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In this study, we analyze the 2020 earthquake swarm on the Reykjanes Peninsula by moment tensor inversion in order to improve our understanding of the seismogenic processes and their relation with magmatic and tectonic activities. The densified seismic monitoring operational during the study period provides a unique dataset for the seismic sequence preceding the 2021 Fagradalsfjall eruption. We perform full moment tensor (MT) inversion for 85 earthquakes with magnitudes Mw > 2.5 using a probabilistic approach. For the first time, we attempted to integrate DAS data into the MT inversion. Focal mechanisms exhibit predominantly strike-slip faulting with a few normal faulting events and are overall compatible with the regional tectonic regime. Earthquake foci are shallow with an average depth of 3 km. We estimate robust, significant, positive isotropic components contributing up to 15% to the moment release. We hypothesize that the origin of such significant non-double-couple (non-DC) components may be attributed to volume changes accompanying the surface uplift and rifting processes in the region. Our study demonstrates that non-DC earthquake source components can be monitored prior to eruption and potentially, their identification may be used as indicator for magma intrusion in the shallow crust., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Typical volcano-seismic signals on volcanoes include LP events, VT events and tremor. These events are detected and listed in catalogs as well as located and interpreted in the context of the volcano. Normally seismometers are used for these tasks. However, besides the translational ground motion, these events also generate rotational ground motion. Within this presentation we will highlight how rotational sensors can be used in this context. Following a few huddle tests in the field, we have installed the sensors in volcanically active regions such as Mount Etna and several interesting sites in Iceland. As a community effort we also started the python package TwistPy, to which more codes will be added in the future., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Madeira is discussed to be a hotspot volcanic complex in the Northeast Atlantic placed on 140 Ma old oceanic lithosphere. Catalog seismicity beneath and around Madeira is sparse and hypocenters are often not well constrained due to lack of station coverage. In 2020 and 2022 two events with Mw 5.3 and Mw 4.9 were widely felt on the island. We used data of a local seismic network consisting of 24 temporary stations in the years 2011-2012 and up to 4 permanent stations to reveal the local seismicity in the Madeira archipelago. We used an adapted velocity model and the LASSIE detection software and found more than 220 additional events, which we located using HYPOSAT. Most of the events concentrate about 30-40 km south of the main island with hypocenter depths in the range of 20 up to 40 km. The seismicity stops at the south coast of Madeira and starts again north of the main island. Other zones of activity are found in the East of Madeira and in the vicinity of Desertas Grande island southeast of Madeira. Hypocenter depths beneath Madeira cluster between 10 and 20 km depth at Moho or sub-Moho level. Our data support the hypothesis that the center of volcanic activity in the archipelago might nowadays be associated with the southern end of the Funchal Ridge., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The interactive web page contains supplementary information to Acoustic signals of a meteoroid recorded on a large-N seismic network and fibre optic cables. It aggregates the probabilistic trajectory inversion results for the observed meteor explosion above south Iceland on July 2, 2022. These inversion results of a hypersonic moving source model (MSM) are based on travel time picks of the first arrival (A1) and the last arrival (LA), both, in homogeneous and layered atmospheric model. Additionally we present the inversion results of a simple point source model (PSM) based on the arrival times of A1 and LA.

State-subsidized programs develop medical data integration centers in Germany. To get infection disease (ID) researchers involved in the process of data sharing, common interests and minimum data requirements were prioritized. In 06/2019 we have initiated the German Infectious Disease Data Exchange (iDEx) project. We have developed and performed an online survey to determine prioritization of requests for data integration and exchange in ID research. The survey was designed with three sub-surveys, including a ranking of 15 data categories and 184 specific data items and a query of available 51 data collecting systems. A total of 84 researchers from 17 fields of ID research participated in the survey (predominant research fields: gastrointestinal infections n=11, healthcare-associated and antibiotic-resistant infections n=10, hepatitis n=10). 48% (40/84) of participants had experience as medical doctor. The three top ranked data categories were microbiology and parasitology, experimental data, and medication (53%, 52%, and 47% of maximal points, respectively). The most relevant data items for these categories were bloodstream infections, availability of biomaterial, and medication (88%, 87%, and 94% of maximal points, respectively). The ranking of requests of data integration and exchange is diverse and depends on the chosen measure. However, there is need to promote discipline-related digitalization and data exchange.

In the frame of the EU-project COSEISMIQ (COntrol SEISmicity and Manage Induced earthQuakes) natural and induced seismic events were monitored in Iceland. A temporary seismic network has been deployed in the Hengill geothermal region in Iceland, where the two largest geothermal power plants of the country are currently in operation. The GFZ contribution was the installation and operation of a small-scale seismic array in 2019-2021 in the vicinity of the broadband station MEI05 (ETH), in cooperation with ISOR (Iceland), ETH (Zurich) and DIAS (Dublin). This dataset is particularly valuable since a very dense network was deployed in a seismically active region where both induced and natural seismicity are occurring. For this reason, the collected COSEISMIQ-dataset can be used within a broad range of research topics in seismology ranging from the development and testing of new data analysis methods to induced seismicity and seismo-tectonics studies.

In a joint project called OMEGA, between GFZ-Potsdam and the Istituto Nazionale di Geofisica e Vulcanologia (INGV), an experimental seismic monitoring system was installed in 2015 near the power plants of the geothermal area of Mt. Amiata (central Italy). The main objectives of this three-year experiment are: i) to monitor the seismic activity connected to any type of seismicity inside the geothermal field, ii) to verify if the low local seismicity rate near Mt. Amiata reported by the INGV bulletin is natural, or due to the sparse distribution of the INGV network, and iii) to discriminate natural from possibly induced seismicity. The eight-station network was extended by a sevenelement seismic array for the first four weeks. The aim of this paper is to present the first automatic hypocentre locations of the joint network/array analysis.

