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2023 marks thirty years since the start of GEOFON operations with the first three stations in Papua New Guinea (Port Moresby, PMG), the Czech Republic (Moravsky Beroun, MORC), in Ireland (Dublin, DSB). The GEOFON program started shortly after creation of the GFZ German Research Centre for the Geosciences in 1992 with the aim to promote global seismic monitoring, standardisation and data exchange. The program has evolved over the three decades in synergy with the seismological community through three important milestones: since late 1990s the development and community adoption of the SeedLink protocol enabling global real-time data exchange; in early 2000s, development of the Arclink protocol as key development to interconnect the EIDA federated data archives, only recently superseded by the use of FDSN web services at global scale; 2008 as the first public release of SeisComP, one of the most widely used seismological packages in seismology, a development triggered after the 2004 Aceh-Andaman earthquake and tsunami within the GITEWS project (German Indian Ocean Tsunami Early Warning System). Although GEOFON‘s heritage goes back to the 1990s and further down to 1889 building on the initial findings from Ernst von Rebeur-Paschwitz, the program is capable of leveraging third party funded challenging projects to keep modernising with the community. In this presentation we outline the most important developments of GEOFON through a journey in time over three decades, building links between current activities and vision still influenced by the initial aims which have shaped the current GEOFON mission., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

On February 6, 2023, southeastern Turkey was hit by two of the most devastating earthquakes in the instrumental period of the country, with Mw 7.8 and Mw 7.5, respectively. Both earthquakes caused massive damage in Turkey and Syria. In this study, we analyze the rupture processes of main- and aftershocks by combining different seismic source characterization techniques using teleseismic, regional, and local data. We perform finite source inversion and back projection-based analyses for the two main shocks and invert for probabilistic centroid moment tensor solutions of both main and aftershocks (M≥4). The first earthquake was bilateral and ruptured a seismic gap along the East Anatolian Fault, with rupture first propagating to the north-east for ~200 km, and in a latter phase propagating to the SSW, probably coming to a halt only on a branch extending into the Mediterranean Sea. The total length of the rupture likely exceeds 500 km. The second event ruptured the EW-oriented Sürgü-Misis Fault to the NW of the first event. It shows a highly concentrated rupture near the epicenter, Rupture directivity analyses for M≥5.3 earthquakes provide additional insights into dynamic source aspects. Preliminary moment tensor solutions of numerous aftershocks indicate a remarkable variability of rupturing mechanisms, suggesting stress changes and the activation of multiple faults in the vicinity of the main ruptures. With our work, we aim to shed light onto multiple aspects of the complex rupture evolution and hope to provide new insights towards a better understanding of the devastating 2023 Türkiye earthquake sequence., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Automated teleseismic earthquake monitoring is an essential part of global seismicity analysis. However, while constraining earthquake epicenters in an automated fashion is an established technique, constraining event depth is substantially more difficult, especially in the absence of nearby stations. One solution to this challenge are teleseismic depth phases but these can currently not be identified by automatic detection methods. Here we propose two deep learning models, DepthPhaseNet and DepthPhaseTEAM to detect depth phases. The first model closely follows the PhaseNet architectures with minor modifications; the latter allows joint analysis of multiple stations by adding a transformer to this basic architecture. For training the models, we create a dataset based on the ISC EHB bulletin, a high-quality catalog with detailed phase annotations. We show how backprojecting the predicted phase arrival probability curves onto the depth axes yields excellent estimates of earthquake depth. The models achieve mean absolute errors below 10 km. Furthermore, we demonstrate that the multi-station model, DepthPhaseTEAM, leads to better and more consistent predictions than the single-station model DepthPhaseNet. To allow direct application of our models, we integrate them within the SeisBench library for machine learning in seismology., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The open-source, seismological software package SeisComP is widely used for seismic monitoring world-wide. Its automatic phase picking module consists of an STA/LTA-based P-wave detector augmented by an AIC onset picker. With proper configuration, it allows detection and accurate onset picking for a wide range of seismic signals. However, it cannot match the performance of experienced analysts. Especially broadband data are often challenging for phase pickers due to the enormous variety of the signals of interest. In order to optimize quality and number of automatic picks and reduce time-consuming manual revision, we chose to develop a machine-learning repicker module for SeisComP based on the SeisBench framework. SeisBench supports several deep-learning pickers and comes pre-trained for different benchmark datasets, one of which was contributed by GFZ Potsdam.The repicking module consists of several submodules that interact with both SeisComP and SeisBench via their Python interfaces. The current workflow is based on existing locations generated with a classical SeisComP setup. Shortly after event detection and preliminary location, our repicker (1) starts to repick previously picked onsets and (2) attempts to generate additional picks.Preliminary results are encouraging. The deep-learning repicker substantially improves pick quality over a large frequency range. The number of picks available per event has approximately doubled and the publication delay is often reduced, especially for small events. The total number of published events has increased by about 20 per cent., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Scientific Technical Report STR; 20/03, The GEOFON program consists of a global seismic network (GE Network), a seismological data centre (GEOFON DC) and a global earthquake monitoring system (GEOFON EQinfo). These three pillars are part of the MESI research infrastructure of the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences aiming at facilitating scientific research. GEOFON provides realtime seismic data, access to its own and third party data from the archive facilities as well as global and rapid earthquake information. The GEOFON Seismological Software can be considered a fourth cross-cutting module of the GEOFON Program. Data, services, products and software openly distributed by GEOFON are used by hundreds of scientists and data centres worldwide. Its earthquake information service is accessed directly by tens of thousands of visitors. The SeisComP software package is the flagship software provided to the community, which is geared for seismic observatory and data centre needs and used extensively to support our internal operations. As all other MESI (Modular Earth Science Infrastructure) modules GEOFON has the majority of users outside the GFZ as well as an external advisory committee that provides advice to the GFZ Executive Board and to the GEOFON team. This report describes the main activities carried out within the three GEOFON pillars and the software development group.

