Report Secondo Anno Agostini Laura

Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014
TITOLO TESI
Thermal anomalies of the Verona Province and sustainable uses of hot water resources
Ph.D. candidate: LAURA AGOSTINI, Geoscienze course
Tutor: Prof. ANTONIO GALGARO
Cycle: XVIII
Abstract
In the present year non-invasive microtremor survey is applied for the preliminary characterization of Caldiero thermal district,
in the eastern Po Plain (Italy), a thermal resource known since the Roman times for the presence of warm springs. The purpose
of work was to try out the possibility of the microtremor passive technique for the preliminary characterization of a thermal
basin, in terms of resonance properties between the alluvial deposit covers and the rocky bedrock with 103 HVSR single
station measurements collected and analyzed in the studied area. HVSR information is integrated with the data relative to 21
deep wells. At the same time, after having contacted the management company of the thermal areas, it is possible to lead a
water sampling campaign, supported by C.N.R. of Pisa, work in progress. The HVSR technique together with other
geophysical surveys and more detailed analysis of the cold waters in Lessini Mountains and hot of the Lake Garda area and
plain, will allow significant knowledge of the territory. In particular chemical and isotope analisys and hydrogeology research
are providing important information regarding the basin water recharge spas, travel times and routes taken by these
underground waters in the Verona area.
Second-year activity
Introduction
The preliminary research allowed to define areas of thermal springs divided into four main districts
including Sirmione area. Now it is possible to distinguish "hot areas" characterized by homogeneous
geological conditions, instead the chemical and isotopic study is in progress. In this year I favoured, in
particular, Caldiero area, being an ancient area of thermal tradition.
In the report I will describe in a first step the geological and geophysical research and the geochemical
research in a second step, dividing the study in thermal districts.
Method used in the first district and results: geological and geophysical research
The first district is focused mainly in the neighbourhood of Caldiero, but also brings together the towns of
Belfiore, Colognola ai Colli, Lavagno, S. Martino Buon Albergo, S. Bonifacio, Zevio, Ronco all'Adige
and Arcole. These thermal wells have not been studied in detail due to time constraints.
After analyzing the geology of the area with a geological relief and controlled the stratigraphic wells
present in the territory, a 103 HVSR single station measurements were collected. I use the HVSR
technique (also known as Nakamura’s technique; Nakamura 1989) because it consists in the passive
recording of natural microtremors (seismic noise) by the use of three component broad band receivers.
The tool is a tromograph (Tromino of Micromed Company). The method aims to identify the subsoil
resonance frequency Fo, assumed as the maximum peak of the ratio between the horizontal and vertical
components of motion (Field and Jacob 1993). HVSR technique proved to be an efficient tool for
estimating the fundamental frequency response Fo of soft deposits, e.g. bedrock and sediments (Field and
Jacob 1995).
The measurements, after to be were calibrated on the stratigraphy of 21 of 125 wells tested, enable us to
define the deep of bedrock and fractured rock. The final result is a bedrock map. It is possible to see in the
figure of left, figure 1. In fact, bedrock depth estimation, in previous studies, is in very good agreement
with the HVSR results. In the right it can be seen as resonance frequency values decrease toward south
direction as attended due to the deepening of the bedrock. The abrupt difference in resonance frequency
behavior seems in good correlation with the fault system of the area (figure 2).
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Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014
Fig.1- Correlation between F0 and quaternary cover
Fig.2- Correlation between resonance frequency and faults
Geological and Hydrogeological Studies in other districts
The second district, based on its hydrogeological conditions, includes the towns of Sant'Ambrogio of
V.lla, where I started a study with HVSR method similar to Caldiero that I have not yet finished, San
Pietro in Cariano, Pescantina. The third district is to the western, where there are warm water wells in the
moraines of the municipalities of Pastrengo, Lazise, Bardolino, Peschiera and Castelnuovo. Sirmione is
the fourth district outside the province of Verona. Every district has different temperatures and different
geological conditions as it has been shown in previous studies (Berlusconi and al. 2013; Castellaccio and
Zorzin 2012). We can see, for example, that the temperature of groundwater is decreasing from west
(68°C measured in Sirmione well) to the east (42°C- Sant’Ambrogio of V.lla well and about 30°C in
Caldiero well).
Geochemical research: Collected samples and laboratory analysis
In all districts, during this year, were collected 47 samples, 37 samples of waters of cold springs in
Lessini mountains, 9 samples of hot waters wells and 1 sample of lake Garda’s water for chemical and
isotopic analysis in CNR-Pisa during November month. Some parameters were measured on site using a
multiparametric probe.
