Stefan Wiemer

Last Name

Wiemer

First Name

Stefan

ORCID

0000-0002-4919-3283

Organisational unit

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

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Publications 1 - 10 of 227

Harnessing the potential of digital twins in seismology
Dal Zilio, Luca; Giardini, Domenico; Carbonell, Ramon; et al. (2023)
Nature Reviews Earth & Environment
Digital twins - virtual replicas of natural systems - are emerging as promising tools for assessing seismic hazard and for aiding disaster decision-making and earthquake rapid response. However, to truly harness their potential, the challenges of exascale computing must be tackled to create systems that are capable of adapting to ever-evolving earthquake dynamics.
The role of three-dimensional fault interactions in creating complex seismic sequences
Yin, Yifan; Galvez, Percy; Heimisson, Elías Rafn; et al. (2023)
Earth and Planetary Science Letters
A physics-based earthquake simulator should reproduce first-order empirical power-law behaviors of magnitudes and clustering. These laws have emerged spontaneously in either discrete or low-dimension continuum simulations without power-law or stochastic heterogeneity. We show that the same emergence can occur in 3-D continuum simulations with fault interactions and rate-and-state friction. Our model approximates a strike-slip fault system as three en echelon faults. Simulations show spatio-temporally clustered earthquake sequences exhibiting characteristic Gutenberg-Richter scaling as well as empirical inter-event time distribution. The Gutenberg-Richter scaling occurs only in partial ruptures that result from fault interactions. With fault interactions, partial ruptures emerge when seismogenic width W over characteristic nucleation length L∞ is larger than 16.24, but none occur without fault interaction. The mainshock recurrence times of individual faults remain quasi-periodic. The system mainshock recurrence time is a combination of short-term Omori-type decay and Brownian passage time. Higher W/L∞ increase short-term clustering probability to at most 30%. These results indicate that physics-based multi-cycle models adequately reflect observed statistical signatures and show practical potential for long-term hazard assessment and medium-term forecasting.
Variability of Seismicity Rates and Maximum Magnitude for Adjacent Hydraulic Stimulations
Kwiatek, Grzegorz; Grigoratos, Iason; Wiemer, Stefan (2025)
Seismological Research Letters
We hindcasted the seismicity rates and the next largest earthquake magnitude using seismic and hydraulic data from two hydraulic stimulation campaigns carried out in adjacent (500 m apart) ultra‐deep wells in Finland. The two campaigns performed in 2018 and 2020 took place in the frame of the St1 Helsinki project producing stable, pressure‐controlled induced seismic activity with the maximum magnitudes of 1.7 and 1.2, respectively. The seismicity rates were modeled using simplified physics‐based approaches tailored to varying injection rates. This is the first time that this framework was applied to a cyclical injection protocol. The next largest earthquake magnitude was estimated using several existing models from the literature. Despite the close proximity of the two hydraulic stimulations and associated seismicity, we obtained strongly different parameterizations of the critical model components, questioning the usefulness of a priori seismic hazard modeling parameters for neighboring stimulation. The differences in parameterization were attributed to the contrasting hydraulic energy rates observed in each stimulation, small differences in the fracture network characteristics of the reservoir and resulting seismic injection efficiency, and potentially to variations in the injection protocol itself. As far as the seismicity rate model is concerned, despite a good performance during the 2018 campaign, the fit during the 2020 stimulation was suboptimal. Forecasting the next largest magnitude using different models led to a very wide range of outcomes. Moreover, their relative ranking across stimulations was inconsistent, including the situation when the best‐performing model in the 2018 stimulation turned out to be the worst one in the 2020 stimulation.
Fault hydromechanical characterization and CO2-saturated water injection at the CS-D experiment (Mont Terri Rock Laboratory)
Wenning, Quinn; Rinaldi, Antonio Pio; Zappone, Alba; et al. (2020)
EGUsphere
Geophysical characterization of the in-situ CO2 mineral storage pilot site in Helguvik, Iceland
Junker, Jonas; Obermann, Anne; Voigt, Martin; et al. (2025)
International Journal of Greenhouse Gas Control
In-situ CO2 mineral storage is moving into focus as a technology for storing substantial amounts of CO2 that would otherwise be released into the atmosphere. However, one of the main drawbacks of this technology is that it requires large amounts of freshwater for injection. To overcome this obstacle, a pilot project in Helguvik, Iceland is testing the effectiveness of carbon mineralization using saline water, similar to seawater. Here, we describe the project and the geophysical characterization of the pilot site using crosshole seismic- and single-hole electrical resistivity measurements. The data show that the subsurface strata are dominated by decameter-thick horizontal layers of basaltic strata, with varying seismic velocities and electrical resistivities. Variations in both seismic velocity and electrical resistivity are in excellent agreement and delineate high and low porosity zones in the subsurface. The results are compared to well logging results and the mineralogical composition of drill cuttings to build a comprehensive subsurface model of the future CO2 mineral storage reservoir, highlighting potential pathways for the injected CO2-charged waters.
