 .5 6. 0 -1 90 14 0 24 8 85 56 18 2 < 0. 1 47 99 0 17 50 n. m . n. m . 8/ 03 17 .3 6. 0 -1 70 13 6 24 1 89 54 19 0 < 0. 1 58 99 0 17 60 3. E -0 2 82 0 9/ 03 17 5. 9 -1 10 13 5 24 3 91 60 17 2 0. 19 60 95 0 17 10 3. E -0 1 86 0 10 /0 3 16 .9 5. 8 -2 50 13 8 24 7 87 54 16 3 < 0. 1 57 95 0 17 00 3. E -0 1 10 00 12 /0 3 16 .6 5. 9 -1 20 13 5 23 9 83 60 17 4 < 0. 1 37 96 0 16 90 3. E -0 1 90 0 01 /0 4 16 .5 5. 5 -2 10 13 2 23 4 82 58 16 5 < 0. 1 49 93 0 16 50 6. E -0 1 80 0 4/ 04 16 .7 5. 7 -2 90 13 8 24 4 82 58 17 6 4. 34 38 96 0 17 00 3. E -0 1 80 0 5/ 04 17 5. 9 -1 40 13 4 24 1 84 58 17 6 < 0. 1 47 94 0 16 80 6. E -0 2 78 0 6/ 04 16 .9 n. m . -1 10 13 5 24 5 87 60 18 1 < 0. 1 44 96 0 17 20 5. E -0 1 86 0 8/ 04 n. m . n. m . n. m . 13 7 24 3 89 59 19 2 < 0. 1 56 95 0 17 30 5. E -0 1 79 0 9/ 04 16 .9 5. 8 14 0 14 2 25 4 90 61 20 1 < 0. 1 72 95 0 17 70 4. E -0 1 77 0 10 /0 4 16 .8 5. 9 -8 5 12 7 24 6 79 63 17 8 < 0. 1 61 95 0 17 10 5. E -0 1 84 0 11 /0 4 16 .7 5. 9 -8 5 13 8 24 3 83 59 17 2 < 0. 1 42 96 0 17 00 8. E -0 1 84 0 3/ 05 16 .8 5. 8 -1 00 13 8 25 4 86 50 17 6 < 0. 1 46 95 0 17 00 3. E -0 1 85 0 4/ 05 16 .7 5. 9 43 12 7 22 7 81 58 16 5 < 0. 1 38 96 0 16 50 2. E -0 1 76 0 6/ 05 16 .9 5. 8 -1 80 13 7 24 4 91 64 19 5 < 0. 1 54 94 0 17 30 4. E -0 1 73 0 7/ 05 16 .9 5. 9 -1 60 13 6 24 1 91 63 20 2 < 0. 1 67 92 0 17 20 4. E -0 4 65 0 8/ 05 16 .9 n. m . n. m . 13 7 24 5 89 62 18 9 < 0. 1 67 94 0 17 30 4. E -0 1 76 0 10 /0 5 16 .8 n. m . n. m . 13 5 24 3 88 63 18 9 < 0. 1 44 95 0 17 10 5. E -0 1 77 0 11 /0 5 16 .4 5. 7 n. m . 13 4 24 1 86 63 17 2 < 0. 1 41 96 0 17 00 5. E -0 1 79 0 3/ 06 16 .7 n. m . n. m . 14 1 24 2 88 62 20 7 < 0. 1 50 94 0 17 30 7. E -0 1 82 0 6/ 06 17 5. 7 n. m . 13 9 24 7 90 65 21 7 < 0. 1 10 1 88 0 17 40 4. E -0 1 71 0 2/ 07 16 .7 n. m . n. m . 14 1 24 4 93 66 22 5 < 0. 1 38 94 0 17 50 n. m . n. m . 6/ 07 n. m . n. m . n. m . 13 8 23 9 95 70 21 8 < 0. 1 41 95 0 17 50 5. E -0 1 82 0 2/ 08 16 .8 5. 9 -2 00 14 0 24 5 92 63 21 4 < 0. 1 40 95 0 17 40 3. E -0 1 84 0 5/ 08 16 .9 n. m . -5 0 14 2 24 8 99 71 23 5 < 0. 1 35 95 0 17 80 n. m . n. m . 10 /0 8 17 .0 5. 9 -2 40 12 7 21 8 86 63 22 6 < 0. 1 56 87 0 16 40 n. m . n. m . 7/ 09 17 .0 6. 0 -2 20 13 5 24 5 94 63 23 2 < 0. 1 48 94 0 17 60 n. m . n. m . 4/ 10 17 .1 n. m . -1 70 12 7 21 8 92 67 19 1 < 0. 1 47 92 0 16 60 n. m . n. m . 7/ 10 17 .5 5. 9 n. m . 13 0 23 7 92 63 22 1 < 0. 1 37 95 0 17 30 3. E -0 1 76 0 Si te 6 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C H 4 cc /l S T P C O 2 cc /l S T P T ab le A 1 (c on ti nu ed fr om p re vi ou s pa ge ). FEDERICO ET AL. 14 Si te 1 3 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) 5/ 98 22 .5 6. 0 -9 0 17 9 32 8 10 5 18 8 36 0 20 .6 24 2 10 90 24 90 11 /9 8 23 .2 6. 0 -1 00 18 5 35 0 10 1 16 7 46 0 < 0. 1 27 5 10 60 25 90 1/ 99 22 .1 6. 2 -7 0 17 5 32 7 10 1 18 0 39 0 3. 2 27 3 10 40 24 90 3/ 99 22 .7 5. 9 -1 10 18 0 33 0 10 1 17 4 42 0 0. 4 26 2 92 0 23 90 5/ 99 23 .2 5. 9 -2 60 17 0 33 3 95 16 6 36 0 0. 2 25 6 90 0 22 90 10 /9 9 23 .3 6. 7 -1 10 17 3 34 2 88 16 4 34 0 3. 5 23 1 10 10 23 20 11 /9 9 23 .3 6. 0 -2 50 15 9 32 1 91 14 9 32 0 6. 8 21 9 95 0 22 40 3/ 00 22 .6 6. 0 -2 70 17 1 30 7 92 16 9 34 0 5. 0 24 7 99 0 23 20 5/ 00 23 .0 6. 0 -1 60 17 9 32 6 96 15 7 38 0 3. 1 25 5 99 0 23 60 7/ 00 23 .2 6. 0 -6 0 17 8 32 4 10 4 18 6 40 0 3. 1 26 8 10 50 25 00 10 /0 0 23 .1 6. 0 -2 00 20 0 36 0 11 2 17 9 42 0 < 0. 1 28 1 10 70 26 20 11 /0 0 22 .9 5. 9 -1 80 17 1 30 6 96 18 0 38 0 1. 8 27 4 10 50 24 50 1/ 01 22 .3 6. 0 n. m . 16 7 34 0 95 22 3 39 0 < 0. 1 26 5 10 40 24 80 3/ 01 22 .4 6. 0 n. m . 18 5 32 5 10 5 19 1 39 0 < 0. 1 28 0 10 70 25 60 4/ 01 22 .8 6. 0 -3 5 17 7 32 5 10 7 19 2 39 0 < 0. 1 26 3 10 80 25 30 5/ 01 23 .0 6. 0 34 18 1 32 6 10 9 19 1 40 0 < 0. 1 28 2 10 30 25 20 6/ 01 22 .8 5. 93 44 18 4 33 5 10 8 18 6 43 0 5. 2 29 3 10 40 25 80 7/ 01 23 .2 5. 99 -2 20 20 6 36 2 11 1 19 2 46 0 6. 7 31 0 11 00 27 40 8/ 01 23 .8 5. 74 -1 00 21 6 36 5 11 6 18 4 47 0 5. 0 31 2 11 00 27 60 9/ 01 23 .2 5. 93 -1 00 21 5 37 2 11 7 19 4 49 0 4. 3 32 4 11 10 28 30 10 /0 1 23 .3 5. 93 -1 00 22 7 38 6 12 3 19 8 48 0 1. 2 31 3 11 30 28 60 11 /0 1 22 .9 5. 95 55 20 5 35 3 12 0 20 0 44 0 < 0. 1 32 9 11 20 27 70 01 /0 2 n. m . 5. 8 -9 0 21 7 39 0 11 9 23 3 47 0 < 0. 1 34 1 11 60 29 40 02 /0 2 22 .9 5. 8 -7 0 22 0 37 6 11 2 20 6 48 0 30 .4 32 3 11 60 28 80 03 /0 2 22 .9 5. 9 -2 00 22 7 40 0 11 9 22 4 50 0 < 0. 1 36 0 11 30 29 60 04 /0 2 23 .2 5. 9 -1 50 21 4 38 6 11 6 23 0 45 0 < 0. 