Articles | Volume 6, issue 1
https://doi.org/10.5194/se-6-207-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/se-6-207-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
16 Feb 2015
Research article |
| 16 Feb 2015
Variations of the crustal thickness in Nepal Himalayas based on tomographic inversion of regional earthquake data
Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Prospekt Koptyuga, 3, 630090, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia, Pirogova 2, 630090, Novosibirsk, Russia
G. Maksotova
Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Prospekt Koptyuga, 3, 630090, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia, Pirogova 2, 630090, Novosibirsk, Russia
S. Mukhopadhyay
Department of Earth Sciences, IIT Roorkee, Roorkee, India
J. Raoof
Department of Earth Sciences, IIT Roorkee, Roorkee, India
J. R. Kayal
School of Oceanographic Studies, Jadavpur University, Kolkata 700032, India
A. Jakovlev
Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Prospekt Koptyuga, 3, 630090, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia, Pirogova 2, 630090, Novosibirsk, Russia
A. Vasilevsky
Trofimuk Institute of Petroleum Geology and Geophysics SB RAS, Prospekt Koptyuga, 3, 630090, Novosibirsk, Russia
Novosibirsk State University, Novosibirsk, Russia, Pirogova 2, 630090, Novosibirsk, Russia
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A new regional seismic tomography model of the upper mantle beneath Italy is presented. Here we identify a high-velocity anomaly, identifiable as a long, narrow sausage-shaped body with a steeply dipping part down to a depth of 400km and then expanding horizontally over ~400km. We propose that it could be made up of infra continental lithospheric mantle of Adria, which is progressively delaminated, whereas its overlying crust becomes progressively accreted into the Apenninic tectonic wedge.
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Presently there is no complete crustal model of the Dinarides. Using the compilations of previous studies, we have created vertically and laterally varying crustal models defined on a regular grid for the wider area of the Dinarides, also covering parts of the Adriatic Sea and the SW part of the Pannonian Basin. In addition to the seismic velocities and density, we also defined three interfaces: sedimentary deposit bottom, carbonate rock thickness and crustal thickness.
Patricia Martínez-Garzón, Dirk Becker, Jorge Jara, Xiang Chen, Grzegorz Kwiatek, and Marco Bohnhoff
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We analyze the 2022 MW 6.0 Gölyaka sequence. A high-resolution seismicity catalog revealed no spatiotemporal localization and lack of immediate foreshocks. Aftershock distribution suggests the activation of the Karadere and Düzce faults. The preferential energy propagation suggests that the mainshock propagated eastwards, which is in agreement with predictions from models, where the velocity in the two sides of the fault is different.
Gabriela Fernández-Viejo, Carlos López-Fernández, and Patricia Cadenas
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The seismic activity of the last 20 years within the West Iberian Margin away from the plate boundaries has been analyzed through the Spanish and Portuguese seismic network public databases. Previously defined as diffuse, the study reveals two distinct clusters in the NW–SE direction. Based on the characteristics of the events, some hypotheses for this activity are put forward and discussed, indicating the need for ocean-bottom seismometer data and high-resolution fault mapping.
Laurens Jan Hofman, Jörn Kummerow, Simone Cesca, and the AlpArray–Swath-D Working Group
Solid Earth, 14, 1053–1066, https://doi.org/10.5194/se-14-1053-2023, https://doi.org/10.5194/se-14-1053-2023, 2023
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We present an earthquake catalogue for the eastern and southern Alps based on data from a local temporary monitoring network. The methods we developed for the detection and localisation focus especially on very small earthquakes. This provides insight into the local geology and tectonics and provides an important base for future research in this part of the Alps.
Fabian Limberger, Georg Rümpker, Michael Lindenfeld, and Hagen Deckert
Solid Earth, 14, 859–869, https://doi.org/10.5194/se-14-859-2023, https://doi.org/10.5194/se-14-859-2023, 2023
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Wind turbines that are located close to a seismometer produce ground tremors that can increase the noise level at the seismic station. Using numerical models, we analyse the effectivity of borehole installations to reduce this impact. We study effects of geophysical parameters on the borehole effectivity and validate our modelling approach with data from real boreholes. Boreholes are effective in reducing the impact of wind turbines; however, this depends on the wavelength of the seismic wave.