The hydrochemical surveys on the stable isotopes of Caldiero oxygen thermal waters, previously obtained
by Sighinolfi and al. 1982, present at an altitude of 1,000 ÷ 1,500 m, the approximate altitude of
infiltration of storm water recharge. This result will be verified with further isotopic analysis, however
crossing the isotopic data with the geological and structural framework of the Verona-Trento area,
appears likely that the recharge area of the "geothermal reservoir" uniting the northern portions of
Lessinia and Monte Baldo, to include the Small Dolomites mountain range and probably the area which
continues further north towards Trento, how it necessary to consider. This situation would testify, on one
hand the vast extent of the hydrothermal system and, secondly, the existence of complex hydrogeological
phenomena. Finally another consideration, but by no means less important which should be defined, will
be the travel time of these waters.
Chemical waters’ analysis are going to complete in C.N.R. of Pisa and then we could choose more
appropriate samples respect e.g. latitude values of temperature, precipitation and rocks’ typologies
crossed. In the Laboratories of the C.N.R. the investigated isotopes will be: oxygen, deuterium, strontium,
tritium and perhaps others isotopes.
Program next year
It is also interesting that, in a research of Insubria University and CNR IAMC Napoli, a
morphobathymetric map of Punta San Vigilio-Sirmione shows a lot of pockmarks in the depth.
Over the coming months we will take water and gas samples from these pockmarks, with a contribute of
Coast Guard of the Lake Garda, to see if they match with the emergence of hot water from the Bojola
spring into the Lake Garda near Sirmione.
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Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014
In this campaign of investigation will be involved researchers and professors at the University of Insubria
and Naples who kindly help us to complete what they had started with the study of morfotettonic in this
area (Berlusconi and al. 2013; Sileo and al. 2008) and could give a positive contribution to the study of
the geochemical research.
Fig.3- In figure a pockmarks in evidence (by dott. Violante CNR IAMC Napoli)
Fig.4- Sirmione and Punta San Vigilio area
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Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014
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Scuola di Dottorato in Scienze della Terra,
Dipartimento di Geoscienze, Università degli Studi di Padova – A.A. 2013-2014
SUMMARY OF ACTIVITY IN THIS YEAR
Courses:
F.GHERARDI, G.MAGRI, M.PENNISI:”Corso di Idrogeologia Isotopica”, Centro Nazionale Ricerche di Pisa
M.FLORIS: “Corso Gis Base e Avanzato”, Dipartimento di Geoscienze, Università degli Studi di Padova
G.DE RUBEIS:”ArcGis Online: le soluzioni Gis sul Web a disposizione di tutti” C.I.R.GEO, Università di Padova
Communications:
No communications
Posters:
“GEOTHERMALISM IN THE PROVINCE OF VERONA Lake Garda and Verona Province case studies” S.G.I. 10-12sept
2014 Milano Laura Agostini Department of Geosciences – University of Padua, Padua (Italy), Collareda M., Castellaccio E. ,
Dal Degan D. Geologists of Vicenza (Italy) and Verona , Antonio Galgaro , Jacopo Boaga, Institute for Geosciences and Earth
Resources, IGG-CNR Padua, Italy
“AN ACQUEDUCT FOR GUARANI” S.G.I. Milano 10-12sept 2014 Milano
P. Brutti Environmental Engineer of Verona; L. Agostini Department of Geosciences – University of Padua; E. Agnelli
Architect, Free Professional of Verona; M. Righetti, Associate Professor - D.I.C.A.M. , University of Trento; Rocio Dosserich
Pastoral Social Caritas Camiri, Camiri, Bolivia, Stefania Croce Caritas of Verona
Publications:
Agostini L., Boaga J. , Galgaro A., Ninfo A. “HVSR technique in near surface thermal-basin characterization: the example of
the Caldiero district (North-East Italy)” 2014 Envir. Earth Sc. - Resubmitted after revision under review
Brutti P., Agostini L., Agnelli E., Architect, Righetti M., Dosserich R., Croce S. “An Acqueduct For Guarani” 2014 Rend.
Online Soc. Geol. It., Suppl. n. 1 al Vol. 31, p.552
Agostini L., Collareda M., Castellaccio E. , Dal Degan D., Galgaro A., Boaga J. “Geothermalism In The Province of Verona.
Lake Garda and Verona Province case studies” 2014 Rend. Online Soc. Geol. It., Suppl. n. 1 al Vol. 31, p.568
Teaching activities:
Teaching assistant: 2 hours, “Corso di geotermia”, Laurea di secondo livello in Scienze Geologiche (A.A. 2013/14).
Other:
Workshop: “La geotermia a bassa entalpia: studi, normative, applicazioni: programma IPA Adriatico Progetto Legend”,
Dipartimento Difesa del Suolo e Foreste – Sezione Geologia e Georisorse della Regione del Veneto - 29 maggio 2014 Rovigo
Workshop: “La Geotermia a bassa entalpia: esperienze a confronto”, Dipartimento Difesa del Suolo e Foreste – Sezione
Geologia e Georisorse della Regione del Veneto - 26 giugno 2014 Venezia
Workshop:”Ricerca di Idrocarburi e gestione del gas metano in Pianura Padana: aspetti di rischio sismico e criticità energetiche
e ammministrative”, Dipartimento di Ingegneria, Università di Brescia - 7 maggio Brescia
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