Effects of Energy Dissipation on Precursory Seismicity During Earthquake Preparation
Bianchi, Patrick; Selvadurai, Paul Antony; Dal Zilio, Luca; et al. (2024)
Seismica
The b-value of the magnitude distribution of natural earthquakes appears to be closely influenced by the faulting style. We investigate this in the laboratory for the first time by analyzing the moment tensor solutions of acoustic emissions detected during a triaxial compression test on Berea sandstone. We observe systematic patterns showing that faulting style influences the b-value and differential stress. Similar trends are observed in a complementary physics-based numerical model that captures mechanical energy dissipation. Both the differential stress and dissipation are found to be inversely correlated to the b-value. The results indicate that, at late stages of the test, the dissipation increases and is linked to a change in AE faulting style and drop in b-value. The patterns observed in the laboratory Frohlich diagrams could be explained by the integrated earthquake model: damaged rock regions form as microcracks coalesce, leading to strain localization and runaway deformation. The modeling results also align with the micromechanics responsible for dissipation at various stages of the experiment and agrees with moment tensor solutions and petrographic investigations. The integration of physics-based models that can capture dissipative processes of the earthquake cycle could assist researchers in constraining seismic hazard in both natural and anthropogenic settings.
Corrigendum to “Hydraulic stimulation and fluid circulation experiments in underground laboratories: Stepping up the scale towards engineered geothermal systems” by Gischig et al. https://doi.org/10.1016/j.gete.2019.100175
Gischig, Valentin S.; Giardini, Domenico; Amann, Florian; et al. (2020)
Geomechanics for Energy and the Environment
On the physics-based processes behind production-induced seismicity in natural gas fields
Zbinden, Dominik; Rinaldi, Antonio Pio; Urpi, Luca; et al. (2017)
Journal of Geophysical Research: Solid Earth
Induced seismicity due to natural gas production is observed at different sites worldwide. Common understanding states that the pressure drop caused by gas production leads to compaction, which affects the stress field in the reservoir and the surrounding rock formations and hence reactivates preexisting faults and induces earthquakes. In this study, we show that the multiphase fluid flow involved in natural gas extraction activities should be included. We use a fully coupled fluid flow and geomechanics simulator, which accounts for stress-dependent permeability and linear poroelasticity, to better determine the conditions leading to fault reactivation. In our model setup, gas is produced from a porous reservoir, divided into two compartments that are offset by a normal fault. Results show that fluid flow plays a major role in pore pressure and stress evolution within the fault. Fault strength is significantly reduced due to fluid flow into the fault zone from the neighboring reservoir compartment and other formations. We also analyze scenarios for minimizing seismicity after a period of production, such as (i) well shut-in and (ii) gas reinjection. In the case of well shut-in, a highly stressed fault zone can still be reactivated several decades after production has ceased, although on average the shut-in results in a reduction in seismicity. In the case of gas reinjection, fault reactivation can be avoided if gas is injected directly into the compartment under depletion. However, gas reinjection into a neighboring compartment does not stop the fault from being reactivated.
Pseudo‐Prospective Forecasting of Induced and Natural Seismicity in the Hengill Geothermal Field
Ritz, Vanille; Mizrahi, Leila; Clasen Repollés, Victor; et al. (2024)
Journal of Geophysical Research: Solid Earth
The Hengill geothermal field, located in southwest Iceland, is host to the Hellisheiði power plant, with its 40+ production wells and 17 reinjection wells. Located in a tectonically active area, the field experiences both natural and induced seismicity linked to the power plant operations. To better manage the risk posed by this seismicity, the development of robust and informative forecasting models is paramount. In this study, we compare the forecasting performance of a model developed for fluid-induced seismicity (the Seismogenic Index model) and a class of well-established statistical models (Epidemic-Type Aftershock Sequence). The pseudo-prospective experiment is set up with 14 months of initial calibration and daily forecasts for a year. In the timeframe of this experiment, a dense broadband network was in place in Hengill, allowing us to rely on a high quality relocated seismic catalog. The seismicity in the geothermal field is characterized by four main clusters, associated with the two reinjection areas, one production area, and an area with surface geothermal manifestations but where no operations are taking place. We show that the models are generally well suited to forecast induced seismicity, despite some limitations, and that a hybrid ETAS model accounting for fluid forcing has some potential in complex regions with natural and fluid-induced seismicity.
Earthquakes in Switzerland and surrounding regions during 2003
Deichmann, Nicolas; Baer, Manfred; Braunmiller, Jochen; et al. (2004)
Eclogae Geologicae Helvetiae

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Stefan Wiemer

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