Sebastian Hellmann, Melchior Grab, Cedric Patzer, Andreas Bauder, and Hansruedi Maurer
Solid Earth, 14, 805–821, https://doi.org/10.5194/se-14-805-2023, https://doi.org/10.5194/se-14-805-2023, 2023
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Acoustic waves are suitable to analyse the physical properties of the subsurface. For this purpose, boreholes are quite useful to deploy a source and receivers in the target area to get a comprehensive high-resolution dataset. However, when conducting such experiments in a subsurface such as glaciers that continuously move, the boreholes get deformed. In our study, we therefore developed a method that allows an analysis of the ice while considering deformations.
Laura A. Ermert, Enrique Cabral-Cano, Estelle Chaussard, Darío Solano-Rojas, Luis Quintanar, Diana Morales Padilla, Enrique A. Fernández-Torres, and Marine A. Denolle
Solid Earth, 14, 529–549, https://doi.org/10.5194/se-14-529-2023, https://doi.org/10.5194/se-14-529-2023, 2023
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Mexico City is built on a unique ground containing the clay-rich sediments of the ancient lake Texcoco. Continuous imperceptible shaking of these deposits by city traffic and other sources allows us to monitor changes in the subsurface seismic wave speed. Wave speed varies seasonally, likely due to temperature and rain effects; it temporarily drops after large earthquakes then starts to recover. Throughout the studied period, it increased on average, which may be related to soil compaction.
Laura Anna Ermert, Maria Koroni, and Naiara Korta Martiartu
Solid Earth, 14, 485–498, https://doi.org/10.5194/se-14-485-2023, https://doi.org/10.5194/se-14-485-2023, 2023
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We investigate women's representation in seismology to raise awareness of existing gender disparities.
By analysing the authorship of peer-reviewed articles, we identify lower representation of women among single authors, high-impact authors, and highly productive authors. Seismology continues to be a male-dominated field, and trends suggest that parity is decades away. These gaps are an obstacle to women’s career advancement and, if neglected, may perpetuate the leaky-pipeline problem.
Jordi Díaz, Sergi Ventosa, Martin Schimmel, Mario Ruiz, Albert Macau, Anna Gabàs, David Martí, Özgenç Akin, and Jaume Vergés
Solid Earth, 14, 499–514, https://doi.org/10.5194/se-14-499-2023, https://doi.org/10.5194/se-14-499-2023, 2023
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We assess the capability of multiple methods based on the interpretation of seismic noise to map the basement of the Cerdanya Basin, located in the eastern Pyrenees. Basement depth estimations retrieved from the different approaches are consistent, with maximum depths reaching 700 m close to the Têt fault bounding the basin to the east. Our results prove that seismic noise analysis using high-density networks is an excellent tool to improve the geological characterization of sedimentary basins.
Zahra Zali, Theresa Rein, Frank Krüger, Matthias Ohrnberger, and Frank Scherbaum
Solid Earth, 14, 181–195, https://doi.org/10.5194/se-14-181-2023, https://doi.org/10.5194/se-14-181-2023, 2023
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Investigation of the global Earth's structure benefits from the analysis of ocean bottom seismometer (OBS) data that allow an improved seismic illumination of dark spots of crustal and mantle structures in the oceanic regions of the Earth. However, recordings from the ocean bottom are often highly contaminated by noise. We developed an OBS noise reduction algorithm, which removes much of the oceanic noise while preserving the earthquake signal and does not introduce waveform distortion.
Jerome Azzola, Katja Thiemann, and Emmanuel Gaucher
EGUsphere, https://doi.org/10.5194/egusphere-2022-1417, https://doi.org/10.5194/egusphere-2022-1417, 2022
Preprint archived
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Distributed Acoustic Sensing is applied to the micro-seismic monitoring of a geothermal plant. In this domain, the feasibility of managing the large flow of generated data and their suitability to monitor locally induced seismicity was yet to be assessed. The proposed monitoring system efficiently managed the acquisition, processing and saving of the data over a 6-month period. This testing period proved that the monitoring concept advantageously complements more classical monitoring networks.
