Johannes Schweitzer

• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter & Schweitzer, Johannes (2025). Balloon seismology enables subsurface inversion without ground stations. Communications Earth & Environment. 6, p. 1–12. doi: 10.1038/s43247-025-02917-7. Full text in Research Archive Show summary

  Earth’s interior structure is derived primarily from data recorded by ground-based seismometers. Such instruments would provide essential insight into the composition and evolution of Venus, but harsh surface conditions hinder their deployment. Balloon-borne seismology offers an alternative by capturing upper-atmospheric infrasonic signatures of seismic waves. We show that subsurface seismic velocities and earthquake source location can be jointly inverted from balloon observations. We demonstrate this method using infrasound signals recorded by four stratospheric balloons following a major earthquake in the Flores Sea, Indonesia. A Bayesian inversion using Markov chain Monte Carlo sampling is implemented to account for trade-offs in the joint location and subsurface velocity estimation. The inverted seismic parameters are consistent with results obtained using ground-based seismometers. This demonstration of the ability to estimate source and velocity parameters without ground deployments motivates further development of seismo-acoustic mission concepts to Venus, and provides new opportunities for seismic exploration in remote Earth regions.

• Schweitzer, Johannes (2025). Travel-Time Corrections for Seismic Event Locations. Journal of the Geological Society of India. ISSN 0016-7622. 101(6), p. 754–758. doi: 10.17491/jgsi/2025/174155. Full text in Research Archive Show summary

  The calculation of theoretical seismic travel times for the location of seismic events can become quite complex because of the differences between the real Earth and standardized mean Earth models. This short contribution explains how such differences in crustal structure and topography at the observing stations or at reflexion points of seismic phases can be addressed and travel-time corrections calculated.

• Jerkins, Annie Elisabeth; Schweitzer, Johannes; Kettlety, Tom; Martuganova, Evgeniia; Kühn, Daniela & Oye, Volker (2025). Relocating seismic events in the North Sea: challenges and insights for earthquake analysis. Geophysical Journal International. ISSN 0956-540X. 241(1), p. 728–742. doi: 10.1093/gji/ggaf068. Full text in Research Archive Show summary

  In this paper, we present a catalogue of relocated seismic events in the North Sea spanning 1961 to 2022. Data from all relevant agencies were combined, incorporating all available seismic phase readings, thereby enhancing station coverage. As a result, our updated locations reveal a more clustered and aligned seismicity pattern compared with the original catalogue. Even with our combined data set, only 157 of the 7089 relocated events have azimuthal gaps of less than 90 deg. Additionally, the distances between onshore stations and offshore events are considerable. Both of these factors lead to relatively poorly constrained hypocentres for most events. We therefore evaluate the performance of 1-D velocity models routinely used by different North Sea adjacent monitoring agencies for earthquake location estimations in the North Sea. The variations in assessments due to the seismic velocity model used are significantly larger than the uncertainty ellipses calculated in the relocation, demonstrating that arithmetic uncertainties systematically underestimate location uncertainties in this setting. Obtaining a realistic estimate of location uncertainty is however crucial, particularly for distinguishing between natural and induced seismicity. This is fundamental to safe monitoring of the North Sea offshore industries, including geological storage. To overcome these discrepancies between the uncertainty ellipses and our multiple relocations, we introduce an alternative method that accounts for variability in the 1-D velocity models. This approach enhances the reliability of the earthquake catalogue, and provides a more robust assessment of seismic activity in the North Sea.

• Kettlety, Tom; Martuganova, Evgeniia; Kühn, Daniela; Schweitzer, Johannes; Weemstra, Cornelis & Baptie, Brian [Show all 11 contributors for this article] (2024). A unified earthquake catalogue for the North Sea to derisk European CCS operations. First Break. ISSN 0263-5046. 42(5), p. 31–36. doi: 10.3997/1365-2397.fb2024036. Full text in Research Archive
• Pedersen, Christina Alsvik; Njåstad, Birgit; Aas, Wenche; Darelius, Elin Maria K.; Descamps, Sebastien & Flått, Stig [Show all 13 contributors for this article] (2024). The Troll Observing Network (TONe): plugging observation holes in Dronning Maud Land, Antarctica. Polar Research. ISSN 0800-0395. 43. doi: 10.33265/polar.v43.10370. Full text in Research Archive Show summary

  Understanding how Antarctica is changing and how these changes influence the rest of the Earth is fundamental to the future robustness of human society. Strengthening our understanding of these changes and their implications requires dedicated, sustained and coordinated observations of key Antarctic indicators. The Troll Observing Network (TONe), now under development, is Norway’s contribution to the global need for sustained, coordinated, complementary and societally relevant observations from Antarctica. When fully implemented within the coming three years, TONe will be a state-of-the-art, multi-platform, multi-disciplinary observing network in data-sparse Dronning Maud Land. A critical part of the network is a data management system that will ensure broad, free access to all TONe data to the international research community.

• Dando, Benjamin; Goertz-Allmann, Bettina; Brissaud, Quentin; Köhler, Andreas; Schweitzer, Johannes & Kværna, Tormod [Show all 7 contributors for this article] (2023). Identifying attacks in the Russia–Ukraine conflict using seismic array data. Nature. ISSN 0028-0836. doi: 10.1038/s41586-023-06416-7. Full text in Research Archive Show summary

  Seismometers are generally used by the research community to study local or distant earthquakes, but seismograms also contain critical observations from regional1,2 and global explosions3, which can be used to better understand conflicts and identify potential breaches of international law. Although seismic, infrasound and hydroacoustic technology is used by the International Monitoring System4 to monitor nuclear explosions as part of the Comprehensive Nuclear-Test-Ban Treaty, the detection and location of lower-yield military attacks requires a network of sensors much closer to the source of the explosions. Obtaining comprehensive and objective data that can be used to effectively monitor an active conflict zone therefore remains a substantial challenge. Here we show how seismic waves generated by explosions in northern Ukraine and recorded by a local network of seismometers can be used to automatically identify individual attacks in close to real time, providing an unprecedented view of an active conflict zone. Between February and November 2022, we observed more than 1,200 explosions from the Kyiv, Zhytomyr and Chernihiv provinces, providing accurate origin times, locations and magnitudes. We identify a range of seismoacoustic signals associated with various types of military attack, with the resulting catalogue of explosions far exceeding the number of publicly reported attacks. Our results demonstrate that seismic data can be an effective tool for objective monitoring of a continuing conflict, providing invaluable information about potential breaches of international law.

• Schweitzer, Johannes (2023). Foundation of the Deutsche Geophysikalische Gesellschaft in its international context. History of Geo- and Space Sciences. ISSN 2190-5010. 14(1), p. 15–22. doi: 10.5194/hgss-14-15-2023. Full text in Research Archive
• Schweitzer, Johannes (2022). Die Gründung der Deutschen Geophysikalischen Gesellschaft im Rahmen der internationalen Beziehungen zu Beginn des zwanzigsten Jahrhunderts. Mitteilungen der Deutschen Geophysikalischen Gesellschaft. ISSN 0934-6554. Full text in Research Archive
• Schweitzer, Johannes (2022). An Unknown Letter of Charles F. Richter about Magnitude Scales and His Relationship to Beno Gutenberg. Seismological Research Letters. ISSN 0895-0695. 93(1), p. 458–464. doi: 10.1785/0220210212. Full text in Research Archive Show summary

  Abstract I document here an unknown letter from Charles F. Richter to Arthur Gutenberg addressing the development of the magnitude scales and Richter’s relationship to Beno Gutenberg. Added to the letter are a description of its background, how it became known, and explanations about its historical contents.

