Seismica

Journal: Seismica

Publisher

McGill University Library

ISSN

2816-9387

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Publications 1 - 10 of 10

Local station correlation: large N-arrays and DAS
Kennett, Brian; Jiang, Chengxin; Smolinski, Krystyna (2023)
Seismica
The use of cross-correlation between seismic stations has had widespread applications particularly in the exploitation of ambient seismic noise. We here show how the effects of a non-ideal noise distribution can be understood by looking directly at correlation properties and show how the behaviour can be readily visualised for both seismometer and DAS configurations, taking into account directivity effects. For sources lying in a relatively narrow cone around the extension of the inter-station path, the dispersion properties of the correlation relate directly to the zone between the stations. We illustrate the successful use of correlation analysis for both a large-N array perpendicular to a major highway and DAS cable along a busy road. For correlation work, the co-array consisting of the ensemble of inter-station vectors provides an effective means of assessing the behaviour of array layouts, supplementing the standard plane-wave array response. When combined with knowledge of the suitable correlation zones for noise sources, the co-array concept provides a useful way to design array configurations for both seismometer arrays and DAS.
Red-light thresholds for induced seismicity in the UK
Schultz, Ryan; Baptie, Brian; Edwards, Benjamin; et al. (2023)
Seismica
Induced earthquakes pose a serious hurdle to subsurface energy development. Concerns about induced seismicity led to terminal public opposition of hydraulic fracturing in the UK. Traffic light protocols (TLPs) are typically used to manage these risks, with the red-light designed as the last-possible stopping-point before exceeding a risk tolerance. We simulate trailing earthquake scenarios for the UK, focusing on three risk metrics: nuisance, damage, and local personal risk (LPR) – the likelihood of building collapse fatality for an individual. The severity of these risks can spatially vary (by orders-of-magnitude), depending on exposure. Estimated risks from the Preston New Road earthquakes are used to calibrate our UK earthquake risk tolerances, which we find to be comparable to Albertan (Canadian) tolerances. We find that nuisance and damage concerns supersede those from fatality and that the safest regions for Bowland Shale development would be along the east coast. A retrospective comparison of our TLP result with the Preston New Road case highlights the importance of red-light thresholds that adapt to new information. Overall, our findings provide recommendations for red-light thresholds (ML 2-2.5) and proactive management of induced seismicity – regardless of anthropogenic source.
Realtime Selection of Optimal Source Parameters Using Ground Motion Envelopes
Jozinovic, Dario; Clinton, John Francis; Massin, Frédérick; et al. (2024)
Seismica
It is increasingly common for seismic networks to operate multiple independent automatic algorithms to characterise earthquakes in real-time, such as in earthquake early warning (EEW) or even standard network practice. Commonly used methods to select the best solution at a given time are simple and use ad hoc rules. An absolute measure of how well a solution (event origin and magnitude) matches the observations by the goodness-of-fit between the observed and predicted envelopes is a robust and independent metric to select optimal solutions. We propose such a measure that is calculated as a combination of amplitude and cross-correlation fit. This metric can be used to determine when a preferred solution reaches an appropriate confidence level for alerting, or indeed to compare two (or more) different event characterisations directly. We demonstrate that our approach can also be used to suppress false alarms commonly seen at seismic networks. Tests using the 10 largest earthquakes in Switzerland between 2013 and 2020, and events that caused false alarms demonstrate that our approach can effectively prefer solutions with small errors in location and magnitude, and can clearly identify and discard false origins or incorrect magnitudes, at all time scales, starting with the first event characterisation.
Chasing the ghost of fracking in the Vaca Muerta Formation: Induced seismicity in the Neuquén Basin, Argentina
Schultz, Ryan; Schultz, Ryan; Tamburini-Beliveau, Guillermo; et al. (2024)
Seismica
Earthquakes are known to be induced by a variety of anthropogenic causes, such as hydraulic fracturing. In the Neuquén Basin of Argentina, hydraulic fracturing has been used to produce hydrocarbons trapped in the shales of the Vaca Muerta Formation. Correspondingly, incidences of seismicity there have increased. We collect information on well stimulations and earthquakes to perform statistical analysis linking these two datasets together. Spatiotemporal association filters suggest that the catalogue of events is biased towards hydraulic fracturing operations. After accounting for false-positives, we estimate that ~0.5% of operations are associated with earthquakes. These associated event-operation pairs show highly correlated temporal signals (>99.99% confidence) between seismicity/injection rates. Based on this evidence, we argue that many of these earthquakes are induced. We support this argument by comparing the geological setting of the Neuquén Basin against conditions needed for fault reactivation in other susceptible/seismogenic basins. This recognition adds to the growing list of (hydraulic fracturing) induced seismicity.
Homogenizing instrumental earthquake catalogs – a case study around the Dead Sea Transform Fault Zone
Grigoratos, Iason; Poggi, Valerio; Danciu, Laurentiu; et al. (2023)
Seismica