Scientific Technical Report STR; 20/06, The GEOFON program consists of a global seismic network (GE Network), a seismological data centre (GEOFON DC) and a global earthquake monitoring system (GEOFON EQinfo). These three pillars are part of the MESI research infrastructure of the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences aiming at facilitating scientific research. GEOFON provides realtime seismic data, access to its own and third party data from the archive facilities as well as global and rapid earthquake information. The GEOFON Seismological Software can be considered a fourth cross-cutting module of the GEOFON Program. Data, services, products and software openly distributed by GEOFON are used by hundreds of scientists and data centres worldwide. Its earthquake information service is accessed directly by tens of thousands of visitors. The SeisComP software package is the flagship software provided to the community, which is geared for seismic observatory and data centre needs and used extensively to support our internal operations. As all other MESI (Modular Earth Science Infrastructure) modules GEOFON has the majority of users outside the GFZ as well as an external advisory committee that provides advice to the GFZ Executive Board and to the GEOFON team. This report describes the main activities carried out within the three GEOFON pillars and the software development group.

Two nuclear explosions were carried out by the Democratic People’s Republic of North Korea in January and September 2016. Epicenters were located close to those of the 2006, 2009, and 2013 previous explosions. We perform a seismological analysis of the 2016 events combining the analysis of full waveforms at regional distances and seismic array beams at teleseismic distances. We estimate the most relevant source parameters, such as source depth, moment release, and full moment tensor (MT). The best MT solution can be decomposed into an isotropic source, directly related with the explosion and an additional deviatoric term, likely due to near‐source interactions with topographic and/or underground facilities features. We additionally perform an accurate resolution test to assess source parameters uncertainties and trade‐offs. This analysis sheds light on source parameters inconsistencies among studies on previous shallow explosive sources. The resolution of the true MT is hindered by strong source parameters trade‐offs, so that a broad range of well‐fitting MT solutions can be found, spanning from a dominant positive isotropic term to a dominant negative vertical compensated linear vector dipole. The true mechanism can be discriminated by additionally modeling first‐motion polarities at seismic arrays at teleseismic distances. A comparative assessment of the 2016 explosion with earlier nuclear tests documents similar vertical waveforms but a significant increase of amplitude for the 2016 explosions, which proves that the 9 September 2016 was the largest nuclear explosion ever performed in North Korea with a magnitude Mw 4.9 and a shallow depth of less than 2 km, although there are no proofs of a fusion explosion. Modeling transversal component waveforms suggests variable size and orientation of the double‐couple components of the 2009, 2013, and 2016 sources.

Scientific Technical Report STR; 20/04, The GEOFON program consists of a global seismic network (GE Network), a seismological data centre (GEOFON DC) and a global earthquake monitoring system (GEOFON EQinfo). These three pillars are part of the MESI research infrastructure of the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences aiming at facilitating scientific research. GEOFON provides realtime seismic data, access to its own and third party data from the archive facilities as well as global and rapid earthquake information. The GEOFON Seismological Software can be considered a fourth cross-cutting module of the GEOFON Program. Data, services, products and software openly distributed by GEOFON are used by hundreds of scientists and data centres worldwide. Its earthquake information service is accessed directly by tens of thousands of visitors. The SeisComP software package is the flagship software provided to the community, which is geared for seismic observatory and data centre needs and used extensively to support our internal operations. As all other MESI (Modular Earth Science Infrastructure) modules GEOFON has the majority of users outside the GFZ as well as an external advisory committee that provides advice to the GFZ Executive Board and to the GEOFON team. This report describes the main activities carried out within the three GEOFON pillars and the software development group.

New Manual of Seismological Observatory Practice 2 (NMSOP-2)

Scientific Technical Report STR; 09/08, This volume contains the results of the DESERT project running from 2000 to 2006. It opens with a review paper (DESERT Group, 2009) followed by 33 special papers, see list of content (529 pages).