• Schweitzer, Johannes; Paulsen, Berit; Antonovskaya, Galina N.; Fedorov, Andrey V.; Konechnaya, Yana V. & Asming, Vladimir Ernest [Show all 7 contributors for this article] (2021). A 24-yr-long seismic bulletin for the European Arctic. Seismological Research Letters. ISSN 0895-0695. 92(5), p. 2758–2767. doi: 10.1785/0220210018. Full text in Research Archive
• Pirli, Myrto; Schweitzer, Johannes; Paulsen, Berit; Konechnaya, Yana & Antonovskaya, Galina (2021). Two decades of seismicity in Storfjorden, Svalbard archipelago, from regional data. Seismological Research Letters. ISSN 0895-0695. 92(5), p. 2695–2704. doi: 10.1785/0220200469. Full text in Research Archive
• Schweitzer, Johannes; Köhler, Andreas & Christensen, Jon Magnus (2021). Development of the NORSAR Network over the Last 50 Yr. Seismological Research Letters. ISSN 0895-0695. 92, p. 1501–1511. doi: 10.1785/0220200375. Full text in Research Archive Show summary

  This contribution describes the development of Norwegian Seismic Array (NORSAR), from its origin 50 yr ago as a project for installing a single seismic array in southern Norway to a seismological research institute operating a network of six arrays and 14 three‐component stations located in Norway and Antarctica. In addition, we document the different instrumentations from narrowband, mostly short‐period sensors to today’s broadband seismometers that are installed at almost all sites.

• Jerkins, Annie; Shiddiqi, Hasbi Ash; Kværna, Tormod; Gibbons, Steven John; Schweitzer, Johannes & Ottemöller, Lars [Show all 7 contributors for this article] (2020). The 30 June 2017 North Sea Earthquake: Location, Characteristics, and Context. Bulletin of The Seismological Society of America (BSSA). ISSN 0037-1106. 110(2), p. 937–952. doi: 10.1785/0120190181. Full text in Research Archive Show summary

  The Mw 4.5 southern Viking graben earthquake on 30 June 2017 was one of the largest seismic events in the Norwegian part of the North Sea during the last century. It was well recorded on surrounding broadband seismic stations at regional distances, and it generated high signal-to noise ratio teleseismic P arrivals at up to 90° with good azimuthal coverage. Here, the teleseismic signals provide a unique opportunity to constrain the event hypocenter. Depth phases are visible globally and indicate a surface reflection in the P-wave coda some 4 s after the initial P arrival, giving a much better depth constraint than regional S-P time differences provide. Moment tensor inversion results in a reverse thrust faulting mechanism. The fit between synthetic and observed surface waves at regional distances is improved by including a sedimentary layer. Synthetic teleseismic waveforms generated based on the moment tensor solution, and a near-source 1D velocity model indicates a depth of 7 km. Correlation detectors using the S-wave coda from the main event were run on almost 30 yr of continuous multichannel seismic data searching for repeating signals. In addition to a magnitude 1.9 aftershock 33 min later, and a few magnitude ∼1 events in the following days, a magnitude 2.5 earthquake on 13 November 2016 was the only event found to match the 30 June 2017 event well. Using double-difference techniques, we find that the two largest events are located within 1 km of the main event. We present a Bayesloc probabilistic multiple event location including the 30 June event and all additional seismic events in the region well recorded on the regional networks. The Bayesloc relocation gave a more consistent seismicity pattern and moved several of the events more toward the west. The results of this study are also discussed within the regional seismotectonic frame of reference.

• Schweitzer, Johannes & Lay, Thorne (2019). IASPEI: Its origins and the promotion of global seismology. History of Geo- and Space Sciences. ISSN 2190-5010. 10(1), p. 173–180. doi: 10.5194/hgss-10-173-2019. Full text in Research Archive Show summary

  International cooperation in seismology emerged rapidly at the beginning of the 20th century following the successful recording of earthquakes at great distances. The International Seismological Association (ISA) founded in 1904 was dissolved in 1922 and evolved into the Seismology Section of the International Union of Geodesy and Geophysics (IUGG), ultimately becoming the International Association of Seismology and Physics of the Earth's Interior (IASPEI) to recognize the important role of the structure and physical properties of the Earth. Through the last hundred years, the commissions and working groups of the association have played a major role in setting international standards in such areas as the naming of seismic phases, data exchanges, travel-time tables, magnitude scales, and reference Earth models. The activities of IASPEI continue to have a focus on the societal impacts of earthquakes and tsunamis, with four regional commissions playing a major role in promoting high standards of seismological education, outreach, and international scientific cooperation.

• Pirli, Myrto & Schweitzer, Johannes (2018). Seismicity along the Mohns—Knipovich Ridge Bend and its correlation to ridge spreading rate. Journal of Geodynamics. ISSN 0264-3707. 118, p. 182–196. doi: 10.1016/j.jog.2018.01.013. Full text in Research Archive
• Pirli, Myrto; Hainzl, S.; Schweitzer, Johannes; Köhler, Andreas & Dahm, Torsten (2018). Localised thickening and grounding of an Antarctic ice shelf from tidal triggering and sizing of cryoseismicity. Earth and Planetary Science Letters. ISSN 0012-821X. 503, p. 78–87. doi: 10.1016/j.epsl.2018.09.024. Full text in Research Archive
• Gibbons, Steven John; Schweitzer, Johannes; Kværna, Tormod & Roth, Michael D. (2018). Enhanced detection and estimation of regional S-phases using the 3-component ARCES array. Journal of Seismology. ISSN 1383-4649. doi: 10.1007/s10950-018-9809-y. Full text in Research Archive
• Pirli, Myrto & Schweitzer, Johannes (2017). BARENTS16: a 1-D velocity model for the western Barents Sea. Journal of Seismology. ISSN 1383-4649. 22(1), p. 69–81. doi: 10.1007/s10950-017-9692-y. Full text in Research Archive
• Roy, Corinna; Winter, A.; Ritter, Joachim R.R. & Schweitzer, Johannes (2017). On the improvement of SKS splitting measurements by the Simultaneous Inversion of Multiple Waveforms (SIMW). Geophysical Journal International. ISSN 0956-540X. 208(3), p. 1508–1523. doi: 10.1093/gji/ggw470. Full text in Research Archive
• Gibbons, Steven John; Antonovskaya, Galina; Asming, Vladimir Ernest; Konechnaya, Yana; Kremenetskaya, Elena O. & Kværna, Tormod [Show all 8 contributors for this article] (2016). The 11 October 2010 Novaya Zemlya earthquake: Implications for velocity models and regional event location. Bulletin of The Seismological Society of America (BSSA). ISSN 0037-1106. 106(4), p. 1470–1481. doi: 10.1785/0120150302. Full text in Research Archive
• Köhler, Andreas; Nuth, Christopher; Kohler, Jack; Berthier, Etienne; Weidle, Christian & Schweitzer, Johannes (2016). A 15 year record of frontal glacier ablation rates estimated from seismic data. Geophysical Research Letters. ISSN 0094-8276. 43(23), p. 12,155–12,164. doi: 10.1002/2016GL070589. Full text in Research Archive Show summary

  We present a unique time series of continuous glacier frontal ablation rates with weekly resolution over 15 years estimated from seismic calving observations at Kronebreen, Svalbard. Using linear statistical models, we calibrate the seismic record with 7 years of satellite‐derived frontal ablation measurements. The two basic input parameters required for our models are the cumulative duration of individual seismic calving events and the incompleteness of the seismic record to correct for the effect of seismic background noise. Frontal ablation follows the seasonal glacier speedup, peaking 1–2 months after the melt season maximum. Short‐lived peaks are associated with melt and rain events. Cumulative frontal ablation of Kronebreen between 2001 and 2015 is about 4.0 km3 (3.7 Gt), with the greatest annual loss (0.45 km3) between 2013 and 2014 at the onset of the recent accelerated retreat of the glacier. Our approach provides a potential method for monitoring tidewater glaciers worldwide that have sufficiently close seismic instrumentation. This article was originally published in Geophysical Research Letters. © 2016 American Geophysical Union