1 33 5 11 40 28 70 05 /0 2 23 .2 6. 0 -2 0 22 4 38 4 11 9 20 7 46 0 < 0. 1 31 4 11 70 28 70 06 /0 2 23 .5 6. 1 -6 22 3 38 2 11 2 21 6 46 0 < 0. 1 31 7 11 20 28 30 07 /0 2 23 .9 6. 1 -1 90 23 1 39 0 11 4 21 0 47 0 < 0. 1 32 5 11 60 29 00 08 /0 2 23 .7 6. 0 -3 50 23 1 39 3 11 2 19 4 47 0 < 0. 1 33 4 11 50 28 80 09 /0 2 23 .7 6. 0 -1 44 22 8 38 9 11 0 19 8 47 0 < 0. 1 33 2 10 90 28 20 10 /0 2 23 .8 5. 9 -1 40 23 3 39 8 11 2 20 1 47 0 < 0. 1 33 2 11 40 28 90 12 /0 2 23 .5 6. 1 -5 9 22 7 38 1 11 1 19 8 45 0 < 0. 1 33 1 11 40 28 40 12 /0 2 23 .5 5. 9 12 21 4 37 8 10 7 19 5 41 0 < 0. 1 29 5 11 30 27 30 01 /0 3 23 .1 5. 9 -4 3 20 2 34 3 10 0 20 8 41 0 < 0. 1 31 8 11 20 27 00 03 /0 3 23 .3 6. 0 -8 3 22 5 35 6 10 4 20 3 41 0 < 0. 1 31 2 11 10 27 30 04 /0 3 23 .2 6. 0 -1 90 21 7 35 1 10 2 20 7 43 0 7 31 8 11 00 27 30 05 /0 3 23 .7 n. m . -1 40 19 6 36 0 98 21 2 41 0 4 30 6 11 20 27 00 T ab le A 2 (c on ti nu es o n ne xt p ag e) . 15 HYDROLOGY AND SEISMICITY ON MT. VESUVIUS Si te 1 3 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) 08 /0 3 24 .1 6. 1 -1 10 20 5 38 0 10 4 19 7 43 0 3 31 4 11 10 27 40 09 /0 3 24 6. 1 -2 00 19 9 36 7 11 5 20 2 44 0 6 31 0 10 90 27 20 10 /0 3 23 .8 6. 1 -9 3 20 3 36 9 10 8 22 0 48 0 7 29 2 11 20 27 90 11 /0 3 23 .6 6. 0 -9 0 21 4 38 7 10 5 19 8 45 0 6 32 0 11 30 28 00 12 /0 3 23 .7 6. 0 -6 2 20 8 38 5 10 0 20 5 42 0 5 30 4 11 40 27 60 01 /0 4 23 .0 5. 9 -2 00 20 5 37 3 10 4 20 5 42 0 5 29 9 11 40 27 40 03 /0 4 23 .3 5. 8 -3 0 18 4 33 5 95 21 4 39 0 0 27 2 10 90 25 70 04 /0 4 23 .3 5. 8 -3 0 18 5 33 0 93 21 2 37 0 6 27 6 11 20 25 80 05 /0 4 23 .7 6. 0 -2 7 18 0 32 4 89 21 0 34 0 2 26 8 10 90 25 00 06 /0 4 23 .6 n. m . -8 2 18 4 33 7 94 20 4 37 0 19 28 1 10 90 25 60 08 /0 4 n. m . n. m . n. m . 20 3 36 0 97 20 0 40 0 2 29 7 11 00 26 50 09 /0 4 24 .1 6. 1 -9 0 20 3 36 8 96 19 1 40 0 2 30 0 10 90 26 40 10 /0 4 23 .9 6. 0 -7 0 17 1 33 0 75 17 9 29 0 16 25 3 10 40 23 40 11 /0 4 23 .5 5. 9 -3 8 16 9 31 0 79 18 0 30 0 12 23 2 10 50 23 20 12 /0 4 23 .5 5. 9 -1 8 17 7 32 2 86 19 3 34 0 4 26 1 10 50 24 20 01 /0 5 23 .5 n. m . -3 7 18 1 32 2 86 18 6 34 0 4 26 5 10 20 24 00 03 /0 5 23 .2 6. 0 -6 0 16 2 31 6 78 17 9 30 0 7 23 4 98 0 22 50 04 /0 5 23 .3 5. 8 70 15 7 28 8 74 16 9 29 0 9 21 4 99 0 21 80 05 /0 5 23 .2 5. 9 -3 .5 17 2 31 4 80 18 1 31 0 < 0. 1 23 8 10 10 23 00 06 /0 5 23 .4 5. 9 -9 2 18 3 33 0 85 18 6 34 0 < 0. 1 26 3 10 20 24 00 07 /0 5 23 .8 5. 9 -3 6 17 9 32 6 84 17 9 34 0 < 0. 1 24 8 10 10 23 60 08 /0 5 23 .5 n. m . n. m . 19 3 34 6 91 18 9 36 0 < 0. 1 27 1 10 50 25 00 10 /0 5 23 .7 n. m . n. m . 17 7 32 0 81 17 7 32 0 < 0. 1 25 2 10 20 23 40 11 /0 5 23 n. m . n. m . 18 2 33 0 86 18 2 33 0 < 0. 1 25 4 10 30 23 90 12 /0 5 23 .1 n. m . n. m . 16 7 29 3 79 17 7 31 0 < 0. 1 22 8 96 0 22 10 01 /0 6 22 .4 n. m . n. m . 17 5 30 5 83 18 3 32 0 < 0. 1 25 1 98 0 23 00 03 /0 6 22 .5 n. m . n. m . 18 3 31 9 86 18 4 35 0 < 0. 1 26 2 98 0 23 70 06 /0 6 22 .7 5. 9 n. m . 16 1 29 4 80 18 6 31 0 < 0. 1 22 8 98 0 22 30 10 /0 6 22 .3 5. 8 -4 0 16 1 29 4 80 18 6 31 0 < 0. 1 22 8 98 0 22 30 02 /0 7 21 .5 n. m . n. m . 14 5 25 9 68 16 6 25 0 < 0. 1 19 2 91 0 19 90 06 /0 7 22 .0 5. 9 -2 0 13 6 24 2 63 15 4 22 0 < 0. 1 16 5 89 0 18 70 02 /0 8 21 .7 5. 8 -3 5 12 8 23 0 60 13 8 20 0 < 0. 1 15 5 91 0 18 24 05 /0 8 21 .2 6. 8 -1 50 11 6 21 3 52 13 0 19 0 < 0. 1 13 7 77 0 16 10 10 /0 8 21 .4 5. 8 -2 30 10 7 19 0 47 11 8 17 0 < 0. 1 11 9 72 0 14 70 07 /0 9 20 .7 5. 9 -2 00 88 16 7 41 10 8 13 0 < 0. 1 97 66 0 12 90 04 /1 0 19 .7 5. 8 n. m . 88 16 3 55 15 4 18 0 < 0. 1 13 2 73 0 15 00 07 /1 0 20 .0 5. 6 n. m . 10 3 19 6 59 16 5 22 0 < 0. 1 16 4 78 0 16 90 07 /1 1 20 .4 5. 9 40 14 2 24 7 68 18 1 28 0 < 0. 1 21 2 90 0 20 20 T ab le A 2 (c on ti nu ed fr om p re vi ou s pa ge ). FEDERICO ET AL. 16 5/ 98 23 .3 6. 3 -1 70 53 0 41 0 76 0 62 0 20 00 < 0. 1 88 40 60 84 70 0. 01 0 50 0 11 /9 8 23 .3 6. 4 -2 60 54 0 41 5 77 0 62 0 22 00 2. 4 86 43 40 89 80 0. 50 0 89 0 1/ 99 23 .2 6. 4 -7 0 56 0 41 3 81 0 59 0 20 20 7. 1 88 43 40 88 10 0. 18 0 74 0 3/ 99 23 .1 6. 4 -9 0 53 0 43 3 76 0 61 0 19 70 0. 7 82 39 10 83 00 0. 19 0 10 10 5/ 99 23 .5 6. 4 -2 60 53 0 41 3 72 0 59 0 18 30 5. 9 87 40 80 84 70 0. 08 0 68 0 10 /9 9 23 .2 6. 4 -1 50 51 0 42 9 83 0 55 0 18 80 1. 7 82 42 90 85 50 0. 13 0 73 0 3/ 00 22 .6 6. 5 -2 00 52 0 42 0 79 0 41 0 21 00 21 .0 11 4 38 20 81 80 0. 07 0 90 0 5/ 00 22 .9 6. 9 -2 50 54 0 41 4 83 0 40 0 20 80 6. 8 11 3 37 70 79 90 0. 19 0 11 80 7/ 00 23 .4 6. 