Verónica Antunes

Last Name

Antunes

First Name

Verónica

ORCID

0000-0002-4825-9180

Organisational unit

02818 - Schweiz. Erdbebendienst (SED) / Swiss Seismological Service (SED)

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Publications 1 - 8 of 8

Insights into the dynamics of the Nirano Mud Volcano through seismic characterization of drumbeat signals and V/H analysis
Antunes, Verónica; Planès, Thomas; Obermann, Anne; et al. (2022)
Journal of Volcanology and Geothermal Research
Mud volcanoes are rapidly-evolving geological phenomena characterized by the surface expulsion of sediments and fluids from over-pressurized underlying reservoirs. We investigate the Nirano Mud Volcano, Northern Italy, with seismic methods to better understand the dynamic evolution of the system and shed light on its subsurface structure. Our study allowed to detect and characterize three different types of high-frequency drumbeat signals that are present in the most active part of the mud volcano plumbing system. With a back-projection method based on the cross-correlation envelope of signals recorded at different station pairs, we can determine the source location of the drumbeats. These coincide with the location of V/H (vertical-to-horizontal) amplitude peaks obtained from an ambient vibration profile and resistivity anomalies identified in a previous study. We observe that the drumbeats are P-wave dominated signals, with characteristics similar to those found in magmatic settings, i.e. LPs (long-period signals). We suggest that such tremors originate from the migration of mud and gas inside the mud volcanic conduits. The source location, waveform and frequency content of the drumbeats evolve over time. We found that drumbeat occurrence is directly linked with morphological changes at surface.
Ambient-noise tomography of the Greater Geneva Basin in a geothermal exploration context
Planès, Thomas; Obermann, Anne; Antunes, Verónica; et al. (2020)
Geophysical Journal International
The Greater Geneva Basin is one of the key targets for geothermal exploration in Switzerland. Until recently, information about the subsurface structure of this region was mostly composed of well-logs, seismic reflection lines, and gravity measurements. As part of the current effort to further reduce subsurface uncertainty, and to test passive seismic methods for exploration purposes, we performed an ambient-noise tomography of the Greater Geneva Basin. We used ∼1.5 yr of continuous data collected on a temporary seismic network composed of 28 broad-band stations deployed within and around the basin. From the vertical component of the continuous noise recordings, we computed cross-correlation functions and retrieved Rayleigh-wave group-velocity dispersion curves. We then inverted the dispersion curves to obtain 2-D group-velocity maps and proceeded to a subsequent inversion step to retrieve a large-scale 3-D shear-wave velocity model of the basin. We discuss the retrieved features of the basin in the light of local geology, previously acquired geophysical data sets, and ongoing geothermal exploration. The Greater Geneva Basin is an ideal natural laboratory to test innovative geothermal exploration methods because of the substantial geophysical data sets available for comparison. While we point out the limits of ambient-noise exploration with sparse networks and current methodology, we also discuss possible ways to develop ambient-noise tomography as an affordable and efficient subsurface exploration method.
Good-Practice Guide for Managing Induced Seismicity in Deep Geothermal Energy Projects in Switzerland
Kraft, Toni; Roth, Philippe; Ritz, Vanille; et al. (2025)
The Swiss Seismological Service at ETH Zurich (SED, www.seismo.ethz.ch) wants to contribute to the sustainable and safe use of deep geothermal energy with this report on good practice in monitoring, assessment, and management of induced seismicity related to the exploitation of deep geothermal energy. The report is aimed at a range of audiences: – field operators, – regulators at the local, cantonal, or federal level, – insurance companies looking to assess the financial risk, – as well as media and the general public that wish to be informed on the topic. The report builds on the broad knowledge and experience that the SED has collected in the past years through participation in the monitoring as well as in the hazard and risk assessment for several deep geothermal projects in Switzerland. These projects include Basel (2006-today), Zurich (2010-2011), St. Gallen (2013-2021), Schlattingen (2013-2015), Geneva (2016-today), and the canton of Vaud (2019-today). In this context, the GEOBEST2020+ project, funded by the Swiss Federal Office of Energy (SFOE), is instrumental in gaining experience in seismic monitoring and induced-seismic hazard and risk assessment. The report also builds on research at the SED and at the Swiss Competence Center for Energy Research – Supply of Electricity (SCCER-SoE) and was coordinated with the international guideline development within the DEEP project. It benefits from the re- search and discussions with colleagues from other countries, such as during the Schatzalp workshops on induced seismicity in Davos in March 2015, March 2017, March 2019, and March 2025. We also profit in many parts from the TA Swiss study ‘Energy from the Earth’ (Hirschberg et al., 2015), where the SED was a major contributor.