Heather Kennedy, Katrin Löer, and Amy Gilligan
Solid Earth, 13, 1843–1858, https://doi.org/10.5194/se-13-1843-2022, https://doi.org/10.5194/se-13-1843-2022, 2022
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The energy transition is an important topic for benefiting the future; thus renewable energy is required to reach net-zero carbon emission goals. Geothermal energy, heat from the ground, can be used in this transition. Therefore, geothermal fields need to be characterized as much as possible to allow for increased productivity within these fields. This study involves and looks at potential fractures within a geothermal field at depth to help increase the overall understanding of this field.
Roberto Cabieces, Mariano S. Arnaiz-Rodríguez, Antonio Villaseñor, Elizabeth Berg, Andrés Olivar-Castaño, Sergi Ventosa, and Ana M. G. Ferreira
Solid Earth, 13, 1781–1801, https://doi.org/10.5194/se-13-1781-2022, https://doi.org/10.5194/se-13-1781-2022, 2022
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This paper presents a new 3D shear-wave velocity model of the lithosphere of northeastern Venezuela, including new Moho and Vp / Vs maps. Data were retrieved from land and broadband ocean bottom seismometers from the BOLIVAR experiment.
Megha Chakraborty, Wei Li, Johannes Faber, Georg Rümpker, Horst Stoecker, and Nishtha Srivastava
Solid Earth, 13, 1721–1729, https://doi.org/10.5194/se-13-1721-2022, https://doi.org/10.5194/se-13-1721-2022, 2022
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Earthquake magnitude is a crucial parameter in defining its damage potential, and hence its speedy determination is essential to issue an early warning in regions close to the epicentre. This study summarises our findings in an attempt to apply deep-learning-based classifiers to earthquake waveforms, particularly with respect to finding an optimum length of input data. We conclude that the input length has no significant effect on the model accuracy, which varies between 90 %–94 %.
Carola Leva, Georg Rümpker, and Ingo Wölbern
Solid Earth, 13, 1243–1258, https://doi.org/10.5194/se-13-1243-2022, https://doi.org/10.5194/se-13-1243-2022, 2022
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The seismicity of Fogo and Brava, Cape Verde, is dominated by volcano-tectonic earthquakes in the area of Brava and volcanic seismic signals, such as hybrid events, on Fogo. We locate these events using a multi-array analysis, which allows the localization of seismic events occurring outside the network and of volcanic signals lacking clear phases. We observe exceptionally high apparent velocities for the hybrid events located on Fogo. These velocities are likely caused by a complex ray path.
Michal Chamarczuk, Michal Malinowski, Deyan Draganov, Emilia Koivisto, Suvi Heinonen, and Sanna Rötsä
Solid Earth, 13, 705–723, https://doi.org/10.5194/se-13-705-2022, https://doi.org/10.5194/se-13-705-2022, 2022
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In passive seismic measurement, all noise sources from the environment, such as traffic, vibrations caused by distant excavation, and explosive work from underground mines, are utilized. In the Kylylahti experiment, receivers recorded ambient noise sources for 30 d. These recordings were subjected to data analysis and processing using novel methodology developed in our study and used for imaging the subsurface geology of the Kylylahti mine area.
Jorge Acevedo, Gabriela Fernández-Viejo, Sergio Llana-Fúnez, Carlos López-Fernández, Javier Olona, and Diego Pérez-Millán
Solid Earth, 13, 659–679, https://doi.org/10.5194/se-13-659-2022, https://doi.org/10.5194/se-13-659-2022, 2022
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The NW Iberian Peninsula provides one of the most complete Variscan sections in Europe, showing the transition between a sedimentary domain with folds and thrust and a metamorphic domain with igneous intrusions. By processing the seismic ambient noise recorded by several seismograph networks in this area, new 3-D S-wave velocity and radial anisotropy models were created. These models reveal the limit between the two domains, delineating the core of the large western European Variscan Belt.
Thierry Camelbeeck, Koen Van Noten, Thomas Lecocq, and Marc Hendrickx
Solid Earth, 13, 469–495, https://doi.org/10.5194/se-13-469-2022, https://doi.org/10.5194/se-13-469-2022, 2022
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Over the 20th century, shallow damaging seismicity occurred in and near the Hainaut coal mining area in Belgium. We provide an overview of earthquake parameters and impacts, combining felt and damage testimonies and instrumental measurements. Shallower earthquakes have a depth and timing compatible with mining activity. The most damaging events occurred deeper than the mines but could still have been triggered by mining-caused crustal changes. Our modelling can be applied to other regions.