• Junek, W.N.; Kværna, Tormod; Pirli, Myrto; Schweitzer, Johannes; Harris, David B. & Woods, M.T. [Show all 7 contributors for this article] (2015). Inferring Aftershock Sequence Properties and Tectonic Structure Using Empircal Detectors. Pure and Applied Geophysics (PAGEOPH). ISSN 0033-4553. 172(2), p. 359–373. doi: 10.1007/s00024-014-0938-0. Full text in Research Archive
• Köhler, Andreas; Nuth, Christopher; Schweitzer, Johannes; Weidle, Christian & Gibbons, Steven John (2015). Regional passive seismic monitoring reveals dynamic glacier activity on Spitsbergen, Svalbard. Polar Research. ISSN 0800-0395. 34. doi: 10.3402/polar.v34.26178. Full text in Research Archive Show summary

  Dynamic glacier activity is increasingly observed through passive seismic monitoring. We analysed near-regional-scale seismicity on the Arctic archipelago of Svalbard to identify seismic icequake signals and to study their spatial–temporal distribution within the 14-year period from 2000 until 2013. This is the first study that uses seismic data recorded on permanent broadband stations to detect and locate icequakes in different regions of Spitsbergen, the main island of the archipelago. A temporary local seismic network and direct observations of glacier calving and surging were used to identify icequake sources. We observed a high number of icequakes with clear spectral peaks between 1 and 8 Hz in different parts of Spitsbergen. Spatial clusters of icequakes could be associated with individual grounded tidewater glaciers and exhibited clear seasonal variability each year with more signals observed during the melt season. Locations at the termini of glaciers, and correlation with visual calving observations in situ at Kronebreen, a glacier in the Kongsfjorden region, show that these icequakes were caused dominantly by calving. Indirect evidence for glacier surging through increased calving seismicity was found in 2003 at Tunabreen, a glacier in central Spitsbergen. Another type of icequake was observed in the area of the Nathorstbreen glacier system. Seismic events occurred upstream of the glacier within a short time period between January and May 2009 during the initial phase of a major glacier surge. This study is the first step towards the generation and implementation of an operational seismic monitoring strategy for glacier dynamics in Svalbard.

• Antonovskaya, Galina; Konechnaya, Yana; Kremenetskaya, Elena O.; Asming, Vladimir; Kværna, Tormod & Schweitzer, Johannes [Show all 7 contributors for this article] (2015). Enhanced earthquake monitoring in the European Artic. Polar Science. ISSN 1873-9652. 9(1), p. 158–167. doi: 10.1016/j.polar.2014.08.003. Full text in Research Archive
• Pirli, Myrto; Matsuoka, Kenichi; Schweitzer, Johannes & Moholdt, Geir (2015). Seismic signals from large, tabular icebergs drifting along the Dronning Maud Land coast, Antarctica, and their significance for iceberg monitoring. Journal of Glaciology. ISSN 0022-1430. 61(227), p. 481–492. doi: 10.3189/2015JoG14J210. Full text in Research Archive
• Junek, W.N.; Kværna, Tormod; Pirli, Myrto; Schweitzer, Johannes; Harris, D.B. & Dodge, D.A. [Show all 8 contributors for this article] (2014). Examination of the Storfjorden aftershock sequence. Seismological Research Letters. ISSN 0895-0695. 85, p. 550–550. Full text in Research Archive
• Schweitzer, Johannes; Pirli, Myrto; Roth, Michael & Kværna, Tormod (2014). TROLL: A new, very broadband seismic station in Antarctica. Seismological Research Letters. ISSN 0895-0695. 85(4), p. 852–862. doi: 10.1785/0220130223. Full text in Research Archive
• Pirli, Myrto; Schweitzer, Johannes & Paulsen, Berit (2013). The Storfjorden, Svalbard, 2008-2012 aftershock sequence: Seismotectonics in a polar environment. Tectonophysics. ISSN 0040-1951. 601, p. 192–205. doi: 10.1016/j.tecto.2013.05.010. Full text in Research Archive

View all works in NVA

• Schweitzer, Johannes (2018). User Manual for HYPOSAT 6 and HYPOMOD 2. GFZ. ISBN 9783980878005. 38 p. Full text in Research Archive

View all works in NVA

• Pedersen, Christina Alsvik; Njåstad, Birgit; Aas, Wenche; Darelius, Elin Maria K.; Descamps, Sebastien & Flått, Stig [Show all 12 contributors for this article] (2026). Sustained Observations from Dronning Maud Land: The TONe Infrastructure. Full text in Research Archive
• Kühn, Daniela; Kettlety, Tom; Martuganova, Evgeniia; Jerkins, Annie Elisabeth; Dichiarante, Anna Maria & Asplet, Joseph [Show all 15 contributors for this article] (2025). Understanding seismicity for risk mitigation of large-scale CO2 injections. Full text in Research Archive Show summary

  Carbon capture and storage (CCS) is a vital component of Europe’s pathway toward net-zero greenhouse gas emissions. As several multi-megaton CO₂ storage projects progress in the North Sea region, a robust understanding of the local and regional seismicity becomes increasingly important. Seismic information helps characterise the tectonic framework, constrain the present-day stress field, and assess how faults may respond to the pressure changes associated with large-scale injection. This knowledge is essential for evaluating containment integrity, improving seismic hazard assessments, and supporting effective communication of subsurface risks. Within the SHARP Storage project, we compiled an extensive and unprecedented North Sea earthquake bulletin by combining data from all major European seismological agencies. After removing duplicates and identifying explosions, the catalogue forms the basis for advanced analyses including refined event relocations, magnitude harmonisation, moment tensor inversion, shear-wave splitting, and stress-drop estimation. Integrating these seismological results with borehole stress measurements and regional geomechanical models enhances our understanding of fault orientations, failure styles, and stress heterogeneity across key storage provinces. This combined framework strengthens our ability to distinguish natural from induced events and underpins updated ground-motion models and regional hazard assessments. By linking long-term seismic observations with geomechanical insights, we improve the foundation for risk mitigation and transparent communication during future CO₂ injection campaigns.

• Jerkins, Annie Elisabeth; Schweitzer, Johannes; Martuganova, Evgeniia; Kühn, Daniela & Oye, Volker (2025). A Relocated Earthquake Catalogue for the North Sea (1961–2022): Challenges and Insights for earthquake analysis. Full text in Research Archive Show summary

  In this study, we present a newly compiled catalogue of relocated seismic events in the North Sea from 1961 to 2022. By combining phase data from multiple monitoring agencies, we improve station coverage, and our new locations reveal a more clustered and aligned seismicity pattern than in the original catalogue. However, most locations remain poorly constrained due to large azimuthal station gaps and significant event–station distances. Only 157 of 7089 events have azimuthal gaps smaller than 90 degrees. To evaluate the impact of these limitations, we examine how standard 1D velocity models—commonly used by monitoring agencies around the North Sea—affect event locations. We find that the choice of velocity model causes greater variation in hypocentre estimates than suggested by formal uncertainty ellipses, indicating that traditional methods often underestimate location error. This has important implications for distinguishing natural from induced seismicity, particularly in areas of offshore development such as CO₂ storage. To improve location reliability, we introduce a complementary relocation approach that incorporates model variability. This approach provides more realistic estimates of location uncertainty for seismic events in the North Sea.

• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter & Schweitzer, Johannes (2025). Behind the paper: Balloon seismology enables subsurface inversion without ground stations. Springer Nature Research Communities. doi: https:/communities.springernature.com/posts/balloon-seismology-enables-subsurface-inversion-without-ground-stations. Full text in Research Archive Show summary

  What if we can’t place a seismometer directly on the ground? Our team has just shown that infrasound waves, recorded by floating balloons, can reveal information about the seismic sources and subsurface. This finding supports the concept of using balloon missions to explore the interior of Venus.

