ALBERT

Description: Public concern about anthropogenic seismic- ity in Italy first arose in the aftermath of the deadly M ≈ 6 earthquakes that hit the Emilia-Romagna region (northern Italy) in May 2012. As these events occurred in a (tectonically active) region of oil and gas production and storage, the question was raised, whether stress perturbations due to underground industrial activities could have induced or triggered the shocks. Following expert recommendations, in 2014, the Italian Oil & Gas Safety Authority (DGS-UNMIG, Ministry of Economic Development) published guidelines (ILG - Indirizzi e linee guida per il monitoraggio della sismicità, delle deformazioni del suolo e delle pressioni di poro nell’ambito delle attività antropiche), describing regula- tions regarding hydrocarbon extraction, waste-water in- jection and gas storage that could also be adapted to other technologies, such as dams, geothermal systems, CO2 storage, and mining. The ILG describe the frame- work for the different actors involved in monitoring activities, their relationship and responsibilities, the procedure to be followed in case of variations of mon- itored parameters, the need for in-depth scientific anal- yses, the definition of different alert levels, their mean- ing and the parameters to be used to activate such alerts. Four alert levels are defined, the transition among which follows a decision to be taken jointly by relevant au- thorities and industrial operator on the basis of evalua- tion of several monitored parameters (micro-seismicity, ground deformation, pore pressure) carried on by a scientific-technical agency. Only in the case of liquid reinjection, the alert levels are automatically activated on the basis of exceedance of thresholds for earthquake magnitude and ground shaking – in what is generally known as a Traffic Light System (TLS). Istituto Nazionale di Geofisica e Vulcanologia has been charged by the Italian oil and gas safety authority (DGS- UNMIG) to apply the ILG in three test cases (two oil extraction and one gas storage plants). The ILG indeed represent a very important and positive innovation, as they constitute official guidelines to coherently regulate monitoring activity on a national scale. While pilot studies are still mostly under way, we may point out merits of the whole framework, and a few possible critical issues, requiring special care in the implementa- tion. Attention areas of adjacent reservoirs, possibly licenced to different operators, may overlap, hence mak- ing the point for joint monitoring, also in view of the possible interaction between stress changes related to the different reservoirs. The prescribed initial blank- level monitoring stage, aimed at assessing background seismicity, may lose significance in case of nearby ac- tive production. Magnitude – a critical parameter used to define a possible step-up in activation levels – has inherent uncertainty and can be evaluated using differ- ent scales. A final comment considers the fact that relevance of TLS, most frequently used in hydraulic fracturing operations, may not be high in case of trig- gered tectonic events.

Description: Published

Description: 1015–1028

Description: 1IT. Reti di monitoraggio e sorveglianza

Description: JCR Journal

Description: Mt. Amiata (Tuscany, Italy) is an extinct volcano whose last eruptive activity was dated about 200 ky ago. Today, its underlying crustal volume is still characterized by a high geothermal gradient, which makes the area particularly suitable for geothermal exploitation. Seismicity in the Tuscan Geothermal Areas is generally observed within the upper crust and is confined in depth by the so called K-horizon, a strong seismic reflector located in between 4-8 km b.s.l., often interpreted as the 400°C isotherme. The overlaying structure presents permeable layers of highly fractured volcanic rocks, saturated with hot water and steam. Geothermal exploitation from these layers started in the 1960's. Since then, shallow earthquakes have been occasionally observed close to the geothermal wells, and the question is whether these event are of natural origin or related to the exploitation of heat. To monitor the seismic activity inside the geothermal field of Mt. Amiata, we installed in 2015 a dedicated 8-station seismic network in the vicinity of the productive geothermal power plants for a 3-years recording period. The main challenges of our experiment are to automatically detect and locate the local microseismicity, trying to discriminate from natural seismicity those events caused by human operations. Due to the strong regional seismic activity of the 2016 Central Italy sequence, the automatic detection of local seismic events resulted challenging. We therefore use a waveform based detector (Lassie, developed at GFZ) to quickly scan the large dataset and automatically detect weak events in the target volume. Lassie provides preliminary event locations, which are then refined in a second step, using standard and waveform based techniques. For those hypocenters that are located close to the geothermal power plants, at a similar depth as the production level (3500 m b.s.l.), it remains very challenging to discriminate between natural and anthropogenic events.

Description: Published

Description: Seattle (WA)

Description: 4T. Sismicità dell'Italia

Description: The geothermal field of Torre Alfina is located in Central Italy, at the boundary between the regions Tuscany and Latium, at the northern extremity of the Vulsini quaternary volcanic complex. Geochemical and geophysical wells drilled in the 1970s and 1980s down to depths ranging from 563 m to 2710 m revealed that Torre Alfina is a medium- enthalpy (T = 140$\,^{\circ}$ C) geothermal field, hosted in buried fractured Mesozoic limestones. Recently a multi-national industrial company received the license for the production of geothermal energy up to a maximum of 5 MW. In 2013 the INGV was commissioned to realize a monitoring system that includes the observation of gas emissions, microseismicity and ground deformation. National guidelines published recently by the Italian Ministry of Economic Development (MISE) regulate in detail the governmental monitoring ordinances exclusively regarding the extraction of hydrocarbons and the fluid injection due to wastewater and CO2 storage but concerning geothermal energy production appropriate regulations are missing. Following the recommendations, described in the Ministerial Decree that regulates the geothermal production activity, the seismic monitoring system should be capable to record (i) the local microseismicity during the phase of geothermal energy production and (ii) the natural seismicity already 12 months before the beginning of the production operations. In 2014 we started to install a seismic network consisting of 5 short period stations within a radius of 5 km (Inner Domain) and thereafter further 5 stations inside an area with a 10 km radius (Outer Domain). The seismic noise level recorded at the single stations is unfavorably high, due to an intensive colonization and numerous settlements of small and medium industries. Transients as well as persistent monochromatic disturbances are recorded very well especially at the southern stations, probably due to a low wave energy dissipation inside the layer of quaternary volcanic rocks.

Description: Published

Description: Reno (Nevada)

Description: 1IT. Reti di monitoraggio e sorveglianza

Description: This article describes the IT infrastructure implemented by the Centre for the Monitoring of Subsoil activities to monitor the areas of competence of which, according to the provisions of the Addresses and Guidelines and following the appointment by the Ministry for Economic Development, the INGV is the Structure in charge of seismic and geodetic Monitoring. Particular attention is paid to the hardware and software infrastructure, the data formats used and their installation is described.

Description: Published

Description: 1-32

Description: 3SR TERREMOTI - Attività dei Centri

Description: N/A or not JCR