Articles | Volume 9, issue 2
https://doi.org/10.5194/se-9-491-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/se-9-491-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
25 Apr 2018
Research article |
| 25 Apr 2018
Geomagnetic field declination: from decadal to centennial scales
Venera Dobrica
CORRESPONDING AUTHOR
Institute of Geodynamics, Romanian Academy, Bucharest, Romania
Crisan Demetrescu
Institute of Geodynamics, Romanian Academy, Bucharest, Romania
Mioara Mandea
Centre National d'Etudes Spatiales, Paris, France
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This investigation was necessary due to the economical and social importance of the Danube lower basin discharge, taking into account the climate change (greenhouse and solar/geomagnetic activity) impact, as well as few approaches on this issue.
By applying robust statistical methods and rigorously testing of results, new indicators were found to estimate the discharge in the Danube lower basin.
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To understand core dynamics, insight from several possible observables is needed. By applying several separation methods, we show spatiotemporal variabilities in the magnetic and gravity fields related to the core dynamics. A 7 years oscillation is found in all conducted analyses. The results in the magnetic field reflect the core processes and the variabilities in the gravity field exhibit new findings that might be an interesting input to build an enhanced model of the Earth’s core.
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While a 6-year oscillation has been reported for some time in the motions of the fluid outer core of the Earth, in the magnetic field and in the Earth rotation, novel results indicate that the climate system also oscillates at this 6 year frequency. This strongly suggests the existence of coupling mechanisms affecting the Earth system as a whole, from the deep Earth interior to the surface fluid envelopes.
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Throughout the International Union of Geodesy and Geophysics' (IUGG's) centennial anniversary, the International Association of Geomagnetism and Aeronomy is holding a series of activities to underline the ground-breaking facts in the area of geomagnetism and aeronomy. Over 100 years, the history of this research is rich, and here we present a short tour through some of the IAGA's major achievements, starting with the scientific landscape before IAGA, through its foundation until the present day.
Roman Sidorov, Anatoly Soloviev, Alexei Gvishiani, Viktor Getmanov, Mioara Mandea, Anatoly Petrukhin, and Igor Yashin
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Decidated to the combined analysis of space weather data (geomagnetic activity, cosmic ray secondaries and ionospheric data) obtained during the September 2017 solar flares and geomagnetic storms, this study is an attempt to construct a technique for circumterrestrial physical data analysis in order to analyze various space weather effects and obtain new mutually supportive information during major space weather events on different phases of geomagnetic storm evolution.
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In this work we analyze signals emitted from wind turbines. They induce sound as well as ground motion waves which propagate through the subsurface and are registered by sensible instruments. In our data we observe when these signals are present and how strong they are. Some signals are present in ground motion and sound data, providing the opportunity to study similarities and better characterize emissions. Furthermore, we study the amplitudes with distance to improve the prediction of signals.
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Chiara Colombero, Myrto Papadopoulou, Tuomas Kauti, Pietari Skyttä, Emilia Koivisto, Mikko Savolainen, and Laura Valentina Socco
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Solid Earth, 13, 85–115, https://doi.org/10.5194/se-13-85-2022, https://doi.org/10.5194/se-13-85-2022, 2022
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The present study shows evidence of fault systems (large cracks in the Earth's crust) hundreds to thousands of kilometers long and several kilometers thick extending from northwestern Russia to the northern Norwegian Barents Sea and the Svalbard Archipelago using seismic, magnetic, and gravimetric data. The study suggests that the crust in Svalbard and the Barents Sea was already attached to Norway and Russia at ca. 650–550 Ma, thus challenging existing models.
Andrei Maksymowicz, Daniela Montecinos-Cuadros, Daniel Díaz, María José Segovia, and Tomás Reyes
Solid Earth, 13, 117–136, https://doi.org/10.5194/se-13-117-2022, https://doi.org/10.5194/se-13-117-2022, 2022
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This work analyses the density structure of the continental forearc in the northern segment of the 1960 Mw 9.6 Valdivia earthquake. Results show a segmentation of the continental wedge along and perpendicular to the margin. The extension of the less rigid basement units conforming the marine wedge and Coastal Cordillera domain could modify the process of stress loading during the interseismic periods. This analysis highlights the role of the overriding plate on the seismotectonic process.
Hossein Hassani, Felix Hloušek, Stefan Buske, and Olaf Wallner
Solid Earth, 12, 2703–2715, https://doi.org/10.5194/se-12-2703-2021, https://doi.org/10.5194/se-12-2703-2021, 2021
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Passive seismic imaging methods use natural earthquakes as seismic sources, while in active seismic imaging methods, artificial sources (e.g. explosives) are used to generate seismic waves. We imaged some structures related to a major fault plane through a passive seismic imaging approach using microearthquakes with magnitudes smaller than 0.9 (Mw). These structures have not been illuminated by a previously conducted 3D active seismic survey due to their large dip angles.