Nicola Piana Agostinetti, Alberto Villa, and Gilberto Saccorotti
Solid Earth, 13, 449–468, https://doi.org/10.5194/se-13-449-2022, https://doi.org/10.5194/se-13-449-2022, 2022
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Sensing the Earth is a fundamental operation for the future where georesources, like geothermal energy and CO2 underground storage, will become important tools for addressing societal challenges. The development of networks of optical fibre cables gives the possibility of a sensing grid with an unprecedented spatial coverage. Here, we investigate the potential of using portions of a optical fibre cable as a standard seismometer for exploring the subsurface and monitoring georesources.
Carolin M. Boese, Grzegorz Kwiatek, Thomas Fischer, Katrin Plenkers, Juliane Starke, Felix Blümle, Christoph Janssen, and Georg Dresen
Solid Earth, 13, 323–346, https://doi.org/10.5194/se-13-323-2022, https://doi.org/10.5194/se-13-323-2022, 2022
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Hydraulic stimulation experiments in underground facilities allow for placing monitoring equipment close to and surrounding the stimulated rock under realistic and complex conditions at depth. We evaluate how accurately the direction-dependent velocity must be known for high-resolution seismic monitoring during stimulation. Induced transient deformation in rocks only 2.5–5 m apart may differ significantly in magnitude and style, and monitoring requires sensitive sensors adapted to the frequency.
Jaroslava Plomerová, Helena Žlebčíková, György Hetényi, Luděk Vecsey, Vladislav Babuška, and AlpArray-EASI and AlpArray working
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Solid Earth, 13, 251–270, https://doi.org/10.5194/se-13-251-2022, https://doi.org/10.5194/se-13-251-2022, 2022
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We present high-resolution tomography images of upper mantle structure beneath the E Alps and the adjacent Bohemian Massif. The northward-dipping lithosphere, imaged down to ∼200 km beneath the E Alps without signs of delamination, is probably formed by a mixture of a fragment of detached European plate and the Adriatic plate subductions. A detached high-velocity anomaly, sub-parallel to and distinct from the E Alps heterogeneity, is imaged at ∼100–200 km beneath the southern part of the BM.
Gregor Rajh, Josip Stipčević, Mladen Živčić, Marijan Herak, Andrej Gosar, and the AlpArray Working Group
Solid Earth, 13, 177–203, https://doi.org/10.5194/se-13-177-2022, https://doi.org/10.5194/se-13-177-2022, 2022
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We investigated the 1-D velocity structure of the Earth's crust in the NW Dinarides with inversion of arrival times from earthquakes. The obtained velocity models give a better insight into the crustal structure and show velocity variations among different parts of the study area. In addition to general structural implications and a potential for improving further work, the results of our study can also be used for routine earthquake location and for detecting errors in seismological bulletins.
Guido Maria Adinolfi, Raffaella De Matteis, Rita de Nardis, and Aldo Zollo
Solid Earth, 13, 65–83, https://doi.org/10.5194/se-13-65-2022, https://doi.org/10.5194/se-13-65-2022, 2022
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We propose a methodology useful to evaluate (1) the reliability of a focal mechanism solution inferred by the inversion of seismological data and (2) the performance of a seismic network, operated to monitor natural or induced seismicity, to assess focal mechanism solutions. As a test case, we studied the focal mechanism reliability by using synthetic data computed for ISNet, a local seismic network monitoring the Irpinia fault system (southern Italy).
Nicola Piana Agostinetti and Giulia Sgattoni
Solid Earth, 12, 2717–2733, https://doi.org/10.5194/se-12-2717-2021, https://doi.org/10.5194/se-12-2717-2021, 2021
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One of the present-day challenges for geoscientists is tackling the big data revolution. An ever-growing amount of data needs to be processed and data are subjectively handled before using them to make inferences on the Earth’s interior. But imposing subjective decisions on the data might have strong influences on the final outputs. Here we present a totally novel and automatic application for screening the data and for defining data volumes that are consistent with physical hypotheses.
