Geochemical continuous signals in seismic areas: the case of the Mugello Basin, Central Italy

2021 ◽  
Author(s):  
Lisa Pierotti ◽  
Enrica Droghieri ◽  
Gianluca Facca ◽  
Fabrizio Gherardi
Keyword(s):  
Electrical Conductivity ◽  
Seismic Risk ◽  
Central Italy ◽  
Monitoring Network ◽  
Seismic Hazard Assessment ◽  
Fault System ◽  
Monitoring Site ◽  
Regional Government ◽  
Monitoring Networks ◽  
Ground Acceleration

<p>The Mugello basin (Tuscany, Italy) is one of the areas with the highest seismic risk of Tuscany, having been subjected in the past to earthquakes up to Mw 6.38 (Rovida et al., 2020). As detailed in the seismic risk map of Italy, this region is characterized by a quite high value of the Peak Ground Acceleration index (PGA> 0.175, Stucchi et al., 2011). As a part of a seismic prevention/prediction program of the Regional Government of Tuscany, the Mugello basin was chosen, ten years ago, as a monitoring site for possible hydrogeochemical precursors of seismic activity. For this purpose, the IGG-CNR of Pisa has realized an automatic continuous monitoring station, equipped with sensors for the concurrent measurement of temperature, pH, redox potential, electrical conductivity, CO<sub>2</sub> and CH<sub>4</sub> dissolved concentration (Cioni et al., 2007). According to literature guidelines (e.g. Martinelli and Albarello, 1997), after a preliminary hydrogeochemical screening carried out on 2011, the automatic surveying station was placed in correspondence of the Postignana spring. This spring is located at an altitude of 476 m a.s.l., in correspondence to a major extensional structure, the Ronta fault system (Sani et al., 2009), held responsible for the Mw = 6.8 destructive earthquake of June 29<sup>th</sup>, 1919. With a stable temperature of 13°C and a permanent outflow of a few liters/minute (with reduced seasonal oscillations), the Postignana spring discharges low salinity waters (600 mg/l). Here we present the anomalous variations in the dissolved content of CO<sub>2</sub> and electrical conductivity recorded by the automatic station, before the Mw 4.5 Mugello earthquake occurred on December 9<sup>th</sup>, 2019.</p><p> </p><p>Cioni, R., Guidi, M., Pierotti, L., Scozzari, A., 2007. An automatic monitoring network installed in Tuscany (Italy) for studying possible geochemical precursory phenomena. Nat. Hazards Earth Syst. Sci. 7, 405–416.</p><p>Martinelli, G., Albarello, D., 1997. Main constraints for siting monitoring networks devoted to the study of earthquake related phenomena in Italy. Ann. Geophys. 40, 1505–1522.</p><p>Rovida A., Locati M., Camassi R., Lolli B., Gasperini P. (2020). The Italian earthquake catalogue CPTI15. Bull Earthq Eng, 18, 652 2953-2984. https://doi.org/10.1007/s10518-020-00818-y</p><p>Sani, F., Bonini, M., Piccardi, L., Vannucci, G., Delle Donne, D., Benvenuti, M., ... & Tanini, C. (2009). Late Pliocene–Quaternary evolution of outermost hinterland basins of the Northern Apennines (Italy), and their relevance to active tectonics. Tectonophysics, 476(1-2), 336-356.</p><p>Stucchi M., Meletti C., Montaldo V., Crowley H., Calvi G.M., Boschi E. Seismic Hazard Assessment (2003-2009) for the 686 Italian Building Code. Bulletin of the Seismological Society of America 2011, 101, 1885-1911.</p>

scholarly journals Model-driven optimization of coastal sea observatories through data assimilation in a finite element hydrodynamic model (SHYFEM v. 7_5_65)