Maximilian O. Kottwitz, Anton A. Popov, Steffen Abe, and Boris J. P. Kaus
Solid Earth, 12, 2235–2254, https://doi.org/10.5194/se-12-2235-2021, https://doi.org/10.5194/se-12-2235-2021, 2021
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Upscaling fluid flow in fractured reservoirs is an important practice in subsurface resource utilization. In this study, we first conduct numerical simulations of direct fluid flow at locations where fractures intersect to analyze the arising hydraulic complexities. Next, we develop a model that integrates these effects into larger-scale continuum models of fracture networks to investigate their impact on the upscaling. For intensively fractured systems, these effects become important.
Klaus Regenauer-Lieb, Manman Hu, Christoph Schrank, Xiao Chen, Santiago Peña Clavijo, Ulrich Kelka, Ali Karrech, Oliver Gaede, Tomasz Blach, Hamid Roshan, Antoine B. Jacquey, Piotr Szymczak, and Qingpei Sun
Solid Earth, 12, 1829–1849, https://doi.org/10.5194/se-12-1829-2021, https://doi.org/10.5194/se-12-1829-2021, 2021
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This paper presents a trans-disciplinary approach bridging the gap between observations of instabilities from the molecular scale to the very large scale. We show that all scales communicate via propagation of volumetric deformation waves. Similar phenomena are encountered in quantum optics where wave collisions can release sporadic bursts of light. Ocean waves show a similar phenomenon of rogue waves that seem to come from nowhere. This mechanism is proposed to be the trigger for earthquakes.
Yinshuai Ding and Alireza Malehmir
Solid Earth, 12, 1707–1718, https://doi.org/10.5194/se-12-1707-2021, https://doi.org/10.5194/se-12-1707-2021, 2021
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In this article, we investigate the potential of reverse time migration (RTM) for deep targeting iron oxide deposits and the possible AVO effect that is potentially seen in the common image gathers from this migration algorithm. The results are promising and help to delineate the deposits and host rock structures using a 2D dataset from the Ludvika mines of central Sweden.
Nikita Afonin, Elena Kozlovskaya, Suvi Heinonen, and Stefan Buske
Solid Earth, 12, 1563–1579, https://doi.org/10.5194/se-12-1563-2021, https://doi.org/10.5194/se-12-1563-2021, 2021
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In our study, we show the results of a passive seismic interferometry application for mapping the uppermost crust in the area of active mineral exploration in northern Finland. The obtained velocity models agree well with geological data and complement the results of reflection seismic data interpretation.
Puy Ayarza, José Ramón Martínez Catalán, Ana Martínez García, Juan Alcalde, Juvenal Andrés, José Fernando Simancas, Immaculada Palomeras, David Martí, Irene DeFelipe, Chris Juhlin, and Ramón Carbonell
Solid Earth, 12, 1515–1547, https://doi.org/10.5194/se-12-1515-2021, https://doi.org/10.5194/se-12-1515-2021, 2021
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Vertical incidence seismic profiling on the Iberian Massif images a mid-crustal-scale discontinuity at the top of the reflective lower crust. This feature shows that upper- and lower-crustal reflections merge into it, suggesting that it has often behaved as a detachment. The orogen-scale extension of this discontinuity, present in Gondwanan and Avalonian affinity terranes into the Iberian Massif, demonstrates its relevance, leading us to interpret it as the Conrad discontinuity.
Peter-Lasse Giertzuch, Joseph Doetsch, Alexis Shakas, Mohammadreza Jalali, Bernard Brixel, and Hansruedi Maurer
Solid Earth, 12, 1497–1513, https://doi.org/10.5194/se-12-1497-2021, https://doi.org/10.5194/se-12-1497-2021, 2021
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Two time-lapse borehole ground penetrating radar (GPR) surveys were conducted during saline tracer experiments in weakly fractured crystalline rock with sub-millimeter fractures apertures, targeting electrical conductivity changes. The combination of time-lapse reflection and transmission GPR surveys from different boreholes allowed monitoring the tracer flow and reconstructing the flow path and its temporal evolution in 3D and provided a realistic visualization of the hydrological processes.
Irene Bianchi, Elmer Ruigrok, Anne Obermann, and Edi Kissling
Solid Earth, 12, 1185–1196, https://doi.org/10.5194/se-12-1185-2021, https://doi.org/10.5194/se-12-1185-2021, 2021
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The European Alps formed during collision between the European and Adriatic plates and are one of the most studied orogens for understanding the dynamics of mountain building. In the Eastern Alps, the contact between the colliding plates is still a matter of debate. We have used the records from distant earthquakes to highlight the geometries of the crust–mantle boundary in the Eastern Alpine area; our results suggest a complex and faulted internal crustal structure beneath the higher crests.
Saeid Cheraghi, Alireza Malehmir, Mostafa Naghizadeh, David Snyder, Lucie Mathieu, and Pierre Bedeaux
Solid Earth, 12, 1143–1164, https://doi.org/10.5194/se-12-1143-2021, https://doi.org/10.5194/se-12-1143-2021, 2021
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High-resolution seismic profiles in 2D are acquired in the north and south of the Chibougamau area, Quebec, Canada located in the northeast of the Abitibi Greenstone belt. The area mostly includes volcanic rocks, and both profiles cross over several fault zones. The seismic method is acquired to image the subsurface down to depth of 12 km. The main aim of this study is to image major fault zones and the geological formations connected to those faults to investigate metal endowment in the area.