Marcel Paffrath, Wolfgang Friederich, Stefan M. Schmid, Mark R. Handy, and the AlpArray and AlpArray-Swath D Working Group
Solid Earth, 12, 2671–2702, https://doi.org/10.5194/se-12-2671-2021, https://doi.org/10.5194/se-12-2671-2021, 2021
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The Alpine mountain belt was formed by the collision of the Eurasian and African plates in the geological past, during which parts of the colliding plates sank into the earth's mantle. Using seismological data from distant earthquakes recorded by the AlpArray Seismic Network, we have derived an image of the current location of these subducted parts in the earth's mantle. Their quantity and spatial distribution is key information needed to understand how the Alpine orogen was formed.
Felix N. Wolf, Dietrich Lange, Anke Dannowski, Martin Thorwart, Wayne Crawford, Lars Wiesenberg, Ingo Grevemeyer, Heidrun Kopp, and the AlpArray Working Group
Solid Earth, 12, 2597–2613, https://doi.org/10.5194/se-12-2597-2021, https://doi.org/10.5194/se-12-2597-2021, 2021
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The Ligurian Sea opened ~30–15 Ma during SE migration of the Calabrian subduction zone. Using ambient seismic noise from stations on land and at the ocean bottom, we calculated a 3D shear-velocity model of the Ligurian Basin. In keeping with existing 2D studies, we find a shallow crust–mantle transition at the SW basin centre that deepens towards the northeast, Corsica, and the Liguro-Provençal coast. We observe a separation of SW and NE basins. We do not observe high crustal vP/vS ratios.
Martin Thorwart, Anke Dannowski, Ingo Grevemeyer, Dietrich Lange, Heidrun Kopp, Florian Petersen, Wayne C. Crawford, Anne Paul, and the AlpArray Working Group
Solid Earth, 12, 2553–2571, https://doi.org/10.5194/se-12-2553-2021, https://doi.org/10.5194/se-12-2553-2021, 2021
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We analyse broadband ocean bottom seismometer data of the AlpArray OBS network in the Ligurian Basin. Two earthquake clusters with thrust faulting focal mechanisms indicate compression of the rift basin. The locations of seismicity suggest reactivation of pre-existing rift structures and strengthening of crust and uppermost mantle during rifting-related extension. Slightly different striking directions of faults may mimic the anti-clockwise rotation of the Corsica–Sardinia block.
Rainer Kind, Stefan M. Schmid, Xiaohui Yuan, Benjamin Heit, Thomas Meier, and the AlpArray and AlpArray-SWATH-D Working Groups
Solid Earth, 12, 2503–2521, https://doi.org/10.5194/se-12-2503-2021, https://doi.org/10.5194/se-12-2503-2021, 2021
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A large amount of new seismic data from the greater Alpine area have been obtained within the AlpArray and SWATH-D projects. S-to-P converted seismic phases from the Moho and from the mantle lithosphere have been processed with a newly developed method. Examples of new observations are a rapid change in Moho depth at 13° E below the Tauern Window from 60 km in the west to 40 km in the east and a second Moho trough along the boundary of the Bohemian Massif towards the Western Carpathians.
Bogdan Grecu, Felix Borleanu, Alexandru Tiganescu, Natalia Poiata, Raluca Dinescu, and Dragos Tataru
Solid Earth, 12, 2351–2368, https://doi.org/10.5194/se-12-2351-2021, https://doi.org/10.5194/se-12-2351-2021, 2021
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The lockdown imposed in Romania to prevent the spread of COVID-19 has significantly impacted human activity across the country. By analyzing the ground vibrations recorded at seismic stations, we were able to monitor the changes in human activity before and during the lockdown.
The reduced human activity during the lockdown has also provided a good opportunity for stations sited in noisy urban areas to record earthquake signals that would not have been recorded under normal conditions.
Ruth Keppler, Roman Vasin, Michael Stipp, Tomás Lokajícek, Matej Petruzálek, and Nikolaus Froitzheim
Solid Earth, 12, 2303–2326, https://doi.org/10.5194/se-12-2303-2021, https://doi.org/10.5194/se-12-2303-2021, 2021
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Rocks in mountain belts have been deformed during continental collision causing a certain alignment of the minerals referred to as crystallographic preferred orientation (CPO). Minerals have anisotropic properties: the velocity of seismic waves travelling through them is direction dependent. This leads to anisotropy of the rocks. We measured the CPO of common rocks within the Alps. With this data and known anisotropic properties of the minerals we calculated the seismic anisotropy of the rocks.