4 -2 00 53 0 40 1 77 0 67 0 19 80 17 .0 10 5 45 90 91 20 0. 00 1 66 0 10 /0 0 23 .0 6. 3 -1 30 56 0 42 2 79 0 51 0 18 80 < 0. 1 77 45 90 89 70 0. 23 0 10 30 11 /0 0 22 .3 6. 3 -8 0 51 0 38 7 79 0 55 0 19 80 < 0. 1 77 44 50 88 60 0. 45 0 10 90 1/ 01 21 .8 6. 6 n. m . 56 0 35 2 80 0 73 0 21 10 1. 2 71 42 90 86 60 0. 35 0 86 0 3/ 01 22 .1 6. 5 n. m . 53 0 40 6 78 0 57 0 18 10 1. 2 80 43 00 84 20 0. 43 0 82 0 4/ 01 22 .1 6. 4 -9 0 51 0 39 2 84 0 61 0 18 60 7. 3 95 43 40 86 40 0. 34 0 80 0 5/ 01 22 .4 6. 2 -8 0 50 0 39 2 79 0 57 0 19 10 0. 8 71 46 20 88 90 0. 33 0 96 0 6/ 01 23 .1 6. 4 -5 8 51 0 38 1 81 0 68 0 20 40 5. 0 84 46 20 91 20 0. 26 0 10 40 7/ 01 23 .7 6. 3 -9 0 54 0 40 5 80 0 70 0 20 10 32 95 46 20 91 80 0. 09 0 11 20 8/ 01 23 .3 6. 5 -8 0 54 0 40 8 83 0 73 0 20 20 21 85 46 10 92 20 0. 06 0 11 00 9/ 01 22 .9 6. 3 -6 0 55 0 40 4 82 0 68 0 20 40 20 84 44 30 90 00 0. 64 0 10 60 10 /0 1 22 .9 6. 3 -6 0 55 0 39 8 81 0 64 0 20 50 6. 0 83 44 10 89 40 n. m . n. m . 11 /0 1 22 .9 6. 2 -4 0 53 0 38 3 86 0 47 0 18 60 < 0. 1 93 41 70 83 70 n. m . n. m . 12 /0 1 23 .1 6. 1 -8 0 55 0 41 5 81 0 65 0 20 10 < 0. 1 97 44 40 89 70 n. m . n. m . 01 /0 2 22 .7 6. 3 -6 0 53 0 40 0 82 0 65 0 19 70 < 0. 1 98 44 90 89 60 0. 05 2 91 0 02 /0 2 22 .6 6. 0 -5 0 55 0 39 2 81 0 62 0 18 90 < 0. 1 10 3 45 80 89 30 0. 14 3 91 0 03 /0 2 22 .8 6. 1 n. m . 56 0 39 6 80 0 58 0 19 50 < 0. 1 94 45 90 89 70 0. 09 9 11 80 04 /0 2 23 .2 6. 4 -3 0 55 0 39 4 81 0 68 0 20 00 11 .8 92 44 20 89 40 0. 06 1 70 0 05 /0 2 23 .3 6. 4 -1 50 56 0 39 4 80 0 64 0 19 10 < 0. 1 91 48 30 92 20 0. 04 7 65 0 06 /0 2 23 .4 6. 5 -1 00 58 0 41 9 80 0 72 0 20 10 < 0. 1 85 46 60 92 70 0. 06 9 67 0 07 /0 2 23 .4 6. 5 -1 50 53 0 39 5 75 0 70 0 19 50 24 83 47 10 91 10 0. 05 1 67 0 08 /0 2 23 .8 6. 7 -1 10 54 0 39 2 78 0 61 0 19 50 < 0. 1 83 46 90 90 30 0. 05 9 69 0 09 /0 2 23 .5 6. 4 -1 30 54 0 39 6 78 0 62 0 19 40 < 0. 1 89 45 20 88 80 0. 17 0 77 0 10 /0 2 23 .3 6. 4 -1 50 55 0 41 1 77 0 57 0 19 30 22 88 44 40 87 60 0. 16 4 81 0 12 /0 2 20 .8 6. 4 -7 0 54 0 38 8 79 0 53 0 18 10 < 0. 1 93 43 80 85 30 0. 29 0 67 0 01 /0 3 20 .8 6. 1 -7 0 55 0 39 2 76 0 53 0 18 40 10 92 44 40 86 00 0. 31 0 68 0 Si te 1 4 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C H 4 cc /l S T P C O 2 cc /l S T P T ab le A 3 (c on ti nu es o n ne xt p ag e) . 17 HYDROLOGY AND SEISMICITY ON MT. VESUVIUS 03 /0 3 n. m . n. m . n. m . 54 0 40 2 73 0 59 0 19 50 12 92 42 70 85 80 0. 39 1 79 0 04 /0 3 23 .4 6. 5 -1 80 59 0 40 3 79 0 68 0 21 60 11 7 95 42 70 89 80 0. 04 6 81 0 06 /0 3 23 .5 n. m . -2 20 56 0 43 1 78 0 72 0 18 80 < 0. 1 88 47 40 92 00 0. 16 5 62 0 07 /0 3 23 .1 6. 3 -1 50 54 0 40 8 77 0 68 0 19 50 < 0. 1 95 47 10 91 50 n. m . n. m . 08 /0 3 23 .7 6. 4 -2 00 55 0 42 1 83 0 67 0 19 50 < 0. 1 99 45 90 91 20 0. 11 7 79 0 09 /0 3 22 .8 6. 5 -1 10 55 0 42 2 79 0 69 0 20 60 < 0. 1 91 46 20 92 20 0. 11 7 77 0 10 /0 3 21 .9 6. 5 -1 10 54 0 41 7 81 0 63 0 19 30 22 .3 12 1 46 70 91 20 0. 61 77 83 0 12 /0 3 22 .6 6. 4 -1 40 55 0 41 8 76 0 67 0 19 30 < 0. 1 10 8 46 60 91 00 0. 16 0 76 0 01 /0 4 22 .2 6. 3 -1 80 53 0 40 5 76 0 67 0 19 30 < 0. 1 10 1 45 60 89 50 n. m . n. m . 03 /0 4 22 .2 6. 3 -1 50 53 0 41 3 73 0 67 0 18 50 < 0. 1 12 4 46 10 89 30 0. 67 1 71 0 04 /0 4 21 .4 6. 3 -1 70 51 0 40 5 74 0 67 0 19 60 < 0. 1 11 0 45 10 89 10 0. 08 9 89 0 05 /0 4 22 .5 6. 5 -1 60 53 0 40 5 79 0 72 0 19 30 < 0. 1 11 3 46 90 91 90 0. 09 2 68 0 06 /0 4 23 .0 6. 7 -1 20 54 0 41 3 78 0 69 0 18 70 < 0. 1 11 2 47 40 91 30 n. m . n. m . 09 /0 4 22 .8 6. 6 -1 40 56 0 42 8 78 0 62 0 20 50 < 0. 1 10 1 44 50 89 80 0. 05 0 75 0 10 /0 4 22 .4 6. 4 -1 50 56 0 42 7 83 0 57 0 19 70 < 0. 1 11 2 43 40 88 10 0. 20 7 76 0 11 /0 4 22 .2 6. 3 -1 10 53 0 40 9 75 0 55 0 19 40 < 0. 1 96 42 70 85 40 0. 23 5 62 0 12 /0 4 22 .0 6. 4 -1 10 53 0 40 7 78 0 55 0 19 40 < 0. 1 88 42 90 85 90 0. 06 6 65 0 01 /0 5 22 .0 n. m . -8 0 53 0 41 0 78 0 59 0 18 90 < 0. 1 11 5 42 70 85 80 n. m . n. m . 03 /0 5 22 .4 6. 2 -1 40 53 0 40 8 78 0 49 0 18 30 < 0. 1 10 6 42 70 84 00 0. 48 1 74 0 04 /0 5 22 .3 6. 2 2. 0 52 0 39 8 75 0 58 0 18 50 < 0. 1 93 43 20 85 00 0. 20 8 61 0 05 /0 5 22 .3 6. 2 -1 40 51 0 39 7 74 0 55 0 18 50 < 0. 1 89 42 10 83 40 n. m . n. m . 06 /0 5 22 .6 6. 4 -1 30 55 0 40 4 79 0 64 0 19 80 < 0. 1 89 44 60 89 20 0. 09 7 52 0 07 /0 5 22 .7 6. 5 -1 40 51 0 38 7 72 0 62 0 19 80 < 0. 1 89 41 50 84 60 0. 13 7 59 0 08 /0 5 22 .6 n. m . n. m . 54 0 41 6 78 0 66 0 19 90 < 0. 1 87 44 20 89 00 0. 