• Froment, Marouchka; Brissaud, Quentin; Näsholm, Sven Peter; Schweitzer, Johannes & Gullbekk, Sophus Bredesen (2025). Revealing the structure of Venus' interiors using planetary rumbles. Full text in Research Archive Show summary

  Seismology has been remarkably successful in probing the interior structure of the Earth, the Moon, and more recently Mars. Could it achieve the same on Venus, and reveal what hides beneath the surface of this mysterious and hellish twin of Earth ? Venus’ surface conditions make the deployments of ground-based seismometers challenging. Instead, several mission concepts have proposed to record venusquakes from above, leveraging the conversion of seismic waves into acoustic waves in the dense atmosphere. Could seismology be conducted from floating balloons, or through satellite imaging ? To explore this possibility, we gather insights from balloon campaigns on Earth and from modeling.

• Goertz-Allmann, Bettina; Dando, Benjamin; Köhler, Andreas; Brissaud, Quentin; Schweitzer, Johannes & Kværna, Tormod (2024). Near-real time detection of conflict-related explosions or suspicious events using seismological data. Full text in Research Archive Show summary

  Apart from classical earthquake monitoring, seismological data can also be used to detect explosions in near-real-time on both regional and global scales. We demonstrate how seismic and infrasound data can provide more comprehensive and objective information about conflict-related explosions or suspicious events that might be the result of targeted attacks. We can identify the underwater explosions at the Nord Stream pipeline infrastructure in the Baltic Sea in September 2022. Cross-correlation analysis allowed us to identify sub-events several seconds apart which can be associate with specific locations along the pipelines. Furthermore, we detect a signal at the Finish seismic array in October 2023 which may be associated with the damage along the Balticconnector. The other example is from Ukraine, where we present the ability to automatically identify and locate ground explosions related to the Russia-Ukraine conflict with data from the Malin array (AKASG). Between February and November 2022, we observe more than 1,200 explosions from the Kyiv, Zhytomyr, and Chernihiv provinces. Both seismic and infrasound detections can be used to verify and improve accurate reporting of military attacks and help to provide an unprecedented view of an active conflict zone. We analyze events with a variety of seismo-acoustic signatures and significant differences in explosive yield. These can be associated with various types of military attacks, including artillery shelling, cruise missile attacks, airstrikes, or the destruction of the Kakhovka dam NE of Cherson.

• Steinberg, Andreas; Gestermann, Nicolai; Ceranna, Lars; Hartmann, Gernot; Lund, Björn & Dunham, Eric [Show all 18 contributors for this article] (2024). Source analysis of the 2022 Nord Stream and 2023 Balticconnector underwater explosions. Full text in Research Archive Show summary

  On 26 September 2022 two seismic events near the Danish island of Bornholm in the Baltic Sea were detected. The first event with a magnitude Mw 2.3 occurred at 00:03 UTC 40 km east-southeast of Bornholm. The determined location and the origin time of the event are consistent with data of the pressure decrease on one of the Nord Stream 2 pipelines. Another sequence of events occurred 17 hours later at 17:03 UTC around 60 km north-east of Bornholm with a maximum magnitude of Mw 2.7. It consists of three closely successive, but separable, single events. Using relative localisation methods and the gas pressure inside the pipeline recorded at the landing site in Germany, we can assign the epicentres of the three events to the locations of the leaks in the pipelines of Nord Stream 1 and 2. Based on comparable events in the region, which include both tectonic earthquakes and explosions, the explosive character of the investigated Nord Stream events can be verified. Infrasound signals associated with the destruction of the Nord Stream pipelines were recorded at two stations (I26DE in the Bavarian Forest and IKUDE near Kühlungsborn) in Germany. Particularly after the event sequence at 17:03 UTC, distinctive signals were registered whose characteristics indicate an explosive event with subsequent gas leakage at the surface. Our modelling of the sources shows that the measured seismic signals can sufficiently be explained by the instantaneous gas release. Synthetic seismograms for such a source and a subsurface model adapted for the study area show high consistency with the measured signals. Based on the released energy and the characteristics of the recorded waveforms, we conclude that the impulsive gas release from the burst gas pipes constitutes the dominant part of the signal source. The model places an upper limit of approximately 50 kg TNT equivalent on the yield of the chemical explosive component of the events, but we note that smaller yields may also be consistent with the data. We also carried out an analysis of the seismic signals of the event on the Balticconnector pipeline between Finland and Estonia on 8 October 2023 and found that again the instantaneous gas release can sufficiently explain the observed data. This supports a possible mechanical cause of the damage.

• Kühn, Daniela; Dichiarante, Anna Maria; Kettlety, Tom; Martuganova, Evgeniia; Asplet, Joseph & Goertz-Allmann, Bettina [Show all 15 contributors for this article] (2024). Stress field information from seismicity to de-risk large-scale CO2 injections in the North Sea Horda platform region. Full text in Research Archive Show summary

  Carbon capture and storage technologies are an essential part of EU’s decarbonisation efforts. Combined with sustainable energy resources, they are necessary to move Europe towards a net zero carbon emissions economy. Currently, several Mt-scale CO₂ storage projects are being developed in the North Sea. Containment risk evaluation includes analysing tectonic earthquake patterns to potentially map faults, reveal their orientation and failure style, invert for stress directions and at later stages, enable the discrimination of natural and induced seismicity. In addition, seismological information may contribute to the geomechanical understanding of the reservoir and caprock response to large-scale CO₂ injection over time. A wealth of data exists from various European seismological agencies, but much of it has not been analysed collectively. Within the framework of the ACT3 project SHARP Storage, an extensive unique earthquake bulletin was compiled using seismicity data from all relevant data centres serving as a basis for further analysis, including event relocation and magnitude homogenisation. Inverted moment tensors, shear-wave splitting measurements, and stress drop analysis will be compared to and complement a review of borehole stress measurements to better gauge the present-day stress field and provide constraints on geomechanical models. In addition, the seismological data is integrated with geomechanical data, further improving the understanding of the state of stress and how this relates to fault failure and slip tendency.

• Pedersen, Christina Alsvik; Njåstad, Birgit; Aas, Wenche; Chiche, Elin Maria Kristina Darelius; Descamps, Sebastien & Flått, Stig [Show all 13 contributors for this article] (2024). The Troll Observing Network (TONe): A contribution to improving observations in the data-sparse region of Dronning Maud Land, Antarctica. Full text in Research Archive
• Kühn, Daniela; Kettlety, Tom; Martuganova, Evgeniia; Jerkins, Annie Elisabeth; Asplet, Joseph & Goertz-Allmann, Bettina [Show all 17 contributors for this article] (2024). Understanding North Sea seismicity to gain stress field information and de-risk large-scale CO2 injections. Full text in Research Archive Show summary

  Carbon capture and storage technologies are an essential part of EU’s decarbonisation efforts. Combined with sustainable energy resources, they are necessary to move Europe towards a net zero carbon emissions economy. Currently, several Mt-scale CO2 storage projects are being developed in the North Sea. Containment risk evaluation includes analysing tectonic earthquake patterns to potentially map faults, reveal their orientation and failure style, invert for stress directions and at later stages, enable the discrimination of natural and induced seismicity. In addition, seismological information may contribute to the geomechanical understanding of the reservoir and caprock response to large-scale CO2 injection over time. A wealth of data exists from various European seismological agencies, but much of it has not been analysed collectively. Within the framework of the ACT project SHARP Storage, an extensive unique earthquake bulletin was compiled using seismicity data from all relevant data centres. Preliminary processing included duplicate removal and explosion identification. The magnitude of completeness of this data set varies both spatially and temporally. The most seismically active regions in the study area are the Viking and Central grabens. Coastal areas are populated with more events than the central part of the North Sea due to the denser distribution of seismic stations onshore allowing for the detection of smaller (M<3) magnitude events. Data sets are planned to being made public after finalising the project. For events occurring after 1990 and possessing magnitudes larger than M > 3.5, waveforms are currently being collected as a basis for further analysis, including event relocation and magnitude homogenisation. Inverted moment tensors, shear-wave splitting measurements, and stress drop analysis will be compared to and complement a review of borehole stress measurements to better gauge the present-day stress field and enhance seismic hazard assessments. Ground motion prediction equations (GMPEs) are being derived for the onshore regions nearest the development CO2 storage projects, and an updated probabilistic seismic hazard analysis is being carried out on a regional scale.