Jean-Baptiste P. Koehl
Solid Earth, 12, 1025–1049, https://doi.org/10.5194/se-12-1025-2021, https://doi.org/10.5194/se-12-1025-2021, 2021
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By using seismic data and fieldwork, this contribution shows that soft, coal-rich sedimentary rocks absorbed most of early Cenozoic, Eurekan, contractional deformation in central Spitsbergen, thus suggesting that no contractional deformation event is needed in the Late Devonian to explain the deformation differences among late Paleozoic sedimentary rocks. It also shows that the Billefjorden Fault Zone, a major crack in the Earth's crust in Svalbard, is probably segmented.
Gilda Currenti, Philippe Jousset, Rosalba Napoli, Charlotte Krawczyk, and Michael Weber
Solid Earth, 12, 993–1003, https://doi.org/10.5194/se-12-993-2021, https://doi.org/10.5194/se-12-993-2021, 2021
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We investigate the capability of distributed acoustic sensing (DAS) to record dynamic strain changes related to Etna volcano activity in 2019. To validate the DAS measurements, we compute strain estimates from seismic signals recorded by a dense broadband array. A general good agreement is found between array-derived strain and DAS measurements along the fibre optic cable. Localised short wavelength discrepancies highlight small-scale structural heterogeneities in the investigated area.
Klaus Regenauer-Lieb, Manman Hu, Christoph Schrank, Xiao Chen, Santiago Peña Clavijo, Ulrich Kelka, Ali Karrech, Oliver Gaede, Tomasz Blach, Hamid Roshan, and Antoine B. Jacquey
Solid Earth, 12, 869–883, https://doi.org/10.5194/se-12-869-2021, https://doi.org/10.5194/se-12-869-2021, 2021
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In this paper we expand on a recent discovery of slow cross-diffusion hydromechanical waves cast into a new concise reaction–diffusion equation for THMC coupling. If waves are excited through the THMC reaction terms unbounded reactions can be captured by inclusion of statistical information from the lower scale through nonlocal reaction–diffusion equations. These cross-diffusion coefficients regularize extreme earthquake-like events (rogue waves) through a new form of quasi-soliton wave.
Christian Emile Nyaban, Théophile Ndougsa-Mbarga, Marcelin Bikoro-Bi-Alou, Stella Amina Manekeng Tadjouteu, and Stephane Patrick Assembe
Solid Earth, 12, 785–800, https://doi.org/10.5194/se-12-785-2021, https://doi.org/10.5194/se-12-785-2021, 2021
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A multi-scale analysis of aeromagnetic data combining tilt derivative, Euler deconvolution, upward continuation, and 2.75D modelling was applied over Cameroon between the latitudes 5°30'–6° N and the longitudes 13°30'–14°45' E. Major families of faults oriented ENE–WSW, E–W, NW–SE, and N–S with a NE–SW prevalence were mapped. Depths of interpreted faults range from 1000 to 3400 m, mylonitic veins were identified, and 2.75D modelling revealed fault depths greater than 1200 m.
Jennifer E. Cunningham, Nestor Cardozo, Chris Townsend, and Richard H. T. Callow
Solid Earth, 12, 741–764, https://doi.org/10.5194/se-12-741-2021, https://doi.org/10.5194/se-12-741-2021, 2021
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This work investigates the impact of commonly used seismic interpretation methods on the analysis of faults. Fault analysis refers to fault length, displacement, and the impact these factors have on geological modelling and hydrocarbon volume calculation workflows. This research was conducted to give geoscientists a better understanding of the importance of interpretation methods and the impact of unsuitable methology on geological analyses.
Jan Henninges, Evgeniia Martuganova, Manfred Stiller, Ben Norden, and Charlotte M. Krawczyk
Solid Earth, 12, 521–537, https://doi.org/10.5194/se-12-521-2021, https://doi.org/10.5194/se-12-521-2021, 2021
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We performed a seismic survey in two 4.3 km deep geothermal research wells using the novel method of distributed acoustic sensing and wireline cables. The characteristics of the acquired data, methods for data processing and quality improvement, and interpretations on the geometry and structure of the sedimentary and volcanic reservoir rocks are presented. The method enables measurements at high temperatures and reduced cost compared to conventional sensors.
Matthias Bücker, Adrián Flores Orozco, Jakob Gallistl, Matthias Steiner, Lukas Aigner, Johannes Hoppenbrock, Ruth Glebe, Wendy Morales Barrera, Carlos Pita de la Paz, César Emilio García García, José Alberto Razo Pérez, Johannes Buckel, Andreas Hördt, Antje Schwalb, and Liseth Pérez
Solid Earth, 12, 439–461, https://doi.org/10.5194/se-12-439-2021, https://doi.org/10.5194/se-12-439-2021, 2021
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We use seismic, electromagnetic, and geoelectrical methods to assess sediment thickness and lake-bottom geology of two karst lakes. An unexpected drainage event provided us with the unusual opportunity to compare water-borne measurements with measurements carried out on the dry lake floor. The resulting data set does not only provide insight into the specific lake-bottom geology of the studied lakes but also evidences the potential and limitations of the employed field methods.