43 0 84 0 10 /0 5 22 .7 n. m . n. m . 55 0 41 8 78 0 57 0 20 60 < 0. 1 95 41 60 86 20 n. m . n. m . 11 /0 5 21 .4 6. 3 n. m . 54 0 41 4 78 0 59 0 19 40 < 0. 1 94 42 70 86 30 0. 43 0 70 0 12 /0 5 22 .3 6. 2 n. m . 57 0 42 2 81 0 59 0 20 60 < 0. 1 85 42 70 88 10 0. 18 4 72 0 01 /0 6 21 .8 6. 3 n. m . 52 0 38 0 73 0 54 0 19 10 < 0. 1 99 39 90 81 70 0. 28 6 74 0 03 /0 6 22 .3 6. 4 n. m . 54 0 39 7 76 0 55 0 20 00 < 0. 1 10 6 40 60 84 00 n. m . n. m . 10 /0 6 22 .8 6. 4 -8 0 54 0 41 2 79 0 59 0 18 90 < 0. 1 89 44 60 87 70 0. 14 3 77 0 02 /0 7 22 .0 n. m . n. m . 54 0 40 7 78 0 57 0 19 90 < 0. 1 84 42 80 86 60 n. m . n. m . 06 /0 7 22 .5 6. 0 -2 00 55 0 41 0 78 0 67 0 19 60 < 0. 1 91 44 70 89 30 0. 30 7 80 0 Si te 1 4 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C H 4 cc /l S T P C O 2 cc /l S T P T ab le A 3 (c on ti nu ed fr om p re vi ou s pa ge ). FEDERICO ET AL. 18 11 /9 8 21 .0 6. 6 14 0 19 5 36 1 11 9 13 6 33 1 74 19 6 12 10 25 00 1/ 99 20 .9 6. 6 13 0 21 2 38 6 13 0 11 0 32 6 84 21 0 11 30 24 60 3/ 99 16 .9 7. 1 17 0 20 2 35 4 11 4 93 30 7 72 18 3 10 90 23 00 5/ 99 21 .1 6. 7 90 19 3 36 0 10 6 97 26 6 78 18 9 10 20 22 00 10 /9 9 20 .8 6. 7 18 0 20 7 36 8 12 2 99 29 4 11 2 19 5 11 50 24 40 11 /9 9 20 .7 6. 6 23 0 20 3 38 4 12 8 11 0 29 9 10 7 19 1 11 40 23 90 3/ 00 20 .0 6. 6 11 0 21 9 38 1 12 1 97 28 3 77 19 1 11 70 24 40 5/ 00 20 .9 6. 7 14 0 21 7 38 0 11 8 93 28 4 73 18 4 11 70 24 10 7/ 00 21 .3 6. 7 20 0 20 6 36 4 12 9 10 7 29 6 74 19 1 12 30 24 70 10 /0 0 20 .8 6. 7 16 0 21 6 38 5 13 2 92 30 0 76 19 1 12 40 25 10 11 /0 0 20 .7 6. 5 18 0 21 4 37 1 13 2 97 32 8 79 20 8 12 80 25 90 1/ 01 19 .2 6. 8 n. m . 20 3 41 4 13 1 12 0 32 3 71 19 1 12 40 25 70 3/ 01 20 .0 6. 5 n. m . 21 8 37 1 13 0 11 2 31 0 76 20 1 12 30 25 60 4/ 01 20 .8 6. 5 15 0 21 5 37 5 12 9 91 30 0 72 18 2 12 30 24 90 5/ 01 21 .2 6. 6 15 0 20 4 36 2 12 9 11 0 31 4 98 19 3 12 50 25 20 6/ 01 21 .0 6. 5 26 0 22 0 37 7 13 7 11 1 32 7 73 19 9 12 50 25 60 7/ 01 21 .4 6. 5 21 0 22 8 39 6 14 0 10 3 33 1 80 20 1 12 60 26 00 8/ 01 22 .5 6. 6 19 0 22 5 38 9 13 3 10 7 32 0 54 19 5 12 90 25 80 9/ 01 20 .9 6. 5 23 0 23 2 39 6 14 2 12 2 34 1 60 20 5 12 70 26 30 10 /0 1 20 .9 6. 5 18 0 24 2 40 4 14 8 12 2 34 1 72 19 1 12 80 26 50 11 /0 1 20 .3 6. 6 19 0 22 6 39 7 14 2 11 4 33 9 77 21 6 13 10 26 80 12 /0 1 20 .2 6. 6 11 0 22 1 37 9 13 0 10 4 32 2 65 20 7 12 80 25 80 01 /0 2 20 .6 6. 3 14 0 21 6 37 9 13 5 11 1 33 8 77 22 2 12 90 26 30 02 /0 2 20 .1 6. 5 24 0 22 9 38 5 12 8 10 2 30 8 70 19 2 12 40 25 20 03 /0 2 20 .0 6. 1 n. m . 22 6 39 6 13 1 10 7 33 4 61 21 7 12 30 25 70 04 /0 2 20 .4 6. 5 -6 0 22 7 39 5 13 0 10 5 33 0 47 21 3 12 50 25 60 05 /0 2 21 .0 6. 6 15 0 22 2 37 9 13 3 10 0 31 9 73 19 5 12 70 25 50 06 /0 2 21 .3 6. 6 17 0 23 1 38 9 13 1 10 2 32 0 76 19 4 12 50 25 60 07 /0 2 21 .5 6. 5 15 0 23 7 40 0 13 4 10 6 32 7 75 19 6 12 70 26 10 08 /0 2 21 .1 6. 6 16 0 23 5 39 4 13 0 98 32 9 76 20 6 12 70 26 10 09 /0 2 20 .4 6. 6 11 0 23 2 39 1 13 1 98 33 4 74 20 6 13 10 26 40 10 /0 2 20 .8 6. 5 14 0 23 5 39 0 12 8 96 31 7 69 19 5 13 20 26 20 12 /0 2 20 .9 6. 5 n. m . 23 1 36 5 13 1 11 7 32 0 72 20 4 13 10 26 20 12 /0 2 19 .8 6. 5 12 0 22 7 39 3 13 0 92 29 1 62 18 1 12 80 25 30 01 /0 3 19 .2 6. 2 12 0 22 4 37 5 12 5 93 30 0 71 19 9 12 60 25 20 03 /0 3 n. m . n. m . n. m . 21 1 33 5 10 3 93 23 9 12 2 21 0 10 30 22 40 04 /0 3 20 .8 6. 7 15 0 19 2 31 0 10 1 99 24 5 13 6 22 2 92 0 21 20 05 /0 3 20 .8 6. 5 16 0 16 4 30 1 87 86 18 9 13 1 19 3 87 0 19 40 Si te 1 9 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) T ab le A 4 (c on ti nu es o n ne xt p ag e) . 19 HYDROLOGY AND SEISMICITY ON MT. VESUVIUS 06 /0 3 20 .9 n. m . 16 0 16 0 28 7 86 94 18 6 13 6 19 0 85 0 19 10 07 /0 3 21 .4 6. 6 16 0 15 3 27 8 85 10 3 19 7 12 8 19 2 85 0 19 00 09 /0 3 21 6. 5 n. m . 17 9 32 6 10 7 11 1 26 1 10 4 20 6 10 40 22 30 10 /0 3 20 .3 6. 6 13 0 19 0 33 3 11 8 11 2 24 6 85 17 9 11 30 22 80 11 /0 3 18 .4 6. 5 18 0 19 8 35 1 11 5 11 9 28 0 93 20 2 11 60 24 00 12 /0 3 18 .4 6. 5 12 0 20 0 36 0 11 0 11 3 26 8 85 19 0 11 50 23 70 01 /0 4 18 .5 6. 3 11 0 19 3 35 0 10 9 11 0 27 0 82 19 0 11 40 23 40 02 /0 4 n. m . 6. 8 14 0 19 2 34 6 11 1 11 0 26 8 75 18 9 11 50 23 30 03 /0 4 19 .8 6. 8 14 0 20 5 36 3 11 6 11 2 28 5 68 19 0 11 60 23 80 04 /0 4 17 .6 6. 6 12 0 21 0 36 9 11 8 10 7 29 6 68 19 8 12 00 24 05 05 /0 4 17 .6 6. 6 50 21 1 37 3 12 2 10 8 29 2 73 19 6 12 00 24 50 06 /0 4 21 .8 6. 5 90 21 3 38 8 12 4 62 30 0 66 19 6 11 90 24 10 08 /0 4 n. m . n. m . n. m . 