2021 ◽  
Vol 14 (1) ◽  
pp. 645-659
Author(s):  
Christian Ferrarin ◽  
Marco Bajo ◽  
Georg Umgiesser
Keyword(s):  
Finite Element ◽  
Data Assimilation ◽  
Water Level ◽  
Tide Gauge ◽  
Monitoring Network ◽  
Monitoring Site ◽  
Square Root ◽  
Monitoring Networks ◽  
Lagoon Of Venice ◽  
Square Root Filter

Abstract. Monitoring networks aims at capturing the spatial and temporal variability of one or several environmental variables in a specific environment. The optimal placement of sensors in an ocean or coastal observatory should maximize the amount of collected information and minimize the development and operational costs for the whole monitoring network. In this study, the problem of the design and optimization of ocean monitoring networks is tackled throughout the implementation of data assimilation techniques in the Shallow water HYdrodynamic Finite Element Model (SHYFEM). Two data assimilation methods – nudging and ensemble square root filter – have been applied and tested in the Lagoon of Venice (Italy), where an extensive water level monitoring network exists. A total of 29 tide gauge stations were available, and the assimilation of the observations results in an improvement of the performance of the SHYFEM model, which went from an initial root mean square error (RMSE) on the water level of 5.8 cm to a final value of about 2.1 and 3.2 cm for each of the two data assimilation methods. In the monitoring network optimization procedure, by excluding just one tide gauge at a time and always the station that contributes less to the improvement of the RMSE, a minimum number of tide gauges can be found that still allow for a successful description of the water level variability. Both data assimilation methods allow identifying the number of stations and their distribution that correctly represent the state variable in the investigated system. However, the more advanced ensemble square root filter has the benefit of keeping a physically and mass-conservative solution of the governing equations, which results in a better reproduction of the hydrodynamics over the whole system. In the case of the Lagoon of Venice, we found that, with the help of a process-based and observation-driven numerical model, two-thirds of the monitoring network can be dismissed. In this way, if some of the stations must be decommissioned due to a lack of funding, an a priori choice can be made, and the importance of a single monitoring site can be evaluated. The developed procedure may also be applied to the continuous monitoring of other ocean variables, like sea temperature and salinity.

scholarly journals Model-driven optimization of coastal sea observatories through data assimilation in a finite element hydrodynamic model (SHYFEM v.7_5_65)

2020 ◽  
Author(s):  
Christian Ferrarin ◽  
Marco Bajo ◽  
Georg Umgiesser
Keyword(s):  
Finite Element ◽  
Data Assimilation ◽  
Water Level ◽  
Tide Gauge ◽  
Monitoring Network ◽  
Monitoring Site ◽  
Square Root ◽  
Monitoring Networks ◽  
Lagoon Of Venice ◽  
Square Root Filter

Abstract. Monitoring networks aims at capturing the spatial and temporal variability of one or several environmental variables in a specific environment. The optimal placement of sensors in an ocean or coastal observatory should maximize the amount of collected information and minimize the development and operational costs for the whole monitoring network. In this study, the problem of the design and optimization of ocean monitoring networks is tackled throughout the implementation of data assimilation techniques in the Shallow water Hydrodynamic Finite Element Model (SHYFEM). Two data assimilation methods – Nudging and Ensemble Square Root Filter – have been applied and tested in the Lagoon of Venice (Italy), where an extensive water level monitoring network exists. A total of 29 tide gauge stations were available and the assimilation of the observations result in an improvement of the performance of the SHYFEM model that went from an initial root mean square error (RMSE) on the water level of 5.8 cm to a final value of about 2.1 and 3.2 cm for the two data assimilation methods, respectively. In the monitoring network optimization procedure, by excluding just one tide gauge at a time, and always the station that contributes less to the improvement of the RMSE, a minimum number of tide gauges can be found that still allow for a successful description of the water level variability. Both data assimilation methods allow identifying the number of stations and their distribution that correctly represent the state variable in the investigated system. However, the more advanced Ensemble Square Root Filter has the benefit of keeping a physically and mass conservative solution of the governing equations, which results in a better reproduction of the hydrodynamics over the whole system. In the case of the Lagoon of Venice, we found that, with the help of a process-based and observation-driven numerical model, two-thirds of the monitoring network can be dismissed. In this way, if some of the stations must be decommissioned due to a lack of funding, an a-priori choice can be made, and the importance of the single monitoring site can be evaluated. The developed procedure may also be applied to the continuous monitoring of other ocean variables, like sea temperature and salinity.