Alireza Malehmir, Magdalena Markovic, Paul Marsden, Alba Gil, Stefan Buske, Lukasz Sito, Emma Bäckström, Martiya Sadeghi, and Stefan Luth
Solid Earth, 12, 483–502, https://doi.org/10.5194/se-12-483-2021, https://doi.org/10.5194/se-12-483-2021, 2021
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A smooth transition toward decarbonization demands access to more minerals of critical importance. Europe has a good geology for many of these mineral deposits, but at a depth requiring sensitive, environmentally friendly, and cost-effective methods for their exploration. In this context, we present a sparse 3D seismic dataset that allowed identification of potential iron oxide resources at depth and helped to characterise key geological structures and a historical tailing in central Sweden.
Alba Zappone, Antonio Pio Rinaldi, Melchior Grab, Quinn C. Wenning, Clément Roques, Claudio Madonna, Anne C. Obermann, Stefano M. Bernasconi, Matthias S. Brennwald, Rolf Kipfer, Florian Soom, Paul Cook, Yves Guglielmi, Christophe Nussbaum, Domenico Giardini, Marco Mazzotti, and Stefan Wiemer
Solid Earth, 12, 319–343, https://doi.org/10.5194/se-12-319-2021, https://doi.org/10.5194/se-12-319-2021, 2021
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The success of the geological storage of carbon dioxide is linked to the availability at depth of a capable reservoir and an impermeable caprock. The sealing capacity of the caprock is a key parameter for long-term CO2 containment. Faults crosscutting the caprock might represent preferential pathways for CO2 to escape. A decameter-scale experiment on injection in a fault, monitored by an integrated network of multiparamerter sensors, sheds light on the mobility of fluids within the fault.
Juvenal Andrés, Puy Ayarza, Martin Schimmel, Imma Palomeras, Mario Ruiz, and Ramon Carbonell
Solid Earth, 11, 2499–2513, https://doi.org/10.5194/se-11-2499-2020, https://doi.org/10.5194/se-11-2499-2020, 2020
Yi Zhang, Xinglin Lei, Tsutomu Hashimoto, and Ziqiu Xue
Solid Earth, 11, 2487–2497, https://doi.org/10.5194/se-11-2487-2020, https://doi.org/10.5194/se-11-2487-2020, 2020
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Spatially continuous strain responses in two monitoring wells induced by a well-drilling process were monitored using high-resolution fiber-optic distributed strain sensing (DSS). The modeling results suggest that the strain polarities and magnitudes along the wellbores may be indicative of the layered-permeability structure or heterogeneous formation damage. The performance and value of DSS as a novel hydrogeophysical tool for in situ subsurface monitoring are emphasized.
Benjamin Schwarz and Charlotte M. Krawczyk
Solid Earth, 11, 1891–1907, https://doi.org/10.5194/se-11-1891-2020, https://doi.org/10.5194/se-11-1891-2020, 2020
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Intricate fault and fracture networks cut through the upper crust, and their detailed delineation and characterization play an important role in the Earth sciences. While conventional geophysical sounding techniques only provide indirect means of detection, we present scale-spanning field data examples, in which coherent diffraction imaging – a framework inspired by optics and visual perception – enables the direct imaging of these crustal features at an unprecedented spatial resolution.
Laurent Guillou-Frottier, Hugo Duwiquet, Gaëtan Launay, Audrey Taillefer, Vincent Roche, and Gaétan Link
Solid Earth, 11, 1571–1595, https://doi.org/10.5194/se-11-1571-2020, https://doi.org/10.5194/se-11-1571-2020, 2020
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In the first kilometers of the subsurface, temperature anomalies due to heat conduction rarely exceed 20–30°C. However, when deep hot fluids in the shallow crust flow upwards, for example through permeable fault zones, hydrothermal convection can form high-temperature geothermal reservoirs. Numerical modeling of hydrothermal convection shows that vertical fault zones may host funnel-shaped, kilometer-sized geothermal reservoirs whose exploitation would not need drilling at depths below 2–3 km.
Joseph Doetsch, Hannes Krietsch, Cedric Schmelzbach, Mohammadreza Jalali, Valentin Gischig, Linus Villiger, Florian Amann, and Hansruedi Maurer
Solid Earth, 11, 1441–1455, https://doi.org/10.5194/se-11-1441-2020, https://doi.org/10.5194/se-11-1441-2020, 2020
Laura Petrescu, Silvia Pondrelli, Simone Salimbeni, Manuele Faccenda, and the AlpArray Working Group
Solid Earth, 11, 1275–1290, https://doi.org/10.5194/se-11-1275-2020, https://doi.org/10.5194/se-11-1275-2020, 2020
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To place constraints on the mantle deformation beneath the Central Alps and the greater Alpine region, we analysed the appropriate seismic signal recorded by more than 100 stations, belonging to AlpArray and to other permanent networks. We took a picture of the imprinting that Alpine orogen history and related subductions left at depth, with a mainly orogen-parallel mantle deformation from Western Alps to Eastern Alps, but also N to S from the Po Plain to the Rhine Graben.