The interactive web page contains supplementary information to Fast and robust earthquake source spectra and moment magnitudes from envelope inversion, Eulenfeld et al. 2021, submitted. It aggregates centroid moment tensor (CMT) inversion results for selected events from the mid-crustal earthquake swarm in the granitic Bohemian massive near Nový Kostel in 2018. Magnitudes of the events are in the range Mw 1.8 - 3.6. The analysis has been performed using the Grond software package (Heimann et al., 2018).

Near Reykjavik/Iceland, a "soft stimulation” geothermal experiment was performed in the frame of the DESTRESS project in 2019. The installed seismic stations consist of short period, and borehole stations in and around Geldinganes, NE of Reykjavik. The task of this network is the monitoring of the seismic events in the area around the stimulation site. The installation started in late 2018 with 6 short period stations (Reykjavik Energy). Since July 2019 additional seismic stations were integrated as a small scale array on the island Geldinganes and additional short period stations. A borehole geophone chain was installed with 17 short period 3-component geophones with a vertical spacing of 10 meter in the depth interval 1040m to 1200 m. Waveform data are available from the GEOFON data centre, under network code YG, and are embargoed until January 2025.

In January 2020, a swarm of earthquakes started under Thorbjorn volcano, Reykjanes, SW Iceland, associated to the uplift of up to 0.5 cm per day. Concern in Iceland is growing and the Iceland Meteorological Office suggested that possibly magma was intruded in the crust at shallow depth (3 to 9 km). The GFZ is starting a seismological Hazard and Risk Team (HART) in cooperation with IMO, ISOR and the University of Iceland Waveform data are available from the GEOFON data centre, under network code 9H, and are embargoed until January 2026.

This interactive webpage contains supplementary information for the publication by Kühn et al. 2020: "Probabilistic moment tensor inversion for hydrocarbon-induced seismicity in the Groningen gas field, the Netherlands, part 1: testing". It allows for an easy comparison between the various tests of inversion parameters and velocity models described for the analysis of the 11th of March 2017 Zeerijp ML 2.1 earthquake on the event induced in the Groningen gas field (Netherlands). Inversion runs collected here comprise the parameters employed for inversion (Problem Config), the inversion results and error estimates (Parameter Results) as well as a multitude of figures.

The AlpArray seismic network (AASN) was operated from 2016 to 2019 by a European initiative aiming for new insights into the orogenesis of the Alps as well as into past and recent geodynamic and tectonic processes. The network included more than 620 temporary and permanent broadband stations with a spacing of 50 - 60 km. It was accompanied by the even denser Swath-D seismic network in the Eastern Alps (~150 stations with 15 km spacing). While the extensive network provides an excellent station coverage for seismicity studies, the large number of stations (up to 100) poses new challenges to MT inversions. Automated quality control and the choice of appropriate configurations becomes crucial for the inversion process. Weak to moderate magnitude events and the complex heterogeneous tectonic setting in the Alps force us to push the limits of full waveform moment tensor inversions.We develop semi-automatic, adaptive approaches for a standardized quality assessment of large seismic networks and for the selection of appropriate waveform fitting targets and frequency ranges. The earthquake source optimization framework ‘Grond’ uses a Bayesian bootstrap-based probabilistic inversion scheme with flexible integration of different waveform attributes in time and frequency domain to provide full or deviatoric moment tensor solutions including uncertainties. The entire workflow from station quality control to moment tensor inversion can handle more than 100 stations simultaneously. The large number of stations allows to study the influence of azimuthal gaps. Further, we are able to compare the inversion results of various methods and configurations in time- and frequency domain using different frequency ranges and epicentral distances. We inverted approximately 100 full moment tensor solutions for events down to Mw 3.1 occurring within the operating time of the AASN. For this magnitude range a combination of frequency-domain spectra and time-domain waveform fitting of surface waves (Z, R and T component, 0.02-0.07 Hz) provides most stable results. In case of distorted absolute amplitudes a combination of frequency spectra and maximum cross-correlation fitting proved to be useful. We find that for smaller events (Mw < 3.0) surface waves are not observed and higher frequency body waves are strongly influenced by complex heterogeneities along the travel path. To extend the source analysis to even weaker events the standard MT inversion approach is combined with network similarity cluster analyses, enabling the association of weaker events to larger ones and therefore the reconstruction of the geometry of active faults.

The interactive web page contains supplementary information for a publication by Hensch et al. 2019: "Deep low-frequency earthquakes reveal ongoing magmatic recharge beneath Laacher See Volcano (Eifel, Germany)". Details on the analysis of three tectonic and nine deep low-frequency earthquakes are given, including parameter results, error estimates, and figures. The analysis has been performed using the Grond software package (Heimann et. al 2018).

In May 2018 a volcano-seismic sequence accompanied the upward migration of a magmatic intrusion from Moho depth to the seafloor led to the drainage of the deep magmatic reservoir and to the birth of a submarine volcano offshore the island of Mayotte, Comoro Islands. This process of magma transport was accompanied by an intense seismic swarm and peculiar long-duration very long period signals. Between 1 January 2018 and 1 May 2019 we detected 407 sources of very long period signals and 6990 volcano-tectonic earthquakes. This report collects detection, location and source parameters catalogs for these two sets of earthquake sources. This data publication provides the catalogues of very long period (VLP) signals and volcano-tectonic (VT) earthquakes, as discussed in Cesca et al. (2019). Here, methods and data used to create the different catalogues are only briefly discussed; a more accurate description is given in Cesca et al. (2019), which furthermore discusses the different processes of dike migration, undersea eruption, deep reservoir drainage and overburden sagging which are responsible for the seismic activity.