On the importance of fault modelling for seismic risk estimate

2020 ◽  
Author(s):  
Oona Scotti ◽  
Francesco Visini ◽  
Lucilla Benedetti ◽  
Paolo Boncio ◽  
Joanna Faure Wlaker ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Earthquake Engineering ◽  
Seismic Risk ◽  
Fragility Curves ◽  
Central Italy ◽  
Active Faults ◽  
Fault System ◽  
Masonry Building ◽  
Slip Rates ◽  
Italian Law

<p>In Central Italy more than 393 thousands people live in villages and towns located at less than 5 km distance from a known, mapped, active fault, capable of generating Mw>6 earthquake. Improving seismic risk estimates in such places requires the use of (i) informative databases of active faults and (ii) the implementation of appropriate building-codes. <br>The current level of knowledge regarding activity of active faults in Central Italy has been stored in a recently compiled database (160 slip rates estimates for 88 faults). Given the complex nature of fault ruptures, we adopted a multi-fault rupture approach (SHERIFS) that accounts for both individual ruptures and multi-fault complex ruptures, involving more than one seismogenic fault section. Our earthquake rupture forecast model includes 1249 possible combinations of fault ruptures with lengths ranging from 7 to 42 km. Slip rates and associated errors are used to estimate recurrences of the ruptures assuming a  Gutenberg-Richter frequency-magnitudedistribution. The computed distribution is validated against the CPTI15 catalogue.<br>The multi-fault model approach and a seismogenic area approach are used to estimate damages based on published typological fragility curves for typical building classes derived from 30 years of data in Italy (Rota et al., 2006) assuming earthquake occurrence for the faults follows a Poisson time-independent process. Two fragility curves are considered here: one for reinforced concrete designed according to seismic regulations and one for masonry with irregular layout and without tie rods and tie beams, a typical typology for the region. Expected levels of damage for 150 villages and towns in Central Italy are computed for all damage states considering a 50 years risk target period. <br>Results obtained with the fault approach show a much higher variability of the estimated risk depending on the location of the village/town w.r.t. the fault system and the hanging-wall/footwall location. The probability of collapse in 50 years for a typical masonry building ranges between 0.01 and 0.07 in the fault approach and 0.01 and 0.04 for the area approach. For both approaches, the probability of collapse for reinforced concrete buildings is ~90 % less than that for typical masonry structures. Even if this can be considered obvious, it must be underlined that most buildings in Italy were built before 1975 (before the first applicative decree of the seismic Italian law No. 64 of 1974). Thanks to the availability of the detailed database of active faults a strategy to prioritize resources for seismic risk reduction could be adopted.<br> <br>Rota, M., Penna, A. & Strobbia, C. (2006). Typological fragility curves from Italian earthquake damage data. First European Conference on Earthquake Engineering and Seismology Geneva, Switzerland, 3-8 September 2006 Paper Number: 386</p>

DEVELOPMENT OF INTEGRATED MONITORING NETWORK FOR MEASURING SALINITY OF SEA WATER

2018 ◽  
pp. 18-26
Author(s):  
Sima Ajdar qizi Askerova
Keyword(s):  
Surface Waters ◽  
Sea Water ◽  
Water Environment ◽  
Monitoring Network ◽  
Monitoring Networks ◽  
The Caspian Sea ◽  
Integrated Monitoring ◽  
Ecological Control ◽  
Different Depths ◽  
Optimal Construction