Łukasz Słonka and Piotr Krzywiec
Solid Earth, 11, 1097–1119, https://doi.org/10.5194/se-11-1097-2020, https://doi.org/10.5194/se-11-1097-2020, 2020
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This paper shows the results of seismic interpretations that document the presence of large Upper Jurassic carbonate buildups in the Miechów Trough (S Poland). Our work fills the gap in recognition of the Upper Jurassic carbonate depositional system of southern Poland. The results also provide an excellent generic reference point, showing how and to what extent seismic data can be used for studies of carbonate depositional systems, in particular for the identification of the carbonate buildups.
Anke Dannowski, Heidrun Kopp, Ingo Grevemeyer, Dietrich Lange, Martin Thorwart, Jörg Bialas, and Martin Wollatz-Vogt
Solid Earth, 11, 873–887, https://doi.org/10.5194/se-11-873-2020, https://doi.org/10.5194/se-11-873-2020, 2020
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The Ligurian Sea opened ~30–15 Ma during the SE migration of the Calabrian subduction zone. Seismic travel time tomography reveals the absence of oceanic crust, documenting that the extension of continental lithosphere stopped before seafloor spreading initiated. The extension led to extreme crustal thinning and possibly exhumed mantle accompanied by syn-rift sedimentation. Our new interpretation of the crust's nature is important for plate reconstruction modelling related to the Alpine orogen.
Yury Alkhimenkov, Eva Caspari, Simon Lissa, and Beatriz Quintal
Solid Earth, 11, 855–871, https://doi.org/10.5194/se-11-855-2020, https://doi.org/10.5194/se-11-855-2020, 2020
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We perform a three-dimensional numerical study of the fluid–solid deformation at the pore scale. We show that seismic wave velocities exhibit strong azimuth-, angle- and frequency-dependent behavior due to squirt flow between interconnected cracks. We conclude that the overall anisotropy mainly increases due to squirt flow, but in some specific planes it can locally decrease as well as increase, depending on the material properties.
Eva Caspari, Andrew Greenwood, Ludovic Baron, Daniel Egli, Enea Toschini, Kaiyan Hu, and Klaus Holliger
Solid Earth, 11, 829–854, https://doi.org/10.5194/se-11-829-2020, https://doi.org/10.5194/se-11-829-2020, 2020
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A shallow borehole was drilled to explore the petrophysical and hydraulic characteristics of a hydrothermally active fault in the crystalline Aar massif of the Alps. A key objective of studying surficial features of this kind is to establish analogies with natural and deep-seated engineered hydrothermal systems. A wide range of geophysical borehole logs was acquired, which revealed a complex fracture network in the damage zone of the fault and a related compartmentalized hydraulic behavior.
Jürg Hunziker, Andrew Greenwood, Shohei Minato, Nicolás Daniel Barbosa, Eva Caspari, and Klaus Holliger
Solid Earth, 11, 657–668, https://doi.org/10.5194/se-11-657-2020, https://doi.org/10.5194/se-11-657-2020, 2020
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The characterization of fractures is crucial for a wide range of pertinent applications, such as geothermal energy production, hydrocarbon exploration, CO2 sequestration, and nuclear waste disposal. We estimate fracture parameters based on waves that travel along boreholes (tube waves) using a stochastic optimization approach.
Felix Kästner, Simona Pierdominici, Judith Elger, Alba Zappone, Jochem Kück, and Christian Berndt
Solid Earth, 11, 607–626, https://doi.org/10.5194/se-11-607-2020, https://doi.org/10.5194/se-11-607-2020, 2020
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Knowledge about physical properties at depth is crucial to image and understand structures linked with orogenic processes. We examined seismic velocities from core and downhole data from the COSC-1 borehole, Sweden, and calibrated our results with laboratory measurements on core samples. Despite a strong mismatch between the core and downhole velocities due to microcracks, mafic units are resolved at all scales, while at sample scale, strong seismic anisotropy correlates with the rock foliation.
Elikplim Abla Dzikunoo, Giulio Vignoli, Flemming Jørgensen, Sandow Mark Yidana, and Bruce Banoeng-Yakubo
Solid Earth, 11, 349–361, https://doi.org/10.5194/se-11-349-2020, https://doi.org/10.5194/se-11-349-2020, 2020
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Time-domain electromagnetic (TEM) geophysics data originally collected for mining purposes were reprocessed and inverted. The new inversions were used to construct a 3D model of the subsurface geology to facilitate hydrogeological investigations within a DANIDA-funded project. Improved resolutions from the TEM enabled the identification of possible paleovalleys of glacial origin, suggesting the need for a reevaluation of the current lithostratigraphy of the Voltaian sedimentary basin.
Susini deSilva and Vernon F. Cormier
Solid Earth, 11, 161–171, https://doi.org/10.5194/se-11-161-2020, https://doi.org/10.5194/se-11-161-2020, 2020
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Seismic waves attenuate with distance due to two effects: (1) removal of energy by internal friction and (2) redistribution of energy into different distances and time windows by scattering from heterogeneous Earth structure. The relative contribution of these two effects is estimated by synthesizing seismograms having varying amounts of internal friction and heterogeneities. The attenuation of observed S waveforms requires contributions from both internal friction and scattering.