21 9 39 0 13 0 10 7 31 7 71 20 5 12 30 25 40 09 /0 4 21 .6 6. 6 10 22 4 40 1 13 0 10 8 32 6 80 21 2 12 60 26 10 10 /0 4 21 .3 6. 5 90 22 9 40 7 13 9 10 8 32 2 76 20 8 12 70 26 20 11 /0 4 19 .6 6. 4 12 0 22 6 40 0 13 0 10 8 32 6 78 20 6 13 00 26 40 12 /0 4 19 .6 6. 5 12 0 22 6 40 3 13 4 10 7 32 7 78 20 7 13 00 26 50 01 /0 5 19 .3 n. m . 70 22 4 40 3 13 0 10 1 30 8 78 19 9 12 70 25 80 03 /0 5 19 .4 6. 4 90 22 3 40 4 13 4 89 30 0 74 19 5 12 60 25 40 04 /0 5 19 .8 6. 4 12 0 22 4 39 7 13 0 10 8 30 9 76 19 6 12 60 25 70 05 /0 5 20 .9 6. 4 10 0 21 6 38 5 12 8 10 4 29 6 74 19 1 12 60 25 30 06 /0 5 21 .6 6. 4 14 0 22 2 39 9 13 2 10 8 32 6 76 20 4 12 60 25 90 07 /0 5 21 .9 6. 6 20 0 22 4 40 1 13 4 11 1 32 6 71 20 4 12 60 26 00 08 /0 5 22 .5 n. m . n. m . 22 2 39 7 13 4 11 7 33 9 81 21 2 12 60 26 30 10 /0 5 20 .8 n. m . n. m . 22 7 40 4 13 7 11 3 33 8 81 21 5 12 70 26 50 11 /0 5 20 .1 6. 4 n. m . 23 1 41 3 14 0 11 2 33 9 80 21 3 12 80 26 60 12 /0 5 18 .2 6. 5 n. m . 23 7 40 4 14 1 11 3 35 3 79 21 2 12 60 26 60 03 /0 6 19 .4 6. 5 n. m . 23 0 39 0 13 6 10 7 33 6 79 20 4 12 60 26 10 06 /0 6 21 .2 6. 3 n. m . 24 4 43 3 15 0 12 3 38 9 10 0 24 6 12 60 27 90 10 /0 6 20 .8 6. 5 10 0 24 0 42 0 15 0 12 1 36 9 89 23 0 13 40 28 10 02 /0 7 19 .1 n. m . n. m . 23 6 41 0 14 3 11 4 33 9 82 21 1 13 20 27 20 06 /0 7 21 .8 6. 5 10 0 21 2 36 3 12 5 10 8 30 4 62 19 7 11 60 24 10 02 /0 8 19 .7 6. 8 13 0 21 3 37 1 12 3 10 5 29 8 68 19 7 11 70 24 20 05 /0 8 20 .3 6. 9 12 0 20 5 35 5 11 7 99 27 0 57 18 5 11 50 23 20 10 /0 8 20 .7 7. 0 12 0 20 3 34 8 11 3 97 27 7 70 18 3 11 40 23 10 04 /1 0 19 .2 6. 6 20 0 16 7 29 0 10 4 93 22 9 68 16 8 98 0 20 00 07 /1 0 21 .5 6. 6 n. m . 18 2 32 6 10 0 83 23 4 69 17 0 10 40 21 00 07 /1 1 22 .3 7. 0 21 0 19 4 34 0 10 9 89 25 6 80 18 4 10 80 22 20 Si te 1 9 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) T ab le A 4 (c on ti nu ed fr om p re vi ou s pa ge ). FEDERICO ET AL. 20 5/ 98 21 .7 7. 0 -3 0 16 3 22 5 68 73 15 3 4. 4 24 1 73 2 16 60 2. 2E -2 56 11 /9 8 21 .5 7. 1 -6 04 15 8 22 9 65 68 18 0 2. 2 24 8 73 8 16 90 2. 8E -2 57 1/ 99 21 .4 7. 3 -1 5 16 2 23 4 73 79 19 1 2. 5 27 2 75 0 17 60 4. 8E -2 44 5/ 99 21 .5 7. 4 -4 0 15 1 21 3 69 58 14 8 1. 4 23 0 62 8 15 00 2. 0E -1 41 10 /9 9 20 .9 7. 0 12 0 16 2 21 7 63 82 14 9 3. 7 22 6 10 07 19 10 6. 9E -2 43 11 /9 9 21 .8 6. 8 12 0 15 0 21 7 74 77 16 3 2. 9 23 5 68 3 17 00 2. 7E -2 60 3/ 00 19 .7 7. 1 11 0 16 0 22 0 67 75 15 4 8. 5 23 2 70 2 16 10 4. 1E -2 44 5/ 00 21 .2 7. 5 70 16 6 23 1 68 68 16 1 6. 2 23 9 72 0 15 70 n. m . n. m . 7/ 00 21 .4 7. 2 55 15 1 21 1 70 83 16 4 7. 5 23 4 73 2 16 60 n. m . n. m . 10 /0 0 21 .2 7. 1 70 16 8 21 9 68 68 14 6 4. 1 22 8 72 0 16 10 2. 2E -2 67 11 /0 0 21 .3 6. 9 10 0 15 6 23 2 70 72 16 5 3. 8 24 7 74 4 16 70 4. 2E -2 54 1/ 01 20 .3 6. 9 n. m . 15 5 22 7 65 71 16 6 3. 1 23 7 72 3 17 30 3. 8E -2 83 3/ 01 21 .3 6. 9 n. m . 16 6 22 6 74 83 17 6 3. 8 25 1 78 1 17 70 n. m . 78 4/ 01 21 .4 6. 8 70 16 1 22 9 80 80 15 8 3. 8 22 7 78 7 17 10 6. 3E -2 12 7 5/ 01 21 .5 7. 0 90 15 2 21 3 74 79 16 9 2. 9 25 0 73 8 16 80 6. 4E -2 76 6/ 01 21 .5 6. 9 10 0 16 0 21 8 74 72 16 9 5. 5 24 7 70 2 16 50 n. m . n. m . 7/ 01 21 .5 6. 7 15 0 16 2 22 3 70 73 16 5 9. 2 24 1 72 0 16 60 n. m . n. m . 8/ 01 22 .0 6. 8 70 15 9 22 2 72 73 15 6 0. 6 23 0 72 6 16 40 n. m . n. m . 9/ 01 21 .5 6. 9 20 0 16 6 22 3 75 78 17 2 4. 3 24 5 74 1 17 00 n. m . n. m . 10 /0 1 21 .6 7. 0 11 0 14 9 21 7 67 70 16 3 10 .4 23 6 73 8 16 50 9. 6E -3 70 01 /0 2 21 .8 6. 7 90 15 3 21 1 66 74 17 6 < 0. 1 26 2 71 7 16 60 n. m . n. m . 02 /0 2 20 .6 6. 7 11 0 15 9 21 4 65 72 14 8 7 22 9 68 3 15 80 5. 4E -2 61 03 /0 2 21 .1 6. 7 n. m . 15 7 23 2 70 69 18 2 < 0. 1 25 9 71 1 16 80 2. 3E -2 62 04 /0 2 21 .5 6. 8 70 16 3 22 9 70 81 18 3 < 0. 1 25 7 74 7 17 30 3. 4E -2 16 5 05 /0 2 21 .9 6. 9 11 0 15 9 21 1 67 65 16 4 < 0. 1 23 6 72 6 16 30 n. m . n. m . 06 /0 2 21 .8 6. 9 60 16 2 22 5 68 77 17 4 < 0. 1 23 6 72 3 16 70 4. 9E -2 69 07 /0 2 21 .5 6. 9 -5 16 4 22 4 66 74 15 4 < 0. 1 23 0 71 7 16 30 8. 7E -2 62 09 /0 2 21 .4 6. 9 -2 5 15 4 21 1 60 67 15 9 < 0. 1 23 4 70 5 15 90 1. 4E -1 59 09 /0 2 21 .1 7. 3 -5 0 15 1 20 9 60 66 15 5 < 0. 1 23 1 70 2 15 70 7. 1E -2 45 10 /0 2 21 .2 7. 0 -3 0 16 3 22 0 65 67 15 9 < 0. 1 23 9 70 8 16 20 1. 4E -1 62 12 /0 2 21 .0 7. 0 40 15 5 21 5 63 66 13 8 < 0. 1 22 1 78 1 16 40 1. 2E -1 52 12 /0 2 20 .9 6. 9 50 15 8 21 8 64 69 14 2 < 0. 1 22 0 73 2 16 00 8. 6E -2 60 01 /0 3 21 .7 6. 8 20 16 6 21 5 65 71 15 6 3 24 7 72 3 16 50 1. 