Mario Arroyo-Solórzano, Diego Castro-Rojas, Frédérick Massin, Lepolt Linkimer, Ivonne Arroyo, and Robin Yani
Solid Earth, 12, 2127–2144, https://doi.org/10.5194/se-12-2127-2021, https://doi.org/10.5194/se-12-2127-2021, 2021
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We present the first seismic noise variation levels during COVID-19 in Central America using 10 seismometers. We study the impact of the seismic noise reduction on the detectability of earthquakes and on the felt reports. Our results show maximum values (~50 % decrease) at seismic stations near airports and densely inhabited cities. The decrease in seismic noise improved earthquake locations and reports. Seismic noise could also be useful to verify compliance with lockdown measures.
Laura Peruzza, Alessandra Schibuola, Maria Adelaide Romano, Marco Garbin, Mariangela Guidarelli, Denis Sandron, and Enrico Priolo
Solid Earth, 12, 2021–2039, https://doi.org/10.5194/se-12-2021-2021, https://doi.org/10.5194/se-12-2021-2021, 2021
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In weakly seismic or poorly monitored areas, the uncritical use of earthquake catalogues can be misleading. This is the case for a central sector in the Po Valley, where the Northern Apennines and Southern Alps collide. We collect and reprocess the available instrumental data of about 300 earthquakes from 1951 to 2019. The seismicity is weak, deeper than expected, and far from some existing human activities carried out underground. The potential tectonic causative sources are still unknown.
Fabian Limberger, Michael Lindenfeld, Hagen Deckert, and Georg Rümpker
Solid Earth, 12, 1851–1864, https://doi.org/10.5194/se-12-1851-2021, https://doi.org/10.5194/se-12-1851-2021, 2021
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Frequency-dependent amplitude decays of seismic signals induced by wind turbines are determined from (up to) 6 months of continuous recordings measured along an 8 km profile located at a wind farm in Bavaria, Germany. The radiation pattern and amplitude decay of the induced signals are accounted for by an analytical approach that includes path and source effects. This approach is generalized to predict the characteristic seismic radiation patterns of arbitrary wind farm configurations.
Alessio Spurio Mancini, Davide Piras, Ana Margarida Godinho Ferreira, Michael Paul Hobson, and Benjamin Joachimi
Solid Earth, 12, 1683–1705, https://doi.org/10.5194/se-12-1683-2021, https://doi.org/10.5194/se-12-1683-2021, 2021
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The localization of an earthquake is affected by many uncertainties. To correctly propagate these uncertainties into an estimate of the earthquake coordinates and their associated errors, many simulations of seismic waves are needed. This operation is computationally very intensive, hindering the feasibility of this approach. In this paper, we present a series of deep-learning methods to produce accurate seismic traces in a fraction of the time needed with standard methods.
Marguerite Mathey, Christian Sue, Colin Pagani, Stéphane Baize, Andrea Walpersdorf, Thomas Bodin, Laurent Husson, Estelle Hannouz, and Bertrand Potin
Solid Earth, 12, 1661–1681, https://doi.org/10.5194/se-12-1661-2021, https://doi.org/10.5194/se-12-1661-2021, 2021
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This work features the highest-resolution seismic stress and strain fields available at the present time for the analysis of the active crustal deformation of the Western Alps. In this paper, we address a large dataset of newly computed focal mechanisms from a statistical standpoint, which allows us to suggest a joint control from far-field forces and from buoyancy forces on the present-day deformation of the Western Alps.
Marcel Paffrath, Wolfgang Friederich, and the AlpArray and AlpArray-SWATH D Working Groups
Solid Earth, 12, 1635–1660, https://doi.org/10.5194/se-12-1635-2021, https://doi.org/10.5194/se-12-1635-2021, 2021
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Using the AlpArray seismic network, we have determined highly accurate travel times of P waves from over 370 major global earthquakes between 2015 and 2019, which shall be used for a tomography of the mantle beneath the greater Alpine region.
Comparing with theoretical travel times of a standard reference earth model, we receive very stable patterns of travel-time differences across the network which provide evidence of varying subduction behaviour along the strike of the Alpine orogen.