Cited articles
Abarco del Rio, R., Gambis, D., and Salstein, D. A.: Interannual signals in length of day and atmospheric angular momentum, Ann. Geophys., 18, 347–364, https://doi.org/10.1007/s00585-000-0347-9, 2000.
Alexandrescu, M., Courtillot, V., and Le Mouël, J. -L.: Geomagnetic field direction in Paris since the mid-sixteenth century, Phys. Earth Planet. Inter., 98, 321–360, 1996.
Alexandrescu, M., Courtillot, V., and Le Mouël, J. -L.: High resolution secular variation of geomagnetic field in Western Europe over the last 4 centuries: comparison and integration of historical data from Paris and London, J. Geophys. Res., 102, 20245–20258, 1997.
Alldredge, L. R.: Geomagnetic variations with periods from 13 to 30 years, J. Geomagn. Geoelectr., 29, 123–135, 1977.
Alldredge, L. R.: A discussion of impulses and jerks in the geomagnetic field, J. Geophys. Res., 86, 7957–7965, 1984.
Alldredge, L. R.: More on the alleged 1970 geomagnetic jerk, Phys. Earth Planet. Inter., 39, 255–264, 1985.
Atanasiu, G.: Variation séculaire des éléments géomagnétiques en Transylvanie et au Banat (Roumanie) durant la période 1848–1968, Rev. Roum. Géol., Géophys., Géogr., Serie de Géophysique, 12, 87–104, 1968.
Barraclough, D. R.: Observations of the Earth's magnetic field made in Edinburgh from 1670 to the present day, Trans. R. Soc. Edinburgh: Earth Sci, 85, 239–252, 1995.
Bloxham, J., Zatman, S., and Dumberry, M.: The origin of geomagnetic jerks, Nature, 420, 65–68, 2002.
Brown, W. J., Mound, J. E., and Livermore, P. W.: Jerks abound: An analysis of geomagnetic observatory data from 1957 to 2008, Phys. Earth Planet. Int., https://doi.org/10.1016/j.pepi.2013.06.001, 2013.
Bucha, V.: Säkular Variation der Verticalcomponent Z, Erdmagnetische Feldes fur Zeitraum 1850-1950 in der Tschechoslovakai, Geophys. Sbornik, 114, 281–300, 1959.
Buffett, B.: Geomagnetic fluctuations reveal stable stratification at the top of the Earth's core, Nature, 507, 484–487, https://doi.org/10.1038/nature13122, 2014.
Buffett, B., Mound, J., and Jackson, A.: Inversion of torsional oscillations for the structure and dynamics of Earth's core, Geophys. J. Int., 177, 878–890, https://doi.org/10.1111/j.1365-246X.2009.04129.x, 2009.
Butterworth, S.: On the theory of filter amplifiers, Wireless Engineer, 7, 536–541, 1930.
Cafarella, L., De Santis, A., and Meloni, A.: Secular variation in Italy from historical geomagnetic field measurements, Phys. Earth Planet. Int., 73, 206–221, 1992a.
Cafarella, L., De Santis, A., and Meloni, A.: Il catalogo geomagnetico storico italiano, 160 pp., Istituto Nazionale di Geofisica, Roma, 1992b.
Chulliat, A. and Maus, S.: Geomagnetic secular acceleration, jerks, and a localized standing wave at the core surface from 2000 to 2010, J. Geophys. Res.-Solid Earth, 119, 1531–1543, https://doi.org/10.1002/2013JB010604, 2014.
Chulliat, A., Thébault, E., and Hulot, G.: Core field acceleration pulse as a common cause of the 2003 and 2007 geomagnetic jerks, Geophys. Res. Lett., 37, L07301, https://doi.org/10.1029/2009GL042019, 2010.
Chulliat, A., Alken, P., and Maus, S.: Fast equatorial waves propagating at the top of the Earth's Core, Geophys. Res. Lett., 42, 3321–3329, https://doi.org/10.1002/2015GL064067, 2015.
Constantinescu, L.: Early geomagnetic information concerning the Romanian territory, Mem. Sect. Sti., Serie IV, 2, 147–165, 1979.
Courtillot, V., Ducruix, J., and Le Mouël, J.-L.: Sur une accélération récente de la variation séculaire du champ magnétique terrestre, C. R. Hebd. Séances Acad. Sci. Paris, Sér. D, 287, 1095–1098, 1978.
Cox, G. A., Livermore, P. W., and Mound, J. E.: The observational signature of modeled torsional waves and comparison to geomagnetic jerks, Phys. Earth Planet. Int., 255, 50–65, https://doi.org/10.1016/j.pepi.2016.03.012, 2016.
Currie, R. G.: Geomagnetic line spectra – 2 to 70 years, Astrophys. Space Sci., 21, 425–438, 1973.
Demetrescu, C. and Dobrica, V.: Multi-decadal ingredients of the secular variation of the geomagnetic field. Insights from long time series of observatory data, Phys. Earth Planet. Inter., 231, 39–55, https://doi.org/10.1016/j.pepi.2014.03.001, 2014.
De Santis, A., Baraclough, D. R., and Tozzi, R.: Spatial and temporal spectra of the geomagnetic field and their scaling properties, Phys. Earth Planet. Int., 135, 125–134, https://doi.org/10.1016/S0031-9201(02)00211-X, 2003.