2E -1 61 03 /0 3 21 .3 7. 2 80 17 5 21 3 64 63 16 3 < 0. 1 25 0 68 6 16 20 8. 5E -2 58 04 /0 3 21 .6 6. 9 -9 0 17 0 21 1 64 69 18 1 1 26 9 67 2 16 40 6. 7E -2 56 05 /0 3 21 .5 n. m . 70 15 3 21 6 63 69 15 7 1 24 9 65 3 15 60 6. 0E -2 63 07 /0 3 21 .8 7. 0 60 15 2 21 4 61 68 15 3 < 0. 1 24 3 64 1 15 30 n. m . n. m . Si te 2 9 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C H 4 cc /l S T P C O 2 cc /l S T P T ab le A 5 (c on ti nu es o n ne xt p ag e) . 21 HYDROLOGY AND SEISMICITY ON MT. VESUVIUS 08 /0 3 21 .8 7. 0 80 14 2 20 4 62 72 14 2 0 23 5 65 3 15 10 3. 3E -2 56 09 /0 3 21 .3 6. 8 n. m . 14 0 20 7 63 69 13 3 3 23 9 62 8 14 80 1. 9E -2 66 10 /0 3 20 .9 7. 0 13 0 14 2 20 7 60 64 12 3 < 0. 1 21 1 64 7 14 50 1. 9E -2 63 11 /0 3 21 .4 7. 0 60 14 8 21 5 60 67 14 0 3 24 1 63 7 15 10 8. 6E -3 58 12 /0 3 21 .1 7. 0 30 14 6 21 3 59 69 13 4 < 0. 1 23 1 67 1 15 20 < 0. 00 1 54 01 /0 4 20 .7 6. 7 50 13 6 20 5 59 69 13 1 4 23 1 63 4 14 70 n. m . n. m . 03 /0 4 21 .0 6. 2 -3 0 14 3 20 7 59 69 12 3 4 24 2 63 7 14 90 2. 9E -2 59 04 /0 4 20 .8 7. 0 30 14 4 20 9 59 69 14 6 2 24 7 65 3 15 30 2. 9E -2 60 05 /0 4 21 .1 7. 0 40 14 3 20 4 63 75 14 4 0 23 9 64 7 15 10 2. 9E -2 59 06 /0 4 21 .3 n. m . 10 14 3 21 1 60 68 13 5 0 23 0 64 7 14 90 1. 2E -2 55 09 /0 4 20 .9 7. 0 40 14 3 21 1 60 71 14 8 0 25 7 64 1 15 30 < 0. 00 1 23 10 /0 4 20 .7 7. 1 30 13 0 20 6 50 68 10 8 0 23 9 63 7 14 40 3. 3E -1 33 11 /0 4 20 .3 6. 9 70 13 9 20 6 57 67 13 9 4 23 8 63 7 14 90 < 0. 00 1 29 12 /0 4 20 .1 7. 3 30 14 0 20 7 60 69 13 8 2 24 5 63 1 14 90 6. 6E -1 10 03 /0 5 20 .3 6. 9 70 14 0 21 1 60 63 13 2 0 23 6 60 7 14 50 3. 8E -3 39 04 /0 5 19 .5 7. 3 30 13 9 21 4 60 73 14 5 0 24 0 60 7 14 80 < 0. 00 1 17 05 /0 5 20 .8 6. 8 -2 13 6 20 4 59 70 13 3 < 0. 1 23 4 60 4 14 40 n. m . n. m . 06 /0 5 21 .1 7. 3 80 14 3 21 3 58 66 13 6 < 0. 1 24 0 60 7 14 60 2. 9E -3 23 07 /0 5 21 .1 6. 7 90 13 4 20 1 58 70 13 6 < 0. 1 24 1 58 0 14 20 3. 9E -3 14 08 /0 5 20 .5 n. m . n. m . 13 5 20 3 58 69 13 5 < 0. 1 24 1 58 0 14 20 4. 9E -3 10 10 /0 5 20 .4 n. m . n. m . 13 5 20 3 58 69 13 5 < 0. 1 24 1 58 0 14 20 n. m . n. m . 11 /0 5 18 .1 6. 9 n. m . 13 2 20 0 58 69 12 8 < 0. 1 23 7 59 2 14 20 9. 3E -3 30 12 /0 5 19 .6 7. 6 n. m . 13 9 20 4 60 71 14 0 < 0. 1 25 4 57 6 14 40 3. 6E -3 10 01 /0 6 19 .7 7. 6 n. m . 13 1 19 5 59 73 13 1 < 0. 1 24 4 57 6 14 10 2. 8E -3 12 03 /0 6 19 .5 7. 4 n. m . 13 4 19 5 56 67 13 3 < 0. 1 24 3 57 6 14 10 < 0. 00 1 20 06 /0 6 20 .2 7. 0 n. m . 13 5 20 6 61 74 13 5 < 0. 1 25 2 59 8 14 60 5. 5E -3 18 10 /0 6 19 .7 6. 9 15 0 n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . 2. 3E -2 42 02 /0 7 19 .6 n. m . n. m . 13 5 20 0 58 72 13 6 < 0. 1 24 8 57 0 14 20 2. 8E -3 25 06 /0 7 20 .4 7. 6 30 13 2 19 8 59 76 15 5 < 0. 1 23 3 57 0 14 20 3. 3E -3 14 02 /0 8 19 .6 7. 6 -1 0 12 8 19 3 58 75 16 1 < 0. 1 22 8 56 4 14 10 4. 2E -3 16 05 /0 8 19 .7 7. 6 10 0 12 4 18 7 52 69 12 4 < 0. 1 22 8 52 5 13 10 2. 8E -3 10 10 /0 8 19 .5 7. 4 70 12 0 18 1 50 64 12 0 < 0. 1 22 0 51 2 12 70 4. 0E -3 12 07 /0 9 19 .8 7. 4 80 11 2 17 7 48 62 11 2 < 0. 1 20 4 50 6 12 20 n. m . n. m . 04 /1 0 19 .7 7. 4 15 0 10 6 16 6 45 54 11 2 < 0. 1 19 7 46 7 11 50 5. 9E -3 16 07 /1 0 22 .2 7. 1 10 7 17 3 43 55 11 3 < 0. 1 19 2 45 8 11 40 7. 8E -3 24 07 /1 1 19 .3 7. 1 14 0 10 8 17 0 41 51 11 1 < 0. 1 18 0 45 1 11 10 4. 0E -3 20 Si te 2 9 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C H 4 cc /l S T P C O 2 cc /l S T P T ab le A 5 (c on ti nu ed fr om p re vi ou s pa ge ). FEDERICO ET AL. 22 5/ 98 19 .0 7. 0 -9 0 30 9 28 5 19 1 14 1 38 3 5. 8 17 3 16 50 31 40 0. 00 01 13 0 11 /9 8 19 .1 7. 0 -9 0 31 3 28 1 18 7 13 3 41 1 2. 7 16 7 16 30 31 20 0. 00 01 17 0 1/ 99 18 .4 6. 9 -9 0 30 0 26 9 17 8 12 4 44 8 0. 0 18 3 15 90 31 00 0. 30 00 14 0 3/ 99 20 .1 7. 0 -1 00 31 0 28 2 18 3 14 1 45 6 1. 2 17 8 15 90 31 40 0. 00 50 80 5/ 99 20 .2 7. 0 -1 20 28 5 27 0 16 8 13 4 39 5 0. 2 18 5 13 80 28 30 0. 00 04 13 0 10 /9 9 19 .7 7. 2 -1 10 30 3 27 7 17 5 12 8 41 2 0. 3 17 7 16 80 31 50 0. 00 30 12 0 11 /9 9 20 .7 6. 8 -9 0 29 7 27 5 18 4 15 4 37 8 0. 2 16 4 15 60 30 70 0. 04 00 23 0 3/ 00 20 .5 7. 0 -9 0 30 2 27 7 17 2 13 5 39 1 8. 7 17 7 16 20 31 50 n. m . n. m . 5/ 00 20 .4 6. 9 -8 0 31 8 28 9 18 2 14 1 40 3 1. 2 17 6 16 50 31 40 < 0. 00 01 17 0 7/ 00 19 .8 6. 8 -9 0 29 0 27 0 18 6 13 9 38 2 3. 2 17 3 15 40 29 80 < 0. 00 01 12 0 10 /0 0 18 .8 6. 7 -1 10 30 1 28 6 19 0 12 2 38 3 < 0. 1 17 6 16 50 31 10 < 0. 