Seismotectonics and 1-D velocity model of the Greater Geneva Basin, France-Switzerland
Antunes, Verónica; Planès, Thomas; Zahradník, Jiří; et al. (2020)
Geophysical Journal International
The Greater Geneva Basin (GGB), located in southwestern Switzerland and neighboring France, is enclosed by the rotating northwestern edge of the Alpine front and the Jura mountains chain. Recently, this basin has received increasing attention as a target for geothermal exploration. Historical and instrumental seismicity suggest that faults affecting the basin may still be active. Moderate-magnitude earthquakes have been located along the Vuache fault, a major strike-slip structure crossing the basin. Before geothermal exploration starts, it is key to evaluate the seismic rate in the region and identify possible seismogenic areas. In this context, we deployed a temporary seismic network of 20 broad-band stations (from September 2016 to January 2018) to investigate the ongoing seismic activity, its relationship with local tectonic structures, and the large-scale kinematics of the area. Our network lowered the magnitude of completeness of the permanent Swiss and French networks from 2.0 to a theoretical value of 0.5. Using a new coherence-based detector (LASSIE - particularly effective to detect microseismicity in noisy environments), we recorded scarce seismicity in the basin with local magnitudes ranging from 0.7 to 2.1 ML. No earthquakes were found in the Canton of Geneva where geothermal activities will take place. We constructed a local ’minimum 1-D P-wave velocity model’ adapted to the GGB using earthquakes from surrounding regions. We relocated the events of our catalogue obtaining deeper hypocentres compared to the locations obtained using the available regional velocity models. We also retrieved eight new focal mechanisms using a combination of polarities and waveform inversion techniques (CSPS). The stress inversion shows a pure strike-slip stress regime, which is in agreement with structural and geological data. Combining the background seismicity with our catalogue, we identified seismogenic areas offsetting the basin.
Optimising Seismic Networks for Enhanced Monitoring of Deep Geothermal Projects in Switzerland
Antunes, Verónica; Kraft, Toni; Toledo, Tania; et al. (2025)
Proceedings of the European Geothermal Congress 2025
Switzerland is investing in geothermal energy to meet its energy and climate goals and become climate-neutral by 2050. However, the potential for induced seismicity remains one of the major concerns for the safety and feasibility of these projects. To overcome this limitation, it is extremely important to design and deploy dedicated seismic networks around the geothermal sites. These networks must be sensitive enough to: 1) detect and monitor the evolution of (possible) induced seismicity; 2) achieve high location accuracy, enabling an easy distinction between natural and geothermal-induced events; and 3) provide earthquake alerts, enabling operators to operate traffic-light systems and take preventive measures before a major felt-event occurs. In this study, we propose a workflow and software package solutions to optimise and evaluate the performance of a seismic network prior to its installation. These solutions are designed to meet the minimum monitoring requirements outlined in the Good Practice Guide for Managing Induced Seismicity in Deep Geothermal Projects in Switzerland: magnitude of completeness of 1.0ML or 0.5ML (depending on the project type) and location uncertainties of 0.5 km horizontally and 2 km vertically. However, the tools can also be applied to other subsurface engineering operations where seismic monitoring is required. Our tools can help to evaluate the network detection sensitivity using the Bayesian Magnitude of Completeness (BMC) method and estimatetheoretical location uncertainties using a synthetic catalogue of events. Both methods consider the actual noise conditions at the stations. We present the network performance results obtained for the geothermal project in Geneva, Switzerland, showcasing the advances in seismic network design and the monitoring capability of our networks.
Tectonics of the Dead Sea Fault Driving the July 2018 Seismic Swarm in the Sea of Galilee (Lake Kinneret), Israel
Haddad, Antoine; Alcanie, Marion; Zahradník, Jiří; et al. (2020)
Journal of Geophysical Research: Solid Earth