Monitoring of sea water condition is one of major requirements for carrying out the reliable ecological control of water environment. Monitoring networks contain such elements as sea buoys, beacons, etc. and are designated for measuringvarious hydrophysical parameters, including salinity of sea water. Development of specialized network and a separate buoy system for measuring thesea water salinity at different depths makes it possible to determine major regularities of processes of pollution and self-recovery of the sea waters. The article describes the scientific and methodological basics for development of this specialized network and questions of its optimal construction. It is well-known that at a depth of 30-45 m of the Caspian Sea salinity decreases and then at a depth of 45-60 m salinity is fully recovered. The mentioned changes of salinity at the relatively upper layer of sea waters is of special interest for studying the effect of ocean-going processes on the climate forming in the Caspian area. In terms of informativeness of measurements of surface waters salinity, the most informative is a layer ata 30-60 m depth, where inversion and recovery of salinity take place. It is shown that in most informative subrange of measurements, i. e. at a depth of 30-60 m optimization of regime of measurements complex should be carried out in order to increase the effectiveness of held researches. It is shown that at a depth of 35-50 m choice of the optimum regime of measurements makes it possible to obtain the maximum amount of information.

scholarly journals The Role of Faults in Groundwater Circulation before and after Seismic Events: Insights from Tracers, Water Isotopes and Geochemistry

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1499
Author(s):  
Davide Fronzi ◽  
Francesco Mirabella ◽  
Carlo Cardellini ◽  
Stefano Caliro ◽  
Stefano Palpacelli ◽  
...  
Keyword(s):  
Preferential Flow ◽  
Central Italy ◽  
Tracer Tests ◽  
Integrated Approach ◽  
Fault System ◽  
Tectonic Structures ◽  
Fault Systems ◽  
Isotopic Analyses ◽  
Before And After

The interaction between fluids and tectonic structures such as fault systems is a much-discussed issue. Many scientific works are aimed at understanding what the role of fault systems in the displacement of deep fluids is, by investigating the interaction between the upper mantle, the lower crustal portion and the upraising of gasses carried by liquids. Many other scientific works try to explore the interaction between the recharge processes, i.e., precipitation, and the fault zones, aiming to recognize the function of the abovementioned structures and their capability to direct groundwater flow towards preferential drainage areas. Understanding the role of faults in the recharge processes of punctual and linear springs, meant as gaining streams, is a key point in hydrogeology, as it is known that faults can act either as flow barriers or as preferential flow paths. In this work an investigation of a fault system located in the Nera River catchment (Italy), based on geo-structural investigations, tracer tests, geochemical and isotopic recharge modelling, allows to identify the role of the normal fault system before and after the 2016–2017 central Italy seismic sequence (Mmax = 6.5). The outcome was achieved by an integrated approach consisting of a structural geology field work, combined with GIS-based analysis, and of a hydrogeological investigation based on artificial tracer tests and geochemical and isotopic analyses.

scholarly journals Seismic Hazard Assessment for the Tianshui Urban Area, Gansu Province, China

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Zhenming Wang ◽  
David T. Butler ◽  
Edward W. Woolery ◽  
Lanmin Wang
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Design ◽  
Hazard Analysis ◽  
Seismic Hazard Assessment ◽  
Gansu Province ◽  
Mitigation Measures ◽  
Peak Ground Velocity ◽  
Ground Acceleration ◽  
Acceleration Time Histories

A scenario seismic hazard analysis was performed for the city of Tianshui. The scenario hazard analysis utilized the best available geologic and seismological information as well as composite source model (i.e., ground motion simulation) to derive ground motion hazards in terms of acceleration time histories, peak values (e.g., peak ground acceleration and peak ground velocity), and response spectra. This study confirms that Tianshui is facing significant seismic hazard, and certain mitigation measures, such as better seismic design for buildings and other structures, should be developed and implemented. This study shows that PGA of 0.3 g (equivalent to Chinese intensity VIII) should be considered for seismic design of general building and PGA of 0.4 g (equivalent to Chinese intensity IX) for seismic design of critical facility in Tianshui.