Dickey, J. O. and de Viron, O.: Leading modes of torsional oscillations within the Earth's core, Geophys. Res. Lett., 36, L15302, https://doi.org/10.1029/2009GL038386, 2009.
Dobrica, V., Demetrescu, C., and Stefan, C.: Toward a better representation of the secular variation. Case study: the European network of geomagnetic observatories, Earth Planet. Space, 65, 767–779, https://doi.org/10.5047/eps.2012.12.001, 2013.
Duan, P., Liu, G., Hu, X., Zhao, J., and Huang, C.: Mechanism of the interannual oscillation in length of day and its constraint on the electromagnetic coupling at the core–mantle boundary, Earth Planet. Sci. Lett., 482, 245–252, 2018.
Finlay, C. C. and Jackson, A.: Equatorially dominated magnetic field change at the surface of the Earth's core, Science, 300, 2084–2086, 2003.
Finlay, C. C., Olsen, N., and Tøffner-Clausen, L.: DTU candidate field models for IGRF-12 and the CHAOS-5 geomagnetic field model, Earth Planet. Space, 67, 114, https://doi.org/10.1186/s40623-015-0274-3, 2015.
Finlay, C. C., Lesur, V., Thébault, E., Vervelidou, F., Morschhauser, A., and Shore, R.: Challenges handling magnetospheric and ionospheric signals in internal geomagnetic field modelling, Space Sci. Rev., 206, 157–189, https://doi.org/10.1007/s11214-016-0285-9, 2017.
Gillet, N., Jault, D., Canet, E., and Fournier, A.: Fast torsional waves and strong magnetic field within the Earth's core, Nature, 465, 74–77, https://doi.org/10.1038/nature09010, 2010.
Gillet, N., Jault, D., Finlay, C. C., and Olsen, N.: Stochastic modeling of the Earth's magnetic field: Inversion for covariances over the observatory era, Geochem. Geophys. Geosyst., 14, 766–786, https://doi.org/10.1002/ggge.20041, 2013.
Gillet, N., Jault, D., and Finlay, C. C.: Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth's core surface, J. Geophys. Res.-Solid Earth, 120, 3991–4013, https://doi.org/10.1002/2014JB011786, 2015.
Hodrick, R. J. and Prescott, E. C.: Postwar U. S. business cycles: An empirical investigation, J. Money, Credit, Banking, 29, 1–16, 1997.
Holme, R.: Large-scale flow in the core, in: Treatise on Geophysics, edited by: Schubert, G. and Olson, P., Vol. 8. Core Dynamics, 2nd Eedition, Elsevier, Amsterdam, 91–113, 2015.
Holme, R. and de Viron, O.: Characterization and implications of intradecadal variations in length of day, Nature, 499, 202–204, https://doi.org/10.1038/nature12282, 2013.
Jackson, A. and Finlay, C. C.: Geomagnetic secular variation and its application to the core, in: Treatise on Geophysics, edited by: Schubert, G. and Kono, M., Vol. 5. Geomagnetism, Elsevier, Amsterdam, 147–193, 2007.
Jackson, A., Jonkers, A. R. T., and Walker, M. R.: Four centuries of geomagnetic secular variation from historical records, Phil. Trans. R. Soc. Lond., 358, 957–990, 2000.
Jackson, L. P. and Mound, J. E.: Geomagnetic variations on decadal time scales: What can we learn from Empirical Mode Decomposition?, Geophys. Res. Lett., 37, L14307, https://doi.org/10.1029/2010GL043455, 2010.
Jin, R. and Thomas, D.: Spectral line similarity in geomagnetic dipole field variations and length of day fluctuations, J. Geophys. Res., 82, 828–834, 1977.
Jonkers, A. R. T., Jackson, A., and Murray, A.: Four centuries of geomagnetic data from historical records, Rev. Geophys., 41, 1006, https://doi.org/10.1029/2002RG000115, 2003.
Korte, M., Mandea, M., and Matzka, J.: A historical declination curve for Munich from different data sources, Phys. Earth Planet. Int., 177, 161–172, 2009.
Kotzé, P. B.: The 2014 geomagnetic jerk as observed by southern African magnetic observatories, Earth Planet. Space, 69, 17, https://doi.org/10.1186/s40623-017-0605-7, 2017.
Langel, R. A., Kerridge, D. J., Barraclough, D. R., and Malin, S. R. C.: Geomagnetic temporal change: 1903-1982, A spline representation, J. Geomag. Geoelectr., 38, 573–597, 1986.
Langel, R. A., Sabaka, T. J., Baldwin, R. T., and Conrad, J. A.: The near-Earth magnetic field from magnetospheric and quiet-day ionospheric sources and how it is modelled, Phys. Earth Planet. Int., 98, 235–267, 1996.
Lesur, V., Wardinski, I., Baerenzung, J., and Holschneider, M.: On the frequency spectra of the core magnetic field Gauss coefficients, Phys. Earth Planet. Int., 276, 145–158, https://doi.org/10.1016/j.pepi.2017.05.017, 2018.
Malin, S. R. C. and Bullard, E. C.: The direction of the Earth's magnetic field at London, 1570–1975, Philos. Trans. R. Soc. London, 299, 357–423, 1981.