• Kettlety, Tom; Voss, Peter; Martuganova, Evgeniia; Schweitzer, Johannes; Dahl-Jensen, Trine & Jerkins, Annie Elisabeth [Show all 7 contributors for this article] (2024). Improving the accuracy of earthquake magnitudes for North Sea seismicity. Full text in Research Archive Show summary

  To effectively design and operate the many CO2 storage projects that are being developed in the North Sea, seismicity needs to be accurately characterised. Measuring seismicity can provide insights into the stress state in the region, fault density and faulting style, as well as fracturing in the overburden. Understanding background seismicity rates is also key to discriminating, determining the risk of, and mitigation against induced seismicity that could result from injection. Communicating earthquake risk is a key challenge in this field, and central to that is the reporting of earthquake sizes or magnitudes. These magnitudes are reported to the public, and thus their integrity needs to be ensured and their uncertainties thoroughly characterised. Magnitudes also are key input into seismic hazard analysis, a necessary step in the site characterisation of CO2 storage projects and other offshore infrastructure. This study compares and re-evaluates the magnitude estimates from a large database of North Sea seismicity compiled by the ACT3 project SHARP Storage. Magnitudes and their associated uncertainties are computed in a consistent manner and compared to the recordings reported by the regional agencies. Systematic differences are explored, and key sensitives are identified. These results will aid in the monitoring of seismicity in the North Sea, risk assessment for CO2 storage and other infrastructure, and the communication of seismic hazard.

• Kühn, Daniela; Martuganova, Evgeniia; Kettlety, Tom; Schweitzer, Johannes; Jerkins, Annie Elisabeth & Goertz-Allmann, Bettina [Show all 16 contributors for this article] (2024). A better understanding of seismicity in the European North Sea for risk mitigation of largescale CO2 injections. Full text in Research Archive Show summary

  Carbon capture and storage technologies are an essential part of EU’s decarbonisation efforts. Combined with sustainable energy resources, they are necessary to move Europe towards a net zero carbon emissions economy. Currently, several Mt-scale CO2 storage projects are being developed in the North Sea. Containment risk evaluation includes analysing tectonic earthquake patterns to potentially map faults, reveal their orientation and failure style, invert for stress directions and at later stages, enable the discrimination of natural and induced seismicity. In addition, seismological information may contribute to the geomechanical understanding of the reservoir and caprock response to large-scale CO2 injection over time. A wealth of data exists from various European seismological agencies, but much of it has not been reported to the ISC and consequently not analysed collectively. Within the framework of the ACT project SHARP Storage, an extensive unique seismic event catalogue including the phase readings was compiled from the bulletins available from all relevant data centres. Preliminary processing included duplicate removal and explosion identification. In total, 15,230 events were observed between the years 1382 and 2022, of which 3,305 were identified as likely or potential explosions. The magnitude of completeness of this data set varies both spatially and temporally. The most seismically active regions in the study area are the Viking and Central grabens. Coastal areas are populated with more events than the central part of the North Sea due to the denser distribution of seismic stations onshore allowing for the detection of smaller (M<3) magnitude events. For events occurring after 1990 and possessing magnitudes larger than M > 3.5, waveforms are currently being collected as a basis for further analysis, including event relocation and magnitude homogenisation.

• Larsen, T; Voss, Peter H.; Dahl-Jensen, Trine; Rinds, N; Lund, B. & Schmidt, P [Show all 15 contributors for this article] (2023). Analysis of the North Stream Underwater Blasts in the Baltic Sea on 26 September 2022. Full text in Research Archive Show summary

  On 26 September, 2022 the International Monitoring System (IMS) detected two seismic events near the Danish island of Bornholm. The events were seen in both seismic and infrasound data and were located near the positions where large gas leaks from the North Stream were later observed. The events were furthermore recorded by seismographs in the surrounding countries and analysed at the National Data Centres. The waveforms exhibited clear properties of underwater blasts with significant P energy and much smaller S- energy, as well as other characteristics not associated with natural earthquakes. Further analysis revealed that particularly the second event may consist of multiple blasts close in time and space. Analysis of the events included integration between IMS data and regional data from Denmark, Sweden, Germany and Norway, and served as an exercise in collaboration during an international crisis.

• Maio, Florencia Victoria De; Stefano, Rita De; Valsecchi, Ruben; Bolletta, Fabio; Basso, Paolo & Cademartori, Marcello [Show all 12 contributors for this article] (2023). Assessment of current and future multi-risk interactions and cascading impacts across Europe: a case study in Oslo, Norway. Full text in Research Archive
• Pedersen, Christina Alsvik; Schweitzer, Johannes; Njåstad, Brigit; Miloch, Wojciech Jacek; Aas, Wenche & Hudson, Stephen [Show all 12 contributors for this article] (2023). The New Norwegian Infrastructure - Troll Observing Network - under Establishment in Dronning Maud Land, Antarctica. Full text in Research Archive Show summary

  Antarctica and the Southern Ocean are important parts of the Earth system. The physical and biological properties here to a large degree control and shape other parts of the Earth through atmospheric, cryospheric and oceanic connections. The Troll Observing Network – TONe - is a new comprehensive infrastructure centered around the Norwegian Troll Research Station in Dronning Maud Land. It will be an important contribution to global research efforts in this part of Antarctica, closing data gaps in Antarctic environmental observations and providing key data required to respond to the fundamental societal challenges and uncertainties facing the world today. The Norwegian and international partner consortium in TONe is in the process to develop the state-of-the-art, multi-platform, multi-disciplinary observatory network for environmental observations, and a remotely piloted aerial system (RPAS) services to collect data for studying and monitoring the atmosphere, terrestrial and marine environment. The observatory network consists of 8 observatories: an integrated cloud observatory, an atmosphere composition observatory, an infrasound array, an ionospheric observatory, a seismic array, an ice-shelf observatory, a multidisciplinary open ocean moored observatory and a sea-bird observatory. The key aspect of TONe is to ensure wide and free access to the data from the observatories and the RPAS services to the entire national and international research community. TONe as a whole will be implemented and fully operational from 2027, while single parts of the infrastructure will be available before that.

• Huang, Chen; Meslem, Abdelghani; Bolin, Håkan; Refsum, Vetle Kind; Kaschwich, Tina & Vezzoso, Alberto [Show all 10 contributors for this article] (2023). The TURNkey scientific engine, an advanced tool for earthquake disaster management. Full text in Research Archive Show summary

  The TURNkey scientific engine is a useful tool for earthquake disaster management. Building upon state-of-the-art methodologies in seismic hazard assessment, risk evaluation and decision-support systems, the scientific engine effectively supports earthquake forecasting, early warning and rapid response actions. This study introduces the three main features of the TURNkey scientific engine. Through case studies, the unique services provided by the scientific engine to the stakeholders are demonstrated. It is shown that the engine improves situational awareness in operational earthquake forecasting (OEF), earthquake early warning (EEW), and rapid response to earthquake (RRE) and thus facilitates earthquake disaster management.