Northern Israel was struck during July 2018 by a ML4.4 earthquake followed by a seismic sequence that lasted about 30 days. This seismic sequence occurred in the center of a temporary seismic network deployed around the Sea of Galilee (Lake Kinneret). The network was installed to investigate the regional kinematics of the Dead Sea Fault, which is a major transform fault running N-S for more than 1,000 km. The data allowed us to develop a local velocity model for the Sea of Galilee. We relocated more than 600 earthquakes and calculated 27 focal mechanisms pointing out a complex kinematic setting, possibly controlled by fluids at depth. The seismic sequence developed along a NNW-striking direction and it is bounded to the east by the N-striking Dead Sea fault. Hypocenter depths range between 6 and 13 km. Directions of the principal stress tensors suggest a transtentional deformation, in agreement with the overall kinematics of the region. We analyze and discuss our data set to investigate mechanisms that potentially triggered the observed seismic swarm, including exacerbated ground water pumping proposed by previous authors. We suggest that the seismic sequence is driven by the dissipation of the elastic load that accumulated in this region.
Tectonic and Anthropogenic Microseismic Activity While Drilling Toward Supercritical Conditions in the Larderello‐Travale Geothermal Field, Italy
Minetto, Riccardo; Montanari, Domenico; Planès, Thomas; et al. (2020)
Journal of Geophysical Research: Solid Earth
This study investigates the seismic activity occurring at the Larderello-Travale geothermalfield, central Italy, from June 2017 to January 2018. We deployed a network composed of nine broadbandstations around the Venelle 2 well drilling for supercritical fluids. During the experiment, we recognizetwo types of seismic events (type 1 and type 2). Type-1 events have clear P and S wave arrivals and occur inclusters both above and below the K-horizon, which is a seismic reflector marking a debated transitionzone at depth. The distribution and evolution of the seismic sequences suggest that the K-horizon could beinterpreted as a fluid-rich region at near-lithostatic pressures. Type-2 events usually occur in swarms andshow a periodic pattern, a narrow frequency band, and almost identical waveforms. Their source isestimated to be located near the well, and their occurrence ceases after about 3 weeks from the conclusionof the drilling. We propose a causal link with the drilling operations where pressure fronts inside the wellmay promote phase changes and fluid flow across the drilled formations. Our study sheds light on thefluid-driven tectonic and anthropogenic seismic activity at the Larderello-Travale geothermal field.More generally, we show that microseismic activity occurring during drilling in high-pressure andhigh-temperature conditions can remain at low magnitudes and that geothermal wells targetinggeothermal fluids in such systems may be handled safely despite the critical conditions encountered atdepth. The drilling of the Venelle 2 well is an encouraging example for the development of geothermalenergy in critical conditions.
Using waveform similarity to enhance the long-term analysis of a Swiss geothermal project
Toledo, Tania; Simon, Verena; Kraft, Toni; et al. (2025)
Proceedings of the European Geothermal Congress 2025
In July 2013, a deep geothermal project was initiated in the city of St. Gallen, Switzerland, with the aim of harnessing energy for district heating and power generation. Reservoir stimulations and well-control procedures triggered a seismic sequence, which culminated in a magnitude Mw3.3 (ML3.5) earthquake led by an uncontrolled gas release (a "gas kick"). Following the significant earthquake, the Swiss Seismological Service (SED) conducted a review to assess the extent to which operations may have contributed to the induced seismicity. In addition to automatically detected events, manually identified events were incorporated into near real-time monitoring, with delays of up to 12 hours for smaller events. Early seismicity, however, did not provide clear signs to the unexpected gas influx. Although this post-event assessment did not reveal substantial new information that could have influenced operational decisions at the time, it highlighted the need for improved near-real-time detection and analysis protocols to enhance responsiveness in future geothermal developments. In this study, we present a consistent long-term analysis of the microseismicity associated with the deep geothermal project, with the aim of identifying previously undetected events across the full seismic sequence—including pre- and post-closure periods—using a semi-automatic workflow. Using the continuous data from the most sensitive station (SGT00), we apply template matching with selected representative templates from a manually assembled catalog. We recalculate magnitudes, relocate detected events, and perform a statistical analysis of the seismicity using the in-house software QuakeMatch. Our goal is to refine the understanding of the reservoir’s response to hydraulic changes triggered by project operations and the observed gas kick, using a consistent, semi-automatic approach. More importantly, we investigate the temporal evolution of the induced seismic sequence and assess the potential for ongoing seismicity related to the terminated project, extending the analysis up to the present day.

Publications 1 - 8 of 8

Verónica Antunes

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