00 01 17 0 11 /0 0 20 .0 6. 8 -9 0 30 0 26 2 18 7 13 7 38 4 < 0. 1 17 8 17 00 31 50 n. m . n. m . 1/ 01 19 .7 6. 9 n. m . 28 8 25 6 17 7 13 2 38 3 < 0. 1 16 5 16 30 30 60 n. m . n. m . 3/ 01 19 .6 6. 8 n. m . 30 6 27 1 19 2 15 9 41 5 < 0. 1 18 5 16 50 31 50 < 0. 00 01 20 0 4/ 01 20 .6 7. 0 -9 0 29 8 26 3 18 7 12 7 41 4 2. 0 16 9 17 10 32 10 0. 05 18 0 5/ 01 20 .4 6. 8 -5 0 28 1 26 6 18 9 13 4 41 2 0. 8 20 8 15 80 30 70 < 0. 00 01 18 0 6/ 01 20 .3 6. 8 -1 0 29 1 27 8 19 9 15 1 42 3 1. 8 21 1 15 80 31 40 n. m . n. m . 7/ 01 20 .5 6. 7 -1 10 30 9 28 0 20 0 15 9 43 2 6. 7 20 0 16 90 32 80 n. m . n. m . 8/ 01 20 .7 6. 9 -7 0 28 7 28 6 20 0 13 0 38 1 7. 3 24 0 16 40 31 70 < 0. 00 01 12 0 9/ 01 19 .9 6. 8 -5 0 30 4 27 1 18 5 14 8 38 5 4. 3 17 5 16 80 31 50 < 0. 00 01 12 0 10 /0 1 19 .8 6. 8 -4 0 28 2 29 1 19 4 14 8 40 8 4. 3 23 4 15 20 30 80 < 0. 00 01 13 0 11 /0 1 19 .9 6. 7 -6 0 31 5 28 1 20 1 14 1 41 6 < 0. 1 22 1 16 90 32 60 < 0. 00 01 15 0 12 /0 1 20 .0 6. 9 -7 0 29 2 25 9 18 1 13 9 38 7 < 0. 1 18 6 16 60 31 00 n. m . n. m . 1/ 02 20 .3 6. 7 -7 0 28 5 26 3 17 9 14 0 37 3 < 0. 1 17 4 16 80 30 90 0. 01 14 0 2/ 02 19 .9 6. 8 -3 0 32 0 28 1 19 5 13 8 40 7 < 0. 1 19 0 16 80 32 10 < 0. 00 01 13 0 3/ 02 20 .1 6. 8 30 5 26 9 18 8 13 8 41 8 < 0. 1 19 9 16 80 32 00 0. 1 20 0 4/ 02 20 .0 6. 9 -8 0 29 4 27 7 18 7 14 5 37 4 < 0. 1 19 4 16 50 31 20 0. 1 21 0 5/ 02 20 .1 6. 9 -6 0 29 8 27 3 19 5 13 6 40 6 < 0. 1 20 4 17 10 32 20 < 0. 00 01 16 0 6/ 02 20 .1 6. 8 -3 0 n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . 0. 01 12 0 Si te 3 1 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C H 4 cc /l S T P C O 2 cc /l S T P T ab le A 6 (c on ti nu es o n ne xt p ag e) . 23 HYDROLOGY AND SEISMICITY ON MT. VESUVIUS 7/ 02 19 .9 6. 9 -8 0 n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . 0. 3 13 0 8/ 02 19 .9 6. 9 -8 0 n. m . n. m . n. m . n. m . n. m . n. m . n. m . 17 00 n. m . 0. 4 13 0 9/ 02 19 .5 7. 0 -8 0 31 5 26 4 17 9 12 1 37 0 < 0. 1 16 6 16 90 31 00 0. 5 14 0 10 /0 2 19 .8 6. 9 -1 10 30 5 27 8 18 2 15 3 41 3 < 0. 1 18 2 16 90 32 10 0. 15 17 0 12 /0 2 19 .7 7. 0 -9 0 31 1 26 7 18 5 12 5 33 8 < 0. 1 14 9 17 20 31 00 0. 5 15 0 12 /0 2 19 .6 7. 0 -1 10 30 6 26 6 18 1 12 0 35 5 < 0. 1 15 9 17 50 31 40 0. 3 11 0 1/ 03 19 .0 6. 8 -8 7 30 5 25 6 17 4 11 8 35 0 < 0. 1 16 0 17 60 31 30 0. 4 14 0 2/ 03 n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . 0. 4 13 0 3/ 03 19 .4 7. 0 -4 0 32 5 21 3 17 7 12 0 35 9 < 0. 1 19 8 16 40 30 40 0. 2 14 0 4/ 03 19 .8 6. 8 -9 0 29 6 27 5 18 6 12 9 39 8 3 21 5 16 70 31 70 0. 2 13 0 5/ 03 19 .6 n. m . -1 00 28 6 28 5 17 8 10 5 39 0 < 0. 1 19 8 17 00 31 40 0. 00 03 11 0 6/ 03 20 .3 n. m . -9 0 28 3 29 1 17 6 11 7 39 0 < 0. 1 20 6 17 00 31 60 < 0. 00 01 13 0 7/ 03 n. m . n. m . n. m . 30 2 29 4 19 5 12 1 36 8 < 0. 1 19 5 16 50 31 20 n. m . n. m . 8/ 03 n. m . n. m . n. m . 26 4 27 1 17 7 10 3 30 8 < 0. 1 19 0 16 20 29 30 n. m . n. m . 9/ 03 n. m . n. m . n. m . 26 5 26 7 19 1 11 0 35 8 2 17 3 15 74 29 40 0. 5 13 0 10 /0 3 n. m . n. m . n. m . 30 6 27 7 18 9 11 5 33 2 < 0. 1 14 1 16 90 30 50 n. m . n. m . 11 /0 3 n. m . n. m . n. m . 30 9 27 6 18 2 14 0 38 9 < 0. 1 17 1 17 10 31 80 0. 4 13 0 12 /0 3 n. m . n. m . n. m . 31 1 28 6 17 2 12 5 36 7 < 0. 1 16 3 16 90 31 20 0. 7 15 0 1/ 04 18 .6 7. 10 -1 70 29 6 27 2 16 8 12 2 34 5 < 0. 1 15 4 16 50 30 10 0. 6 15 0 2/ 04 n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . n. m . 0. 5 15 0 3/ 04 19 .5 7. 20 -1 30 29 8 27 9 18 0 12 9 35 5 < 0. 1 17 7 16 60 30 80 0. 4 15 0 4/ 04 19 .6 6. 80 7 29 4 26 9 17 3 12 5 36 6 9 16 3 16 00 30 00 0. 8 14 0 5/ 04 19 .4 6. 9 -1 50 29 6 26 9 17 2 11 9 41 7 < 0. 1 24 16 20 29 10 0. 6 16 0 6/ 04 19 .9 n. m . -1 10 29 3 27 2 17 5 11 9 32 5 < 0. 1 14 3 16 80 30 00 < 0. 00 01 15 0 8/ 04 n. m . n. m . n. m . 29 0 26 6 17 1 11 9 35 6 < 0. 1 15 8 16 00 29 60 0. 5 12 0 9/ 04 19 .1 7. 0 -1 80 29 5 27 3 17 2 11 5 35 6 < 0. 1 16 0 16 60 30 30 0. 6 13 0 10 /0 4 19 6. 9 -1 00 29 9 26 9 18 9 11 4 36 5 < 0. 1 16 6 16 40 30 40 0. 6 14 0 11 /0 4 19 .1 6. 9 -1 00 29 9 27 2 17 4 12 3 35 3 < 0. 1 16 7 16 90 30 70 0. 5 15 0 1/ 05 19 .1 n. m . -1 30 29 9 27 8 17 9 11 6 35 3 < 0. 1 15 8 16 50 30 30 0. 6 14 0 Si te 3 1 D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C H 4 cc /l S T P C O 2 cc /l S T P T ab le A 6 (c on ti nu ed fr om p re vi ou s pa ge ). FEDERICO ET AL. 24 5/ 98 13 .2 8. 0 11 0 50 72 22 78 36 56 52 40 0 73 0 n. m . 11 /9 8 14 .1 7. 7 18 0 52 75 20 70 37 60 57 40 0 74 0 8 1/ 99 10 .7 8. 