• Köhler, Andreas; Alvizuri, Celso; Dando, Benjamin; Goertz-Allmann, Bettina; Schweitzer, Johannes & Oye, Volker [Show all 15 contributors for this article] (2023). Relative locations and moment tensors of the Nord Stream pipeline events. Full text in Research Archive Show summary

  Two clear seismic events were observed on 26th September 2022 associated with the reported leaks from the Nord Stream 1 (Event 1, NE of Bornholm) and Nord Stream 2 pipelines (Event 2, SE of Bornholm). Arrivals of both events were detected and associated using data from several arrays in Norway and Finland, including the IMS stations NOA, FINES and ARCES. Additional signal analysis with data from the Swedish National Seismic Network and the Danish station on Bornholm enabled a third event to be identified. Auto-correlation analysis of the Event 2 revealed the third event (Event 2B) about 7 seconds after the main amplitude of the P onset (Event 2A). In contrast, for Event 1 SE of Bornholm no additional events could be identified from auto-correlation analysis, which increases confidence that these additional arrivals are not caused by interaction with geological structures. We also observe an arrival 7 s after the Pn phase before the Pg arrival on the NORES array. However, we cannot exclude that this onset interferes with the arrival of the PnPn phase. We then use the time differences between Event 2A and 2B measured by auto-correlation analysis on the Swedish and Danish network stations to determine relative epicentre locations. The results suggest that the two overlapping events occurred just about 220 m apart from each other. The relative locations fit very well with the distance between both pipelines of Nord Stream 1 at the Westernmost gas plume location (NE of Bornholm). We also estimated preliminary full moment tensors for Event 1 and 2 using seismic waveform data and analysed them on a source-type diagram. The results show positive isotropic parameters consistent with explosion-type mechanisms.

• Lund, B.; Eggertsson, G; Tryggvason, Ari; Schmidt, P.; Roth, Michael & Larsen, T.B. [Show all 17 contributors for this article] (2023). The Nord Stream underwater explosions: location, classification and yield estimation. Full text in Research Archive Show summary

  Soon after midnight on 26 September 2022 the Swedish National Seismic Network, using data from Sweden, Denmark and Germany, automatically detected a seismic event in the Baltic southeast of the Danish island of Bornholm. The event was followed 17 hours later by a second, more complex, event northeast of Bornholm. The automatic locations of the events were within 6-9 km of later reported gas leaks in the Nord Stream 1 and 2 pipelines. Using recently developed, machine learning based, classifiers both events were automatically classified as explosions. Subsequent analysis of the second event revealed that it was in fact two blasts, separated by about 7 seconds. As the events occurred in the transition zone between the Fennoscandian Shield and the younger terranes of Denmark and northern Germany, 3D tomographic P- and S-velocity models were developed to improve locations and assess uncertainties, bringing the locations closer to the pipelines. Spectral analysis of the blast data show clear reverberations consistent with underwater explosions and a blast depth of approximately 75 m. The conclusion that the events are underwater blasts are further supported by data on known underwater explosions and a few earthquakes in the area. The magnitude of the first event was estimated at ML 1.9 and the combined second and third event had ML 2.3. Estimating the equivalent yield in the explosions is, however, non-trivial. Comparison to ground truth underwater explosions suggests yields of one to a few hundred kilos of equivalent TNT. The contribution to the seismic energy from suddenly outflowing methane gas is under investigation and results will be included in the presentation.

• Pirli, Myrto; Schweitzer, Johannes & Paulsen, Berit (2023). Seismotectonics of Hornsund, Spitsbergen, European Arctic, based on moderate magnitude seismicity. Full text in Research Archive
• Pedersen, Christina Alsvik; Njåstad, Birgit; Descamps, Sebastien; Hattermann, Tore; Hudson, Stephen & Flått, Stig [Show all 11 contributors for this article] (2023). Troll observing network – for useful new data about Antarctica. Fram Forum. ISSN 1893-5532. 12, p. 120–125. Full text in Research Archive
• Kühn, Daniela; Martuganova, E; Kettlety, T; Schweitzer, Johannes; Baptie, Brian & Dahl-Jensen, T [Show all 11 contributors for this article] (2023). Understanding North Sea seismicity for risk mitigation of large-scale CO2 injections. Full text in Research Archive
• Pincheiro, K; Korte, M.; Schweitzer, Johannes; Sharan, S; Rogers, H & Kamenitka, T (2023). Geoscience Connections. Full text in Research Archive
• Schweitzer, Johannes (2023). Improving seismic monitoring capabilities at Troll in Dronning Maud Land, Antarctica. Full text in Research Archive
• Brissaud, Quentin; Schweitzer, Johannes; Näsholm, Sven Peter; Vorobeva, Ekaterina & Eggen, Mari Dahl (2023). Infrasound arrays as probes for atmospheric and ice dynamics in polar regions. Full text in Research Archive
• Huang, Chen; Bever, Ivan Van; Ibrahim, Osman Mohammad; Oye, Volker & Schweitzer, Johannes (2023). Multi-hazard risk-informed decision-support system: A case study in Oslo, Norway. Full text in Research Archive
• Larsen, T.B.; Voss, Peter H.; Dahl-Jensen, Trine; Rinds, N; Lund, B. & Schmidt, P [Show all 15 contributors for this article] (2023). Integrating IMS data in the analysis of the Nord Stream underwater blasts in the Baltic Sea. Full text in Research Archive Show summary

  On September 26, 2022 the International Monitoring System (IMS) of the CTBTO detected two seismic events near the Danish island of Bornholm as reported in the Reviewed Event Bulletin (REB). In the REB phases include both seismic and infrasound data up to 1600 km away and the events are located near the positions where large gas leaks from the Nord Stream pipelines were also observed. The events were recorded clearly by the Danish seismograph network with the closest two seismographs located on Bornholm at distances of 40 – and 70 km. Furthermore, seismographs in the surrounding countries picked up the signals and data were analysed at the national data centers. The waveforms exhibited clear properties of underwater blasts with significant P-energy and much smaller S-energy, as well as other characteristics not associated with natural earthquakes. Further analysis revealed that the second event may consist of multiple blasts close in time and space. Analysis of the events included integration between IMS data and regional data from Denmark, Sweden, Germany and Norway, communication with CTBTO experts, and served as an exercise in collaboration during an international crisis.

• Schweitzer, Johannes (2022). 30 Years of Cooperation Between Central Asia and NORSAR. Full text in Research Archive
• Schweitzer, Johannes (2022). Seismic Station Troll, Dronning Maud Land, East Antarctica – the first 10 Years. Full text in Research Archive
• Halldorsson, Benedikt; Balan, S; Gehl, P; Melis, N; Borzi, B & Ruigrok, E [Show all 10 contributors for this article] (2022). The TURNkey European testbeds for consistent real-time monitoring and other geophysical markers. Full text in Research Archive
• Schweitzer, Johannes (2022). TONe Work Package 4: A New Seismic and a New Infrasound Array. Full text in Research Archive
• Schweitzer, Johannes (2022). J. Schweitzer: TONe Work Package 4: A New Seismic and a New Infrasound Array. Full text in Research Archive
• Schweitzer, Johannes; Paulsen, Berit; Antonovskaya, G.N; Fedorov, A.; Konechnaya, Yana & Asming, Vladimir Ernest [Show all 7 contributors for this article] (2022). The European Arctic Seismic Bulletin for the years 1990 – 2013. Full text in Research Archive
• Schweitzer, Johannes (2022). Seismic Station TROLL – the First Decade. Full text in Research Archive
• Schweitzer, Johannes (2022). 25 Years of Earthquake Locations with HYPOSAT. Full text in Research Archive
• Schweitzer, Johannes (2022). 25 Years of Earthquake Locations with HYPOSAT. Full text in Research Archive
• Schweitzer, Johannes (2022). Presentasjon av H2020 EU prosjektet TURNkey. Full text in Research Archive
• Huang, Chen; Meslem, Abdelghani; Bolin, Håkan; Refsum, Vetle Kind; Kühn, Daniela & Kaschwich, Tina [Show all 8 contributors for this article] (2022). A synthetic case study using the turnkey scientific engine for earthquake disaster management. Full text in Research Archive Show summary

  During the risk management process, multi-disciplinary information and data from various sources need to be integrated and promptly processed to assist the identified stakeholders (e.g., civil protection, emergency responders) to react at the earliest stage to earthquake events to reduce the direct and indirect impacts and consequences. The TURNkey scientific engine was developed for this purpose. The TURNkey scientific engine is a comprehensive software incorporating state-of-the-art methodologies in hazard assessment, risk evaluation and decision-support systems to enable earthquake forecasting, early warning, and rapid response actions. Through a synthetic case study, this paper illustrates that the scientific engine can update the seismic hazard estimates as well as the risk and loss estimation in near real-time, taking into account the instrumental data, Did-You-Feel-It reports and eyewitness reports. With the help of the scientific engine, the stakeholders can understand the impact and consequences of the damaging earthquake to facilitate emergency response.