National Park Service geologic type section inventory: Mojave Desert Inventory & Monitoring Network

2021 ◽  
Author(s):  
Tim Henderson ◽  
Vincent Santucci ◽  
Tim Connors ◽  
Justin Tweet
Keyword(s):  
Mojave Desert ◽  
National Park ◽  
National Park Service ◽  
Monitoring Network ◽  
Geographic Area ◽  
Support Network ◽  
Monitoring Networks ◽  
The Public ◽  
Type Section ◽  
Park Service

A fundamental responsibility of the National Park Service (NPS) is to ensure that park resources are preserved, protected, and managed in consideration of the resources themselves and for the benefit and enjoyment by the public. Through the inventory, monitoring, and study of park resources, we gain a greater understanding of the scope, significance, distribution, and management issues associated with these resources and their use. This baseline of natural resource information is available to inform park managers, scientists, stakeholders, and the public about the conditions of these resources and the factors or activities that may threaten or influence their stability and preservation. There are several different categories of geologic or stratigraphic units (supergroup, group, formation, member, bed) that represent a hierarchical system of classification. The mapping of stratigraphic units involves the evaluation of lithologies, bedding properties, thickness, geographic distribution, and other factors. Mappable geologic units may be described and named through a rigorously defined process that is standardized and codified by the professional geologic community (North American Commission on Stratigraphic Nomenclature 2005). In most instances when a new geologic unit such as a formation is described and named in the scientific literature, a specific and well-exposed section or exposure area of the unit is designated as the type section or other category of stratotype (see “Definitions” below). The type section is an important reference exposure for a named geologic unit which presents a relatively complete and representative example for this unit. Geologic stratotypes are important both historically and scientifically, and should be available for other researchers to evaluate in the future.. The inventory of all geologic stratotypes throughout the 423 units of the NPS is an important effort in documenting these locations in order that NPS staff recognize and protect these areas for future studies. The focus adopted for completing the baseline inventories throughout the NPS was centered on the 32 inventory and monitoring networks (I&M) established during the late 1990s. The I&M networks are clusters of parks within a defined geographic area based on the ecoregions of North America (Fenneman 1946; Bailey 1976; Omernik 1987). These networks share similar physical resources (e.g., geology, hydrology, climate), biological resources (e.g., flora, fauna), and ecological characteristics. Specialists familiar with the resources and ecological parameters of the network, and associated parks, work with park staff to support network-level activities such as inventory, monitoring, research, and data management. Adopting a network-based approach to inventories worked well when the NPS undertook paleontological resource inventories for the 32 I&M networks. The planning team from the NPS Geologic Resources Division who proposed and designed this inventory selected the Greater Yellowstone Inventory & Monitoring Network (GRYN) as the pilot network for initiating this project. Through the research undertaken to identify the geologic stratotypes within the parks of the GRYN methodologies for data mining and reporting on these resources were established. Methodologies and reporting adopted for the GRYN have been used in the development of this report for the Mojave Desert Inventory & Monitoring Network (MOJN). The goal of this project is to consolidate information pertaining to geologic type sections that occur within NPS-administered areas, in order that this information is available throughout the NPS to inform park managers and to promote the preservation and protection of these important geologic landmarks and geologic heritage resources. The review of stratotype occurrences for the MOJN shows there are currently no designated stratotypes for Joshua Tree National Park (JOTR) or Manzanar National Historic Site (MANZ); Death Valley...

Geostatistical screening of flood events in the groundwater levels of the diverted inner delta of the Danube River: implications for river bed clogging

2018 ◽  
Vol 10 (1) ◽  
pp. 64-78 ◽  
Author(s):  
Balázs Trásy ◽  
Tamás Garamhegyi ◽  
Péter Laczkó-Dobos ◽  
József Kovács ◽  
István Gábor Hatvani
Keyword(s):  
Spatial Autocorrelation ◽  
Groundwater Monitoring ◽  
Shallow Groundwater ◽  
Monitoring Network ◽  
Danube River ◽  
Monitoring Networks ◽  
Flood Events ◽  
Raw Data ◽  
Monitoring Wells ◽  
Autocorrelation Structure