3 60 52 74 23 65 38 61 60 35 0 69 0 7 3/ 99 9. 2 8. 2 19 0 52 75 22 63 37 60 63 32 0 66 0 4 5/ 99 12 .8 8. 0 12 0 53 73 24 79 38 58 60 34 0 69 0 7 10 /9 9 13 .7 6. 8 -1 50 55 78 24 81 38 64 64 41 0 77 0 19 11 /9 9 12 .7 8. 1 24 0 51 80 27 68 38 64 62 37 0 72 0 3 3/ 00 10 .8 8. 2 23 0 54 70 21 60 44 52 57 31 0 62 0 4 5/ 00 12 .7 7. 9 13 0 53 76 22 78 37 57 60 32 0 64 0 3 7/ 00 13 .4 7. 9 21 0 51 73 25 76 36 60 62 43 0 77 0 7 10 /0 0 13 .5 7. 7 16 0 56 78 25 72 34 56 61 41 0 76 0 7 11 /0 0 13 .3 7. 8 17 0 50 72 22 66 36 51 60 39 0 70 0 9 1/ 01 9. 3 8. 3 n. m . 52 60 20 61 32 42 48 35 0 67 0 2 3/ 01 12 .2 8. 1 n. m . 50 72 24 71 34 51 50 37 0 68 0 3 4/ 01 12 .4 8. 0 15 0 47 69 23 69 32 40 46 40 0 69 0 8 5/ 01 13 .2 7. 9 18 0 47 69 22 67 34 42 53 40 0 70 0 7 6/ 01 13 .5 8. 0 28 0 49 72 22 74 41 44 59 41 0 73 0 n. m . 7/ 01 13 .7 8. 0 14 0 54 76 23 75 37 46 53 43 0 75 0 n. m . 8/ 01 13 .8 7. 8 24 0 53 76 24 75 37 45 53 43 0 75 0 n. m . 9/ 01 13 .6 7. 9 23 0 55 76 25 74 36 49 53 43 0 77 0 5 10 /0 1 13 .8 7. 8 33 0 55 75 24 67 33 45 51 41 0 73 0 4 11 /0 1 11 .4 8. 0 43 0 54 73 22 68 36 45 53 38 0 70 0 5 12 /0 1 7. 2 7. 9 25 0 54 68 20 68 42 47 60 37 0 68 0 n. m . 01 /0 2 8. 4 7. 9 29 0 51 68 21 69 40 49 60 37 0 69 0 4 02 /0 2 9. 7 8. 2 19 0 52 69 20 64 41 43 57 38 0 69 0 n. m . 03 /0 2 9. 1 8. 1 16 0 51 71 22 66 36 38 54 36 0 66 0 3 04 /0 2 10 .7 8. 0 11 0 53 70 23 66 37 36 54 38 0 68 0 n. m . 05 /0 2 13 .2 8. 0 14 0 54 71 23 64 39 42 57 38 0 70 0 5 06 /0 2 13 .2 7. 9 17 0 56 76 23 74 44 43 56 38 0 71 0 4 07 /0 2 13 .6 7. 8 16 0 57 76 23 73 43 43 61 38 0 72 0 4 08 /0 2 13 .9 7. 9 18 0 54 75 22 69 43 46 62 39 0 72 0 6 09 /0 2 12 .5 7. 9 13 0 52 72 21 63 41 38 59 38 0 68 0 n. m . 10 /0 2 13 .6 7. 8 18 0 51 71 22 69 40 38 55 39 0 70 0 3 12 /0 2 11 .6 8. 3 11 0 57 67 21 65 35 38 52 37 0 67 0 5 12 /0 2 8. 3 8. 2 30 49 67 19 59 35 34 52 35 0 63 0 n. m . 01 /0 3 9. 7 8. 1 17 0 51 67 20 62 40 35 55 36 0 65 0 4 03 /0 3 13 .2 7. 9 18 0 58 73 21 58 39 58 60 43 0 76 0 9 04 /0 3 13 .0 7. 6 25 0 57 73 22 84 49 49 73 39 0 75 0 4 05 /0 3 13 .3 n. m . 21 0 55 74 22 87 39 45 59 44 0 78 0 4 O li ve ll a D at e (m o/ yr ) T (° C ) pH E h (m V ) N a+ (m g/ l) K + (m g/ l) M g2 + (m g/ l) C a2 + (m g/ l) C l− (m g/ l) N O 3− (m g/ l) SO 42− (m g/ l) H C O 3− (m g/ l) T D S (m g/ l) C O 2 cc /l S T P T ab le A 7 (c on ti nu es o n ne xt p ag e) . 25 HYDROLOGY AND SEISMICITY ON MT. VESUVIUS 06 /0 3 13 .7 n. m . 19 0 55 76 23 88 39 43 58 45 0 79 0 12 07 /0 3 14 .7 7. 9 17 0 55 77 22 83 41 45 62 42 0 77 0 n. m . 08 /0 3 14 .3 7. 6 10 0 52 73 23 99 38 49 58 46 0 81 0 6 09 /0 3 14 .0 7. 7 -5 0 53 76 23 89 39 44 61 44 0 79 0 5 10 /0 3 13 .8 7. 8 17 0 51 73 22 82 36 42 51 42 0 74 0 5 11 /0 3 13 .4 7. 9 21 0 52 73 22 75 36 41 52 42 0 74 0 6 12 /0 3 11 .2 7. 8 90 53 71 23 78 35 40 48 42 0 74 0 6 01 /0 4 8. 80 7. 9 20 0 49 69 23 77 37 37 46 42 0 72 0 n. m . 02 /0 4 7. 90 7. 8 19 0 47 66 22 74 35 31 45 39 0 68 0 4 03 /0 4 8. 6 7. 9 14 0 54 69 22 72 35 33 45 42 0 71 0 3 4/ 04 11 .9 7. 7 15 0 47 67 21 72 34 29 45 40 0 68 0 4 5/ 04 12 .8 7. 9 80 50 71 22 79 36 40 52 41 0 72 0 7 06 /0 4 13 .4 n. m . 11 0 49 72 22 85 36 37 55 42 0 74 0 5 08 /0 4 n. m . n. m . n. m . 50 70 23 76 35 33 54 42 0 73 0 5 09 /0 4 13 .7 7. 6 70 54 76 23 89 44 48 71 43 0 79 0 6 10 /0 4 13 .8 7. 7 70 55 79 26 94 39 37 62 47 0 83 0 6 11 /0 4 12 .9 7. 9 20 53 74 24 86 36 37 58 45 0 79 0 5 12 /0 4 12 .5 7. 8 15 0 49 70 21 67 33 30 51 39 0 68 0 5 01 /0 5 12 .5 n. m . 40 49 69 22 84 35 38 52 43 0 74 0 3 03 /0 5 12 .7 n. m . 80 44 66 23 85 29 35 40 43 0 73 0 5 04 /0 5 13 .0 7. 9 80 49 70 23 89 33 34 50 45 0 76 0 6 05 /0 5 13 .4 7. 7 40 51 73 23 92 35 37 54 46 0 79 0 n. m . 06 /0 5 13 .6 7. 7 13 0 55 76 23 92 37 39 57 46 0 80 0 6 07 /0 5 13 .8 7. 7 22 0 53 75 23 80 40 37 62 42 0 75 0 6 08 /0 5 13 .8 n. m . n. m . 55 77 24 89 40 38 63 44 0 79 0 4 09 /0 5 13 .7 n. m . n. m . 54 76 24 89 39 38 61 44 0 78 0 n. m . 10 /0 5 13 .7 n. m . n. m . 51 72 22 80 37 31 56 41 0 72 0 6 12 /0 5 12 .0 7. 8 n. m . 51 71 21 69 30 24 44 42 0 70 0 2 06 /0 6 13 .4 7. 6 n. m . 51 73 24 94 35 33 57 46 0 79 0 7 10 /0 6 13 .8 7. 8 24 0 51 73 24 94 35 33 56 46 0 79 0 7 02 /0 7 11 .1 n. m . n. m . 52 72 23 78 38 31 60 42 0 73 0 3 06 /0 7 13 .3 7. 7 20 0 52 73 24 79 36 32 64 42 0 75 0 14 02 /0 8 10 .6 8. 0 12 0 52 72 24 82 38 30 64 42 0 75 0 3 05 /0 8 12 .3 7. 5 20 0 51 70 23 85 32 26 51 42 0 73 0 6 10 /0 8 13 .4 7. 7 20 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