• Alvizuri, Celso; Huang, Chen; Jerkins, Annie; Schweitzer, Johannes & Oye, Volker (2022). Source parameters and shakemap (PGV) for the Mag. 5 North Sea earthquake on 2022-03-21. Full text in Research Archive
• Huang, Chen; Meslem, Abdelghani; Bolin, Håkan; Refsum, Vetle Kind; Kühn, Daniela & Kaschwich, Tina [Show all 8 contributors for this article] (2022). An overview of the scientific engine of the TURNkey platform. Full text in Research Archive
• Schweitzer, Johannes; Christensen, Jon Magnus; Sickel, Morten A. K.; Mykkeltveit, Svein & Köhler, Andreas (2021). New Small Aperture Broadband Arrays in the European Arctic. Full text in Research Archive Show summary

  As part of the EPOS-Norway infrastructure project, NORSAR received funding from the Research Council of Norway for a new regional seismic array on Bjørnøya (Bear Island) in the European Arctic. After along planning phase, a six-element broadband array was installed by NORSAR staff in August 2019 and has been providing data to NORSAR in near real-time since then. Due to several logistical and administrative constraints the 6-element array has an aperture of only 300 m. All sites are equipped with Kinemetrics MBB-2 sensors and Earth Data EDR-209 digitizers that are installed in near-surface vaults. Data are automatically copied to the Norwegian node of the European Integrated Data Archive (EIDA) and are openly available. Due to environmental restrictions less than the planned 9 array sites could be installed on Bjørnøya and the non-used instruments are now available to extend the broadband station Hornsund (HSPB), Southern Spitsbergen, to another small aperture broadband array, also with 6 sites. The array installation had to be postponed because of the ongoing pandemic and is now planned for the Arctic summer 2021.

• Schweitzer, Johannes & Lay, Thorne (2019). The contribution of the International Association of Seismology and Physics of the Earth’s Interior (IASPEI) and its forunners to seismology. Full text in Research Archive Show summary

  The International Union of Geodesy and Geophysics (IUGG) was founded 100 years ago. This anniversary is a welcome opportunity to review the contributions of the International Association of Seismology and Physics of the Earth’s Interior (IASPEI) to seismology. Older than the IUGG, international cooperation in seismology was from the beginning one of the important components of geophysics and the IUGG. The International Seismological Association (ISA) was founded in 1904 and dissolved in 1922. It evolved into the Seismology Section of the International Union of Geodesy and Geophysics (IUGG), ultimately becoming the International Association of Seismology and Physics of the Earth’s Interior (IASPEI), a name recognizing the important role of structure and physical properties of the Earth’s interior for understanding our planet. Through the last hundred years, the commissions and working groups of the Association have played a major role in setting international standards in such areas as the naming of seismic phases, data exchange, travel time tables, magnitude scales and reference Earth models. The activities of IASPEI continue to have a focus on the societal impacts of earthquakes and tsunamis, with four Regional Commissions playing a major role in promoting high standards of seismological education, outreach and international cooperation.

• Assumpção, M & Schweitzer, Johannes (2019). The International Association of Seismology and Physics of the Earth’s Interior (IASPEI) and the Latin American and Caribbean Seismological Commission (LACSC)Fimbul Ice Shelf, East Antarctica, from Tidally Modulated Cryoseismicity. Full text in Research Archive
• Pirli, Myrto; Hainzl, S.; Schweitzer, Johannes; Köhler, Andreas & Dahm, Torsten (2019). Dynamics of Fimbulisen, Antarctica, as revealed from tidally modulated cryoseismicity. Full text in Research Archive
• Schweitzer, Johannes (2019). CTBT Capacity Building in Central Asia. Full text in Research Archive
• Satake, Kenichi; Lay, Thorne & Schweitzer, Johannes (2019). IASPEI- activities, history and Japan’s contribution. Full text in Research Archive Show summary

  IASPEI (International Association of Seismology and Physics of the Earth’s Interior) is one of the eight associations of IUGG, and promotes the study of earthquakes and other seismic sources, the propagation of seismic waves, and the Earth's internal structure, properties, and processes. IASPEI has seven commissions on seismological observation and interpretation, on tectonophysics and crustal structure, on earthquake generation process - physics, modelling, and monitoring for forecast, on earth structure and geodynamics, on earthquake hazard, risk and strong ground motion, on earthquake source mechanics, and on education and outreach. Besides these topical commissions, IASPEI has their regional commissions in Europe (since 1951), Asia (since 1996), Africa (since 2011) and Latin America (since 2013). These regional commissions meet bi-annually, typically with training courses, to promote seismology in each region. Seismology started as national scale for describing the earthquake phenomena and their effects. First seismological societies were established in Switzerland (1878), in Italy (1879) and in Japan (1880). After the first teleseismic recording in Germany from an earthquake in Japan (1889), seismology became an international science, and Frist International Seismological Conference was held in Strasbourg in 1901, representing 8 countries including Japan. In 1904, International Seismological Society was established. In 1922, it became a part of IUGG (established in 1919), with changing name to IAS in 1930 and IASPEI in 1951. IASPEI plays important roles in unifying seismological observations, such as naming seismic phases, defining measurement procedures, or improving the network of seismic stations, and published Manuals of Seismological Observatory Practice (the latest version in 2012). IASPEI has a close relation with International Seismological Centre, which has produced seismological bulletins based on the IASPEI standard. IASPEI also provided standard seismic velocity structure models of the earth, such as iasp91 or ak135. Global distribution of earthquakes in the earth and the reference earth models have been important basic data for developing the science such as plate tectonics, or structure and dynamics of the earth’s interior. IASPEI also conducted peer reviews and evaluated the published precursory phenomena for earthquakes. IASPEI developed and distributed seismological software, and International Handbook of Earthquake and Engineering Seismology. IASPEI supports FDSN (International Federation of Digital Seismograph Networks) which is composed of groups responsible for installation and maintenance of seismological networks, and activities of CTBTO (Comprehensive Test-Ban Treaty Organization) which uses seismic data to detect nuclear explosions. IASPEI also supports joint commissions with other associations of IUGG, such as ILP (International Lithosphere Project), on tsunamis, volcanology or on space geodesy. The IASPEI commission of Seismological Society of Japan practically acts as the national committee of IASPEI, and disseminates IASPEI information to Japanese seismological community, nominates officers and award candidates. SSJ has made financial supports to ASC and IASPEI, for travel support of participants and for management of the ASC meetings. Several members of executive committees and chairs of commission are elected from Japan. The last scientific assembly of IASPEI, jointly held with IAG, has held in Kobe, Japan, in 2017 with great success.