Itzhak Lior, Anthony Sladen, Diego Mercerat, Jean-Paul Ampuero, Diane Rivet, and Serge Sambolian
Solid Earth, 12, 1421–1442, https://doi.org/10.5194/se-12-1421-2021, https://doi.org/10.5194/se-12-1421-2021, 2021
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The increasing use of distributed acoustic sensing (DAS) inhibits the transformation of optical fibers into dense arrays of seismo-acoustic sensors. Here, DAS strain records are converted to ground motions using the waves' apparent velocity. An algorithm for velocity determination is presented, accounting for velocity variations between different seismic waves. The conversion allows for robust determination of fundamental source parameters, earthquake magnitude and stress drop.
Sarah Mader, Joachim R. R. Ritter, Klaus Reicherter, and the AlpArray Working Group
Solid Earth, 12, 1389–1409, https://doi.org/10.5194/se-12-1389-2021, https://doi.org/10.5194/se-12-1389-2021, 2021
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The Albstadt Shear Zone, SW Germany, is an active rupture zone with sometimes damaging earthquakes but no visible surface structure. To identify its segmentations, geometry, faulting pattern and extension, we analyze the continuous earthquake activity in 2011–2018. We find a segmented N–S-oriented fault zone with mainly horizontal and minor vertical movement along mostly NNE- and some NNW-oriented rupture planes. The main horizontal stress is oriented NW and due to Alpine-related loading.
Gesa Maria Petersen, Simone Cesca, Sebastian Heimann, Peter Niemz, Torsten Dahm, Daniela Kühn, Jörn Kummerow, Thomas Plenefisch, and the AlpArray and AlpArray-Swath-D working groups
Solid Earth, 12, 1233–1257, https://doi.org/10.5194/se-12-1233-2021, https://doi.org/10.5194/se-12-1233-2021, 2021
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The Alpine mountains are known for a complex tectonic history. We shed light onto ongoing tectonic processes by studying rupture mechanisms of small to moderate earthquakes between 2016 and 2019 observed by the temporary AlpArray seismic network. The rupture processes of 75 earthquakes were analyzed, along with past earthquakes and deformation data. Our observations point at variations in the underlying tectonic processes and stress regimes across the Alps.
Azam Jozi Najafabadi, Christian Haberland, Trond Ryberg, Vincent F. Verwater, Eline Le Breton, Mark R. Handy, Michael Weber, and the AlpArray and AlpArray SWATH-D working groups
Solid Earth, 12, 1087–1109, https://doi.org/10.5194/se-12-1087-2021, https://doi.org/10.5194/se-12-1087-2021, 2021
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This study achieved high-precision hypocenters of 335 earthquakes (1–4.2 ML) and 1D velocity models of the Southern and Eastern Alps. The general pattern of seismicity reflects head-on convergence of the Adriatic Indenter with the Alpine orogenic crust. The relatively deeper seismicity in the eastern Southern Alps and Giudicarie Belt indicates southward propagation of the Southern Alpine deformation front. The derived hypocenters form excellent data for further seismological studies, e.g., LET.
Javier Ojeda and Sergio Ruiz
Solid Earth, 12, 1075–1085, https://doi.org/10.5194/se-12-1075-2021, https://doi.org/10.5194/se-12-1075-2021, 2021
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In Santiago, Chile, the lockdown imposed due to COVID-19 was recorded by seismological instruments. This analysis shows temporal changes in the surface vibrations controlled by lockdown phases, mobility, and epidemiological factors. Our findings suggest that
dynamic lockdownand the early deconfinement in April 2020 caused an increase in mobility and therefore virus transmission. We propose that seismic networks could be used to monitor urban mobility as a new proxy in public policies.
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Short summary
We estimate variations of the crustal thickness beneath the Nepal Himalayas based on tomographic inversion of regional earthquake data. The obtained variations of crustal thickness match fairly well with the free-air gravity anomalies and correlate with magnetic field. We propose that elevated magnetic values can be associated with more rigid segments of the incoming Indian crust which cause more compression in the thrust zone and lead to stronger crustal thickening.
We estimate variations of the crustal thickness beneath the Nepal Himalayas based on tomographic...