The creation of a homogenized earthquake catalog is a fundamental step in seismic hazard analysis. The homogenization procedure, however, is complex and requires a good understanding of the het- erogeneities among the available bulletins. Common events within the bulletins have to be identified and assigned with the most suitable origin time and location solution, while all the events have to be harmonized into a single magnitude scale. This process entails several decision variables that are usually defined using qualitative measures or expert opinion, without a clear exploration of the associated uncertainties. To address this issue, we present an automated and data-driven workflow that defines spatio-temporal margins within which duplicate events fall and converts the various reported magnitudes into a common scale. Special at- tention has been paid to the fitted functional form and the validity range of the derived magnitude conver- sion relations. The proposed methodology has been successfully applied to a wide region around the Dead Sea Transform Fault Zone (27N-36N, 31E-39E), with input data from various sources such as the International Seismological Centre and the Geophysical Institute of Israel. The produced public catalog contains more than 5500 events, between 1900 and 2017, with moment magnitude Mw above 3. The MATLAB/Python scripts used in this study are also available.
The need for open, transdisciplinary, and ethical science in seismology
Dallo, Irina; Herrmann, Marcus; Supino, Mariano; et al. (2023)
Seismica
Reducing the seismic risk for societies requires a bridge between scientific knowledge and so-cietal actions. In recent years, three subjects that facilitate this connection gained growing importance: openscience, transdisciplinarity, and ethics. We outline their relevance in general and specifically at the example of‘dynamicseismic risk’as exploredina dedicatedworkshop. We arguethatthesereflectionscanbetransferredto other research fields for improving their practical and societal relevance. We provide recommendations forscientists at all levels to make science more open, transdisciplinary, and ethical. Only with a transition canwe, as scientists, address current societal challenges and increase societies’ resilience to disasters.
Earthquake source inversion by integrated fiber-optic sensing
Müller, Nils; Noe, Sebastian; Husmann, Dominik; et al. (2024)
Seismica
We present an earthquake source inversion using a single time series produced by integrated fiber-optic sensing in a phase noise cancellation (PNC) system used for frequency metrology. Operating on a 123 km long fiber between Bern and Basel (Switzerland), the PNC system recorded the Mw3.9 Mulhouse earthquake that occurred on 10 September 2022 around 10 km north-west of the northern fiber end. A generalised least-squares inversion in the 4 - 13 s period band constrains the components of a double-couple moment tensor with an uncertainty that corresponds to around 0.2 moment magnitude units, nearly independent of prior information. Uncertainties for hypocenter location and original time are more variable, ranging between 4 - 20 km and 0.1 - 1 s, respectively, depending on whether injected prior information is realistic or almost absent. This work is a proof of concept that quantifies the resolvability of earthquake source properties under specific conditions using a single-channel stand-alone integrated (non-distributed) fiber-optic measurement. It thereby constitutes a step towards the integration of long-range phase-transmission fiber-optic sensors into existing seismic networks in order to fill significant seismic data gaps, especially in the oceans.
Locating the Nordstream explosions using polarization analysis
Stähler, Simon Christian; Zenhäusern, Géraldine; Clinton, John Francis; et al. (2022)
Seismica
The seismic events that preceded the leaks in the Nordstream natural gas pipelines in the Baltic Sea have been interpreted as explosions on the seabed. We use a polarization-based location method initially developed for marsquakes to locate the source region without the need for a subsurface velocity model. We show that the 2 largest seismic events can be unambiguously attributed to the methane plumes observed on the sea surface. The two largest events can be located with this method, using 4 and 5 stations located around the source, with the uncertainties in elliptical bounds of 30 x 30 km and 10 x 60 km, respectively. We can further show that both events emitted seismic energy for at least ten minutes after the initial explosion, indicative of resonances in the water column or the depressurizing pipeline.
What does my technology facilitate? A toolbox to help researchers understand the societal impact of emerging technologies in the context of disasters
Kuratle, Lorena Daphna; Dallo, Irina; Marti, Michèle; et al. (2024)
Seismica
Disaster risk is increasing globally. Emerging technologies – Artificial Intelligence, Internet of Things, and remote sensing – are becoming more important in supporting disaster risk reduction and enhanc ing safety culture. Despite their presumed benefits, most research focuses on their technological potential, whereas societal issues are rarely reflected. Taking a societal perspective is vital to ensure that these tech nologies are developed and operated in ways that benefit societies’ resilience, comply with ethical standards, are inclusive, and address potential risks and challenges. Therefore, we were particularly interested in under standing how societal impacts can be considered and leveraged throughout the development process. Based on an explorative literature review, we developed a toolbox for professionals working on emerging technolo gies in disaster risk reduction. By applying a Delphi study with experts on AI in seismology, we iteratively adapted and tested the toolbox. The results show that there is a need for guided reflection in order to foster discussion on the societal impacts. They further indicate a gap in the common understanding of how a tech nology is defined and what role it should play in disaster risk reduction. That is crucial for developing inclusive technologies or defining regulations. Our toolbox wasfound to be usefulfor professionals in reflecting on their developments and making technologies societally relevant, thereby enhancing societies’ resilience.To extend the implementation of the toolbox, it is essential to facilitate additional promotion through avenues such as workshops and conferences. This process should align with the established framework of project manage ment and the policy cycle.
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.

Publications 1 - 10 of 10

Journal: Seismica

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