• Mykkeltveit, Svein; Mikhailova, Natalia; Abdrakhmatov, K; Aristova, I; Berezina, A & Schweitzer, Johannes (2019). Capacity Building in Central Asia to Monitor the CTBT. Full text in Research Archive
• Dinescu, Raluca; Chica, Daniela; Schweitzer, Johannes; Näsholm, Sven Peter; Popa, Michaela & Ionescu, Constantin (2019). Monitoring man-made hazards using data recorded with the Romanian seismic and infrasonic arrays. Full text in Research Archive Show summary

  Seismic events observed with the Romanian Seismic Network, operated by the National Institute for Earth Physics, are produced by various sources: earthquakes, mining and quarry blasts, thunderstorms, atmospheric and underground explosions. To monitor man-made seismic sources, data recorded by the Romanian seismic and infrasonic arrays deployed at Plostina seismo-acoustic site (PLOR and IPLOR stations) and at Bucovina seismo-acoustic site (BURAR and BURARI stations) are jointly analyzed in order to build an efficient tool for discrimination between anthropogenic and natural events, i.e. between explosions and tectonic earthquakes. At the same time, our work supports the attempt to clean the Romanian seismic catalogue from non-tectonic events. A specific methodology for the seismo-acoustic analysis has been developed. The main analysis steps consist of: (1) selection of natural and artificial reference events detected by seismo-acoustic arrays considered; (2) analysis of the infrasound detections using standard array processing methods – array data processing software “ep” – provided by NORSAR, in order to extract the signal features (backazimuth, apparent velocity, frequency content, amplitude, SNR); (3) analysis of the seismic detections using the same array data processing software, in order to extract the characteristics of their seismic signature (waveform shape, frequency content, amplitude, particle motion; (4) combination of the infrasonic detections with seismic ones in order to associate them with the reference events based on comparison of the backazimuth estimates and arrival time measurements with the theoretical/expected values and taking in account the effect of the atmospheric propagation conditions; (5) identification of the near-surface explosions produced in the local quarries using the analyzed seismo-acoustic signals and discrimination between these blasts and tectonic earthquakes. In the future we aim to extract templates of the seismo-acoustic signals generated by the man-made explosions and compare them with the continuously recorded waveforms in order to develop an automatic event identification process.

• Chamarczuk, M; Gajek, w; Geissler, W.; Köhler, Andreas; Majdanski, M & Schweitzer, Johannes [Show all 7 contributors for this article] (2019). Seismological monitoring of Svalbard’s cryosphere: status and future directions - a contribution to the SIOS SESS report 2019. Full text in Research Archive
• Pirli, Myrto; Hainzl, S.; Schweitzer, Johannes; Köhler, Andreas & Dahm, T. (2019). Localised, ephemeral grounding of the Fimbul Ice Shelf, East Antarctica, as revealed from tidally modulated cryoseismicity. Full text in Research Archive
• Pirli, Myrto; Hainzl, S.; Schweitzer, Johannes; Köhler, Andreas & Dahm, T (2019). Pinning Point Identification at the Fimbul Ice Shelf, East Antarctica, from Tidally Modulated Cryoseismicity. Full text in Research Archive
• Schweitzer, Johannes & Lay, Thorne (2019). Contributions of the International Association of Seismology and Physics of the Earth’s Interior (IASPEI) and its forerunners to seismology. Full text in Research Archive
• Schweitzer, Johannes; Köhler, Andreas & Weidle, Christian (2018). Regional Seismicity observed with two temporary seismic arrays in Kongsfjorden, Svalbard. Full text in Research Archive
• Pirli, Myrto; Hainzl, S.; Schweitzer, Johannes; Kohler, A & Dahm, Torsten (2018). Localised thickness variations and ephemeral grounding of the Fimbul Ice Shelf, East Antarctica, from tidally modulated cryoseismicity. Full text in Research Archive
• Schweitzer, Johannes (2018). A joint bulletin for Central Asia. Full text in Research Archive
• Schweitzer, Johannes (2018). NORSAR’s Event Location Program HYPOSAT. Full text in Research Archive
• Dahm, Torsten; Hainzl, S.; Pirli, Myrto; Schweitzer, Johannes & Köhler, Andreas (2018). Predicting size and occurrence time of coseismic rupture using a single fault stick slip model: examples from the Fimbul ice shelf, Antarctica. Full text in Research Archive
• Pirli, Myrto; Schweitzer, Johannes; Antonovskaya, Galina; Konechnaya, Yana & Paulsen, Berit (2018). Decennial of the 21 February 2008, Storfjorden earthquake: contributions to Svalbard seismotectonics. Full text in Research Archive
• Schweitzer, Johannes; Köhler, Andreas & Weidle, Christian (2018). Two temporary seismic arrays in the high Arctic. Full text in Research Archive
• Köhler, Andreas; Buscaino, Giuseppa; Lefeuvre, Pierre-Marie; Maupin, Valerie; Nuth, Christopher & Petlicki, Michal [Show all 7 contributors for this article] (2018). Seismic monitoring of glaciers and permafrost: What micro-seismicity and ambient noise can tell us about cryospheric processes in Svalbard. Full text in Research Archive
• Köhler, Andreas; Lefeuvre, Pierre-Marie; Nuth, Christopher; Schweitzer, Johannes; Buscaino, Giuseppa & Weidle, Christian [Show all 9 contributors for this article] (2018). Monitoring and quantification of frontal ablation at Kronebreen, Svalbard, using records of seismic calving signals. Geophysical Research Abstracts. ISSN 1029-7006. Full text in Research Archive
• Schweitzer, Johannes & Lay, Thorne (2018). Obituary Brian J. Mitchell (1936 – 2018). IASPEI Newsletter. Full text in Research Archive
• Pikoulis, Erion-Vasilis; Psarakis, E & Schweitzer, Johannes (2018). Joint signal detection and parameter estimation in seismic arrays. Full text in Research Archive
• Jerkins, Annie; Gibbons, Steven John; Kværna, Tormod & Schweitzer, Johannes (2018). Location and Depth Estimation of the North Sea Earthquake of 30 June 2017. Geophysical Research Abstracts. ISSN 1029-7006. Full text in Research Archive
• Schweitzer, Johannes (2018). Arrays at NORSAR. Full text in Research Archive
• Köhler, Andreas; Buscaino, Giuseppa; Lefeuvre, Pierre-Marie; Maupin, Valerie; Nuth, Christopher & Petlicki, Michal [Show all 8 contributors for this article] (2018). Studying and quantifying glacier dynamics in Svalbard using cryoseismology. Full text in Research Archive
• Jerkins, Annie; Kværna, Tormod; Schweitzer, Johannes & Gibbons, Steven John (2018). Location and depth estimation of the North Sea earthquake 30 June 2017. Full text in Research Archive
• Gaina, Carmen; Lebedeva-Ivanova, Nina; Minakov, Alexander; Nikishin, Anatoly; Faleide, Jan Inge & Schweitzer, Johannes [Show all 11 contributors for this article] (2016). 4D Arctic: Structure and Evolution of Arctic Crust and Mantle Based on Multi-Scale Geophysical Studies – results from an international, multi-disciplinary project. Full text in Research Archive
• Minakov, Alexander; Buiter, Susanne; Faleide, Jan Inge; Gaina, Carmen; Mjelde, Rolf & Lebedeva-Ivanova, Nina [Show all 9 contributors for this article] (2016). GoNorth - A new initiative for High Arctic research. Full text in Research Archive
• Zschau, Jochen; Lühr, Birger; Milkereit, Klaus; Schweitzer, Johannes; Parolai, Stefano & Dahm, Torsten [Show all 8 contributors for this article] (2015). Peter Bormann 1939 - 2015. GMIT Geowissenschaftliche Mitteilungen. ISSN 1616-3931. p. 102–103. Full text in Research Archive
• Köhler, Andreas; Nuth, Christopher; Sevestre, Heidi; Benn, Doug; Luckman, Adrian & Schweitzer, Johannes [Show all 7 contributors for this article] (2014). Seismic Observations of Glacier Calving and Surging on Spitsbergen, Svalbard. Full text in Research Archive
• Schweitzer, Johannes & Roth, Michael (2017). The NORSAR Data Center in 2017 (FDSN Network Code NO). NORSAR. Full text in Research Archive Show summary

  Biannual Report prepared for the FDSN Meeting during Joint IAG-IASPEI Scientific Assembly in Kobe, 2017

View all works in NVA