Abstract The efficient operation of shallow groundwater (SGW) monitoring networks is crucial to water supply, in-land water protection, agriculture and nature conservation. In the present study, the spatial representativity of such a monitoring network in an area that has been thoroughly impacted by anthropogenic activity (river diversion/damming) is assessed, namely the Szigetköz adjacent to the River Danube. The main aims were to assess the spatial representativity of the SGW monitoring network in different discharge scenarios, and investigate the directional characteristics of this representativity, i.e. establish whether geostatistical anisotropy is present, and investigate how this changes with flooding. After the subtraction of a spatial trend from the time series of 85 shallow groundwater monitoring wells tracking flood events from 2006, 2009 and 2013, variography was conducted on the residuals, and the degree of anisotropy was assessed to explore the spatial autocorrelation structure of the network. Since the raw data proved to be insufficient, an interpolated grid was derived, and the final results were scaled to be representative of the original raw data. It was found that during floods the main direction of the spatial variance of the shallow groundwater monitoring wells alters, from perpendicular to the river to parallel with it for over a period of about two week. However, witht the passing of the flood, this returns to its original orientation in ~2 months. It is likely that this process is related first to the fast removal of clogged riverbed strata by the flood, then to their slower replacement. In addition, the study highlights the importance of assessing the direction of the spatial autocorrelation structure of shallow groundwater monitoring networks, especially if the aim is to derive interpolated maps for the further investigation or modeling of flow.

scholarly journals Geological monitoring networks for risk management close to large rock cliffs: the case history of Gallivaggio and Cataeggio in the italian Alps

2021 ◽  
Vol 76 (1) ◽  
pp. 85-101
Author(s):  
Luca Dei Cas ◽  
Maria Luisa Pastore ◽  
Andrea Pavan ◽  
Nicola Petrella
Keyword(s):  
Early Warning ◽  
Rock Slope ◽  
Monitoring Network ◽  
Monitoring Networks ◽  
Italian Alps ◽  
Synthetic Aperture Radar Interferometry ◽  
Reliable Monitoring ◽  
Critical Issues ◽  
History Of ◽  
Short Time

Abstract. In areas located near large rock cliffs, risk reduction by early warning monitoring systems highligts potentiality but also critical issues and limits. The paper examines two rock slope failures that occurred in a short time from each other near inhabited areas in the Italian Alps. The viscous behavior of the rock mass was reconstructed through data processing from ground-based Synthetic Aperture Radar Interferometry (InSAR), and elaboration of acceleration and speed curves. Landslides types and underlying complexity associated with rock detachment mechanisms suggest the identification of precautionary alarm thresholds for collapse forecasting. The analysis of financial outlay, both for mitigation works and for monitoring activities, highlight the adequacy and the opportunity to combine passive systems, like embankments or rockfall drapery meshes, with a reliable monitoring network for early warning.

scholarly journals Seismic hazard of Northern Eurasia

1999 ◽  
Vol 42 (6) ◽  
Author(s):  
V. I. Ulomov ◽  
. The GSHAP Region Working Group
Keyword(s):  
Seismic Hazard ◽  
Strong Motion ◽  
Seismic Hazard Assessment ◽  
Exceedance Probability ◽  
Hazard Mapping ◽  
Northern Eurasia ◽  
Ground Acceleration ◽  
Border Regions ◽  
Seismic Catalogue ◽  
Close Cooperation

The GSHAP Regional Centre in Moscow, UIPE, has coordinated the seismic hazard mapping for the whole territory of the former U.S.S.R. and border regions. A five-year program was conducted to assemble for the whole area, subdivided in five overlapping blocks, the unified seismic catalogue with uniform magnitude, the strong motion databank and the seismic zones model (lineament-domain-source), which form the basis of a newly developed deterministic-probabilistic computation of seismic hazard assessment. The work was conducted in close cooperation with border regions and GSHAP regional centers. The hazard was originally computed in terms of expected MSK intensity and then transformed into expected peak ground acceleration with 10% exceedance probability in 50 years.

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