Mandea, M. and Le Mouël, J.-L.: After some 350 years – zero declination again in Paris, Hist. Geo Space Sci., 7, 73–77, 2016.
Mandea, M., Bellanger, E., and Le Mouël, J.-L.: A geomagnetic jerk for the end of 20th century? Earth Planet Sci. Lett., 183, 369–373, 2000.
Mandea, M., Holme, R., Pais, A., Pinheiro, K., Jackson, A., and Verbanac, G.: Geomagnetic jerks: Rapid core field variations and core dynamics, Space Sci. Rev., 155, 147–175, https://doi.org/10.1007/s11214-010-9663-x, 2010.
McLeod, M. G.: Spatial and temporal power spectra of the geomagnetic field, J. Geophys. Res., 101, 2745–2763, 1996.
Mound, J. and Buffett, B.: Detection of a gravitational oscillation in length-of-day, Earth Planet. Sci. Lett., 243, 383–389, 2006.
Olsen, N. and Mandea, M.: Investigation of a secular variation impulse using satellite data: The 2003 geomagnetic jerk, Earth Planet. Sci. Lett., 255, 94–105, 2007.
Olsen, N., Mandea, M., Sabaka, T. J., and Tøffner-Clausen, L.: CHAOS-2–A geomagnetic field model derived from one decade of continuous satellite data, Geophys. J. Int., 179, 1477–1487, https://doi.org/10.1111/j.1365-246X.2009.04386.x, 2009.
Ou, J., Du, A., and Finlay, C. C.: Quasi-biennial oscillations in the geomagnetic field: Their global characteristics and origin, J. Geophys. Res.-Space Phys., 122, 5043–5058, https://doi.org/10.1002/2016JA023292, 2017.
Paige, R. and Trindade, A.: The Hodrick-Prescott Filter: A special case of penalized spline smoothing, Elec. J. Stat., 4, 856–874, https://doi.org/10.1214/10-EJS570, 2010.
Pinheiro, K. J., Jackson, A., and Finlay, C. C.: Measurements and uncertainties of the occurrence time of the 1969, 1978, 1991, and 1999 geomagnetic jerks, Geochem. Geophys. Geosyst., 12, Q10015, https://doi.org/10.1029/2011GC003706, 2011.
Qamili, E., De Santis, A., Isac, A., Mandea, M., Duka, B., and Simonyan, A.: Geomagnetic jerks as chaotic fluctuations of the Earth's magnetic field, Geochem. Geophys. Geosyst., 14, 839–850, https://doi.org/10.1029/2012GC004398, 2013.
Roberts, P.H., Yu, Z., and Russell, C.: On the 60-year signal from the core, Geophys., Astrophys. Fluid Dyn., 101, 11–35, https://doi.org/10.1080/03091920601083820, 2007.
Silva, L., Jackson, L., and Mound, J.: Assessing the importance and expression of the 6 year geomagnetic oscillation., J. Geophys. Res., 117, B10101, https://doi.org/10.1029/2012JB009405, 2012.
Soare, A., Cucu, G., and Mandea Alexandrescu, M.: Historical geomagnetic measurements in Romania, Ann. Geofis., 41, 539–554, 1998.
Stefan, C., Dobrica, V., and Demetrescu, C.: Core surface sub-centennial magnetic flux patches: characteristics and evolution, Earth Planet. Space, 69, 146, https://doi.org/10.1186/S40623-017-0732-1, 2017.
Torta, J. M., Pavón-Carrasco, F. J., Marsal, S., and Finlay, C. C.: Evidence for a new geomagnetic jerk in 2014, Geophys. Res. Lett., 42, 7933–7940, https://doi.org/10.1002/2015GL065501, 2015.
Valach, F., Vaczyova, M., and Dolinski, P.: Geomagnetic repeat stations network over the territory of Slovakia, Contrib. Geophys. Geodesy, 34, 21–42, 2004.
Verbanac, G., Lühr, H., Korte, M., and Mandea, M.: Contributions of the external field to the observatory annual means and a proposal for their corrections, Earth Planet. Space, 59, 1–7, 2007.
Wardinski, I. and Holme, R.: Signal from noise in geomagnetic field modeling: denoising data for secular variation studies, Geophys. J. Int., 185, 653–662, https://doi.org/10.1111/j.1365-246X.2011.04988.x, 2011.
Yukutake , T. and Cain, J. C.: Solar cycle variations of the first degree spherical harmonic components of the geomagnetic field, J. Geomagn. Geoelectr., 11, 509–544, 1979.
Zatman, S. and Bloxham, J.: Torsional oscillations and the magnetic field within the Earth's core, Nature, 388, 760–763, 1997.
Short summary
By analyzing frequency constituents of declination secular variation at inter-decadal and sub-centennial timescales from geomagnetic observatories with data longer than 1 century and several historical data sets, we suggest that the geomagnetic jerk concept should be considered as a more general notion, namely the evolution of the secular variation as a result of the superposition of two (or more) constituents describing the effects of processes in the Earth’s core at two (or more) timescales.
By analyzing frequency constituents of declination secular variation at inter-decadal and...
